The Application Of Silica Modifidied By Polyurethane Prepolymer In Rubber

Polyurethane has excellent physical properties and processing performance, such as highstrength, good toughness andexcellentabrasion resistance. NCO-terminated polyurethaneprepolymer contains free-NCO groups, so it can react with hydroxyl compounds. We used apolyurethane prepolymer named PUB to modify silica with toluene as solvent. The structure,thermal properties, particle size and surface morphology ofPUB-modified silicawere fullyinvestigated by FTIR, TG, DLS and SEM. The chemically grafting of PUB on silica wasverified.In order to improve the dispersion of silica in rubber, andimprove the tensile strength,tear strength and abrasion resistanceof rubber at the same time, polyurethane prepolymer wasused as a novel in situ interfacial modifier for rubber/silica composites. First, PUB was addedto rubber matrix through the directmethodand pretreatment method. The PUB/rubber/silicacomposites were prepared by mechanical blending. The vulcanization performance andmechanical properties of the blends were investigated. PUB was found to increase theminimum torque of the blends, it is because PUB is a viscous liquid. What’s more, PUBsignificantly improvedmechanical properties of blends. Then, different kinds ofNCO-terminated polyurethane prepolymerswere synthesized. When blending withrubber/silica, the NCO-terminated polyurethane prepolymers synthesized byhydroxyl-terminated polybutadiene(HTPB) can obviously improve the tensile strength, tearstrength andabrasion resistance of the vulcanizates.Finally, a series of polyurethane prepolymers were synthesized by two kinds of HTPBwhich have different microstructure and isophorone diisocyanate (IPDI) at R=2,3,4,5(R=n(-OH)/n(-NCO)). They were blended with rubber/silica, the R-value was found to have asmall impact on the vulcanization performance and mechanical properties ofthe blends,but themicrostructure of HTPB has a significant impact on that of the blends. NCO-terminatedpolyurethane prepolymers synthesized by HTPB mainly containing1,4-trans configurationcan effectively improve the tensile strength, tear strength and abrasion resistance ofthevulcanizates.