BRPI0904021A2 - polymer nanocomposite with improved co2 barrier properties and use - Google Patents

Abstract

POLYMERIC NANOCOMPOSIT WITH PROPERTIES OF BARRIER TO PERFECT CO ~ 2 ~ AND USE THEREOF. The present invention pertains to the field of polymeric nanocomposites, more specifically treated organophilic vermiculite based nanocomposites, high crystallinity grade polyolefin and maleic anhydride grafted polypropylene or polypropylene having superior CO 2 barrier properties compared to the prepared analogues. with bentonite.

Description

POLYMERIC NANOCOMPOSIT WITH IMPROVED CO2 BARRIER PROPERTIES AND USE

FIELD OF INVENTION

The present invention belongs to the field of polymeric nanocomposites, more specifically vermiculite-polyolefin or vermiculite-polyolefin nanocomposites modified with maleic anhydride, nanocomposites having superior CO2 barrier properties over analogues prepared with bentonite.

BACKGROUND OF THE INVENTION

Composites are physical mixtures of two or more materials, combined to form a new material with properties different from those of their individual constituents. Composites are a class of multiphase materials, polymeric or not. In these materials, one of the discontinuous components is responsible for the main resistance to stress (structural component or reinforcement) and the other, continuous, is the transfer medium of this effort (continuous or matrix component).

Currently, polymers have been reinforced with minerals, metals and fibers, with the intention of promoting properties such as thermal stability, flame resistance and / or mechanical properties. However, the resulting materials may present deficiencies in the interface interaction between their constituents, leading to performance limitations. Improvement in structural performance can usually be achieved if the reinforcing elements have good interaction with the matrix and smaller dimensions, ie their dimensions are atomic or molecular level.

The incorporation of inorganic fillers in polymers has the advantages of allowing the achievement of high chemical and mechanical resistances and thermal stability. Nanometer-sized (1-500 nm) fillers have high surface areas promoting better dispersion in the polymer matrix and thus an improvement in their physical properties, which depend on the homogeneity of the final blend.

The preparation of polymeric matrix composites with nanometric loads in many cases makes it possible to obtain a material at low cost due to the use of less filler and a high level of performance which may result from synergy between components.

A wide variety of lamellar materials can be found in nature such as clays (aluminosilicates), transition metal halides, divalent metal hydroxides and tetravalent metal phosphates. The crystals are formed by the overlap of lamellae, which are loosely joined by van der waals and hydrogen bonds.

Layered silicates, often used in polymeric nanocomposites, belong to the family known as 2: 1 phyllosilicates. Its crystals consist of two-dimensional layers, where the central octahedral layer of aluminum oxide (AI2O3) or magnesium oxide (MgO) is attached to two outer tetrahedral silica molecules (SiO2) at the ends so that the oxygen ions octahedral layer also form part of the tetrahedral layer. The thickness of the layer is about 1nm and the side dimensions of these layers can range from 300 µm to several microns and may even be larger depending on the particular silicate. The layers are organized to form piles, with a regular interval between them called interlayer spacing or galleries. Substitutions of higher valence cations with lower valence cations within the layers (for example, Al2 + replaced by Mg2 + or Fe2 +, or Mg2 + substituted by Li +) are not always compensated for in the structure of some clay minerals. As a consequence, an excess of negative charges is generated. These negative charges are counterbalanced by alkaline or alkaline earth metal cations within the galleries. Because the forces holding the cells together are relatively weak (weak van der Waals interactions), the interleaving of small molecules in the layers is relatively easy. These materials have received much attention as polymer reinforcing materials due to their high aspect ratios and exceptional interleaving / exfoliation characteristics.

These phyllosilicates are characterized by their moderate negative surface charge, known as cation exchange capacity (CEC), usually expressed as meq / 100g. Charge varies from one layer to another, presenting an average value for every crystal.

Vermiculite is a mineral of the mica family, whose crystals are formed by very thin superimposed coverslips that contain a small amount of water inside. When subjected to temperatures above 800 ° C it expands, increasing its volume up to 20 times, becoming a material of high porosity and lightness. The name vermiculitavem from the Latin "vermiculare", since the appearance of this clay when being warmed resembles that of "worms". Vermiculite belongs to the 2: 1 aluminosilicate family and has the general chemical formula: (Mg, Fe, AI) 3 (AI, Si) 4O0 (OH) 2Mgx (H2O) n.

It is formed mainly by the alteration of biotite. The vermiculite CTC is also high, from 100-150 meq / 100g. Vermiculite is a mineral formed essentially of hydrated aluminum and magnesium silicates. The vermiculitatem has low density and has lamellar shape. It has many applications in civil construction, such as thermal and acoustic insulation, light brick production, fireproof panels, partitions and doors and agriculture as a soil conditioner.

Already bentonite is a clay consisting essentially of one or more mineral minerals of the group of smectites, especially montmorillonite, regardless of the geological origin. Bentonite is a 2: 1 aluminosilicate (Mg, Ca) O.AlH 3 O 3 Si (H 2 O) n formed from the decomposition of volcanic ash. Natural bentonites have more often the Na +, Mg2 + and Ca2 + cationable cations. The most common occurrence is a cation-predominant bolicite bentonite, such as Na + nasbentonite from Wyoming (USA) or Ca2 + in Mississippi bentonite. One of the main properties of bentonites is the cation exchange capacity (CTC). Exchangeable cations in bentonites may be attached to the lateral surfaces and between the layers of the clay mineral. The cations attached to the side surfaces come from the charges resulting from the disruption between Si-O and AI-OH, and the presence of interchangeable cations between layers is due to the substitution of higher valence cations by lower valence cations (eg , Si4 + exchange for Al3 + tetrahedral layer or Al3 + for Mg2 + in octahedral layer). In aqueous or wet dispersion, clay minerals have the ability to exchange these cations through chemical reactions with other cations without changing their crystal structure. The Bentonite CTC ranges from 80 to 150 meq / 100g, and is generally much higher than that of other minerals (CTC less than 40 meq / 100g).

Silicates are naturally hydrophilic, which makes interaction and mixing ability with nonpolar polymeric matrices difficult. Thus, the ion exchange process is often employed for nanocomposite development, improving the compatibility between the clay and the polymer matrix. In order for hydrophilic phylosilicates to become organophilic, the hydrated interlayer oscations must be exchanged. The exchange usually occurs with cationic surfactants (alkylammonium ions). These modified clays (or organo clay) have lower surface energy and are compatible with organic polymers and increase the interlayer distance (basal space, "d-spacing"), which facilitates intercalation by both monomers and polymers. See in this regard the articles by Alexandre, M; eDubois, P. Polymer-Iayered silicate nanocomposites: preparation, properties and uses of a new class of materials. Materials Science and Engineering, v. 28, no. 1-2, p. 1-63, 2000; Cho, J.W .; and Paul, D.R. Nylon 6 nanocomposites by meltcompounding. Polymer1 v. 42, no. 3, p. 1083-1094, 2001 and others.

A polymeric composite consists of the combination of two or more materials, where the continuous phase or matrix is represented by the polymer while the dispersed phase is represented by the reinforcing or not reinforcing fillers. The discontinuous component (load) offers the main load resistance and the other continuous (matrix) offers the transfer medium of this load.

The performance and properties of composites depend on the individual properties of their components and their compatibility.

The tendency to create composite materials is aimed at reducing costs, specific applications, enhancing properties by combining expensive materials with cheaper materials. The properties of composites depend not only on their components, but also on the proportion between them, the nature of the material. interface and system morphology. The size, shape of charge particle, and charge-polymer interfacial distribution are parameters that must be considered to predict the reinforcement characteristics in the polymer.

When appropriate fillers are applied to thermoplastics, they provide improvements in their physical and thermal properties, modify their surface appearance and processing characteristics, and reduce material cost.

The literature presents works of composites and nanocomposites of polypropylene and bentonite according to the articles by Araújo, S.S. et al. PP / betonite nanocomposites employing a Wyoming bentonite treated with three different types of quaternary ammonium salts. Matter magazine, v. 9, no. 4, p. 426-436, 2004; Burmistry, M.V. et al. Synthesis, structure, thermal and mechanical properties of nanocomposites based on linear polymers and Iayeredsilicates modified by polymeric quaternary ammonium salts (ionenes). Polymer, v. 46, no. 26, p. 12226-12232, 2005; Filho et al. PP / Bentonite Green Sludge Nanocomposites. I - Influence of modification and clay content on mechanical properties. Matter magazine, v. 10, no. 1, p. 24-30, 2005; Garcia-Lopez et al. Polypropylene-clay nanocomposites: effect of compatibilizing agents on claydispersion. European Polymer Journal, v. 39, no. 5, p. 945-950, 2003; Othman, N. et al. Effect of compatibilisers on mechanical and thermal properties ofbentonite filled polypropylene composites. Polymer Degradation and Stability, v.91, no. 10, p. 1761-1774, 2006; and Sarkar, M. et al. Polypropylene-clay compositeprepared from Indian bentonite. Bulletin of Materials Science, v. 31, no. 1, p. 23-28, 2008.

However, there are only three studies in the literature reporting the use of vermiculite in polypropylene composites, namely Tjong, S.C.et al. Novel preparation and properties of polypropylene-vermiculitenanocomposites. Chemistry of Materials, v. 14, no. 1, p. 44-51, 2002; Tjong, S.C.e Meng, Y.Z. Impact-modified polypropylene / nanocomposite vermiculite. Journal of Polymer Science: Part B: Polymer Physics, v. 41, no. 19, p.2332-2341,2003 and Valásková, Μ. et al. Organovermiculite nanofillers in polypropylene.Applied Clay Science, v. 43, no. 1, p. 108-112, 2009, although vermiculite is an abundant and cheaper silicate type than bentonite, see articles by Xu, J. et al. Preparation and properties of poly (vinylalcohol) -Vermiculitenanocomposites. Journal of Polymer Science Part B: Polymer Physics, v. 41, no. 7, p. 749-755, 2003 and Xu, J. et al. Preparation of poly (propylenecarbonate) / nanocomposite organo-vermiculite via direct melt intercalation.European Polymer Journal, v. 41, no. 4, p. 881-888, 2005.

The term nanocomposite is used to refer to composite materials which contain more than one solid phase in which the dispersed phase has at least one of its nanoscale dimensions (10 "9 m) and is therefore a particular type of composite. Polymers are a new class of materials that have properties superior to conventional polymer composites or pure polymers, due to the small size of the structural unit and its large surface area, which greatly increases the possibilities of interactions between phases.

Polymer-mineral nanocomposites are classified into three general categories: conventional, in which the mineral acts as a conventional filler; the intercalated ones, in which the polymeric matrix insertion occurs regularly between the mineral lines; and, delaminated or exfoliated, in which the mineral layers are delaminated and dispersed in the continuous polymeric matrix. This last structure allows the obtainment of better properties in relation to the intercalated one, because it maximizes the polymer-mineral interaction.

Nanocomposites can be prepared by four methods: in situ polymerization, emulsion polymerization, sol-gel process and molten state mixture. In the latter, nanocomposites may be obtained by melt polymer intercalation, in which the polymeric chains diffuse into the space between the layers or galleries of the clays. The method depends on the thermodynamic interaction between polymer chains and clay and the transport of these chains from the melt to the clay chains. Fused polymer interleaving has been shown to be efficient, as well as being an alternative to traditional interleaving processes, limited both to the choice of monomers and the availability of polymer-solvent compatible systems. This method is also very attractive due to its versatility, absence of solvents, compatibility with conventional processing techniques, simplicity and lower cost than in situ polymerization processes.

Of all the techniques for processing polymer in the melt, the twin screw extruder has proven to be the most efficient for exfoliating and dispersing silicate layers. For composites prepared in a single screw extruder, full exfoliation is usually not achieved due to lower shear rates and shorter residence times when compared to the double screw extruder.

US 6,451,897 deals with nanocomposites prepared from grafted polypropylene (PP) decopolymers. The nanocomposite comprises a exchangeable cation smectite clay that has been treated with at least one organic swellant uniformly dispersed in a graft copolymer with a porous propylene polymer backbone. The total content of inorganic material in the composite varies between 0.5 and 10% in relation to the total weight of the composite. After graft polymerization, the polymerized demonomer chains formed intercalate in the clay and produce a uniform dispersion of clay particles within the polypropylene particulate material.

The structure of nanocomposites brings improvements in the material's deburring properties. This improvement results in reduced permeability and increased resistance to solvents. The Iamelar structure of some reinforcing fillers found in nanocomposites may offer advantages for these barrier properties, especially in packaging. One justification for the decrease in permeability in nanometric structures in the Iamelar form would be that when they are dispersed in the polymer they create a kind of maze hindering the diffusion of gases and solvents through the polymeric material. It is very likely that the fine dispersion of plate-shaped nanoparticles will increase the path to the solvent gas diffusion path.

US Published Application US 20060252870 describes a process for the preparation of polyolefin nanocomposites in which one composite can be prepared simply, efficiently and economically through one-step. The process consists of mixing polyolefin resin such as polyethylene or polypropylene and others, the nanomaterial, grafting monomer and peroxide to disperse the nanomaterial and graft the monomers simultaneously. The components are hot-extruded mixed at temperatures between 150-200 ° C. The nanomaterial comprises an organophilic clay such as montmorillonite, hectorite and vermiculite. However, this document does not mention the improved CO2 barrier properties exhibited by such composites when the polypropylene nanocomposite clay is vermiculite as in the present invention.

International publication W0 / 2000/034180 relates to a nanocomposite having improved barrier properties, the nanomaterial comprising a clay interspersed with a mixture of two or more organic cations and the matrix polymer comprising a polyester, polyetherester, polyamide, polyesteramide, polyurethane, polyimide, polyetherimide. , polyurea, polyamideimide, polyphenylene oxide, phenoxy resin, epoxy resin, polyolefin, polyacrylate, polystyrene, polyethylene co-vinyl alcohol, same copolymer or a mixture thereof.

Despite academic work and patents on the subject, the technique still requires a polymeric nanocomposite with enhanced barrier properties over similar bentonite-based materials. Such a barrier property composite can be obtained from organophilic micro-granite, such nanocomposite and use thereof being described and claimed in the present application.

SUMMARY OF THE INVENTION

Broadly, the present invention is a nanocomposite based on organophilic vermiculite base and polypropylene or maleic co-grafted polypropylene with improved barrier properties, ditonanocomposite comprising, by mass:

(a) from 0,1 to 10% organophilic vermiculite obtained by treatment with a quaternary ammonium anion;

b) from 75 to 99% of a high crystallinity polyolefin; and

c) from 0.1 to 10% anhydridomaleic grafted polypropylene copolymer.

Nanocomposite is prepared according to one of the usual techniques for this type of material by mixing in the molten state in a twin screw extruder.

Thus, the present invention provides a vermiculite and polypropylene base polymer nanocomposite with improved barrier properties.

The present invention also provides a pure polypropylene or vermiculite-based polymeric nanocomposite based on maleic anhydride with improved CO2 barrier properties over similar bentonite based compositions.

The present invention further provides a vermiculite and polypropylene polymeric nanocomposite with improved barrier properties for use in industrial and food packaging, sheets and bottles in addition to a variety of new applications.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying FIGURE 1 shows the in natura VMT (A) and organically modified VMT (B) FTIR Spectrum.

The accompanying FIGURE 2 shows the X-ray Diffractograms of (A) VMT in natura, (B) VMT-Na and (C) VMT-org clays.

The accompanying FIGURE 3 shows the X-ray Diffractograms of PP and PP / VMT-org composites.

The accompanying FIGURE 4 shows the X-ray Diffractograms of PP / PP-g-MA and PP / PP-g-MA / VMT-org composites.

DETAILED DESCRIPTION OF THE INVENTION

The object of the present invention is a nanocomposite based on an organophilic and anhydridomale grafted polypropylene or polypropylene micro-granite having improved barrier properties, said nanocomposite comprising, by mass:

(a) from 0,1 to 10% organophilic vermiculite obtained by treatment with a quaternary ammonium anion;

b) from 75 to 99% of a high crystallinity polyolefin; and

c) from 0.1 to 10% anhydridomaleic grafted polypropylene copolymer.

For this invention, the quaternary ammonium anion contained in a) is an alkaline quaternary ammonium salt, belonging to the group consisting of: cetyltrimethylammonium chloride, cetyltrimethylammonium bromide, alkyldimethylbenzylammonium bromide, dimethyldecammonium bromide,

Where in b), high crystallinity polyolefin may be selected from high density polyethylene and polypropylene.

Alternatively, the polyolefin of b) is polypropylene (referred to herein as PP) mixed with the maleic anhydride grafted polypropylene copolymer in c) and referred to herein as PP-g-MA.

Obtaining nanocomposite of organophilic vermiculite-PP or organophilic vermiculite-PP-g-MA with improved barrier properties with respect to analogous compounds prepared with organophilic bentonite-PP follows the usual procedures of the field technology.

In general the clay treatment of the invention is followed by the procedure described by Xu1 J. Preparation of poly (propylenecarbonate) / organo-vermiculite nanocomposites via direct melt intercalation. European Polymer Journal, v. 41, no. 4, p. 881-888, 2005.

It should be made clear to those skilled in the art that while the present document refers to polypropylene as the polyolefin that has been used experimentally, high density polyethylene and other crystalline polyolefins are equally useful and as such are within the scope of the invention.

In the case of blends of maleic grafted grafted polypropylene copolymer, the proportion of polypropylene is between 90 wt.% And 99 wt.% Of the mixture.So, vermiculite (VMT) and bentonite (BENT) in natura after characterization of the pure materials by techniques X-ray diffractometry (XRD) and thermogravimetric analysis (TGA), are chemically treated to produce organophilic clays, which are also characterized by X-ray fluorescence, infrared absorption spectroscopy (FTIR), XRD1 scanning electron microscopy (SEM) ) and TGA.

The resulting organophilic clays are mixed with PP or PP / PP-g-MA in order to evaluate the possibility of obtaining nanocomposites and obtaining a material with low gas permeability.

In parallel untreated clays (in natura) are also mixed with PP or PP / PP-g-MA for the purpose of comparing results.

In order to characterize the composites, bodies of compression proofing are made.

The composites are then characterized by morphological analysis (XRD), solid state nuclear magnetic resonance spectroscopy (NMR), thermal analysis (differential scanning calorimetry - DSC, TGA) and permeability analysis.

VMT and BENT clays are treated with sodium chloride to exchange the ions present in the clays with a single type of ion (Na +). Following this cation exchange, the two clays are modified with an alkaline ammonium salt belonging to the group consisting of: cetyltrimethylammonium chloride, cetyltrimethylammonium bromide, stearyldimethylammonium chloride, dimethyldioctadecylammonium bromide, or bromide. Preferably, in this invention as quaternary ammonium alkaline salt is employed for intercalation of the organic compound in the clay galleries is cetyltrimethylammonium chloride.

X-ray fluorescence spectrometry, FTIR and XRD results confirm the chemical modification and incorporation of the ammonium salt between the clay layers.

Vermiculite and bentonite incorporated with unincorporated ammonium salt (unincorporated) are mixed with PP to obtain masterbatches containing 10 and 50% m (by mass) of clay, with an average value of 32% m. Subsequently these masterbatches are diluted to obtain decomposites with clay contents between 0.1 and 10% m, with an average value between 1 and 5% m. Masterbatches and composites are obtained in a co-rotating twin screw extruder.

Inorganic vermiculite and bentonite composites and organophilics are characterized for morphological, thermal, mechanical and CO2 permeation properties.

XRD results of composites prepared with the organophilic clays (VMT-org and BENT-org) show the intercalation of the polymer between the clay yamels and the possible obtainment of partially intercalated and (or) exfoliated nanocomposites.

DSC results from all composites show the clay effect on crystallization of the polymeric matrix.

It is observed through the TGA technique that the thermal stability of composites prepared with VMT is superior to that of pure polymer and composites with BENT.

Composites prepared with 1.3% m of VMT-org without PP-g-ΜΑ and 4.2% m of VMT-org with PP-gr-MA show a significant reduction in CO2 gas permeability of 59 and 65% respectively. for pure PP and PP / PP-g-MA polymers. These composites also had better barrier properties than composites prepared with aBENT-org.

Composites prepared with 1.3% m of VMT-org without PP-gr-MA and 4.2% m of VMT-org with PP-gr-MA show a significant reduction in CO2 gas permeability of 59 and 65% respectively. for pure PP and PP / PP-g-MA polymers.

Vermiculite and bentonite with uniform grain size in the 40 mesh range are treated with sodium chloride (NaCl) solution to make the interlamellar spacing as homogeneous and regular throughout its extension. For this purpose, 20 g of fresh clay (vermiculite or bentonite), 100 g of NaCl and 200 ml of deionized water are used. The ingredients are added to a three-necked flask and heated under stirring for about 72 hours. After removal of the supernatant water, the trochacidonic clays are transferred to tubes and the solution is centrifuged for 30 minutes at a speed of 3,500rpm. The product is centrifuged with deionized water (3000mL) to remove Cl "anions. The absence of chloride is verified by reaction with a 0.1 molar AgNO3 solution. Clays in sodium formalin are dried in a circulating oven. at 60 ° C for 48 hours for removal of excess water and stored in the absence of moisture.

To make the clay compatible with the polymer, the sodium-present ions between the clay yamels are exchanged for ions of quaternary ammonium salt (cetyltrimethylammonium chloride) to produce the organophilic clay. It should be made clear that other quaternary ammonium salts are equally useful for the practices of the invention. Quaternary ammonium ions are additionally selected from cetyltrimethylammonium bromide, stearyldimethylammonium chloride, alkyldimethylbenzylammonium chloride, dimethyldioctadecylammonium bromide, or dimethyldioctadecylammonium bromide.

The organophilization reaction is performed according to the same sodium ion exchange procedure described above. Sodium homoionic 20g of sodium (vermiculite or bentonite), 24g of decethyltrimethylammonium chloride and 400 ml of deionized water are used. The absence of chloride is verified by reaction with a 0.1 molar AgNO3 solution. The obtained organophilic clay agglomerates are oven dried with air circulation at 60 ° C for 48 hours and mechanically disaggregated to powdery materials and stored under moisture.

In order to evaluate the chemical, structural, morphological and morphological characteristics of these charges, the clay samples (vermiculite and bentonite) before and after modification are characterized by X-ray fluorescence spectroscopy, infrared absorption spectroscopy (FTIR), diffractometry. X-ray (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA).

From the results of Figure 1 it can be observed that VMT-showed new absorption ranges at 2922 and 2847 cm "1 (attributed to the symmetrical and asymmetrical stretching of the CH2l group respectively) and at 1472cm" 1 (due to the flexural vibrations of the CH3 group). ). These results indicate that salt molecules have been incorporated into the clay structure.

In order to verify possible changes in the crystallographic plane of VMT treated with NaCI and ammonium salt, an XRD analysis was performed.

X-ray diffractograms of unmodified VMT (A) 1 of sodium VMT (B) and organically modified VMT (C) are shown in Figure 2.

The X-ray diffractogram of VMT in natura (A) shows the picocharacteristic (plane (001)) of vermiculite at 2Θ = 6.46 °. The peak that appears 2Θ = 18.73 °, although with low intensity, is characteristic of the VMT. This sample has impurity as small quantities of quartz (2Θ = 24.92 and 26.91 °) and sepiolite (2Θ = 31.24 °). X-ray diffractograms (A, B, and C) confirmed that the two treatments employed for the cation exchange process promoted significant changes in the displacement of the characteristic diffraction peak (plane (001)) of the in natura VMT (2Θ = 6.46). °) which will be further detailed in Table 1 below.

Table 1 presents the position of the characteristic diffraction peak (plane (001)) (2Θ) of the in natura VMT, the VMT-Na and the VMT-org and their respective interplanar distances.

TABLE 1

<table> table see original document page 15 </column> </row> <table>

The characteristic (flat (001)) peak of VMT in natura at 2Θ = 6.46 ° corresponds to an interplanar distance of 13.68 A. Similar result was found by Santos et al., Characterization and uses of evermiculite bentonite clays for adsorption of copper (II) in solution. Pottery, v. 48, no. 308, p.178-182, 2002.

VMT-Na XRD analysis showed that the domineral interplanar distance decreased from 13.68 (in natura VMT) to 11.74 A (2Θ = 7.53 °). The result is consistent with the expected, as calcium and potassium being exchanged for sodium are ions with a radius and larger atomic volume, the distance should decrease proportionally to their size.

VMT-org presented three distinct peaks at 2Θ = 3.02 °, 5.83 ° and 6.68 °, corresponding to values of interplanar distances of 29.25, 15.16 and13.23 A, respectively.

According to Le-baron, P.C. et al., Polymer-Iayered silicatenanocomposites: An overview. Applied Clay Science, v. 15, no. 1, p. 11-29,1999, the appearance of three distinct peaks for the VMT-org probably indicates differences in the orientation of the ammonium salt between the clay layers. It should be noted that the interplanar distance of 29.25 A is significantly greater than that presented. VMT-Na, which had an interlamellar spacing of 11.74 A. The greatest distance from the galleries of the clay indicates that the quaternary ammonium salt may be intercalated between the silicate layers.

Clay samples are previously oven dried at 60 ° C for 24 hours before the extrusion step.

The vermiculite composites are obtained from four different masterbatches: 1) PP and fresh vermiculite \ 2) PP, innatura vermiculite and PP-g-MA (10% m); 3) PP and modified vermiculite; and 4) PP, modified vermiculite and PP-g-MA (10% m). PP-g-MA copolymer is used to evaluate possible improvement in the interaction between PP and vermiculite.

The bentonite composites are obtained by prior preparation with different masterbatches: 1) PP and bentonite in natura and 2) PP and bentonite modified.

In all masterbatches the clays are added by a side feeder. Masterbatches are prepared in a co-rotating twin-screw extruder with a thread diameter of 20 mm and L / D = 36, with a speed of 300 rpm and a temperature of 200 ° C. Thereafter, the appropriate amount of PP is added to give the concentrations of 1 to 5% m of clay. The processing speed and temperature profile are the same as those used for masterbatch preparation. The circular die coupled to the extruder outlet directs the molten polymer into a running water channel, causing it to solidify in the continuous defilement form. The material is then shredded in size close to the original PP grain.

The specimens for the different tests (morphological, mechanical and thermal) are stamped from plates obtained by compression on the Carver bench type. Tensile tests are performed according to ASTM Method D-882 (ASTM, 1986).

For permeability analysis, compression specimens are also prepared.

The composites are then characterized and evaluated for their properties.

Determination of the actual charge content in composites and copolymer PP-gr-MA by thermogravimetry.

The actual (residual) load content incorporated in masterbatches and composites is verified by thermogravimetry. Analyzes are performed on masterbatches, composites and pure polymer for certification and comparison of results.

The content of the PP-g-MA copolymer present in the composites is also calculated. The test is performed on the thermogravimetric analyzer (TGA) at a temperature range of 25 ° C to 700 ° C with a heating rate of 10 ° C / min and a nitrogen atmosphere.

For morphological characterization, the X-ray diffraction (XRD) technique is employed.

The charge-matrix interaction is evaluated using the solid state NMR technique. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques are used for the thermal characterization of the composites.

The DSC technique evaluated the crystalline melting temperature (Tm), the crystallization temperature during cooling (Tcc) and the degree of crystallinity (Xc). The influence of the presence of lamellar material on the thermal transitions and crystallinity degrees of the composites is also evaluated.

Thermogravimetric Analysis (TGA): This analysis allows us to evaluate the effect that clay may have had on the thermal resistance of polyolefin. The values related to the thermal stability of the polypropylene are compared with the thermal decomposition impurves of the polypropylene matrix in the obtained composites.

Mechanical Characterization: The tensile strength of pure PP and modified PP and fresh clay composites is evaluated according to ASTM D882.

The barrier property of the polymer matrix with the clay insert is evaluated through the permeability analysis of the pure polymer, free of lamellar material, and the composites with vermiculite and innatural bentonite clays. The composites chosen for this analysis are those with higher values of crystallinity degree Xc, because this parameter greatly influences the permeability of the material.

Permeability is determined with the aid of specific membrane equipment for gas permeation measurements.

Considering the unidirectional gas flow through the membrane, permeability (P) can be described by Equation 1.

<formula> formula see original document page 18 </formula>

Equation 1

Where J is the gas flow through the membrane, after the pressure difference and / is the membrane thickness. Considering the optimal gas behavior, the flow can be calculated as presented in Equation 2.

<formula> formula see original document page 19 </formula>

- Equation 2

Where A is the permeation area, D is the gas constant, Pcntp and Tcnt are the pressure and temperature under normal temperature and pressure conditions, dn / d is the change in the number of moles of gas over time and V is the volume of gas. .

The change in number of moles over time, dn / dt, can be calculated by considering optimal behavior for the gas that occupies the permeate, whose volume is known (Vs, equal to system volume), according to Equation 3.

<formula> formula see original document page 19 </formula>

Equation 3

Where also is ambient temperature and dp / dt is the pressure variation over time, determined by the calibration curve for the system, where the signal (mA) is converted to pressure. Substitution of these equations in Equation 2 results in Equation 4.

<formula> formula see original document page 19 </formula>

Equation 4

The most commonly used units for permeability are GPU (gaspermeatiori unit, equivalent to 10 "6 cm3 (CNTP) .cm" 2.s "1.cmHg" 1) and Barrer (corresponding to 10 "10cm3 (CNTP) .cm.cm "2.s" 1.cmHg "1).

The morphological characterization of the composites is made by X-ray diffraction (XRD) analysis.

Table 2 below shows the main peak value (001) of the VMT and its interplanar distance for the PP / VMT and PP / PP-gf-MA / VMTTABELA 2 composites.

<table> table see original document page 20 </column> </row> <table>

X-ray results showed that there was a subtle shift from the main peak of the VMT (001) to low angle regions, indicating an increase in the distance between the clay layers. The most significant change occurred for the composite processed with 4.5% m VMT without PP-g-MA, whereas the interplanar distance of the mineral increased from 13.68 (in natura VMT) to 15.21 A. However, this small displacement did not increase. confirms the occurrence of polymer interleaving or exfoliation between the galleries of the clay.

Figures 3 and 4 show respectively the X-ray diffractograms of the organically modified vermiculite (VMT-org) composites in the absence and presence of PP-g-MA.

According to Gianelli, W. et al., Effect of matrix features onpolypropylene Iayered silicate nanocomposites. Polymer, v. 46, no. 18, p. 7037-7046, 2005 and Liu, X. et al. Facile synthesis of exfoliated polyaniline / vermiculitenanocomposites. Materials Letters, v. 60, no. 15, p. 1847-1850, 2006, the direct dispersion of phyllosilicate in the molten polymer enables the obtainment of intercalated or exfoliated hybrid structures and the evidence of interleaving can be studied by X-ray diffraction (GIANELLI, W., 2005; LIU, X., 2001). .

From the X-ray results (Figures 3 and 4) it was observed that these changes in the dispersion level of the VMT blades in the polymer chains actually occurred. In samples without PP-g-MA, the absence of the main peak of the VMT-org can be verified, but the composites still show peaks in regions from lower angles. For composites processed with PP-g-MA, no peak was observed for VMT-org.

The same values for composites with organically modified vermiculite (VMT-org) in the absence and presence of PP-g-MA are shown in Table 3 below, which lists the peak diffraction and interplanetary distance values of VMT-org and PP / g composites. VMT-org and PP / PP-g-MA / VMT-org

TABLE 3

<table> table see original document page 21 </column> </row> <table>

The composites without PP-g-MA do not show the main peak of VMT-org at 2Θ = 3.02 °. However, peaks at 2Θ = 4.52 ° and 6.54 ° are noted for the 1.3% m VMT-org composite, at 2Θ = 6.47 ° for the 4.0% m VMT composite -org and at 2Θ = 4.93 ° when 7.7% m VMT-org is added. This behavior suggests that exfoliation of part of the clay occurs. The other diffraction peaks that appear shifted to smaller angles correspond to the interleaving of the polymer chains between the clay layers. VMT-org peaks are not observed in PP-g-MA composites, indicating a possible obtaining of exfoliated structures. The solid state NMR technique measures the return time from core to ground state when excited by a magnetic field. This parameter is the spin network relaxation time (T1H) and can give important information about the interaction forces between polymer chains.

Generally, the increase in T-iH values indicates lower chain mobility, as a result of higher material rigidity, showing good interaction between the polymer matrix and the loads. The percentage value reveals the percentage of structures (domains) with the same magnitude of interaction.

In the VMT composites submitted to NMR analysis the T1H values of an exponential, the T1H value of each domain and their respective percentages were collected, being presented in Tables 4 and 5. In natura VMT cannot be analyzed by low field NMR, probably due to the large amount of metal present and also the little hydrogen available in the chemical composition of the VMT sample. For VMT-org it was possible to observe a single TiH value in 0.6 ms due to the adsorbed water (see Rodrigues, T.C., 2008, cited below). Table 4 lists the T1H values of an exponential, T1H of the detected domains and percentages of these PP, PP-g-MA domains, and VMT innatura composites.

TABLE 4

<table> table see original document page 22 </column> </row> <table> <table> table see original document page 23 </column> </row> <table> <table> table see original document page 24 < / column> </row> <table>

From the data listed in Table 4 it is possible to observe that there were not many changes in T1H values of an exponential (also called average TiH) for composites obtained with in natura VMT in relation to pure PP. Only for the higher clay composite, a slight increase in the value of this parameter was observed. The pure polymer (PP) had an exponential T1H value of 315 ms. The composites with 1.5, 4.5 and 8% m of fresh VMT presented values of 316, 315 and 318ms, respectively. These results show that the presence and increase of the amount of VMT did not alter the rigid PP domains.

For PP / PP-g-MA composites obtained with fresh VMT, an exponential increase in T1H was observed over pure PPP / g-MA (300 ms). The composites with 2.0, 4.5 and 7.3% m of clay showed values of 314, 309 and 310 ms, respectively. The results suggest a slight increase in material stiffness relative to the pure polymer. However, composites with higher load contents have slightly lower stiffness than composite with lower VMT content.

The exponential T1H values for PP-g-MA copolymer composites are generally slightly lower than those shown for composites without PP-g-MA, ie at molecular level the system becomes more flexible.

The values obtained from domain 3 T1H (third value, in ascending order, T-iH presented for each sample in Table 4) make an expressive contribution to the composites relaxation process and confirm the observation in the previous paragraph, which points to a slightly lower stiffness for the composites prepared in the presence of PP-g-MA polymer.

Table 5 shows a decrease in T1H values of an exponential of all composites obtained PP / VMT-org and PP / PP-g-MA / VMT-org in relation to pure polymers (PP and PP / PP-g -BAD). Except for the PP / 1.3% VMT-org composite where no variation of this parameter was observed, the low VMT content did not influence the PP stiffness. PP / VMT-org composites with 4.0 and 7.7% load showed T1H values of exponential 290 and 286 ms, respectively. The PP / PP-gr-MA / VMT-orb composites showed values of 298, 277 and 257 ms for load contents of 1.4, 4.2 and 7.2% m, respectively. The decrease in TiH values obtained from an exponential increase in charge content can be attributed to the structural change generated by the addition of organophilic clay, forming a new system in which the interactions created (polymer-organophilic clay) are not as strong as those that existed before. (polymer-polymer). As cited in: Preparation of PVC composites / wood dust and solid state nuclear magnetic resonance characterization. 2008. 164 p. Thesis (Doctorate in Polymer Science and Technology) - Institute of Macromolecules Professor EloisaMano, Federal University of Rio de Janeiro, RJ, 2000.

As observed for composites with VMT in natura, composites prepared in the presence of the PP-g-MA copolymer of one general had lower exponential TiH values than those shown for composites without PP-g-MA.

Generally, for both in-natured aVMT and VMT-org composites, the lowest clay concentration has the TiH value of a higher exponential than other higher clay composites. Probably, this fact may be related to the distribution and interaction of the polymeric clay matrix particles. When in small concentration, the clay is more evenly distributed, providing greater interaction with the polymer. At high concentrations, particle agglomeration may occur, making it difficult to interact between particles and PP. This steric hindrance hinders the possible chemical interaction between polymer molecules.

After incorporation of the organophilic clay into the polymeric matrix, the solid state NMR results showed that the composites showed a decrease in TiH of an exponential and in the domain 2 deltaxation time, which indicates the presence of nanometric sized particles. According to Rodrigues, T.C. Development of high density polyethylene nanocomposites and organophilic clay. 2008,242 p. PhD Thesis in Polymer Science and Technology) - Institute of Macromolecules Professor Eloisa Mano, Federal University of Rio de Janeiro, RJ, 2008. The metals in the clay structure act by decreasing the relaxation time of the hydrogen nuclei near them, because they are paramagnetic. , which indicates the tendency of exfoliation of clay in the polymeric matrix. Possibly, for these materials, increased mobility may have occurred due to matrix loading interactions after clay exfoliation when processed under the processing condition employed in this work. The decrease in TiH values indicates an increase in the molecular mobility of the polymeric chains after the insertion of the modified clay that can act as a nucleating agent, leading to a change in the crystal size and separation of the chains (amorphous region and crystalline region), suggesting a good clay dispersion in the clay. polymeric matrix and consequently an indication of exfoliation and obtaining nanocomposites. This tendency of greater exfoliation character corroborates the results observed by XRD.

Through DSC analysis it is possible to verify the degree of crystallinity and the thermal behavior of PP in the presence of VMT.

The crystalline melt temperature (Tm), the crystallization temperature during cooling (Tcc), and the degree of crystallinity (Xc) of the pure polymer and composites are determined and detailed in Table 6.

Polymer samples can be found in varying degrees of chain organization. Depending on factors such as stereoregularity, symmetry, among others, the polymers will present greater or less tendency to crystallize.

The quantitative relationship between the crystalline and amorphous region of a polymer is expressed in terms of percent crystallinity or degree of crystallinity (Xc). The degree of crystallinity is evaluated from the picoendothermic corresponding to the crystalline fusion. The calculation is based on the effective amount of crystallinity of the pure material or mixture.

The following Table 6 lists the thermal properties of PP1 PP / PP-g-MA and PP / VMT and PP / PP-g-MA / VMT composites.

TABLE 6

<table> table see original document page 27 </column> </row> <table>

The crystallinity degrees of VMT-containing 1.5 and 4.5% m composites without PP-g-MA and VMT-containing composites with 2.0% m with PP-g-MA practically do not vary from PP and PP / PP-g-MA pure.

The PP / PP-g-MA / 4.5% VMT composite exhibits a slight increase in degree of crystallinity Xc.

For high load contents, 8.0 and 7.3% m of VMT in the absence and presence of PP-g-MA, a decrease in Xc of the material in the order of 7% and 18%, respectively, is observed in relation to the pure polymer. . These results indicate that the formation of PP crystals is negatively affected by the amount of clay present in the composite, when greater than 7%. The addition of higher VMT contents to PP and PP / PP-g-MA would appear to crystallize the polymer.

Table 7 shows the DSC-coated thermal properties data for pure PP, PP / PP-g-MA and for composites with organophilized VMT in the absence and presence of PP-g-MA.TABELA 7

<table> table see original document page 28 </column> </row> <table>

The Tcc of all composites increases in relation to PP and PP-g-MApuros, but most of them have slightly lower values than those presented by in natura VMT composites (Tables 6 and 7). This behavior indicates that VMT-org as well as unmodified VMT also acts as a nucleating agent.

There is a tendency to decrease the degree of crystallinity of non-PP-g-MA composites with increasing amount of VMT-org, indicating that crystal formation was possibly affected by the glycyl content. The composites with PP-g-MA did not show the same trend, because the Xc of the composites with 1.4 and 4.2% m of VMT-org showed no variation. The composite Xc with 7.2% m decreased to 76%. With the addition of copolymer, increased crystallization of PP was found. The goal of PP-g-MA addition is to improve interfacial adhesion, however, this action has not yet been sufficient to maintain the tendency of crystallinity increase in mixtures with percentages of organophilic vermiculite greater than 7%.

The crystallinity degree of all composites without and with PP-g-MA were higher than those with in natura clay (Tables 6 and 7). There is a significant increase in the crystallinity degree of some composites, which shows that These materials have a higher degree of polymeric chain ordering when compared to untreated clay composites. These results were quite evident for the materials with 1.3 and 1.4% m of VMT-org without and with PP-g-MA (85 and 83%, respectively) and 4.2% m VMT (85%) with PP. -g-ma.

Table 8 shows the thermal degradation values of PP, PP / PP-g-MA, masterbaches and composites with in natura VMT in the absence and presence of PP-gr-MA.

TABLE 8

<table> table see original document page 29 </column> </row> <table>

Tmax = maximum degradation temperature

PP / VMT and PP / PP-g-MA / VMT masterbaches have better thermal stability than pure polymer. The masterbach prepared with PP and VMT in natura has initial T and maximum T of 380 and 434 ° C, respectively. Already the masterbach with PP-g-MA and VMT in natura has T jniciai and maximum T of 445 and 460 ° C, respectively.

All composites without and with PP-g-MA have a degradation temperature higher than pure PP (363 ° C) and PP / PP-g-MA (359 ° C), except for PP / 1.5% VMT composites. (361 ° C) and PP / PP-gr-MA with 2.0 and 7.3% m wt (363 and 3610C, respectively). Most materials show maximum degradation temperature (Tmax) values higher than pure dopolymer. Only for PP / 1.5% VMT and PP / PP-g-MA composites with 2.0 and 7.3% m VMT, this increase is not observed. The most pronounced increase in Tjniciai and Tmax occurs for the composite with 8.0% m VMT without PP-g-MA, being 374 and 424 ° C, respectively.

In general, the addition of PP-g-MA does not significantly improve the thermal stability of composites. Only the PP / PP-g-MA / 4.5% VMT composite shows an increase of 9 ° C and 4 ° C in the initial temperature and maximum degradation temperature in relation to the pure polymer.

According to the article by Gilman, J. W. Flammability and thermal stability studies of polymer layered-silicate (clay) nanocomposites. Applied ClayScience, v. 15, no. 1, p. 31-49, 1999, the high thermal stability of polymers in the presence of clay nanoparticles may be due to the deburring effect caused by the exfoliated or intercalated clay layers, creating a tortuous path which hinders the diffusion of volatile products through the polymeric material. According to some studies, the mass loss curve of nanocomposites is almost vertical, which means that the decomposition of nanocomposites, once initiated, is very rapid.

Table 9 shows the thermal degradation values of PP, PP / PP-g-MA, masterbaches and VMT-org composites in the absence and presence of PP-g-MA.

TABLE 9

<table> table see original document page 30 </column> </row> <table> Tinidai = initial degradation temperatureTmax = maximum degradation temperature

PP / VMT-org and PP / PP-g-MA / VMT-org masterbaches have better thermal stability than PP and PP / PP-g-MA pure. The masterbach prepared with PP and VMT-org presented initial T and maximum T of 445 and 460 ° C, respectively. Masterbach with PP / PP-g-MA and VMT-org presented initial T and maximum T of 478 and 493 ° C, respectively.

It is noted that the thermal stability of all composites is significantly improved with the presence of VMT-org compared to composites with in natura VMT (Table 8). The presence of only 1.3% m of VMT-org promoted an improvement of approximately 60 and 33 ° C in TjniCiai and Tmax. When compared to the composite with 1.5% m of in natura VMT. There was a slight upward trend in composites Tincture with increasing VMT-org content. The composites with 1.3, 4.0 and 7.7% m of VMT-org show TiniCiaide values 421, 429 and 432 ° C, respectively.

The maxima of the composites was higher than the pure PP (411 ° C), but the value did not vary with the increase of the VMT-org content. The values were 447, 446 and 448 ° C for the compounds with 1.3, 4.0 and 7.7% mt of VMT-org, respectively.

The composites with 1.4 and 4.2% m of VMT-org in the presence of PP / PP-g-MA showed the same TiniCiai value (432 ° C), about 73 ° C higher than oPP / PP-g. -MA (359 ° C). The composite with higher VMT-org content (7.2% m) had a Tjnidai of 438 ° C, about 6 and 79 ° C higher than composites with lower VMT-org content (1.4 and 4.2%). m) and that PP / PP-g-MA, respectively.

The maximum degradation temperature of all composites with PP, PP-g-MA and clay was also significantly higher than that of PP / PP-g-MA, regardless of the incorporated VMT-org content. The PP / PP-g-MA composites with 1.4, 4.2 and 7.2% m of VMT-org presented Tmax values of 447.449 and 452 ° C, respectively. The increase in VMT-org content did not show much influence on the composites Tmax. These higher values corroborate the DSC results. Increased thermal stability of mixtures containing the copolymer, a material that historically improves interfacial adhesion, may be associated with the increased degree of crystallinity of the PP-g-MA mixtures observed in DSC results. This higher crystallinity gave the composites a higher thermal stability probably due to the barrier effect caused by the presence of the crystalline regions. According to García-López, D. et al., Polypropylene-clay nanocomposites: effect of compatibilizing agentson clay dispersion. European Polymer Journal, v. 39, no. 5, p. 945-950, 2003, maleic anhydride groups may react with hydroxyl groups on the clay surface by destroying the clusters or reducing their size.

Table 10 presents the comparison of the results of the CO2 gas barrier properties of the composites with VMT and in natura BENT in relation to the pure polymer, respectively.

The data in Table 10 below refer to the CO2 permeability and crystallinity degree (Xc) of the PP, PP / PP-g-MA membranes and some composites with in natura VMT and VMT-org.

TABLE 10

<table> table see original document page 32 </column> </row> <table>

The Table above shows that the 1.3% PP composite with organophilic micro-granite exhibits excellent CO2 barrier property. The PP / PP-g-MA composite with 4.2% m of vermiculite has similar debarking properties. The results presented in Table 10 show that CO2 permeability is dependent on the amount of nanoparticles, as observed in the NMR results (Table 4) and on the degree of crystallinity of the samples.

The composites with the highest percent crystallinity grade Xc are the ones with the lowest permeability values. CO2- The PP / 1.3% VMT-org composite with an Xc of 85% shows a 59% reduction in permeability compared to Pure PP.

Composites with 1.4 and 4.2% m of VMT-org in the presence of PP-g-MA show CO2 permeability reductions of 49 (Xc = 83%) and 65% (Xc = 85%) when compared to PP / PP-g-MA pure.

The best permeability results are obtained for materials prepared with organophilic vermiculite. These results corroborate the X-ray and NMR analyzes that show possible exfoliated decompositions.

According to Sarantópoulos, C.I.G.L. et al., Flexible plastic packaging. Campinas: CETEA / ITAL, 2002. 267p Polymer crystallinity effects in relation to the permeation process show that the permeant diffusion process through the polymeric material is inversely proportional to the crystalline content, since the crystalline region is impermeable thus increasing the tortuosity of the path. permeation.

Possibly the presence of exfoliated clay nanolayers and the possible obtaining of nanocomposites as observed by the NMR technique contributed to the decrease of CO2 gas permeability of the material due to better dispersion and charge interaction with the polymer matrix. According to Gusev, A.A. et al., Rational Design of nanocomposites for barrierapplications. Advanced Materials v. 13, no. 21, p. 1642-1643, 2001; Ray, S.S. etal., Polymer-Iayered silicate nanocomposites: a review from preparation toprocessing. Progress in Polymer Science v. 28, no. 11, p. 1539-1641, 2003; Chaicko, J.D. et al., Thermal Transitions and Barrier Properties of Olefinicnan Compounds. Chemistry of Materials v. 17, no. 1, p. 13-19, 2005 and others the nanocomposite structure brings improvements in the material barrier properties. This improvement can be shown in reducing the permeability of gases and increasing resistance to solvents. The Iamelar structure of some reinforcing fillers found in nanocomposites may offer advantages for these barrier properties, especially in packaging. One justification for the decrease in permeability in nanometric structures in the Iamelar form would be that when they are dispersed in the polymer they create a kind of maze hindering the diffusion of gases and solvents through the polymeric material. It is very likely that the fine dispersion of plate-shaped nanoparticles will increase the path to the solvent gas diffusion path.

As can be seen from Table 11 below, an analogous composite prepared with organophilic bentonite has much lower barrier properties than the vermiculite composite. Only the PP / 2.8% BENT-org composite that showed a Xc crystallinity degree of 81% showed a more significant reduction in permeability of 37% compared to pure PP, a result much lower than that observed for vermiculite composites. This informs that vermiculite is a clay with greater potential to be used in parts that require less permeability compared to bentonite.

Table 11 lists the CO2 permeability and degree of crystallinity (X0) values of the membranes of some BENT in naturae with BENT-org composites.

TABLE 11

<table> table see original document page 34 </column> </row> <table>

The Applicant's research giving rise to this application differs from the article published by Tidjani, A., Polypropylene-gra / if-maleic anhydride-nanocomposites: Il - fire behavior of nanocomposites produced under nitrogen in air. Polymer Degradation and Stability, v. 87, no. 1, p. 43-49, 2005, as vermiculite clay, which according to Du1X.S. et al., Synthesis of pol (arylene disulfide) -vermiculite nanocomposites via the ring-opening reaction of cyclic oligomers. European Polymer Journal, v. 39, no. 9, p. 1735-1739, 2003 and Xu1 J. et al., Preparation and properties of poly (vinylalcohol) -Vermiculite nanocomposites. Journal of Polymer Science Part B: Polymer Physics, v. 41, no. 7, p. 749-755, 2003 is a mineral belonging to the mica family and not the montmorillonite clay often used in composites with polymeric matrices.

Claims (11)

1. Polymeric nanocomposite with improved CO2 barrier properties, characterized in that said nanocomposite comprises: (a) 0.1 to 10% organophilic vermiculite obtained by treatment with a quaternary ammonium anion; a high crystallinity polyolefin; and c) from 0.1 to 10% anhydridomaleic grafted polypropylene copolymer. Nanocomposite according to Claim 1, characterized in that the quaternary ammonium anion is selected from decyltrimethylammonium chloride, cetyltrimethylammonium bromide, stearyldimethylammonium chloride, alkyldimethylbenzylammonium bromide, or dimethyldioctadecylammonium bromide. Nanocomposite according to Claim 2, characterized in that the quaternary ammonium anion is cetyltrimethylammonium chloride. Nanocomposite according to Claim 1, characterized in that a high crystallinity grade polyolefin is selected from high density polyethylene and polypropylene. Nanocomposite according to Claim 4, characterized in that the high crystallinity apolyolefin is polypropylene. Nanocomposite according to Claim 1, characterized in that the CO2 barrier properties, as measured by equipment for membrane permeability measurement, will be improved with respect to: (i) pure polypropylene; () polypropylene grafted with maleic anhydride); and ii) analogous nanocomposites obtained from bentonite clay. Nanocomposite according to Claim 6, characterized in that the PP / 1.3% VMT-org composite shows a 59% reduction in CO2 permeability relative to pure polypropylene. Nanocomposite according to Claim 6, characterized in that the PP / PP-gr-MA / 1.4% VMT-org and PP / PP-g-MA / 4.2% VMT-ore compounds exhibit reductions in the CO2 permeability of respectively-49 and 65% when compared to pure PP / PP-g-MA. Nanocomposite according to claim 6, characterized in that the PP / 1.3% VMT-org composite shows a 58% reduction in CO2 permeability relative to the PP / 1.1% BENT-org bentonite based analog. Use of the nanocomposite according to Claims 1, 2, 3, 4, 5 and 6, characterized in that it is in industrial and food packaging which requires improved CO2 barrier properties. Use according to claim 10, characterized in that it is in bottled sheets.