Thermoplastic elastomers (TPEs) based on new generation ultrahigh molecular weight styrene‐ethylene‐butylene‐styrene (SEBS) and thermoplastic polyurethane (TPU) are developed and characterized especially for automotive applications. Influence of maleic anhydride grafted styrene‐ethylene‐butylene‐styrene (SEBS‐g‐MA) and maleic anhydride grafted ethylene propylene rubber (EPM‐g‐MA) as compatibilizers has been explored and compared on the blends of SEBS/TPU (60:40). The amount of compatibilizers was varied from 0 to 10 phr. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies revealed the dramatic changes from a nonuniform to finer and uniform dispersed phase morphology. This was reflected in various mechanical properties. SEBS‐g‐MA modified blends showed higher tensile strength. EPM‐g‐MA modified blends also displayed considerable improvement. Elongation at break (EB) was doubled for the entire compatibilized blends. Fourier‐transform infrared spectrometry (FTIR) confirmed the chemical changes in the blends brought about by the interactions between blend components and compatibilizers. Both SEBS‐g‐MA and EPM‐g‐MA had more or less similar effects in dynamic mechanical properties of the blends. Additionally, melt rheological studies have also been pursued through a rubber process analyzer (RPA) to get a better insight.

Meticulous investigation of reactive blending of maleic anhydride grafted styrene–ethylene–butylene–styrene (SEBS‐g‐MA) and thermoplastic polyurethane (TPU) is carried out to achieve systems with controllable morphology and superior mechanical properties. Two types of SEBS‐g‐MA (abbreviated as M1, M2) with different maleic anhydride content were used to separately blend with TPU. Formation of imide group from the interaction of isocyanate and maleic anhydride predicted from the plausible reaction scheme was confirmed through Fourier transform infrared spectroscopy. High tensile strength of the blends along with appreciable elongation at break was witnessed. Morphology analyses using scanning electron microscopy and atomic force microscopy exposed a vivid and homogenous droplet morphology in all the blends presumably due to in situ formation of a suitable copolymer at the interface. Differential scanning calorimetry was used to pursue the thermal characteristics of the blends. Melt‐rheological behavior of the blends was examined using a rubber process analyzer. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48727.

Temperature scanning stress relaxation (TSSR) measurement of peroxide vulcanized polymer blends of polypropylene (PP) and ultrahigh molecular‐EPDM (UHM‐EPDM) rubber has been performed to study the thermomechanical behavior of thermoplastic vulcanizates (TPVs). Co‐agents play crucial roles in the enhancement of properties of TPVs. Different types of co‐agents (Triallyl cyanurate‐TAC; N, N‐m‐phenylene‐dimaleimide‐HVA2; zinc dimethacrylate‐ZDMA; and in‐situ formed zinc dimethacrylate‐ZMA) have been explored in this work. TSSR study shows that higher T50 and T90 values have been achieved in ZMA co‐agent assisted‐TPV. Higher TSSR‐index (RI) value was also found for the same co‐agent ZMA, indicating higher elastic behavior. TSSR result supports the mechanical and rheological properties, and it is found that the ZMA and ZDMA show higher mechanical strength. Cross‐linked‐density calculated by modified Flory–Rehner equation and the cross‐link‐density as obtained from TSSR method have been compared and the trend was found to be the same. Stress relaxation study shows the slow relaxation‐phenomena of the ZMA‐TPV with slowest relaxation‐time (θr) than the other TPVs, which correlates with superior material strength. Thermogravimetric analysis proves that there is a difference in degradation temperature of the blends at approximately 5–10°C. Ultrahigh molecular weight‐EPDM/PP based TPVs reveal superior thermomechanical and physico‐mechanical properties with ZMA and ZDMA co‐agent over TAC and HVA2. These ultrahigh molecular weight‐EPDM based TPVs can be used in automotive seals/strips, hoses, bellows, and 2 K‐molds for automotive applications.

Epoxidized natural rubber (ENR) is a modified form of NR bearing polar epoxy groups. The focus is on dispersion of highly dispersible silica (HDS) filler with three different specific surface areas in ENR 25/ENR 50 composites. The effect of three different specific surface areas of HDS on bound rubber content, Payne effect, physicomechanical properties, and viscoelastic properties of the green composites was studied in detail. Also, the influences of epoxide content in ENRs in the absence of silane coupling agent are evaluated on the overall properties of green composites. The highest level of reinforcement was obtained for the intermediate specific surface area of HDS due to the homogenous dispersion in the ENR matrix. Small-angle X-ray scattering (SAXS) has been used to analyze the particle network and cluster establishment in the green composites. The present SAXS method provides a unique insight into the aggregate formation according to the Beaucage model. On the other hand, SAXS results demonstrate that the particle network can be efficiently suppressed by increasing the specific surface area of HDS.

The effects of electron beam (EB) radiation in thermoplastic elastomers based on SEBS/TPU and SEBS‐g‐MA/TPU are evaluated. 60/40 blend of both the systems were subjected to EB using an ILU type industrial accelerator. Radiation dose was varied from 0 to 100 kGy, and the sol–gel content evaluation along with detailed analysis of mechanical, thermal, rheological, and morphological implications was conducted. The interplay between crosslinking and chain scission was quantified using the Charlesby‐Pinner equation. Both the blends showed the presence of a three‐dimensional cross‐linked network in them after the irradiation. The tensile strength of SEBS/TPU was found to deteriorate with an increase in radiation dose, but an opposite trend was observed in SEBS‐g‐MA/TPU. Improvement in interfacial adhesion between SEBS‐g‐MA and TPU was confirmed. The morphological analysis through atomic force microscopy and scanning electron microscopy clearly showed the appearance of rough ridges and pits due to irradiation along with the cross‐linked networks. From differential scanning calorimetry analysis, the changes in glass transitions and melting endotherm were assessed. Thermogravimetric analysis results indicated an improvement in the thermal stability of the blends. The storage modulus and complex viscosity of the samples enhanced as perceived from the rheological measurements. X‐ray diffraction patterns of the blends also showed considerable variation after irradiation.