Research On Strengthening And Toughening Modification Of Urea Formaldehyde Foam

In China, energy consumption has increased in recent years, of which buildingenergy consumption accounts for about30%. It is greatly important of exterior wallthermal insulation materials for building energy efficiency retrofit. However, thecommonest insulation materials currently, polystyrene and polyurethane foam, areeasy to burn; phenolic foam is flame retardant, but the main drawback to it is thecost. Flame retardance and lower cost become a pressing problem of the day forthermal insulation foam material.This article selects urea formaldehyde resin which is flame retardant to preparefoam material, and studies how these factors phosphoric acid as curing agent,phosphate calcium carbonate as foaming agent, surfactants, viscosity of ureaformaldehyde resin, impact on the properties of the foam. The results show thatchemical foaming method is better than other methods; the content of phosphoricacid should be5.0wt%~7.0wt%; the percentage of calcium carbonate is about3.0wt%; the proportion of water is15wt%; and the content of surfactant Span80is0.9wt%. But the poor mechanical property of urea formaldehyde foam results incracking and peeling more easily. Therefore it needs a large amount of work to bedone to enhance its strength and toughness.Subsequently this paper compares the enhancement effect of polyvinyl alcoholfiber and basalt fiber on urea formaldehyde foam. When the content of the kinds offibers are both0.1wt%, the compression strength of urea formaldehyde foam is0.2152MPa and0.2196MPa respectively and the bending fracture force is22.2Nand23.6N. Obviously the reinforcing effect of basalt fiber is much better, as thereinforcement finally. But the friability of the foam reaches into9.12%.Two kinds of hydroxypropyl methyl cellulose which is conventionaltoughening agent used in building materials industry are selected in this research.The viscosity of it is7500s and10000s respectively. When the percentage of bothkinds of cellulose ether is2.0wt%, the friability of toughed basalt fiber/ureaformaldehyde foam is minimized,3.17%and2.24%respectively. So the celluloseether with viscosity of10000s is the best choice.The properties of the urea formaldehyde foam prepared are texted as follows:apparent density is0.117g/cm3, compression strength is0.2370MPa, the bendingfracture force is26.4N, friability is2.24%, the coefficient of thermal conductivity is0.026W/(m K), oxygen index is35.7. Several of performance indicators of ureaformaldehyde foam meet the requirement of practical application.