The Research Of Polyether Phosphate Ester Reaction Toughening Epoxy Resin

Epoxy resin is one of the most frequently used engineering materials. However, due to its own structure, it becomes brittle with low impact resistance, and it restricts its application in many fields, so it needs to be toughened. The most successful method is to increase the toughness by using rubber elastomers, such as carboxyl-terminated poly(butadiene-co-acrylonitrile) (CTBN), which improves the tenacity of epoxy resin greatly, but it has the disadvantage in viscosity and high price. So it is necessary to search more technology and materials of the epoxy resin toughening. This paper bases on the previous studies, through the commercial polyether polyols esterification by phosphoric acid, then realizes the reaction toughening epoxy resin, and has achieved good results.Propylene oxide (PPO) polyols reacted with polyphosphoric acid first, then modified polyether polyols phosphate with the structure of single phosphoric acid ester was got. And surplus phosphoric acid can react with epoxy groups, then chain period of PPO grafted to the epoxy cross linking network. Because PPO is incompatible with epoxy resin and form dispersed phase like a "island" structure to realize toughening epoxy resin. By analysis the data of impact properties, tensile strength, flexural strength and glass transition temperature, polyether polyols structure and esterification degree of phosphate ester has been systematic studied. The results show that the polyether phosphate ester can improve the epoxy resin toughness remarkably, even close to the toughening effect of CTBN. Meanwhile, it hardly affects glass transition temperature, tensile properties and bending performance of epoxy resin. Through the scanning electron microscope (SEM) analysis mechanism of the polyether polyols toughening, the test result indicates that with different esterification degree of polyether phosphate ester, the extent of the structure and size of polyether points can be controlled; realize effective control of the dispersed phase. When small particles of disperse phase of polyether phosphate ester maintain certain degree of density and size, it can reach the best tenacity effect. Because of the low price and low viscosity of polyether and simple and convenience of phosphate modification, it can be a kind of very promising toughening modification methods.