SYNOPSISThe scorch property of accelerated sulfur vulcanization of three grades of epoxidized natural rubber (viz. ENR 10, ENR 25, and ENR 50) was studied by using Mooney Shearing Disk Viscometer in the temperature range of 10O-18O0C. Effects of accelerator types, concentration of accelerator, and carbon black on ENR 10 were also determined. Results obtained indicate a similar scorch behavior as that reported earlier for SMR L. However, some differences in the magnitude of scorch times in the temperature and concentration studies are observed between ENR and SMR L. These differences are attributed to the activation of a double bond by the adjacent epoxide group in ENR, the effect being more significant for a higher degree of epoxidation of natural rubber. In the case of ENR 50, differential scanning calorimetry measurement suggests that additional crosslink occurs via a ringopening reaction at about 155OC. Based on first-order reaction kinetics, the apparent activation energy of vulcanization for the rubbers studied is estimated and discussed. I NTRO DUCT10 NEpoxidized natural rubber (ENR) is obtained by chemical modification of natural rubber latex (Hevea brasiliensis type) with peracetic acid.' This type of chemically modified natural rubber has been the subject of recent research interest after the realization that ENR has shown some physical properties similar to those of synthetic rubbers. Most studies of ENR concentrate mainly on its physical and mechanical properties, 2-5 vulcanization, and aging b e h a v i~r .~.~ Recently, a study on the blend properties of ENR with plasticized poly (vinyl chloride) was also reported? However, there is very limited study on the scorch behavior of ENR, particularly its temperature dependence of scorch time. Thus, it is our aim in this paper to report some of our findings in this field of interest. EXPERIMENTAL MaterialsENR 10, ENR 25, and ENR 50 having 10, 25, and 50 mol % of epoxidation, respectively, were supplied

Low-density polyethylene (LDPE) is ubiquitous in the packaging industry owing to its flexibility, toughness, and low cost. However, it is typically contaminated with other materials, seriously limiting options for mechanical recycling. Interest in chemical recycling techniques such as pyrolysis and hydrothermal liquefaction is growing, but most of these processes face technoeconomic challenges that have limited commercial deployment. This study concerns a hybrid chemomechanical approach using reactive twin-screw extrusion (TSE) for tailoring the molecular weight and chain structure of reclaimed LDPE. Two types of zeolite catalysts at several loading levels are evaluated over a range of processing conditions. Structural, thermal, and rheological properties of the extruded samples are investigated and compared to virgin LDPE and LDPE extruded without the catalyst. NMR spectroscopy is used to investigate changes in the structure of the polymer. LDPE extruded with microporous Y zeolite shows lower degradation temperature and increased short chain branching. Mesoporous MCM-41 also induces increased branching but has no effect on the degradation temperature. The theoretical mechanical energy input for the chemical modification is calculated by using process modeling. The demonstrated hybrid reactive extrusion process provides a potential low-cost, simple approach for repurposing LDPE-based flexible packaging as coatings and adhesives.

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The polypropylene/(recycled natural rubber gloves)/ (halloysite nanotubes) (PP/rNRg/HNTs) composites were prepared by using an internal mixer. The effect of HNTs loading on processibility, tensile properties, thermal stability, and morphology of PP/rNRg/HNTs composites were investigated. The stabilization torque increased with HNTs loading. Two parts by weight per hundred parts of resin of HNTs-filled PP/rNRg/HNTs composites shows the highest tensile strength. The scanning electron micrographs show good dispersion of HNTs and good filler-matrix interaction, particularly at 2 parts by weight per hundred parts of resin of HNTs. The incorporation of HNTs also improved the thermal stability of PP/rNRg/HNTs composite. J. VINYL ADDIT. TECHNOL., 22:487-491, 2016.

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