No abstract

A series of chlorinated polyethylene rubber (CM)/ethylene vinyl acetate (EVA) blends were prepared at different blending ratio. The blends were foamed by compression molding and azodicarbonamide (AZDC) was used as chemical blowing agent. Cure characteristics were researched first, and then the morphology and physical properties were investigated. It was found that neat CM foams presented a series of problems such as low hardness and high shrinkage ratio. To solve the above problems, some EVA was added into CM matrix. And the results indicated that these aforementioned defects were improved after the addition of EVA component. Tensile strength increased first and then fell, and morphology properties of CM/EVA blends were also investigated. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers

TPVs filled with different amounts (0-50 phr) of carbon black were prepared via melt mixing by dynamic vulcanization in Haake plasticorder at 150 C and 40rpm and then the properties of them were studied. Torque-time curves showed that the curing degree reached a biggest value at 10 phr and then decreased with the increase of filling content while the curing rate was always rising. Mechanical properties such as tensile strength, tear strength, modulus as well as hardness increased with the increment of carbon black content while the tension set at break was reduced dramatically. Two phase morphology was observed by SEM photographs and the effect of carbon black on curing extent was testified. To illuminate the effect of carbon black, curometer curves and carbon black dispersion pictures were also analyzed. Rubber processing analyzer (RPA) experiments proved that there was a progressive nonlinear behavior, which was more and more clearly expressed with the increment of carbon black content and could be explained via the Payne effect. But the TPVs containing highest carbon black exhibited the fastest drop of G 0 with increasing strain amplitude as obtained from the value of G 0 0 À G 1 0 . The order of tand at different carbon black content was tand (10 phr) < tand (0 phr) < tand (30 phr) < tand (50 phr) at lower strain amplitude.

The usage of waste tire powder as dispersed phase in polypropylene matrix offers an interesting opportunity for recycling of the waste tire. In order to obtain 'value added products' from polypropylene (PP)/waste ground rubber tire powder (WGRT) composites, in this study, the processing of foamedPP/WGRT composites was investigated using a single-screw foam extrusion setup and chemical blowing agent. The regression models were constructed to study the relationships between the foam structure (i.e., void fraction, average cell size, and cell density) of foamed PP/WGRT composites, the processing conditions (extruder's die temperature and screw speed), and the formulation compositions (WGRT content and blowing agent concentration) by applying a four-factor central composite design (CCD) statistical approach. The response surface plots generated using the regression models allow the rapid selection of the proper process parameters to obtain PP/WGRT composite foams with the desired density and morphology.