摘要:

AbstractA servo‐hydraulic testing system which can simultaneously produce high loads and rapid response is described. This system allows the testing of relatively large plastic specimens, which makes it possible to perform dynamic‐mechanical and transient experiments on high modulus materials, specimens routinely molded for tensile testing, and specimens removed from actual processed articles. Such large specimens also permit the use of extensometers directly attached on the gage section, providing important data for the accurate calculations of material properties. Dynamic‐mechanical data on poly(methyl methacrylate), glass‐filled nylon, and talc filled polypropylene specimens removed from an injection‐molded dishwasher tub were obtained to demonstrate the capability of the system. Stress relaxation experiments in the nonlinear range were performed on polycarbonate to illustrate the transient testing capability of t

ISSN:0032-3888    

DOI:10.1002/pen.760251502

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractPhotocurable materials such as photoresists, UV‐curable inks and paints, etc., can be analyzed by a variety of techniques. Commonly, these analyses are performed in a discontinuous mode, i.e., samples are exposed to light for varying times and subsequently they are subjected to analysis. Rates of reaction, conversion, etc., are determined from the residual functionalities; in the case of differential scanning calorimetry, these parameters are derived from the residual heat of reaction. In order to determine “photo speed” or sensitivity, a number of exposures of varying duration are necessary to obtain rates of reaction. By combining an exposure unit with a differential scanning calorimeter, the photoreaction can now he observedin situ. Determination of speed or rate of reaction is reduced to a single experiment. As a consequence, effects of wavelength, intensity, temperature, and environment are quickly examined as is demonstrated here for a photoresist. During the second scan residual exotherms can be used to determine reaction extend or formation of new thermally active products. Conversion may be limited if Tgrises during polymerization to exceed exposure temperatures. In addition, the formation of inaccessable functionalities has to be accounted for during evalu

ISSN:0032-3888    

DOI:10.1002/pen.760251503

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe equilibrium phase behavior of the partially miscible system polystyrene‐polybutadiene‐chloroform was studied at 25°C and 1 atm pressure by using gel permeation chromatography to analyze the conjugate phases. Three narrow molecular weight distribution samples of each polymer were used to provide nine examples of the system for study. The Flory‐Huggins theory was used to determine the polymer‐polymer interaction parameter χ23, When literature values of the two polymer‐solvent interaction parameters χ12 and χ13 were used, the χ23 values generally were found to be negative and to show no distinct concentration dependence. No significant improvement was found when the literature value of only the polybutadiene‐chloroform interaction parameter was used to simultaneously generate values of χ23 and χ12. Values of χ23 at the critical point, χ23,cr, were found to increase with increasing p

ISSN:0032-3888    

DOI:10.1002/pen.760251504

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractA new rapidly crystallizing aromatic‐aliphatic polyamide has been developed by reacting 4,4′‐methylene bis(phenylisocyanate) (MDI) with aliphatic dicarboxylic acids. The polymer has a Tgof 130°C and Tm, of 290°C. Glass reinforced resin shows better flexural creep resistance at high stress levels (3000 psi) at elevated temperatures (75°C) than most reinforced semicrystalline commercial polymers i.e., nylons, thermoplastic polyesters and acetal because of its high Tg. Glass reinforced polyamide can be injection molded on conventional equipment to afford flexural moduli in excess of 1,000,000 psi and HDT's as high as 250°C at 264 psi. Because of the high level of crystallinity these parts will not dissolve or swell in most organic solvents and this aromatic aliphatic polyamide is also far less sensitive to moisture than commerci

ISSN:0032-3888    

DOI:10.1002/pen.760251505

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractAn expression is presented which can be used to correlate and predict, in an empirical fashion, polymer self‐diffusion coefficients in solution over a wide range of concentrations and molecular weights, and whose parameters can be established with a minimal amount of data. Predictions thus made have been found to agree well with the limited amount of available experimental data over the entire concentration‐molecular weight spectrum studied to date. This is in marked contrast to other available expressions, whose validity is confined to a narrow range of concentrations and/or molecular weig

ISSN:0032-3888    

DOI:10.1002/pen.760251506

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractKinetics of simultaneous interpenetrating networks (SIN) composed of a polyurethane resin (PU) and an unsaturated polyester resin was studied. A differential scanning calorimeter (DSC) was used to monitor the polymerization course. It was found that increasing the polyester content in a PU‐polyester SIN enhanced the polymerization of PU due to the “solvent effect” of polyester. On the other hand, increasing the PU content in the SIN retarded the polymerization of polyester due to the “cage effect” of PU. Polymerization sequence of the SIN could be controlled by employing different initiators for polyester reaction. The degree of crosslinking in each SIN component had a significant effect on the dynamics of the SIN formation and on the limiting conversion of the polyester

ISSN:0032-3888    

DOI:10.1002/pen.760251507

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThis paper deals with a procedure to simulate the foaming process of polyurethane integral skin foams. The process involves heat generation by chemical reaction, heat loss through the mold, and local vaporization and condensation of the solvent. To simulate this dynamic process, a boundary mobile cell model was proposed. Each cell contains a certain mass of the solvent. The volume, temperature, and pressure of each cell call be estinlated by the quantity of heat which is generated and/or transferred in the cell, assuming that no pressure gradient exists and the total volume of each cell is constant. For a typical polyurethane system, apparent density profiles were predicted theoretically, as well as chemical conversion, temperature, and pressure profiles. Experimental results were compared with the theoretical values. Rather good agreement between them was obtained, though no adjusting parameter was introduced.

ISSN:0032-3888    

DOI:10.1002/pen.760251508

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractInterest in potential high‐performance polymers, leading to characterization and development of the rodlike poly(p‐phenylene benzobisoxazoles) (PBO) and poly(p‐phenylene benzobisthiazoles) (PBT), has recently been extended to a related group of polymers referred to as AAPBO, ABPBO, AAPBT, and ABPBT. In this study, geometry‐optimized CNDO/2 molecular orbital calculations have been carried out on AAPBO and ABPBO model compounds to determine conformational energies as a function of rotation about each type of rotatable bond within the repeat units. For AAPBO, which contains two types of rotatable bonds per repeat unit, the bond between the benzoxazole group andp‐phenylene group prefers the coplanar conformation with a barrier to free rotation of 2.1 kcal mol−1, while the bond between the benzoxazole groups prefers a conformation approximately 60 degrees away from coplanarity with a barrier to coplanarity and to free rotation of 3.6 kcal mol−1. For ABPBO, which contains only the former type of rotatable bond per repeat unit, the coplanar conformations were preferred with a barrier to free rotation of 1.6 kcal mol−1. These results are in excellent agreement with the results of both theoretical and experimental studies on the structurally analogous PBO. They are also consistent with the liquid crystalline behavior found for ABPBO bu

ISSN:0032-3888    

DOI:10.1002/pen.760251509

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractCapillary flow studies on bulk molding compound (BMC) using an instrumented injection‐molding machine are reported. The significance of extensional flow effects with fiber‐reinforced materials is emphasized. The extensional flow behavior in converging dies is modeled, and a means of evaluating both extensional and shear viscosity from capillary flow data is proposed. Methods of correcting results for the effect of deformation heating are discussed. The shear and extensional flow behavior of BMC in the temperature region 18 to 58°C can be fitted to a simplified Arrhenius

ISSN:0032-3888    

DOI:10.1002/pen.760251510

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractOrifice flow measurements have been performed at high strain rates on bulk molding compound (BMC) using convergent dies. A range of die angles and bore diameters was examined. Two models for flow behavior have been compared. It appears that, with BMC, there is a transition from constrained convergence to convergence with recirculation at a die semiangle of approximately 56 degrees.

ISSN:0032-3888    

DOI:10.1002/pen.760251511

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY