ISSN:0032-3888    

DOI:10.1002/pen.760040402

出版商:Society of Plastics Engineers, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractPoly‐β‐hydroxybutyric acid has been isolated in quantities sufficient for characterization and evaluation of mechanical properties from bothBacillus megateriumand a special strain of Rhizobium. Its presence in a larger variety of bacteria than previously suspected has been demonstrated by a screening method based on density‐gradient centrifugation. The intrinsic viscosity of the isolated polymer has been shown to depend on the technique of isolation; basic solvents facilitate hydrolytic cleavage of the polyester. Mechanical properties of the polymer are based on the high crystallinity and polarity of the material; in a highly crystallized state, it is quite brittle, but its rigidity exceeds that of polypropylene. Thermal degradation of molecular weight, due to beta‐eliminatin of the carboxyl group from the polyester structure, severely limits processing of the polymer in

ISSN:0032-3888    

DOI:10.1002/pen.760040403

出版商:Society of Plastics Engineers, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractToluene diisocyanate was partially replaced by monobrominated toluene diisocyanate in conventional rigid polyurethane foam formulations, producing self‐extinguishing foams for thermal insulation, with only moderate sacrifce of compressive strength, and with no significant effects upon reactivity, odor, density, cell structure, or resistance to agin

ISSN:0032-3888    

DOI:10.1002/pen.760040404

出版商:Society of Plastics Engineers, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractThe thickness of the adsorbed layer of two glass finishes, vinyl tris (2‐methoxyethoxy) silane and gamma‐aminopropyltriethoxysilane, was measured by ellipsometry. The vinyl silane was adsorbed on glass from solutions in water and in methyl ethyl ketone. The adsorption from water resulted in a film initially at least 50 Å thick, which increased in thickness with time. Adsorption from methyl ethyl ketone solution resulted in a film of about 10 Å. The amino silane was adsorbed on glass and on chrome from soutions in water. Adsorption on glass resulted in a film at least 60 Å in thickness, which remained constant over a period of about 5 hours. Adsorption on chrome resulted in a film about 10 Å in thickness. From the results it appears that a polymer, rather that small molecules of glass finish, is adsorbed from the water solution on glass and that small unpolymerized “finish” molecules are adsorbed from the methyl ethyl keto

ISSN:0032-3888    

DOI:10.1002/pen.760040405

出版商:Society of Plastics Engineers, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractThe combination fo dicyandiamide and diaminodiphenyl sulfone in the presence of a tertiary amine, like 2,4,6‐tris (dimethyl amino methyl) phenol, will crosslink liquid epoxy resins (E.E.W. 180‐200) of diglycidyl ether of Bisphenol A type, or brominated resins, and if used to impregnate glass cloth will produce printed circuit laminated boards combining interlaminar bond and flexural strength retention of NEMA‐G‐10 and G‐

ISSN:0032-3888    

DOI:10.1002/pen.760040406

出版商:Society of Plastics Engineers, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractThe moduli of elasticity of reinforced plastics with uni‐directional filaments either parallel or normal to an applied force are evaluated in terms of the material composition. Expressions are then derived which relate its moduli of elasticity and Poisson's ratios for an arbitrary filament orientation with its material properties in the direction of and normal to the unifilament orientation with its material properties in the direction of and normal to the unidirectional filaments. Filaments. The stress‐strain relations of filament reinforced plastics are also deri

ISSN:0032-3888    

DOI:10.1002/pen.760040407

出版商:Society of Plastics Engineers, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractBueche and Harding [J. Polymer Sci. 32 177 (1958)] obtained an empirical “standard flow curve” to relate viscosity and shear rate by using a particular poly(styrene) solution and positioning the flow curve on a dimensionless rate of shear axis via the viscosity average molecular weight, MVand Bueche's expression for the relation time, τ, where\documentclass{article}\pagestyle{empty}\begin{document}$$ \tau = 12\eta _{\rm o} {\rm M}_{\rm R} /\pi ^2 {\rm RTC} $$\end{document}Here R is the gas constant, ηois the low rate of shear Newtonian viscosity, T is the absolute temperature, C is the Concentration in grams per cubic centimeter, and MRis te molecular weight which determines the relaxation time. Bueche implies by his standard curve that MVcorrelates with MR. In Gereral, it was found that: 1) MRdoes not equal MVbut it is usually significantly lower than MVor MW; (2) the value of MRincreases with increasing polymer concentration and temperature; and (3) the shapes of the flow curves are slightly different from the shape of the standard curve. A survey of the data available in the lon the flow of polymer melts supports these conclusions. Thus, the Bueche‐Harding method can only give semi‐quantitative help I predicting the flow behavior of polyme

ISSN:0032-3888    

DOI:10.1002/pen.760040408

出版商:Society of Plastics Engineers, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractCreep experiments under variable loading conditions are reported for tubular specimens of cellulose acetate butyrate. Experiments include the application of torque loading that corresponded to various loading programs. Results indicate that the material response in creep is nonlinear. The character of the results is described reasonably by assuming the behavior as linear and using the Botzmann superposition principle. However, the interpretation of the data based upon a non‐liner creep law and modified superposition principle yields better agreement with experiments in certain case

ISSN:0032-3888    

DOI:10.1002/pen.760040409

出版商:Society of Plastics Engineers, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractDupre's theory that work of rupture equals increase in surface energy, and Griffith's hypothesis (based upon Dupre's that a crack propagates when strain energy decrease equals or exceeds work required to creat two new surfaces are shown to be incorrect. Work is required for deformation to repture, not for the actual rupture.An alternative criterion, i. e., that crack propagation occurs when strain energy decrease exceeds the increase required for elastic deformation of the “critical domain” to the breaking point, offers the following advantages: (1) continuity between macro‐ and micro‐effects, (2) avoidance of surface energy (unmeasurable for solids), (3) accounting for heat effect, (4) reasonable explanation of unexpectedly high “surface energ

ISSN:0032-3888    

DOI:10.1002/pen.760040410

出版商:Society of Plastics Engineers, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractIt has been shown that a standard screw‐extruder with a little modification is very useful for the measurement of flow properities of various plastics melt over a wide range. Results obtained are very interesting and it is expected that they have applicability to polymer processing. A range of flow rates covering both extrusion and injection molding applications were considere

ISSN:0032-3888    

DOI:10.1002/pen.760040411

出版商:Society of Plastics Engineers, Inc.    

年代:1964

数据来源: WILEY