ISSN:0032-3888    

DOI:10.1002/pen.760301702

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractPhase phenomena in mixtures containing any combination of aliphatic and aromatic polyamides can be formulated by the application of a mean‐field binary interaction model. This has been achieved by the quantitative analysis of the solubility of an aromatic polyamide, denoted as nylon 3Me6T, in a homologous series of aliphatic polyamides. A critical feature of this development required an estimation of the upper and lower bound concentration of methylene units of the latter for which the aromatic polyamide moved from a miscible to immiscible condition. The fabrication of random copolyamides of caprolactam‐laurolactam and 2‐pyrrolidinone‐caprolactam, respectively, has allowed an accurate determination of these critical limits. A survey of the behavior of polyamide blends will be discussed in light of this improved quantitative definition of the model. A principal feature of these analyses is the exclusion of a role for hydrogen bonding interactions. Details concerning the nature of interactions in these systems and how they are influenced by chemical structure are di

ISSN:0032-3888    

DOI:10.1002/pen.760301703

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper reviews the literature of polymer blends containing low and high molar mass liquid crystals. Low molar mass liquid crystals have been used as plasticizers for thermoplastic polymers and in applications such as electrooptics, optical recording media, and membranes. High molar mass liquid crystalline polymers have been primarily used in polymer blends as processing aids and as an incipient reinforcing phase for “self‐reinforced” materials. This review discusses the phase behavior, rheology, and mechanical properties of these b

ISSN:0032-3888    

DOI:10.1002/pen.760301704

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractThe uniaxial extensional flow behavior of polystyrene/low density polyethylene blends (PS/LDPE) was studied using a Rheometrics Extensional Rheometer, Model RER‐9000, at 150°C within the range of the extension rates\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \varepsilon $\end{document}= 0.0005 to 1.0 (s−1). The measurements were repeated several times at each deformation rate to ascertain reliability. The effect of the suspending silicone oil was found to be neglig

ISSN:0032-3888    

DOI:10.1002/pen.760301705

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractThe flow behavior of linear low density polyethylene blended with polycarbonate (LLDPE/PC) was studied at 245°C using an Instron Capillary Rheometer and a Rheometrics Mechanical Spectrometer. The capillary measurements were repeated several times for each crosshead speed and capillary. The averaged values were corrected for shear heating as well as the pressure, entrance‐exit, and power‐law fluid effects. In spite of the utmost care, blend results were erratic with a standard deviation of 25 to 35 percent. Analysis of the capillary data suggested a telescopic flow with the lower viscosity component of the blend migrating toward the capillary wall. The experimental difficulties resulted from the flow and time induced variations of blend morphology. By contrast, the dynamic shear test results were found to be rapid and reproducible with a standard deviation for the complex viscosity of blends not exceeding four percent. The shear moduli of blends indicated the presence of an apparent (time dependent) yield stress, originating from interaction between domains of the dispersed phase. At frequencies exceeding a critical value, shear coalescence of the dispersed phase was observed near the rim of the rheometer pl

ISSN:0032-3888    

DOI:10.1002/pen.760301706

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractPoly(l,4‐cyclohexylene dimethylene terephthalate) (PCT) exhibits superior heat deflection temperature when compared to conventional polyesters such as poly(butylene terephthalate) or poly(ethylene terephthalate). It is subject to degradation, however, at the processing temperatures normally employed to extrude or mold this material. Several approaches were taken to broaden the processing window of this material including: blending PCT with other crystalline and amorphous polymers to allow for lower processing temperatures, addition of conventional stabilizers, addition of crosslinking agents to maintain viscosity during processing and the addition of lubricants to improve processing. Key parameters included physical properties, rate of degradation, extruder torque measurementsvs.time, and Differential Scanning Calorimetry (DSC) analysis (melting point and glass transition). All systems tested produced significant reduction of the intrinsic viscosity (molecular weight) for PCT during processing. The most successful approach was the blending of various polymers with PCT to lower extruder processing temperatures. Reductions in processing temperature may have resulted from improved heat transfer due to the presence of a lower melting polymer, reduction in melting point of the blend, or changes in the frictional characteristics of the PCT in the extruder. Transesterification may have played a role in compatibilizing some polyester mixtures. As expected, certain polymers had major'effects on the flow behavior of the blend. Tradeoffs were obtained in physical and thermal properties. A combined approach of polymer blending and the use of lubricants, stabilizers or crosslinking agent may hold the most promise for future development work. Thermal resistance under vapor phase soldering conditions was best for LCP/PCT blends and worst for PBT/PCT blends. Additional evaluations of the blend materials will include solvent resistance, processability, thermal resistance, dimensional stability, heat aging resistance, flammability, and specific end use test

ISSN:0032-3888    

DOI:10.1002/pen.760301707

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractThis work deals with the effects of material and processing parameters on the mechanical behavior and morphology of noncompatlbilized polypropylene‐polycarbonate (PP‐PC) blends. The blends containing between 0 and 40 vol. percent of polycarbonate were compounded using a twin screw extruder and converted by injection molding using molds with rectangular as well as dogbone shaped cavities. The blends exhibit a complex skin‐core morphology which evolves with the composition. Despite the absence of interfacial adhesion, the low strain modulus increases with PC concentration and follows approximately the Takayanagi model for systems with perfect adhesion. A slight increase of stiffness and strength with increasing PP/PC viscosity ratio is also observed. Weldline strength of these blends is generally poor and decreases with the increasing PC concentr

ISSN:0032-3888    

DOI:10.1002/pen.760301708

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractReactive extrusion of functionalized polymers provides a convenient, commercially attractive route for the preparation of copolymers useful in compatibilization of polymer blends. In the current study, the grafting chemistry of maleic anhydride to poly(phenylene oxide) in the absence of a radical initiator is contrasted to that of efficient quinone‐methide trapping agents such as maleimides. In the case of maleic anhydride, functionalization is shown to occur randomly along the polymer backbone whereas maleimides react to give both main chain and end‐group derivatives. Use of this anhydride‐functionalized polyfphenylene oxide and an end‐group functionalized analog in blends with polyamide‐6,6 affords high levels of graft and diblock copolymers respectively, sufficient for the preparation of highly ductile materials. The properties of these polyamide blends are found to depend on the amount of copolymer formed during extrusion with final copolymer levels being in turn returned to the degree of anhydride functionalization. The properties and morphology of blends containing graft or diblock copolymers derived from main‐chain and end‐group functionality respectively, are rationalized in terms of the relative effectiveness of different copolymer structures in blend comp

ISSN:0032-3888    

DOI:10.1002/pen.760301709

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractThe objective of this work was to investigate the compatibilization of a blend of linear low density polyethylene with polypropylene by Injection of a free radical initiator during extrusion. The reactive extrusion process utilized a single screw extruder equipped with two static mixers. The initiator was injected into the extruder feedport and temperature programming used to cause most reaction to occur within the static mixers. Although elongation at yield was increased by 37 percent, impact strength and yield strength decreased by 17 and 54 percent, respectively. Scanning electron microscopy showed that the maximum size of the dispersed phase decreased from a maximum size of four microns to less than two microns upon addition of initiator. Size exclusion chromatography (SEC), temperature rising elution chromatography (TREF), and differential scanning calorimetry showed that the polypropylene in the blend was degrading while the polyethylene was increasing in molecular size. The combination of SEC and TREF was particularly useful in elucidating this result. No copolymer was discerned by any of the methods used.

ISSN:0032-3888    

DOI:10.1002/pen.760301710

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY

摘要:

AbstractThe morphology and impact properties of polystyrene‐maleic anhydride/bromobutyl rubber blends have been studied as a function of interfacial modification and melt processing conditions. It is found that dimethylaminoethanol (DMAE) serves as a reactive compatibilizing agent for these blends and that the addition of DMAE results in a five‐fold reduction In the size of the dispersed phase. Evidence for covalent bond formation between the DMAE and the elastomer and reactive polystyrene phases is presented. The volume average diameter of the minor phase increases significantly as the screw rotation speed and the material throughput increase. In fact, control of various material and processing parameters can be used to effectively control the particle size distribution during compounding. Impact strength measurements are shown to be clearly dependent on the quantity of DMAE in the system as well as the concentration of elastomer. Saturation of the interface with DMAE is shown to be an important considerat

ISSN:0032-3888    

DOI:10.1002/pen.760301711

出版商:Society of Plastics Engineers    

年代:1990

数据来源: WILEY