ISSN:0032-3888    

DOI:10.1002/pen.760231102

出版商:Society of Plastics Engineers, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractThe production of polymer blends increases at a rate of about 13 percent/y. Most of the commercial blends are multiphase systems of complex morphology, determined by the thermodynamic properties of the components and the rheology. Since the diffusion rates are relatively low, the blends are seldom at equilibrium. In most cases, the blend products have properties imposed by the morphology, created by a particular combination of the thermal and deformational history. There are three main reasons for studying the melt flow of blends: optimization of the processing conditions, search for the appropriate means to generate the desired morphology, and the interest in the basic study of the rheology of these complex systems.In this paper the results published during the last five years are reviewed. The data for polymer blends are compared with those obtained for simpler model systems: liquid mixtures, emulsions, and polymer blends. From the rheological point of view, the blends are divided into three groups: those where viscosity shows positive deviation from the log‐additivity rule, PDB, those where the opposite effect is observed, NDB, and the remaining mixed‐behavior systems, PNDB. To PDB belong the miscible blends and those with strong inter‐domain interactions. To NDB belong those where the interactions are weak. To PNDB belong the blends in which there is a concentration‐dependent transition of structure. The shear dependent properties of blends are also di

ISSN:0032-3888    

DOI:10.1002/pen.760231103

出版商:Society of Plastics Engineers, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractA master curve hypothesis is established based on a mass balance and an assumption of continuous stress through interfaces for well dispersed two phase systems with “defined” zero shear viscosity. The master curve, which is in reasonable accordance with experimental data is represented in a double logarithmic plot of log (ηT/T,0) against log\documentclass{article}\pagestyle{empty}\begin{document}$ \left({\frac{{\eta _{T,0} M_C H\rho}}{{c^2 RT}}\dot \gamma _T} \right) $\end{document}.Mcis the molecular weight between entanglements,H= M̄w/M̄n, ρ is the density,cis the polymer concentration, all defined for the continuous phase. ηTand ηT,0are the viscosity and zero shear viscosity of the blend, ηTis the apparent shear rate,Rthe gas constant, andTis absolute t

ISSN:0032-3888    

DOI:10.1002/pen.760231104

出版商:Society of Plastics Engineers, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractConventional thermodynamic reasoning would predict that it would be very difficult to melt blend incompatible polymers and that if such blends were made they would be highly unstable and would phase separate upon heating. A method has been developed to melt blend incompatible polymers (such as poly(methylmethacrylate) and polyethylene) to form two continuous interpenetrating phases and that upon prolonged heating the stability of the structure is increased rather than decreased.

ISSN:0032-3888    

DOI:10.1002/pen.760231105

出版商:Society of Plastics Engineers, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractParticular rheology compositions (PRC) so far observed for blends of polyolefins are confirmed with composition dependence of melt elasticity and viscosity functions for polypropylene/rubbers and blends of other commercial polymers. Particular morphology at PRC was indirectly ascertained from the composition dependence of specific volume,vT–compositions for which the maximumvTobserved are those of minimum viscoelasticity. Direct evidence from scanning electron microscopy (SEM) indicates that the disperse morphology undergoes distinct change at PRC: from uniform into bimodal, with coarser core. Rubber rich mixtures display stratified texture confirming that the melt elasticity ratio (Van Oene's) criterion for disperse/stratified morphology transition is valid in case of polypropylene/rubber blends. For a set of polymers of given melt elasticity ratios and at a composition ratio, static and rotational distributive mixers generate polyblends differing significantly in the melt rheology—morphology interact

ISSN:0032-3888    

DOI:10.1002/pen.760231106

出版商:Society of Plastics Engineers, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractPolymer blends with varying amounts of poly(vinyl chloride) (PVC), acrylonitrile‐butadiene‐styrene (ABS) and polyester have been developed to produce parts with highly flexible, good impact strength, and flame retardant hinge properties. In the present work, the rheological and dynamic mechanical properties are balanced by changing the blend formulations. It is shown that blends morphology and rheology have greater impact on the dimensional stability and delamination at the surface of the molded hinge pa

ISSN:0032-3888    

DOI:10.1002/pen.760231107

出版商:Society of Plastics Engineers, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractMold filling studies have shown that thermotropic liquid crystalline copolyesters of p‐hydroxybenzoicacid (PHB) and polyethyleneterephthalate (PET) fill by an advancing front mechanism similar to flexible chain polymers. The structure and orientation developed during filling as determined on solid specimens by an etching method, X‐ray diffraction, and shrinkage study on thin microtomed samples appear to be most pronounced at the surface. Based on this information copolymers of 60 and 80 mole percent PHB/PET were co‐injection molded with filled PET under various processing conditions. Because of the low viscosity of the copolyesters, they readily coated filled PET under most processing conditions to give a sheath/core structure. The bending modulus of co‐injection molded bars with as little as 35 percent PHB/PET was as high as the sample consisting of 100 percent liquid crystalline copolyester. Electron micrographs of fracture surfaces revealed excellent adhesion between the two p

ISSN:0032-3888    

DOI:10.1002/pen.760231108

出版商:Society of Plastics Engineers, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractData have been obtained regarding the tensile and impact behavior of pure poly(ethylene terephthalate) (PET) and polyamide 6,6 (PA) and blends of PA in PET in concentrations of 5, 10, 25, 30 and 35 percent by weight of PA. The measurements were carried out at −40, 23 and 70°C. Dispersion and sample preparation were carried out in a reciprocating screw injection‐molding machine. All blends exhibited brittle behavior and low strength, when compared to pure components. Although some enhancement of mechanical properties might be realized by orientation, it is suggested that the observed behavior might be attributed to the low quality of dispersion achievable in injection molding process. This conclusion is supported by microscopic evid

ISSN:0032-3888    

DOI:10.1002/pen.760231109

出版商:Society of Plastics Engineers, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractAn expanding application for compounding extruders is the production of materials with new and outstanding properties by blending two or more polymer components. Mixing is essential to control domain size and insure nongradient properties whether the components are miscible, multiphase with discreet domains, or multiphase with stratified structure. This paper will comment on important mechanisms for dispersion in single‐screw and twin‐screw compounding extruders. A theoretical model for mixing via kneading blocks in twin‐screw corotating extruders is experimentally verified. The pigment distribution was found experimentally to agree generally with theory. The commercially interesting polyblend systems and compounder geometries are more complicated than the theoretical model. Practical compounder design considerations for miscible, rubber‐toughened and two‐phase stratified systems are

ISSN:0032-3888    

DOI:10.1002/pen.760231110

出版商:Society of Plastics Engineers, Inc.    

年代:1983

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760231101

出版商:Society of Plastics Engineers, Inc.    

年代:1983

数据来源: WILEY