ISSN:0032-3888    

DOI:10.1002/pen.760060102

出版商:Society of Plastics Engineers, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe plastics industry is now coming to realize that copolymers are unique thermoplastics which have broad areas of application. It is believed that ethylene‐methyl acrylate copolymers of 2 melt index may be extrusion coated to paper by a cap‐coat process or by use of a chill roll with an adhesive coating. Copolymers of ethylene and vinyl monomers can be made into film by the same methods used for polyethylene. Methyl acrylate and methyl methacrylate copolymers may be processed on a wide range of molding equipment. Table VII in the article gives a list of applications for each polymer, along with expected physical propert

ISSN:0032-3888    

DOI:10.1002/pen.760060103

出版商:Society of Plastics Engineers, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe literature on radiation‐induced solid state polymerization has been increasing exponentially in the last five years. Major advances have been made in retention of crystalline morphology during polymerization, in stereospecific polymerization, in modification of reactivity ratios in copolymerization and in molecular weight control of the product. However, at the present time, no commercial products have resulted from the study of radiation‐induced solid state polymerization. Chemically induced polymerization techniques have been keeping abreast of this explosive development in the solid state polymerization field and have up to this time precluded the use in industry of solid state polymerization. The major potential at the present time appears to be in the area of producing fibers without additional process

ISSN:0032-3888    

DOI:10.1002/pen.760060104

出版商:Society of Plastics Engineers, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractStress concentration effects and strengths of bonded and bolted butt joints were investigated for a glass fabric polybenzimidazole lalminate at room temperatuer and 700°F for a gloass fabric phenolic laminate at room temperature and 500°F. Specimen configurations included: (1) standard tensile specimen, (2) stress concentration specimen, (3) bolted double shear butt joint, (4) bolted single shear butt joint, (5) bonded double shear butt joint and (6) bonded single shear butt joint.Both polybenzimidazole and phenolic laminates exhibited high room temperature tensile strengths and little degradation of that strength occured as a result of elevated temperature exposure. However, low joint effencies (22 to 32%) were obtained for bolted butt joint specimens. Although bonded joints exhibited higher efficiencies, they suffered from a thermal expansion mismatch between the plastic laminate and the Inconel butt plate

ISSN:0032-3888    

DOI:10.1002/pen.760060105

出版商:Society of Plastics Engineers, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe paper reviews the various classical failure theories essentially developed for metals and then seeks to show that the same theories with slight modifications could be used to describe failure of polymeric materials. These modifications consist in the consideration of the effect of rate loading on failure behavior. In addition, the paper reports experimental results on failure of two polymeric materials under uniaxial tension loading and several biaxial stress fields corresponding to pure internal pressure, internal pressure combined with tension and torque loadings and several biaxial stress fields corresponding to pure internal pressure, internal pressure cobined with tension and torque loadings. The failure behavior under various stress fields has been studied for maximum principal rates ranging from 0.05 to 60 psi. sec. The predictions based on various criteria of faliure, which considers the effect of rate of loading, are compared with the experimental results. Finally, it is shown that failure behavior under triaxial stress fields can be reasonably predicted from biaxial stress failure data.

ISSN:0032-3888    

DOI:10.1002/pen.760060106

出版商:Society of Plastics Engineers, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThis paper is an account of some studies of the mechanism of degradation of an uncrosslinked polyurethan prepared from poly(propylene oxide) (PPO) and 2,4‐tolylene diisocyanate (TDI) at temperatures up to 320°C in a vacuum or inert atmosphere. Fractionation of polymers before and after degradation provides information about the mechanism of degradation since the molecular weight distributions obtained are dependent on the mode and sites of bond scission. A recent publication describes the column elution method of fractionation developed for undergraded and slightly degraded PPG‐TDI. PPO‐TDI gives essentially most probable molecular weight distributions at an initial intrinsic viscosity [η] of ∼ 0.68 dl/g and also after degradation to [η]∼ 0.24 dl/g. This invariancy of the distribution strongly suggests a randon scission process. Other types of degradation, e.g., free‐radical unzipping initiated at the chain ends, could also give invariant most probable distributions. However, such depolymerizations would be accompanied by much larger extents of volatilization than were observed for these polymers (<5% v

ISSN:0032-3888    

DOI:10.1002/pen.760060107

出版商:Society of Plastics Engineers, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe feasibility of monitoring curing processes in large reinforced plastics structures by electrical volume resistivity techniques has been studied. It has been found, by embedding electrodes and thermocouples within a heavy‐walled structure during fabricaton and by monitoring the change is resistance during the curing process, that information indicative of the rate and extent of curing can be obtained. The resin system used in this study was Epon 826/MNA/BDM

ISSN:0032-3888    

DOI:10.1002/pen.760060108

出版商:Society of Plastics Engineers, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractWhen a thermoplastic shape is extruded and drawn into a quenching medium and the drawing speed increases continuously, the cross‐sectional extrudate area decreases. At a critical take‐up speed, a cyclic gauge pulsation begins, becoming more pronounced with increasing drawing speed until the extrudate eventually breaks at the air‐coolant in terface. This phenomenon, “draw resonance,” originates in the air gap and is independent of any melt fracture phenomena. Correlations show increasing pulsation severity with increases in speed ratio, air gap, viscosity‐average molecular weight, and decreasing melt temperatures. Draw resonance occurs with polypropylene and various types of polyethylene and polystyrene. Ribbon‐type and round‐hole dies give equivalent results. A semi‐quantitative theory is advanced is explain these phenomena in terms of thermodynamic relationships and basic mol

ISSN:0032-3888    

DOI:10.1002/pen.760060109

出版商:Society of Plastics Engineers, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractThe Phenomenon of draw resonance and the cyclic size fluctuation of an extruded shpae are related to basic changes in the “melt strength” (force per average cross‐sectional area required to draw the molten fiber down under fixed conditions). Melt strength values are obtained by a modified rheometer which consists of a vertical chamber to melt and hold the polymers at 190–250°C, a piston for extrusion, a take‐up system, a strain gauge to measure the drawdown force and a recorder for continuous force‐time plots. Melt strength increases with take‐off speed but not proportionally. At higher velocities, draw resonance is apparent through a sinusoidal‐like variation in fiber diameter. The amplitudes of melt strength and diameter waves are correlated with molecular weight, melt viscosity, swell, melt temperature and

ISSN:0032-3888    

DOI:10.1002/pen.760060110

出版商:Society of Plastics Engineers, Inc.    

年代:1966

数据来源: WILEY

摘要:

AbstractCertain ester‐acetal derivatives of azelaaldehydic acid have been evaluated as a new type of plasticizer of PVC. In gerneral, these compouonds have high compatibility and impart excellent low‐temperature, mechanical, heat‐ and light ‐stability properties to the plasticized PVC. The 2‐ethylihexyl ester bis (2‐methoxyethyl) acetal, in particular, appeared to have the best combination of properties for a useful plasticizer. The results indicate that a unique and useful type of plasticizer‐stabilizer can be obtained from derivatives of azelaa

ISSN:0032-3888    

DOI:10.1002/pen.760060111

出版商:Society of Plastics Engineers, Inc.    

年代:1966

数据来源: WILEY