摘要:

AbstractCompatibilized and dynamically vulcanized thermoplastic elastomer blends of poly(butylene terephthalate) (PBT) and ethylene propylene diene terpolymer (EPDM) can be prepared by using an EPDM rubber that contains reactive epoxy groups. During melt mixing the epoxy groups react with PBT endgroups to form graft copolymer. The compatibilized blends can be dynamically vulcanized by conventional vulcanization agents for EPDM such as peroxides or by vulcanization agents that react with residual epoxy groups on the EPDM such as diamines. This paper describes the effects of compatibilization and dynamic vulcanization on microstructure and mechanical properties.

ISSN:0032-3888    

DOI:10.1002/pen.760320102

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractBlends containing polyethylene (LDPE, LLDPE, or LDPE‐LLDPE) with different weight percent of styrene‐isoprene‐styrene (SIS) triblock copolymers have been obtained by extrusion‐blowing. The morphology of the blends, investigated by scanning electron microcopy (SEM), has been related to composition but also to different parameters such as viscosity, nature of the polyethylene phase, and extrusion conditions. A large range of morphologies is observed and indicates that the main factors determining the morphology of the blends are the composition, the elongational fields at the exit of the die and, in certain limits, the relative viscosities of the components of the

ISSN:0032-3888    

DOI:10.1002/pen.760320103

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractThe shear and elongational viscosities of a thermotropic liquid crystalline polymer (LCP), polycarbonate (PC), and their 20%LCP/80%PC blend, were studied using a capillary rheometer. The investigation focused on experimental studies using two sets of capillaries. The first set comprised capillaries having a converging entrance followed by a cylindrical section. The second set, “zero length” set, included capillaries having only the converging section. In the two sets various entrance angles were used. Experimental results have shown that shear viscosities and entrance pressures are practically independent of the entrance angles. The entrance pressure drop was small in the case of PC and reached 50% of the total pressure drop for LCP. The elongational viscosities of the LCP were found to be higher than those of the PC in the elongational‐rate range studies, while shear viscosities of the LCP were higher in the lower shear rate region and lower in the higher shear rate region compared to those of PC. This was attributed to the orientability of LCP in elongational and shear

ISSN:0032-3888    

DOI:10.1002/pen.760320104

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractStudies based on fracture mechanics have been made on polyacetal toughened with a synthesized thermoplastic polyurethane. The effects of elongation rate and defects like holes and notches on tensile properties have been investigated. Using three‐point bending specimens, fracture mechanics parameters such as strain energy release rate,G, Rice's contour integral,J, and fracture toughness,Khave also been determined under plain stress conditions. The mechanical loss from the hysteresis curves, and ductile, brittle fractography using scanning electron microscopy have also been studie

ISSN:0032-3888    

DOI:10.1002/pen.760320105

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractBlends of poly (vinyl chloride) (PVC) and acrylonitrile‐butadiene styrene (ABS) terpolymer were prepared in different ratios by a melt blending technique. ABS containing three different levels of rubber content were used. A quantitative assessment of ABS in PVC/ABS blends has been shown by infrared studies. ABS content has been shown as the presence of the characteristic acrylonitrile peak. Differential scanning calorimetry (DSC) studies have been carried out to study the glass transition (Tg) behavior of the blends. TwoTgvalues corresponding to PVC and styrene‐acrylonitrile (SAN) copolymer have been observed. Thermogravimetric analysis (TGA) reveals a significant improvement in thermal stability of these blends as compared to PVC. Mechanical properties show a significant increase in the impact strength which is related to rubber content of the ABS used. Morphological studies have been carried out by scanning electron microscopy which support the observation that an increase in rubber content results in greater ductil

ISSN:0032-3888    

DOI:10.1002/pen.760320106

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractIncreasing utilization of the electrical properties of polymeric blends and composites has prompted our renewed interest in developing a general working relationship which can explain the electrical properties of polymer composites and blends in terms of processing characteristics, morphology, and compositions. Here, we restrict our attention to the following two‐component systems: (1) two component systems with conductive particulate inclusions (e.g. carbon black) embedded in a continuous polymeric matrix, and (2) two component polymer blend systems with one conductive polymer (e.g., polyether copolymer) dispersed in another continuous polymeric matrix. The following processing aspects related to the electrical property of particulate filled composites are discussed: (1) critical concentration of rigid conductive fillers, ϕc, and (2) redistribution of conductive fillers upon processing. An equation based on the crowding factor of concentrated suspension rheology and Janzen's particle contacts percolation is proposed to describe the relationship between ϕc, and the maximum packing fraction of conductive fillers. The relationship is used to explain the influence of particle morphology on conductivity, and the conductivity difference in the high shear and the low shear region of a processed polymer composite part. Furthermore, some qualitative guidelines for blending a low conductivity polyether copolymer to achieve an overall balance of antistatic and mechanical properties of polymer blends are also discus

ISSN:0032-3888    

DOI:10.1002/pen.760320107

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractA commercial thermotropic polyesteramide and its blends with polyarylate are the object of a slit die flow rheological study. The measurements are carried out at 280°C, a temperature slightly above the melting temperature of the thermotropic, covering a shear rate range 10−1s−1to 102s−1. Except in the case of the thermotropic polymer, the pressure profiles are upward parabolic which is attributed to the dependence of the viscosity on pressure. The most striking result is the observed downward curvature in pressure profiles obtained for the liquid crystalline polyesteramide: no explanation is given for this phenomenon, for the present. The elasticity of the polymer melts is expressed in terms of the exit pressure and the extrudate swell. The thermotropic polyesteramide presents negative values of both parameters (e.g. samples shrink instead of swell). Viscosity and elasticity present negative deviation from linearity when plotted against composition; this reduction in the rheological functions, caused by the addition of liquid crystal, is more pronounced at high shear

ISSN:0032-3888    

DOI:10.1002/pen.760320108

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractBlends of zinc neutralized sulfonated ethylene‐propylene‐diene elastomer (ZnS‐EPDM) with poly(styrene‐co‐vinyl pyridine) have been compared with mixtures of the unfunctionalized rubber with the same copolymer. These binary component blends contain relatively low levels of interacting groups, which are, however, sufficient for the formation of intermolecular complexes. As a result of these interactions, marked enhancement in properties have been observed. In this study, small angle neutron scattering (SANS) is used to determine domain dimensions. The SANS experiments clearly show a decrease in domain size by three orders of magnitude when compatibilization via the sulfonate groups takes place. This reduction correlates with large changes in mechanical p

ISSN:0032-3888    

DOI:10.1002/pen.760320109

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractBlends of polyphenylene sulfide (PPS) with a commercial, wholly aromatic, liquid crystal copolyesteramide (Vectra‐B950) have been prepared by meltblending. The crystallization behavior of neat and blended PPS has been studied by differential scanning calorimetry (DSC), under both non‐isothermal and isothermal conditions. It has been found that blending PPS with Vectra‐B leads to an increase of the temperature of non‐isothermal crystallization and to a pronounced acceleration of the isothermal crystallization, without any reduction of the degree of crystallinity. All these effects have been found to occur independent of the Vectra‐B concentration, within the investigated range (2 to 20%, w/w). The results have been interpreted in terms of an incrased nucleation density of the blends, probably due to heterogeneous substances, initially present in the Vectra‐B bulk, which dissolve to saturation in the PPS phase, during me

ISSN:0032-3888    

DOI:10.1002/pen.760320110

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractThe elongational viscosity (EV) of two series of linear low‐density polyethylene/low‐density polyethylene blends was estimated using an entry flow analysis. The difference,t−n, between the power law indextof the elongational viscosity and the power law indexnof the viscosity, is proportional to the LDPE content for both series of blends investigated. Comparison of theEVof the LLDPE/LDPE blend estimated from the analysis of the flow into an orifice die to theEVvalue estimated from the analysis of the flow into a capillary die with a flat entry, showed that the difference in geometry had little effect on theEVesti

ISSN:0032-3888    

DOI:10.1002/pen.760320111

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY