Journal of Elastomers & Plastics

Radiation crosslinking of NBR-LLDPE blends with different blend ratios has been carried out. It has been found that the addition of LLDPE markedly improves the mechanical properties of NBR. For instance, Young's modulus attains about 7MPa and the tensile strength attains 14MPa in the blend containing 80wt.% LLDPE, while these values do not exceed 0.5 and 2MPa for the blend containing 20wt.% LLDPE. These values depend on both blend ratio and irradiation dose. It has also been found that the soluble fraction of the samples in different solvents depends on the blend ratio and irradiation dose. The thermal characteristics of the blends using DSC showed that the two blends are incompatible with each other and the glass transition temperature of NBR is shifted to a higher temperature by increasing the radiation dose.

Carboxy Terminated Liquid Natural Rubber (CTNR) was prepared by photochemical reaction using maleic anhydride and masticated natural rubber (NR). The use of CTNR as an adhesive in bonding rubber to rubber and rubber to metal was studied. The peel strengths and lap shear strengths of the adherends which were bonded using CTNR were determined. The effect of using a tri isocyanate with CTNR in rubber to metal bonding was also studied. It is found that CTNR can effectively be used in bonding rubber to rubber and rubber to mild steel.

Recycling of rubber waste poses a challenging environmental, economical, and social problem. In the present study, we propose a new two-stage recycling process to reuse a rubber waste. First, the granulates of the waste were pulverized into small particles using a single screw extruder in the Solid State Shear Extrusion (SSSE) process. Then, the produced powder was compression molded in the absence of virgin rubber. The slabs prepared at various molding conditions were subjected to mechanical, chemical, and microscopic tests. It is found that the slabs have high extensibility with low-medium tensile strength. Compressive creep of the powder, self-adhesion of rubber molecules, and interchange reactions of polysulfidic crosslinks are proposed as the basis of particle bonding.

Braiding is an efficient method of arranging fibers. Fiber orientation and placement can be precisely controlled by the braiding mechanism. Two limitations to the fast manufacturing of braided composites have been the impregnation and thermal curing process of the resin. The resin application process is limited by the nature of braiding mechanism. Thermal curing of resin has a slow heating rate, and is controlled by the heat transfer process. The purpose of this study is to develop a novel process that can be suitable for the braiding process and the fast fabrication of the products. The effect of microwave curing on the kinematics of the glass-epoxy composite system and the relations among the microwave radiation parameters (such as radiation time and power setting) and network structures are addressed. Manufacturing, testing and properties of net-shape, braided epoxy composites are given. How to carefully analyze, balance these important factors and finally find the best solution for the novel processing of braided net-shape composites is explained.

Molecular dynamics of specially prepared triblock copolymers of polystyrene and polycarbonate were studied by dielectric spectroscopy over wide ranges of frequency; 10^-1 - 10⁵ Hz and temperature; 50-200°C. Two block copolymers are used in the current investigation; carbonate-styrene-carbonate, CSC and styrene-carbonate-styrene, SCS, which have blocks with the same molecular weights but with different positions. The dielectric relaxation spectra and d.s.c scans showed that these block copolymers CSC and SCS exhibit two relaxation processes corresponding to the glass transitions of the two microseparated PS- and PC-phases. It is surprising to find that the molecular dynamics of either PS- or PC-blocks are different in CSC and SCS and also differ from the dynamics of the corresponding homopolymers with same molecular weight, i.e. the molecular dynamics of the blocks depends on their position within the chain. The results are assessed and discussed in terms of the different factors that could affect the glass transition and its dynamics for different blocks; namely: the number of free end groups per block and the morphological confinement that influence the size of the cooperative regions responsible for the glass transition.