摘要:

Infrared (IR) spectroscopy has become a powerful tool for chemical and physicochemical characterization of polymeric materials. The growth in IR spectroscopy after 1945 was provided by development of reliable electronic amplifiers and radiation detectors. More recently new innovations have been made in this field with the commercial introduction of the computer-controlled Fourier transform infrared (FTIR) spectrophotometer.

ISSN:0360-2559    

DOI:10.1080/03602558808070112

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The Food Protein Research and Developments Center's Industrial Crops Extraction Pilot Plant, with a nameplate capacity of 1 ton/24 h, was used to evaluate effects of shrub type, preparation methods, different solvents, and operating parameters on rubber yield. Shrub sources which have been evaluated include baled whole plants from USD A in Weslaco, Texas, and from Texas A&M plantings in Pecos, Texas. The USDA types included native, California bulk, dryland, and improved varieties. The A&M plantings evaluated were varieties 11,605 and 12,229. All shrubs were processed as received; that is their leaves were not removed. Toluene, xylene, pentane, and blends of pentane/perchloroethylene as solvents, in combination with methyl alcohol as precipitant, were investigated at different extraction and precipitating temperatures. Approximately 600 pounds of guayule rubber have been prepared during a series of runs over a 3-year time period on an actual plant-operating basis of around 4 months. Rubber yields on a daily time basis increased by up to 500% in comparison with a batch process developed earlier at the center. This dramatic increase is attributed principally to replacing the batch-mixing/screw-pressing extraction step with a continuous extraction operation. New shrub preparation and extraction conditions were determined and found to be critically important for high rubber recovery efficiencies. An additional precipitation step, downstream from the primary desolventizing screen used for precipitation of rubber, also improved recovery rates. Rubber yields as high as 92% of the rubber contained in the shrub, based on Soxhlet analyses, have been achieved. Shrub type and/or harvest time, age, and storage conditions were found to affect rubber yield. Additional processing highlights are also outlined. Selected molecular weight analyses and physical test results are indicative of overall premium rubber quality. Weight molecular weights, M(w), up to as high as 1.25 million have been obtained. Tensile strengths above 4150 psi have also been obtained.

ISSN:0360-2559    

DOI:10.1080/03602558808070113

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A new sulfide crosslinkable resin was synthesized from condensation of dihydroxydiphenylsulfide with formaldehyde in a one-pot reaction system, and then purified and characterized. The tetrmethylol resin sets thermally to a very hard product. The thermosetting characteristics of the resin were investigated by four techniques: moisture evolution analysis, DSC, spectrorheometry, and thermogravimetry. The activation energy of the setting reactions was determined by these techniques; the values determined were 78.87, 14.56, and 144.48 kJ/mol as determined by the first three techniques, respectively. The suggested mechanism for the crosslinking reaction is also included. The thermally set resin showed outstanding thermal stability as found by thermogravimetric analysis technique.

ISSN:0360-2559    

DOI:10.1080/03602558808070114

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Kinetic models for Ziegler-Natta polymerizations differ from those for many other types of chemical reactions in that their kinetic parameters depend upon the values of operating conditions such as catalyst composition, temperature, and moisture level. This complication makes the use of established procedures for discriminating among a set of candidate polymerization models much more difficult, requiring additional experimental effort to identify the functional dependencies and modification of the model discrimination criterion to take account of those dependencies. In this paper a procedure is described, using available data for the reaction under study, to provide guidance in the selection of further experimental runs for effective model discrimination. This approach is illustrated using data for polymerization of butadiene initiated with a cobalt catalyst.

ISSN:0360-2559    

DOI:10.1080/03602558808070115

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The wire coating and cable sheathing processes are very similar in many respects. In both cases, molten polymer is extruded into a cross-head die, through which passes the wire or cable to be coated. Upon emerging from the head, the coated product is cooled in a water bath, continuously tested, and then invariably wound onto a reel.

ISSN:0360-2559    

DOI:10.1080/03602558808070116

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0360-2559    

DOI:10.1080/03602558808070117

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0360-2559    

DOI:10.1080/03602558808070118

出版商:Taylor & Francis Group    

年代:1988

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:10.1080/03602558808070111

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor