Preparation Of Isocyanate Functionalized SEBS And Its Blending With Polyamide 6

Styrene-Ethylene-Butadiene-Styrene Copolymer (SEBS) was functionalized with 3-Isopropenyl-alpha,alpha-dimethylbenzyl Isocyanate(TMI), by using dicumyl peroxide (DCP) as an initiator in xylene solution. FT-IR was used to confirm the formation of SEBS-g-TMI. The peak at 2256 cm-1, characteristic of -NCO groups in SEBS-g-TMI, revealed an evidence of grafting occurrence. The grafting degree was determined by using both chemical titration and FT-IR. Grafting degree could be adjusted and the maximum was over 6wt% without any gelation. The molar mass distribution (MMD) of SEBS-g-TMI was narrower, compared to that of SEBS. Rheological behavior of both SEBS-g-TMI and SEBS was investigated by using a rotational rheometer. The apparent viscosity of SEBS-g-TMI is higher than that of SEBS and increased with increasing the grafting degree of TMI. Surface analysis by contact angle measurement showed that contact angles of SEBS-g-TMI samples to a given polar liquid decrease with increasing grafting degree of TMI. we also obTMIn the dispersion component of surface free energy (γsd), the polar component of surface free energy (γsp) and the total surface free energy (γs=γsd+γsp) of the grafted SEBS. These parameters increase with the enhancement of grafting degree, which gives us the quantitative estimation of the polar contribution of the grafted TMI to the total surface free energy of SEBS-g-TMI. Adhesive property of SEBS-g-TMI with aluminum foil was studied. The peeling strength between SEBS-g-TMI plate and aluminum foil increases dramatically with enhancing grafted TMI content in SEBS-g-TMI.Reactive Blending of SEBS-g-TMI with polyamide 6 (PA6) was investigated in this paper. FTIR analysis revealed the evidence of the chemical reaction between the end groups of PA6 and SEBS-g-TMI. Thermal, rheological, morphological, and mechanical properties of the resultant system were investigated. DSC analysis indicated that the crystallization of PA6 in SEBS-g-TMI/PA6 blends was inhibited, due to the chemical reaction that occurs at the interface of PA6 and SEBS-g-TMI. A comparison with the blends obTMIned from ungrafted SEBS and PA6 shows that complex viscosity and storage modulus of SEBS-g-TMI/PA6 were dramatically enhanced and the increase was strongly dependent upon the grafting degree of TMI. After examining the morphology of both blending systems, smaller particle size, more homogeneous distribution of domains and improved interfacial adhesion between matrix and domains were observed in the compatibilized system. Mechanical properties such as tensile strength, Young's modulus, flexural strength and modulus, as well as notched and un-notched impact strength of SEBS-g-TMI/PA6 blends were also found to improve gradually with increasing the content of grafted TMI.