Reinforcing Effect of Organo-Modified Fillers in Rubber Composites as Evidenced from DMA Studies

Abstract

The use of organically enhanced kaolin clay as reinforcing filler for NR (natural rubber) and blends of NR with NBR (nitrile-butadiene rubber) and poly BR (butadiene rubber) system were investigated on the basis of DMA (dynamic mechanical analysis). Kaolin clay was modified using a chemical complex of HH (hydrazine hydrate) and SRSO (sodium salt of rubber seed oil). Intercalation of SRSO into kaolin under optimized condition showed an inter-lamellar layer expansion to 4.668 nm, compared to the characteristic d001 XRD (X-ray diffraction) peak of pristine kaolin at 0.714 nm. The morphology, visco-elastic behavior, modulus property, polymer miscibility and Tg (glass transition temperature) of nano-kaolin filled NR and its blend with synthetic rubbers have been studied in detail. DMA showed a diminution in tanδ peak height and a modulus shift in correspondence with increased CLD (crosslink density). Pure NR shows only ~1% increase in storage modulus (E′) while adding nanoclay rather than micron sized pristine clay under experimental conditions, because of the feeble interaction between filler and matrix, as compared to blend. An increment of ~76% and ~117% in E′ was recognized by the addition of 4 wt% nanoclay in blends such as BR mK and NBR mK. With loss modulus (E″) pure NR shows only ~7% decrease while adding nanoclay, compared to blend. A decrement of ~54% and ~55% in E″ by the addition of 4 wt% nanoclay in BR mK and NBR mK blends were observed. As a whole, DMA was performed to figure out the effect of surface modification enabling to materialize composite.