摘要:

The scientific and patent literature on polymerization of vinyl chloride (VCM) is very extensive. A comprehensive review covering the literature up to about 1984 was recently done by Felger (1986). Some less comprehensive but very useful monographs have also been published fairly recently (see Burgess, 1982, and Butters, 1982). The present account primarily deals with fundamental work on VCM polymerization. No attempts have been made to include in this report contributions which are solely reported in the patent literature. The report concentrates on those aspects of VCM polymerization where recent work has provided us with a better understanding or new insight. The progress in the field made during the last few years is mainly due to the fad that new or strongly improved experimental techniques (e.g., more powerful spectroscopic methods) have become available.

ISSN:0360-2559    

DOI:10.1080/03602558808070100

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The influence of temperature on the mechanical properties of a thermoplastic elastomer, 1,2-polybutadiene (1,2-PBD), has been investigated. The tensile strength and tear strength of both clay-filled and unfilled 1.2-PBD register a drastic fall in the temperature range 50-60°C, while the ultimate elongation and hardness of these systems consistently decrease with increasing temperature. The energy loss during hysteresis at low strain decreases with increasing temperature and is negligible at 80°C, just below the crystallite melting point. The tensile and tear fracture surfaces of unfilled and filled 1,2-PBD have been examined by a scanning electron microscope and found to be drastically altered by the test temperature. For instance, the cracks and folds observed in the tensile fractograph of 1,2-PBD at room temperature are replaced by a meandering slip pattern at elevated temperature. Near the melting point of 1,2-PBD the tensile and tear fractographs exhibit similar characteristics. This is true for both unfilled and filled 1,2-PBD.

ISSN:0360-2559    

DOI:10.1080/03602558808070101

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The viscosity control of PVAc latex in the presence of PVA as a protective colloid based on an initiator has been investigated. The polymerization was carried out not by the former techniques such as speed of stirrer, PVA amount, kind of PVA, and charged VAc amount, etc., but by the new and simple means such as the amount of an initiator and its addition method. In polymerization initiated by HPO, the viscosity of PVAc latexes was easily controlled to obtain the thixotropy, Newtonian, or dilatancy flow, and also an increase or a decrease, by means of the amount of HPO and its addition method. It may be concluded that the viscosity of PVAc latexes containing PVA is determined mainly by the initiator amount at an early stage of polymerization. In other words, the particle number depends on the initiator amount at an early stage of polymerization, because particles produced are effectively protected by PVA. The confirmation of the graft copolymer between PVA and PVAc undertaken by the extraction method stands in need of reexamination, as the residual polymers increase more with smaller initiator amount. Through a series of studies, the PVA-PVAc composite porous membrane was prepared by extraction of PVAc with acetone from the film of the PVAc latex polymerized in the presence of PVA by HPO. The membrane consists of spherical cells which were made up of PVA and grafted PVAc or insoluble PVAc-like microgels. Unexpectedly, the PVA-PVAc composite porous membrane is permeated by n-hexane but is not appreciably permeated by benzene. Based on these properties, a new use beyond adhesives, paints, and textile finishes is now being found for PVAc latex containing PVA.

ISSN:0360-2559    

DOI:10.1080/03602558808070102

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A semiempirical model is described for predicting the extrusion performance of polymeric materials. The model relates polymer molecular weight and molecular weight distribution to rheological coefficients measured in a capillary rheometer and applies the onedimensional expressions of drag and pres sure flow for single-screw extruders to predict the extrusion performance of compounded EPDM stocks. The generalized model offers a mechanistic approach to designing improved extruding polymers from a knowledge of the molecular properties of the polymer.

ISSN:0360-2559    

DOI:10.1080/03602558808070103

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

This paper describes an attempt to correlate the nature of polar-polar interaction between the reinforcement and matrix in a polymer composite with the boundary phase structure formed in contact with the reinforcement. It is shown by analyzing the mechanical dispersion data that the reinforcement-matrix interaction of Kevlar fiber reinforced poly(hydroxypropyl ether of bisphenol A) (P) is increased by blending poly(ethylene oxide) (E) or poly(ethylene adipate) (A) as a part of matrix, and that E is more efficient than A for the increase of the interaction. These results can be supported at the molecular level from the inspection of the Fourier transform infrared spectra on the Kevlar fiber coated with matrix polymers and the mixture of matrix polymers with benzanilide, which is used as a model compound of Kevlar fiber. It can be shown from the electron spectroscopy for chemical analysis on the films of PIE and P/A blend polymers formed on nylon 6 substrate (N), which is also used as a model material for the reinforcement, that A concentrates on the N-facing side for P/A film and that E concentrates on the air-facing side for PIE film. This result indicates the different susceptibility between P/A and PIE blends to the surface force from N, and hence, it likewise indicates the different interaction with the reinforcement in each blend, as shown by the mechanical dispersion data.

ISSN:0360-2559    

DOI:10.1080/03602558808070104

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0360-2559    

DOI:10.1080/03602558808070099

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor