ВЛИЯНИЕ ФИЗИЧЕСКОГО ПЕНООБРАЗОВАТЕЛЯ НА СВОЙСТВА ЖЕСТКИХ ПЕНОПОЛИУРЕТАНОВ

Abstract

The article discusses the properties of rigid polyurethane foams (PU foams) obtained with the use of various environmentally friendly physical foaming agents - cyclopentane, cycloisopentane mixtures (CIP), methylal, methyl formate and methyl tert-butyl ether. No significant differences were noted in the use of various blowing agents during technological samples free foaming. In the course of further research, it was confirmed that the physical and mechanical properties of the finished foam significantly depend on the type of gas in the closed cells of the material. Foams obtained with the use of hydrocarbon blowing agents have a fine-meshed structure without defects, cavities and voids. It has been established that in the case of foaming with cyclopentane and cycloisopentane compositions, the introduction of isopentane provides an increase in the strength of the finished foams in compression in the horizontal direction in accordance with the direction of foam rise. It is also noted that materials foamed with methylal and methyl formate have the lowest compressive strength values. A slight difference was also noted in the thermal conductivity of the foamed products. The lowest values of thermal conductivity in the present study were noted for foams based on cyclopentane and cycloisopentane mixtures. It was also of interest to establish the change in the thermal conductivity of finished products based on cyclopentane and CIP over time. Experimentally found that after 500 days the thermal conductivity of the samples increased and reached equal values. This effect is due to the diffusion of the foaming component molecules through the walls of the foam cells, as a result of which air with a much higher thermal conductivity coefficient diffuses into the cells. It was shown in a comparative analysis that the mixtures of polyurethane foam components have good fluidity in the case of cyclopentane and cycloisopentane use, which contributes to uniform filling of the mold and reduction of losses during pouring. Based on the work done, cycloisopentane mixtures can be recommended as foaming components in the production of polyurethane foam insulation.