Preparation and characterization of poly(styrene-co -butadiene) and polybutadiene rubber/clay nanocomposites

ELASTOMER NANOCOMPOSITES BASED ON BR/EPDM/ORGANOCLAY

Elastomer nanocomposites based on BR, EPDM, and Cloisite 15A were prepared via melt compounding on a laboratory scale two-roll mill. Effect of BR/EPDM composition ratio (0/100, 75/25, 50/50, 25/75, and 100/0) and nanoclay content (3, 5, 7, and 10 w/w) on the microstructure, mechanical, and rheological properties of BR/EPDM/organoclay nanocomposites were studied. Cure characterization results of the prepared elastomer nanocomposites are indicative of the accelerative role of nanoclay in the vulcanization reaction of matrix elastomer chains. The remarkable increase observed in the torque values as well as the increasing trend of gel contents represent the cross-link density increment at the presence of organoclay. Results of x-ray diffraction (XRD) analysis showed an increase in the d-spacing values associated with the silicate layers indicating the intercalation of matrix elastomer chains into the clay galleries. Transmission electron microscopy micrographs of nanocomposite samples depict an intercalated/partially exfoliated microstructure confirming XRD results. According to the measured mechanical pr7operties, incorporation of organo-modified montmorillonite improved the mechanical properties of BR/EPDM compounds. This could be ascribed to the establishment of interactions between silicate layers and polymer matrix that was evidenced by scanning electron microscopy photomicrographs and enhanced rheological properties.

Elastomer Nanocomposites Based on NR/EPDM/Organoclay: Morphology and Properties

Natural rubber/Ethylene Propylene Diene Monomer (NR/EPDM) blends of five different compositions (0/100), (25/75), (50/50), (75/25) and (100/0) with 1, 3, 5 and 7 phr organo-modified nanoclay (Cloisite 15A) were prepared by two-roll mill. The effect of organo-modified layered nanosilicates and composition on the cure characteristics, microstructure, mechanical, and rheological properties of the nanocomposites were studied. Results suggested the intercalation of polymer chains into the silicate layers which was evidenced by d-spacing results of X-ray diffraction patterns. TEM micrographs also directly confirmed XRD results. Mechanical properties of the nanocomposites depicted a nearly 40% percents increase respectively in the tensile modulus of 75NR/25EPDM containing 7 wt.% nanoclay.

Preparation and Properties of EPDM/NBR/Organoclay Nanocomposites

In this research work, three different types of nano-composites based on EPDM/NBR blend (70/30 wt.%) have been prepared: one type including Cloisite 20A in EPDM phase, the other one containing Cloisite 30B in NBR phase and the third type consisting of Cloisite 20A in EPDM and Cloisite 30B in NBR phases simultaneously (called EN-xAB). XRD and TEM techniques showed intercalated or exfoliated structures for all types of nano-composites. According to SEM results, the most roughness of the surface was observed at EN-xAB nano-composites. Cure characteristics of the samples showed that the lowest scorch and cure time and highest crosslink density was devoted to EN-xAB samples. Comparison of mechanical properties of the nano-composites showed that the best properties were found in the samples consisted of both types of organo-clays simultaneously.

Synthesis and characterization of cationic surfactants in the preparation of organobentonite and study their effectiveness on the properties of styrene-butadiene rubber/bentonite composites

Two cationic surfactants ( N-isopropyl- N, N-dimethyldodecan-1-aminium bromide (S1) and N-isopropyl- N, N-dimethylhexadecan-1-aminium bromide (S2)) are synthesized. The chemical structure of the synthesized surfactants was confirmed by Fourier transform infrared (FTIR) and 1H Nuclear magnetic resonance spectroscopy. Critical micelle concentration (CMC) of the synthesized cationic surfactants was determined. CMC decreased with increasing alkyl chain length. Organobentonites are prepared using cationic surfactants (S1 and S2) and characterized by x-ray diffraction (XRD), FTIR spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy. Results of XRD, FTIR, SEM and TGA showed that the surfactants were intercalated into the interlamellar space of bentonite. Organobentonites fillers were added to styrene-butadiene rubber and cured by conventional vulcanization system. The filler loading was varied from 0 to 10 parts per hundred parts of rubber (phr). The compounds were characterized with respect to their curing characteristics and mechanical properties. The vulcanization rate and torque value of the organobentonites compounds are sensibly higher than the unmodified bentonite compound.