The Preparation Of Rigid Cross-linked Foamed Polyvinyl Chloride Sheet

Rigid cross-linked foamed Polyvinyl Chloride (PVC) sheet was produced by molding method and by utilizing the functional groups of isocyanate forming cross-linked structures. The selection of the base resins was discussed in the thesis. Effects of azodicarbonamide (AC) foaming agent content, Dioctyl-Phthalate(DOP) plasticizer content and the processing technic were studied in the research, which affects properties of the foamed produce.The results showed that the sheet has better properties by using the SG-3 type of PVC resins. Through analyzing DOP content affecting foaming effects and limited oxygen index, ten phr DOP content is the best value. With extending the period of hot water foaming time, the density of foamed sheet was decreased. But the time extending enough, the density of sheet has small changes. When the period of hot water foaming time was four hours, the density of sheet meet a criterion and gel content of the product was up to a standard. It was observed that surface layer gel content is more than center of the sheet. Compared to three foaming agents affecting foamed sheet, the foaming effect of cyclohexane foaming agent was the same as others foaming agents, but its rigid value and cross-linked was better than theirs.Furthermore, It was showed that maleic anhydride and styrene grafted the main chain of PVC, and then reaction with isocyanate formed cross-linked structure by FTIR.The properties of rigid cross-linked foamed PVC sheet were very good. Under the high temperature, the sheet turned soft and occurred deformation of creep difficultly. Heat Deflection temperature got 82 degrees centigrade. Flame retardant property of the sheet was very well by admeasuring.