摘要:

AbstractPolystyrene, poly(phenylene oxide), and solution‐cast blends of the parent homopolymers were exposed to normal hexane in the liquid and vapor phase. The kinetics of absorption and desorption, the sorption equilibria, and the kinetics of morphological changes were studied as a function of temperature and blend composition.Absorption kinetics ofn‐hexane vapor in all blends were largely controlled by polymer relaxations. The sorption rates from the vapor phase varied monotonically with blend composition and increased over a range of four orders of magnitude with increasing poly(phenylene oxide) content. The equilibriumn‐hexane content similarly increased monotonically with poly(phenylene oxide) content although the increase was only by a factor of two over the entire range of compositions. These results were interpreted in light of and were completely consistent with earlier findings with pure polystyrene homopolymer.Films immersed in liquidn‐hexane produced a white, opaque outer shell surrounding an essentially unaffected central core. The kinetics of this whitening process were much more rapid for each of the homopolymers than the kinetics characterizing morphological changes in the blends. These data suggest that film whitening is caused by crazing in the polystyrene‐rich samples and that solvent‐induced crystallization is involved in the whitening of the poly (phenylene oxide) ri

ISSN:0032-3888    

DOI:10.1002/pen.760130202

出版商:Society of Plastics Engineers, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractNylon 6‐polyoxybutylene block copolymers were prepared by reacting polyoxybutylene diamine with caprolactam in the presence of phosphoric acid. The copolymerization was carried out in a Helicone‐type reactor and the effect of time, temperature, and caprolactam concentration on the properties of the products was recorded. Differential Scanning Calorimetry studies of the products suggest the presence of both the ABA and AB types of sequences, where A and B represent nylon 6 and polyether blocks, respectively. Dynamic mechanical measurements of typical copolymers revealed the presence of at least two different nylon moieties. The melt rheology data reflect a general increase in the pseudoplasticity of the copolymer with the increase of the polyether content. Increases of the polyether content in the copolymer result in an increased elongation and a decreased tensile strength and modu

ISSN:0032-3888    

DOI:10.1002/pen.760130203

出版商:Society of Plastics Engineers, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractZinc laurate was a powerful but short‐lived primary stabilizer. Epoxidized soybean oil, catalyzed by a trace of zinc, was a fairly good primary stabilizer. Organic phosphite ester served primarily to prevent premature failure due to zinc; phosphite/zinc mol ratio of 4.5/1 was optimum. These combined effects are consistent with present theories of stabilizer synergism, and also suggest some further possible mechanisms. Practically, the 3‐component system offers a low‐cost, efficient, non‐toxic stabilizer for plasticized polyvinyl c

ISSN:0032-3888    

DOI:10.1002/pen.760130204

出版商:Society of Plastics Engineers, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractFilling cold mold cavities with hot polymer melts at high pressures is of great practical interest. The transport approach to this process of solving the general equations of change with suitable equations of state to describe the flowing material has been largely ignored. No analytic solution is possible, and the non‐steady state flow adds a dimension which makes digital computation discouraging because of the core storage and execution time requirements.The mold filled in this simulation is a disk which hot polymer melt enters through a tubular entrance located at the center of the top plate. The tube is 2.54 cm. long and has a radius of 0.24 cm. The plate separation and outer radius of the disk cavity may be varied. A constant pressure applied at the entrance of the tube causes the flow. The cavity walls are kept at various low temperatures. The reported results are for rigid polyvinyl chloride (PVC).The general transport equations, i.e. continuity, momentum, and energy, for a constant density power law fluid are used to solve the flow problem. Convergence to the differential solutions is guaranteed but since a lower limit was imposed on the time increment by the core storage limit of the computer facilities (27K) and long execution times, all results are semiquantitative for the problem as stated.Using the results obtained it is possible to predict “fill times”. The formation of a frozen polymer skin as the cavity fills may be followed via the velocity profiles. The temperature profiles which reflect cooling and the amount of viscous heat generated provide the basis for studying resin thermal degradation effects.Finally, because so much of the total pressure drop is disispated in the entrance tube, and so much viscous heat is generated there, this study indicates that the design of the gate and runner system is perhaps the most important facet of success in mold fi

ISSN:0032-3888    

DOI:10.1002/pen.760130205

出版商:Society of Plastics Engineers, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractSome of the problems associated with the study of failure are reviewed and exemplified by results on two commercial grades of PVC. The whole range of failure phenomena, from crazing to fracture, and the effect of notches on durability is discussed. A test schedule involving minimum experimental effort for the evaluation and comparison of the long term durability of thermoplastic materials is proposed.

ISSN:0032-3888    

DOI:10.1002/pen.760130206

出版商:Society of Plastics Engineers, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractWe have investigated the low temperature transitions in a urethane prepolymer crosslinked with various amines and triols by measuring their dynamic mechanical properties over a temperature range of 25°C to approximately − 190°C. In the formulations studied, a low temperature transition was observed near − 140°C and the transition was shown to be related to the electronic and steric influences of the curing agent structure at the crosslink site. A quantitative relationship was demonstrated between the low temperature transition peak intensity and the polymer's crosslink density. The above relationships were derived from torsion pendulum and solvent swell experimen

ISSN:0032-3888    

DOI:10.1002/pen.760130207

出版商:Society of Plastics Engineers, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractThe various types of extensional flows and extensional viscosities are defined and methods of measurement discussed. The role that each of these extensional viscosities plays in various polymer fabrication processes is discussed with examples. Finally, it is shown how engineering analyses of these complex flow fields are conducted using simplified phenomenological equations for the rheological behavior. This approach is recommended for use until such time as tensorially correct, mathematically tractable constitutive equations that are based on molecular theory are available.

ISSN:0032-3888    

DOI:10.1002/pen.760130208

出版商:Society of Plastics Engineers, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractSome commonly used empirical equations of state for polymers are considered: the Spencer‐Gilmore equation with two and three adjustable parameters, the Whitaker‐Griskey equation, and the Rehage‐Breuer equation. Also, a new equation is proposed: the Inverse Volume equation. These equations are evaluated with regard to fitting experimentalP‐V‐Tdata and agreement with experimental data on isothermal compressibility and thermal expansion coefficient. The adjustable parameters for each equation are determined with the help of Rosenbrock's optimum‐seeking technique. Analysis of the residuals on specific volume for a variety of materials suggests that the Spencer‐Gilmore equation with three adjustable parameters, the Rehage‐Breuer and the Inverse Volume equations yield the smallest and most random residuals and thus the least systematic error. The same three equations mentioned above yield results in good agreement with experimental isothermal compressibility data. However, among all the equations considered in this study, the Inverse Volume equation yields the best agreement with experimental thermal expansion coefficient data. Furthermore, it is the only equation to correctly predict the rise in thermal expansion coefficient with increas

ISSN:0032-3888    

DOI:10.1002/pen.760130209

出版商:Society of Plastics Engineers, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractTwo naturally occurring micas, phlogopite and muscovite, were ground and classified according to their average aspect ratios (flake equivalent diameter to thickness ratio). These flakes were then used to reinforce a polystyrene copolymer and a polyester resin. The compression molded test pieces were tested in flexure and the flexural strengths and flexural moduli determined for each aspect ratio. The experimental results indicate a strong dependence of strength and modulus on the flake aspect ratio up to a value of 100–200 for these systems. At high volume fractions, 0.6 to 0.7, high aspect ratio mica composites yielded flexural strengths of 35–45,000 psi with flexural moduli of 10–14 million psi. Notched Izod values were in the range of 0.5–1.4 ft lb per inch of notch. These results were compared with the theoretical treatments of Padawer and Beecher, an

ISSN:0032-3888    

DOI:10.1002/pen.760130210

出版商:Society of Plastics Engineers, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractUsing Oxygen Index and the XP‐2 test to measure flammability and smoke characteristics, a broad spectrum of thermoplastic and thermoset polymers, both commercial and experimental, were investigated to elucidate the effect of structure on fire properties.In general, polymers with aliphatic backbones are very flammable, but their tendency to generate smoke is minimal. The addition of flame retardants, especially halogen compounds, while reducing their tendency to burn, increases the evolution of smoke. Halogen‐containing polymers are usually non‐flammable, with high Oxygen Indices, but display high smoke generation. Polymers containing an aromatic group in the side chain, such as polystyrene, are both highly flammable and high smoke producing. However, polymers with the aromatic group in the main chain, such as polysulfone, polycarbonate and polyphenylene oxide, are intermediate in both Oxygen Index and smoke generation.After investigation of the various test methods available, it is concluded that no one test will be satisfactory to measure the flammability characteristics of polymers and that a combination of methods must be

ISSN:0032-3888    

DOI:10.1002/pen.760130211

出版商:Society of Plastics Engineers, Inc.    

年代:1973

数据来源: WILEY