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

Abstract

Dynamic vulcanization was studied in terms of the change in a-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 ¼ 8.30 Â 10 5 g mol À1 and M n ¼ 2.62 Â 10 5 g mol À1 , prepared by the in situ ozonolysis reaction of natural rubber latex, was used in this study. The significant change in the a-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.

Influence of chloroacetate group on physical properties of natural rubber and its interaction with fillers

“…The important peaks corresponding to the chloroacetate group showed at δ 1.31 ppm for CH 3 C, at δ 3.64 ppm for COH, and at δ 4.09 ppm for CH 2 Cl as analyzed by 1 H‐NMR [Figure (a)] and at δ 40.30 ppm (q) for CH 2 Cl and at δ 70.46 ppm (r) for COH as analyzed by 13 C‐NMR [Figure (b)]. The interpretation of the chloroacetate peaks was in agreement with previous reports,_ENREF_19 , though the CO peak was not observed because of the drastically high number‐average molecular weight of the CNR molecule, which is about 8.3 × 10 5 g/mol …”

“…The interpretation of the chloroacetate peaks was in agreement with previous reports, 19,20 _ENREF_19 ,21 though the C@O peak was not observed because of the drastically high number-average molecular weight of the CNR molecule, which is about 8.3 3 10 5 g/mol. 22 From the molecular structure characterized by the FTIR and NMR techniques, the molecular structure of the CNR chemically modified from the NRL was clarified to be composed of multifunctional groups including epoxy and hydroxyl present on the main chain and the chloroacetate present as pendant groups of a rubber molecule. The proposed mechanism of the chemical modification of NR producing the CNR is as shown in Figure 3.…”

Bio‐based blends from poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) and natural rubber for packaging applications

“…As PHBV and NR are inherently immiscible due to entropy constraints (strong polarity differences), the interfacial adhesion existing between the two phases is probably caused by polymer crosslinking, at low loadings including PHBV grafts onto NR, while at high loadings these are probably mostly NR‐NR crosslinks. PHBV molecules may entangle across PHBV and NR interfaces and lock in loops inside the NR network . The restricted crystallization behavior of the PHBV in the blends observed in DSC was partially caused by restricted movement of the PHBV molecular chains locked within localized NR networks.…”

Effect of Peroxide Loading on Properties of Natural Rubber and Low-density Polyethylene Composites

“…12 Sulphur and peroxide vulcanising systems employed in ozonolysed NR/LDPE (40/60) blends revealed that the sulphur vulcanising system provides a higher degree of crosslink density than the peroxide vulcanising system, and attributed to improved damping and homogeneous phase morphology. 13 However, the blends with the peroxide vulcanising system showed relatively enhanced tensile strength and elongation at break. Furthermore, tensile strength, elongation at break and damping properties of the blends vulcanised with both systems improved with the increasing ozonolysed NR content.…”