Polyisoprenes on the Properties of their Rubber Mixtures and Vulcanizates. Part 1. Influence on the Mooney Viscosity, Payne Effect, and G´ Modulus of Rubber Compounds

Abstract

The influence of the average molecular weight (Mn) of 1,4-cis-polyisoprenes of various types (NR, SPI-Ti, SPI-Nd, SPI-Gd), their polydispersity coefficient (CD) and the content of the low molecular weight fraction (LMF) in them on the viscosity of the properties of a mixture of rubbers (ηмr)is studied in detail and rubber compounds made from them (ηmrm), the Payne effect (EP) and the shear modulus (G´). It was found that the ηmrm index increases in proportion to Mn and decreases parabolically with CD growth. The low ηmrm value of the NR rubber compound is due to the low Mn value and high CD. The SPI-Gd rubber compound has the largest ηmrm due to the highest value of Mn and the lowest CD. For these reasons, NC's ηmr was higher than its ηmrm, while SPI-Gd and SPI-Nd had lower revs. The shear modulus G´ of 1,4-cis-polyisoprene rubber compounds decreases with increasing CD and LMF content, and the shear modulus G´ of rubber compounds decreases with increasing LMF. The described facts are explained in terms of molecular-kinetic concepts and corresponding quantitative dependences are obtained.