Reaserach On Synthesis And Application Of Liquid Polyisoprene

The anionic polymerization method was used to prepare a series of liquid polyisoprene with different molecular weights and 3,4-structural contents.They were characterized by nuclear magnetic resonance techniques and gel chromatography.The produced liquid polyisoprene was added to the natural rubber,and prepared the compounds and vulcanizates.The application of liquid polyisoprene as a plasticizer in natural rubber was studied by curing curve,tensile testing machine,dynamic mechanical analyzer and electron microscope.The experimental results showed that the 3,4-structure content decreased with increase of the reaction temperature,when the molar ratio of the tetrahydrofuran/lithium was constant.The glass transition temperature and the decomposition temperature increased with increase of the 3,4-structure content for the the liquid polyisoprene with the same molecular weight.The glass transition temperature was 5.34 ? and the decoposition temperature was 375.4 ?,when the 3,4-structure content was 64.21%.The glass transition temperature and decomposition temperature slightly increased with increase of the molecular weight for the liquid polyisoprene with the same 3,4-structure content.The aromatic oil played a plasticizing role only in the rubber compound.The liquid polyisoprene not only played a plasticizing role,but also participated in the cross-linking reaction,and the co-cross-linking network formed between liquid polyisoprene and the NR,compared with the aromatic oil filled system.The stress at definite elongation and tear strength increased,whereas the elongation at break and the Payne effect decreased with increase of the 3,4-structure content for the liquid polyisoprene filling NR vulcanizates.It was in favor of improving the CB dispersion.Meanwhile,the system had good wet resistance and low rolling resistance.The cross-linking density,hardness,modulus and stress at definite elongation increased with increase of the liquid polyisoprene molecular weight to some different degrees.However,the wet resistance,rolling resistance and the aging characteristics almost kept constant.The cross-linking density and the hardness decreased,whereas the heatbuilding of the compression fatigue and the compression set increased with increase of the liquid polyisoprene content for the filled NR vulcanizates.The combination property was the best for 7 phr liquid polyisoprene filling NR vulcanizates.