Effect of surface modification of silicon carbide nanoparticles on the properties of nanocomposites based on epoxidized natural rubber/natural rubber blends

Improvement of the properties of rubber nanocomposites is a challenge for the rubber industry because of the need for higher performance materials. Addition of a nanometer‐sized filler such as silicon carbide (SiC) to enhance the mechanical properties of rubber nanocomposites has rarely been attempted. The main problem associated with using SiC nanoparticles as a reinforcing natural rubber (NR) filler compound is poor dispersion of SiC in the NR matrix because of their incompatibility. To solve this problem, rubber nanocomposites were prepared with SiC that had undergone surface modification with azobisisobutyronitrile (AIBN) and used as a filler in blends of epoxidized natural rubber (ENR) and natural rubber. The effect of surface modification and ENR content on the curing characteristics, dynamic mechanical properties, morphology and heat buildup of the blends were investigated. The results showed that modification of SiC with AIBN resulted in successful bonding to the surface of SiC. It was found that modified SiC nanoparticles were well dispersed in the ENR/NR matrix, leading to good filler‐rubber interaction and improved compatibility between the rubber and filler in comparison with unmodified SiC. The mechanical properties and heat buildup when modified SiC was used as filled in ENR/NR blends were improved. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45289.     

Novel dynamic vulcanization of polyethylene and ozonolysed natural rubber blends: Effect of curing system and blending ratio

Dynamic vulcanization was studied in terms of the change in α‐relaxation temperatures of the LDPE matrix, morphology, and mechanical properties of LDPE/ozonolysed NR blends which were vulcanized at various blend ratios and with different curing systems, i.e., peroxide and sulfur systems. The ozonolysed NR with M _w = 8.30 × 10⁵ g mol⁻¹ and M _n = 2.62 × 10⁵ g mol⁻¹, prepared by the in situ ozonolysis reaction of natural rubber latex, was used in this study. The significant change in the α‐relaxation temperature of LDPE in the LDPE/ozonolysed NR, dynamically vulcanized using the sulfur system, suggested that sulfur vulcanization of the blend gave a higher degree of crosslink density than using peroxide and corresponded with the improved damping property and homogenous phase morphology. However, the peroxide cured blends of LDPE/ozonolyzed NR gave more improvement of tensile strength and elongation at break than the sulfur cured system. Furthermore, the mechanical properties of tensile strength, elongation at break, and damping were improved by increasing the ozonolyzed natural rubber content in both DCP and sulfur cured blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Improved cure characteristics and mechanical properties of an epoxidized natural rubber filled with cerium oxide nanoparticles: Influence of epoxide levels and filler loading

In this study, cerium oxide nanoparticles (nanoceria, CeNP) were used as a nanofiller in epoxidized natural rubber with varying epoxide levels, including 25% epoxidation (ENR-25) and 50% epoxidation (ENR-50). Co-precipitation methods were employed to synthesize a pure phase of CeNP with an average particle size of 11.4 ± 2.0 nm. CeNP was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. The effect of CeNP loading with 0–3 parts per hundreds of rubber (phr) on the properties of rubber nanocomposites was explored. ENR-25 nanocomposites with 1 phr of CeNP exhibited higher tensile strength and elongation at break compared to ENR-50 nanocomposites. These findings correspond to a lower Payne effect, improved scorch safety, and better processability. The strongest and most effective CeO₂–ENR interactions via silane linkages are expected to outperform sulfur crosslinking in ENR-25 having 1 phr of CeNP. Microstructural evaluation of an ENR-25 sample containing 1 phr of CeNP indicated well-distributed nanofillers in the ENR-25 matrix, indicating that CeNP and ENR-25 appeared to be well-matched. Hardness of all ENR nanocomposites increased with CeNP loading. The cracking resistance, creep properties, and thermal stability of rubber nanocomposites were unaffected by addition of CeNP in the ENR-25 and ENR-50 samples.