摘要:

In the immiscible blends of poly(phenylene sulfide) (PPS) and polyarylate (PAR), absorbed moisture partitioned into each phase according to the equilibrium value of the homopolymers. The water diffusivity was observed to decrease with increasing PPS concentration and at >45%, when PPS became the major component in the skin region, the diffusivity was equal to that of neat PPS. The molecular weight of the PAR fraction was found to degrade linearly with time due to hydrolysis.

ISSN:0360-2559    

DOI:10.1080/03602559108020141

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Extrusion is one of the most important operations in the polymer-processing industry. In order to improve their productivity, polymer processors must rely on computer-aided design, engineering, and manufacturing (CAD/CAE/CAM). The performance of an extruder is governed by its capacity to convey, melt, and pump the polymeric material. In the past, a great deal of effort, theoretical and experimental, has been put into the analysis of plasticating single-screw extruders. Despite these developments, the perfect model that could help the practicing polymer engineer to design extruder screws does not exist. A comprehensive model has been developed for steady-state computer simulation of a single-screw plasticating extruder (barrier and conventional screws) in order to predict the performance of the extruder, the optimum screw design, and the operating conditions. The model takes into account the three zones of the extruder: the solids-conveying section, the plasticating section, and the metering section.

ISSN:0360-2559    

DOI:10.1080/03602559108020142

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The various die designs that have been proposed for the manufacture of sheets and flat films from polymeric materials are reviewed, along with the corresponding flow analysis and derived design equations. Successively, the T-die, the linearly tapered coat-hanger die, the curvilinearly tapered coat-hanger die (with manifold of circular or rectangular cross-section), and the fishtail die are examined. In each case, care is taken to outline the assumptions used to derive the equations, and to state the advantages and disadvantages of each design. The limits of these mentioned assumptions are explained and illustrated. Particular attention is paid to the aspects of the design which affect the processing of sensitive or reactive materials (i.e., residence time distribution and wall shear stress).

ISSN:0360-2559    

DOI:10.1080/03602559108020143

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Finite element analysis and analytical geometric analysis are two active approaches to calculating local wall thicknesses in simple vacuum formed parts. FEA requires substantial computational skills and mainframe computer access. Analytical geometric analysis is usually restricted to relatively simple shapes such as cones and wedges. In this paper, an easy-to-learn protocol is proposed for calculating wall thickness of relatively complex shapes. A portion of the protocol is based on the Fukase blow-molding scheme. The protocol is applied to a rectangular cookie tray with wall thickness accuracies to within 30% for most sections of the part. 3D corner agreement is excellent but vertical 2D corner agreement is not good.

ISSN:0360-2559    

DOI:10.1080/03602559108020144

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

One method of prestretching rubbery polymer sheet prior to thermoforming involves pressing a mechancial shape, orpluginto the stretched sheet. Current popular methods of predicting local wall thickness of thermoformed sheet—finite element analysis and analytical geometric analysis—have not addressed mechanical prestretching. A relatively simple geometric protocol, based partially on the Fukase blow-molding scheme, is proposed for 2-dimensional parts. The protocol is used to illustrate the effect of depth of plug penetration on sheet reallocation in 2-dimensional corners.

ISSN:0360-2559    

DOI:10.1080/03602559108020145

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Soda lignins of raphia petiole have completely different structure from kraft lignins. Soda lignins have higher methoxyl content and fewer phenolic hydroxyl group. From nitro benzene oxidation, soda lignins have a higher percentage of syringaldhyde 18.20 and also a higher S/V molar ratio. This is the reason that soda lignin is composed mainly of syringyl units, while kraft lignin is composed of guaiacyl units. IR spectra show remarkable differences: soda lignins show the strongest bands at 1230–1330 cm−1, attributed to syringyl nucleus; whereas kraft lignins show the strongest bands at 1030 cm−1and 1270 cm−1, which are attributed to the guaiacyl nucleus. NMR spectra were also studied.

ISSN:0360-2559    

DOI:10.1080/03602559108020146

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Examination has been made of the possibility of increasing the heat resistance of diane oligomers by means of the introduction of Cu2+, Co2+, or Ni2+ions into the polymer matrix. This was carried out by the hardening of epoxy oligomers with chelates of metals and aliphatic amines. The properties of polymers produced and their dependence on the quantity and structure of chelate hardener have been investigated. It has been established that maximal heat resistance is rendered by Cu2+, affording stability of DGEBA hardened to 280–300°C both in vacuum and in air. The heat resistance of copper-containing polymers has been shown to be higher than that of epoxy oligomers with known hardeners.

ISSN:0360-2559    

DOI:10.1080/03602559108020147

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The effect of zinc-neutralized sulfonated EPDM (Zn-SEPDM) on the compatibility and the crystallizing behavior of isotactic polypropylene (IPP), and also the morphology of the blend were studied through WAXD, DSC, TEM, and mechanical properties test. The results show that addition of Zn-SEPDM decreases both the melting point and the crystallizing temperature of IPP. The widths at half-height of the melting peak and the crystallizing peak become narrower; the d-spacings of the crystal planes are unchanged, revealing the existence of interactions between Zn-SEPDM and the amorphous region of IPP. The higher the sulfonation level, the smaller the average distances across the IPP phase and the EPDM phase. As Zn-SEPDM content exceeds 20%, Zn-SEPDM in the blend becomes continuous and an abrupt change in impact strength is incurred therefrom. Owing to the incorporation of ionic groups into EPDM, the strong interactions between the chains make both the impact and the tensile strength of IPP remarkably higher.

ISSN:0360-2559    

DOI:10.1080/03602559108020148

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0360-2559    

DOI:10.1080/03602559108020140

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor