摘要:

AbstractThe phase morphology of injection molded blends of polyarylate (PAR) and a copolyester (PCTG‐5445) was studied by transmission electron microscopy (TEM) and X‐ray diffraction (XRD). The use of ultramicrotomy to prepare ⋍ 50 nm thin section TEM specimens and solvent etching to dissolve the PAR phase revealed PCTG as the matrix phase in the as‐molded state which crystallized into PCTG spherulites upon annealing. The most consistent morphological information vs. concentration of PCTG and the highest structural integrity of the PCTG spherulites was obtained from thin sections treated with a mixture of 75% methylene chloride as the solvent for the PAR and 25% 2‐propanol as the nonreactive diluent. XRD results from the annealed PCTG/PAR blends show crystalline reflections of 0.59, 0.53, 0.46, 0.38, and 0.35 nm, which disappear into the amorphous background below

ISSN:0032-3888    

DOI:10.1002/pen.760292102

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThermal analysis of oriented polymers involves several transitional processes which may be coupled in a complex way. The disorientation process that occurs during heating is often accompanied by dimensional shrinkage which may occur in both amorphous and crystalline oriented polymers. From differential scanning calorimetry (DSC) measurements it has been determined that shrinkage is an exothermic process. In amorphous atactic polystyrene (PS), hot drawn uniaxially, the shrinkage occurs just aboveTg. In triaxially oriented polyethylene (PE) and isotactic polypropylene (iPP), shrinkage and melting take place concomitantly, producing multiple melting peaks. In rolltruded (and also in biaxially oriented) poly(ethyleneterephthalate) (PET) films, shrinkage and crystallization are found to be coupled and to occur betweenTgandTmupon heating. If the enthalpy contribution due to shrinkage is ignored, it follows that crystallinities determined by DSC are incorrect. In this study, the influence of shrinkage upon transitional changes in oriented polymers is investigated in a systematic manner.

ISSN:0032-3888    

DOI:10.1002/pen.760292103

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThe orientation of the reinforcing fibers in glass fiber filled polypropylene tubular extrudates has been controlled effectively by the superposition of the linear flow in a melt extruder with torsional flow generated by rotating the capillary portion of the extrusion die of the extruder. The so produced extrudates have mechanical properties which can be balanced along the hoop and extrusion direction by adjusting the extrusion rate and the rotational speed of the die for example, the breaking load of 75N along the hoop direction increases by ∼40% when the capillary of the die was rotated at 80 rpm. At the same time the Young's modulus in the extrusion direction decreased from 1100 MPa under conventional extrusion conditions to 800 MP

ISSN:0032-3888    

DOI:10.1002/pen.760292104

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractA study of orientation development in polystyrene film by biaxial stretching is described. Stretch ratios up to 7.2 × 7.2 were used. Mechanical properties of polystyrene films were correlated with the level of molecular orientation developed by uniaxial or biaxial stretching. Sensitivity of the mechanical properties to change due to development of orientation varied as follows: Yield strength

ISSN:0032-3888    

DOI:10.1002/pen.760292105

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThe present paper describes an analysis of the orientation developed in biaxially stretched polystyrene films in terms of the kinematics of the process and a viscoelastic constitutive equation. It was possible to achieve reasonable agreement of predicted and experimental birefringences through use of a convected Maxwell model and the Rheo‐Optical La

ISSN:0032-3888    

DOI:10.1002/pen.760292106

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractA study was conducted of blends of poly(vinyl chloride) (PVC) with a poly(methyl methacrylate co imide). The latter polymer was found to be miscible in PVC and to raise the glass transition temperature of the blend. Blends of all compositions could be oriented, but the processing temperature increased in proportion withTg. For a given blend composition, orientation increased with increasing stretch ratio and strain rate and with decreasing stretch temperature. Increasing copolyimide content and increasing orientation generally lead to improved mechanical properties, though the blends containing high levels of copolyimide exhibited low ductilities.

ISSN:0032-3888    

DOI:10.1002/pen.760292107

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractWe offer a detailed study on the anisotropic optical properties in uni and simultaneous biaxially stretched Poly(ethylene terephthalate) (PET) films. Cast amorphous sheets of PET were stretched to a series of extension ratios in two mutually perpendicular directions at 80, 90, and 100°C. Additionally, 0selected films were subsequently “heat‐set” by annealing with their width and lengths constrained. The principal refractive indices at sodium D wavelength of these, asstretched and heat‐set films were obtained using a modified Abbe refractometer. The changes in the principal refractive indices with the processing history were correlated with the orientation of PET chains and phenyl plane normals, which were determined independently by wide angle X‐ray (WAXS) pole figure

ISSN:0032-3888    

DOI:10.1002/pen.760292108

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractFive blends of polycarbonate (PC) with linear low density polyethylene (LLDPE) were studied. Characterization of the blends was made by means of rheological measurements and domain morphology determined by SEM microscopy. A fine dispersion was obtained for the 25/75 PC/LLDPE. The blends were then oriented, LLDPE and 25/75 PC/LLDPE at room temperature, and the others at 165°C. For the hot drawn blends (50/50 and 75/25 PC/LLDPE), a significant increase in tensile strength and elongation at break is observed. For the room temperature drawn samples, modulus and tensile strength values increase whereas elongation at break decreases. This is explained in terms of morphological and molecular orientation effects. Comparison of the experiments to the predictions of different models for the modulus shows a good agreement for unoriented blends. However, for oriented samples, important discrepancies are observed, suggesting that the morphology and orientation are important factors in predicting the modulus of these blends. A model which takes into account these factors is proposed and a good fit of the modulus is obtained

ISSN:0032-3888    

DOI:10.1002/pen.760292109

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760292101

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY