GB741826A - Improvements in or relating to polymeric substances - Google Patents

Abstract

Substances of high molecular weight, characterized by a structure of chains largely or wholly of carbon atoms, a substantial proportion of which have one or two, preferably an average of at least 1.5 hydrogen atoms attached thereto, e.g. polyethylene, are subjected to the action of ionizing radiations which consist of or include thermal neutrons, in the presence of atomic species having a high capture cross-section for thermal neutrons and emitting gamma rays on neutron capture, e.g. cadmium 113 and boron 10, whereby the decrease in solubility is obtained at a lower dosage. A minimum dose of 0.02 units, where one unit is 1017 thermal neutrons per square centimetre, from a thermal nuclear reactor operating, for example with a thermal neutron flux of 1012 per square centimetre and a power of about 3 megawatts, may be used. The high molecular weight substance may be enclosed in a container comprising the atomic species, e.g. polyethylene enclosed in a container of thin steel having an electrodeposited coating of cadmium, or the substance may be coated with such atoms. The change in solubility of the polymer is obtained at a lower dosage. Specification 732,047 is referred to.ALSO:Substances of high molecular weight characterized by a structure of chains largely or wholly of carbon atoms, a substantial proportion of which have one or two hydrogen atoms attached and preferably have an average of at least 1.5 hydrogen atoms attached thereto, of natural origin e.g. rubber or synthetic origin e.g. polyethylene, are subjected to the action of ionizing radiations which include or consist of thermal neutrons, in the presence of atomic species having a high-capture cross-section for thermal neutrons and emitting gamma rays on neutron capture e.g. cadmium 113 and boron 10. A dosage of 0.02 or more units from a thermal nuclear reactor, for example, one operating with a thermal neutron flux of 1012 per square centimetre and a power of about 3 megawatts or more, may be used, where one unit is 1017 thermal neutrons per square centimetre. The substance of high molecular weight may be in a container comprising the atomic species e.g. polyethylene enclosed in a container of thin steel having a coating of cadmium metal electrodeposited thereon, and the substance may be coated with such atoms. The change in solubility of the polymer is obtained at a lower dosage. Specification 732,047 is referred to.ALSO:Substances of high molecular weight, characterized by a structure of chains, largely or wholly of carbon atoms, a substantial proportion of which have one or two hydrogen atoms attached and preferably have an average of at least 1.5 hydrogen atoms attached thereto, e.g. natural rubber, are subjected to the action of ionizing radiations which include or consist of thermal neutrons, in the presence of atomic species having a high capture cross-section for thermal neutrons and emitting gamma rays on neutron capture, e.g. cadmium 113 and boron 10. A dosage of 0.02 or more units from a thermal nuclear reactor, for example, one operating with a thermal neutron flux of 1012 per square centimetre and a power of about 3 megawatts or more may be used, where one unit is 1017 thermal neutrons per square centimetre. The rubber may be in a container comprising the atomic species, e.g. polyethylene enclosed in a container of thin steel having a coating of cadmium metal electrodeposited thereon, or the substance may be coated with such atoms. The change in solubility of the polymer is obtained at a lower dosage. Specification 732,047 is referred to.