ISSN:0032-3888    

DOI:10.1002/pen.760030402

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractA determination of the performance indices of ablative plastics is indeed a formidable task because of the severity of the high‐temperature test environment, nonstandard test methods, limitations of available evaluation facilities and the complex interrelationship between materials performance and environmental parameters. In spite of these difficulties, considerable progress has been made in establishing new test methods for evaluating very high‐temperature (ablative) plastics. This article describes the test facilities and measurement techniques available for obtaining research and design data on ablative plast

ISSN:0032-3888    

DOI:10.1002/pen.760030403

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractThe influence of bulk physical properties on the bond strength of an adhesive was studied. A conventional epoxy resin when cured with various mixtures of phthalic acid and anhydride exhibits maximum bond strength when the curing agent is 75% acid and 25% anhydride. This effect is explained on the basis of physical properties of the unfilled resin systems. Most significant of these were the heat distortion temperature and the compressive break and yield strengths.

ISSN:0032-3888    

DOI:10.1002/pen.760030404

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractSeventeen different samples of styrene polymers and copolymers were examined in a capillary extrusion rheometer over broad ranges of temperatures and shears. They were injection molded in a spiral mold over the same temperature range. If viscosities at constant shear stress are obtained from the rheometric data, they cannot be correlated with spiral flow results. However, if viscosities are calculated at a proper “high” shear rate, capillary data correlate will with spiral flow results at all temperatures and for all materi

ISSN:0032-3888    

DOI:10.1002/pen.760030405

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractThe problems of unsteady‐state heat transfer associated with the melting and cooling of crystalline plastics such as polyacetals, high density polyethylene and polypropylene, are complex because of the latent heat of fusion that must be dealt with in problems where the temperature range being considered extends across the melting range. In the case of polyacetals, the use of a computer is shown in the literature to provide solutions to those problems. For many molding shops, such aids are not available. Numerical methods for the solution of such problems have been investigated, and their results are compared with those obtained using a computer and published for polyacetals. Cooling curves derived from numerical calculations, for slabs and rods made from high density polyethylene and polypropylene, are presented. Applications of the method are indicate

ISSN:0032-3888    

DOI:10.1002/pen.760030406

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractDilatometric measurements show that both isotactic and atactic polypropylenes have two distinct glass transition temperatures. Because of the two transitions, three values for the cubical coefficient of thermal expansion are necessary to accurately define the volume expansion of polypropylene from −80° to +90°C. A method is outlined for calculating the content of amorphous atactic, amorphous isotactic, and crystalline isotactic polymer in a given polypropylene sam

ISSN:0032-3888    

DOI:10.1002/pen.760030407

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractThe chemical changes taking place in polyethylene in the process of flame spraying have been investigated qualitatively and quantitatively by a spectroscopic method. It has been shown that oxidation occurs during the process with the formation of acidic, ketonic, ester carbonyls, associated hydroxyls and ‐C‐O−bonds. The degree of unsaturation also increases due to growth in the number of vinyl andtrans‐vinylene groups. A small increase in the number of CH3groups is also o

ISSN:0032-3888    

DOI:10.1002/pen.760030408

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractFilms of polytetrafluoroethylene, irradiated in halogen atmospheres, decrease in ultimate tensile strength and elongation at break almost as rapidly as in oxygen. The rate of degradation is approximately independent of chlorine pressure down to about 1 mm Hg. The phenomena can be explained semi‐quantitatively in terms of first order, cage reactions of scission, recombination, and reaction with chlorine, complicated by diffusion at low pressures. However, all reaction and diffusion parameters must shift with gradual increase of crystallinity.For a given decrease of elongation at break, polytetrafluoroethylene irradiated in a vacuum retains a relatively higher ultimate tensile strength. In the copolymer of tetrafluoroethylene and hexafluoropropylene, the changes in ultimate tensile strength and elongation at break are much slower under all conditions. Both polytetrafluoroethylene and the copolymer retain appreciable tensile strength but little elongation up to a dose of 2 x 108

ISSN:0032-3888    

DOI:10.1002/pen.760030409

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

摘要:

AbstractThe radiation‐induced polymerization of n‐tetradecafluoroheptene‐1 was investigated at pressures of 8100, 11,900 and 17,100 atmospheres and temperatures between 90 and 267°C. The data are interpreted in terms of a free radical mechanism and the polymer has a low ceiling temperature. As temperature is increased, the depropagation step becomes important and reduces the rate of polymerization. Under some conditions transfer seems to be a significant part of the mechanism. Several radiation‐induced polymerizations at high pressure were carried out with 1,1,2‐trifluorovinylphenyl ether as well as one with 1,2,3,4,5‐pentafluorophenyl 1,1,2‐trifluorovinyl ether. The results suggest that transfer limits the molecular weight o

ISSN:0032-3888    

DOI:10.1002/pen.760030410

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760030401

出版商:Society of Plastics Engineers, Inc.    

年代:1963

数据来源: WILEY