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The ternary blends of acrylate rubber (ACM), poly(butylene terephthalate) (PBT), and liquid crystalline polymer (LCP) were prepared by varying the amount of LCP but fixing the ratio of ACM and PBT, using melt mixing procedure. The influence of interactions on thermal and dynamic mechanical properties of the blends was investigated over the complete composition range. The techniques applied were Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetry (TG), and dynamic mechanical analysis (DMA). The FTIR spectroscopy analysis showed reduction in the intensity of the peak corresponding to epoxy groups of ACM with increasing heating time at 290°C. This implies that there is a chemical reaction between the epoxy and end groups of PBT and LCP. Glass transition temperature (Tg) and melting temperature (Tm) of the blends were affected depending on the LCP weight percent in the ACM/PBT blend, respectively. This further suggests the strong interfacial interactions between the blend components. In presence of ACM, the nucleating effect of LCP was more pronounced for the PBT phase. The thermogravimetric study showed improved thermal stability for the blends with the increasing LCP content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3904–3912, 2006

Devulcanization of waste rubber poses a challenging environmental, economical, and disposal problem in the world because of their cross‐linked three‐dimensional network structure. Devulcanization of gum natural rubber vulcanizate containing three different sulfur/accelerator ratios was carried out in 90°C for 10 min with the help of open two‐roll cracker cum mixing mill in presence and absence of thiol acid as a devulcanizing agent. The vulcanizate properties markedly depended on devulcanizing agent and also devulcanization techniques. Revulcanized rubber obtained by devulcanizing with thiol acid offered better mechanical properties. Decrease in scorch time and increase in rheometric torque were observed for revulcanized rubber containing devulcanizing agent. The onset degradation temperature largely depended on presence of thiol acid. IR spectroscopic results revealed that the main polymeric chain did not oxidize at the time of milling above the room temperature. Increase in storage modulus and decrease in loss modulus were observed for revulcanized rubber from DMA study. The SEM was considered to study the failure mechanism and homogeneity of the vulcanizate. By adopting this devulcanization technique, more than 85% mechanical property of vulcanized natural rubber was retained. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2831–2840, 2006

In this study, the prime factor determining the size, shape, and distribution of liquid-crystalline polymer (LCP) was the viscosity ratio at the processing conditions. The fiber-forming capacity of the LCP depended on the viscosity of the ethylene–propylene–diene monomer rubber (EPDM). With increasing LCP content, the tensile and tear strengths did not increase, perhaps because of incompatibility between the EPDM and LCP. The hardness increased because of the hard mesogenic groups in the LCP. The percentage swelling decreased as the LCP content increased. With increasing LCP content, processability became easier because of a lower melt viscosity. The scorch time increased at higher LCP levels. A higher percentage crystallinity was observed with increasing LCP content. Scanning electron microscopy clearly showed the fiber phase formation, which was two-dimensionally isotropic in nature, confirming fiber formation even in a shear field. The addition of LCP improved the thermal stability. The onset degradation temperatures shifted to higher values with increasing LCP content. Dynamic mechanical thermal analysis revealed that with the addition of LCP, the mechanical damping increased at its lower level. High-temperature processing increased the effective amorphous zone. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 711–718, 2004

Elastic memory was introduced into heat-shrinkable polymer blends in the form of an elastomeric phase and through subsequent crosslinking. Blends of ethylene vinyl acetate and carboxylated nitrile rubber with different curative systems were studied with respect to their shrinkability. With an increase in the cure time (the crosslinking density, or memory point), shrinkage increased for the blends with all the curative systems except dicumyl peroxide (DCP). Increasing the elastomer content increased shrinkability because of the increasing driving retraction force of the oriented elastomer phase. A sample stretched at a high temperature (HT) showed greater shrinkage than a sample stretched at room temperature (RT) because of the greater concentration and degree of orientation of the extended chains. Generally, the crystallinity of the stretched (RT and HT) samples was higher than that of ordinary unstretched and shrunk samples, and this increased the effectiveness of intermolecular interactions in the former. For all systems except DCP, RT-stretched samples showed higher crystallinity than corresponding HT-stretched samples. With RT stretching, rapid extension and subsequent recrystallization occurred in samples molten at high local values of the stored elastic energy. An increase in the crosslinking density and orientation of the blends increased the thermal stability because of the formation of strong networks and compact structures. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1414–1420, 2003

Heat shrinkability, which is a collective property of polymers, is being utilized in various applications, mainly in the field of encapsulation. Elastic memory is introduced into the system in the form of an elastomeric phase. Here the blends of ethylene vinyl acetate and chlorosulfonated rubber were studied with reference to their shrinkability. It was found that an increase in the elastomer content increased the shrinkage and an increase in cure time also increased the shrinkage. It was seen that high temperature (H-T) stretched samples showed higher shrinkage than the low (room) temperature (R-T) stretched one. Generally, the crystallinity of the H-T stretched sample was higher than that of the low temperature stretched sample, which was again higher than that of the original unstretched sample; but for the low elastomer content blend the crystallinity of the R-T stretched sample was found to be greater than the corresponding H-T stretched one. The H-T differential scanning calorimetry showed that an increase in the CSM content caused the stability toward oxygen to increase. The first decomposition temperatures were found to be higher and the second decomposition temperatures appeared to be lower for the H-T shrunk sample than the corresponding unstretched sample. The rate of degradation appeared to be enhanced initially, then after 50% decomposition the rate started going down compared to the usual unstretched sample. From SEM it was seen that the H-T stretched sample was more elongated than the R-T stretched one. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 707–715, 2000

Effects of cure systems on shrinkability of polyolefin and EPDM blends have been studied as a function of cure time and amount of elastomers added. During measurement one of the parameters is kept constant while the other varies. The shrinkability of the blends increases with the increase in cure time when elastomer content is fixed. Similarly, at constant cure time higher loading of elastomer increases the shrinkability of the blends. Samples stretched under high temperature show higher shrinkability than those stretched under room temperature. Dicumylperoxide (DCP) is a more effective curing agent for making a particular set of blends more shrinkable than the sulfur. The changing morphological pattern with DCP-cured shrunk samples from those of sulfur cured samples is corroborated by the SEM studies where the elastomer phase appears to be globular in nature. The crystallinity of the blend depends on the dose and type of the elastomer used in polyolefin. The curing efficiency of the elastomerphase depends on the polyolefin used as blend partner. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 597–603, 1998