摘要:

AbstractA new trifunctional epoxy resin, Tris‐(hydroxyphenyl)methane triglycidyl ether, was compared to a state‐of‐the‐art resin, 4,4′‐diaminodiphenyl methane (TGDDM), in graphite composites. Rubber‐toughened brominated and nonbrominated formulations were compared for their mechanical performance, environmental stability, thermochemical behavior, and flame retardancy. It was found that the new resin performs almost the same way as the TGDDM does, but has some improved properties. The fracture toughness of the various formulations was studied carefully and the overall performance of the new resin

ISSN:0272-8397    

DOI:10.1002/pc.750060202

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractInitial screening of carboxy‐terminated butadiene acrylonitrile (CTBN) rubber‐toughened brominated formulations for graphite composites has been reported previously. This study is a further investigation, focusing on the performance of the brominated polymeric additives as a potential flexibilizing agent for graphite composites, using different molecular weights of the Br source. Increasing segment lengths of the polymeric backbone chain of brominated polymeric additives (BPA) are examined in a new development, trifunctional epoxy resin and is compared with a 10 percent rubber‐toughened formulation of the same epoxy resin. Results show that when the Br content in the graphite composite was increased without the use of rubber, the mechanical properties improved. Mechanical and other properties of the graphite composites are disc

ISSN:0272-8397    

DOI:10.1002/pc.750060203

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe performance of short fiber molded composite structures is determined uniquely by the properties of the molding material and the process induced fiber orientation. Consequently, the capability to accurately predict the fiber orientation distribution is of fundamental importance in computer‐aided mold design. Methodology for the numerical prediction of fiber orientation during the mold‐fill process is presented for a short glass fiber thermoset (57 percent phenolic resin, 10 percent calcium carbonate filler, and 33 percent glass fiber by volume). On the basis of a finite element flow characterization, Jeffery's orientation equation is numerically integrated along streamlines to calculate fiber orientation. Correlation of experimental and numerical results for an end‐gated bar with a molded‐in hole is reasonab

ISSN:0272-8397    

DOI:10.1002/pc.750060204

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractMicroscopic observations of thermoplastic poly(ethylene terephthalate) reinforced with short E‐glass fibers revealed a unique matrix microstructure influenced by the orientation of densely packed glass fibers. The observed platelets tend to surround a fiber in a cylindrical sheath pattern. This observation of the crystalline platelet morphology is possible by the combination of ion‐etching and the shadowing effect of protruding fib

ISSN:0272-8397    

DOI:10.1002/pc.750060205

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractPropropylene was reinforced with various concentrations of glass fiber (0, 10, 20, 28, and 35 percent by weight) and standard test samples were prepared by injection molding under identical conditions. The influence of fiber concentration on the morphology and mechanical properties was investigated using polarizing microscope, scanning electron microscope, Instron universal testing machine, etc. Tensile strength, tensile modulus, and flexural strength were found to increase with glass fiber content, while impact strength was reduced. These observed changes in mechanical properties were explained in terms of alterations in skin‐core morphology, spherulite size, transcrystallinity, etc. The efficiency of reinforcement factor (K) was calculated for all the composites. It was found thatKdecreases with the increase of fiber concentration. This study attempts to correlate fiber concentration and polymer morphology with mechanical properties and the overall efficiency of reinforcement. This would help in optimizing the fiber content to prepare molded composites with desired mechanical propertie

ISSN:0272-8397    

DOI:10.1002/pc.750060206

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThis paper describes three‐phase syntactic foams consisting of microballoons, resin, and air voids. The microballoons comprise carbon and silica spheres in various proportions, always at a close‐packed structure (0.6 volume fraction). Compressive, electric, and dielectric properties are demonstrated as functions of parameters like resin content, temperature, and various carbon/glass proportions. The good combination of mechanical, thermal, and electrical properties may qualify these foams for applications including attenuation of electromagnetic radiat

ISSN:0272-8397    

DOI:10.1002/pc.750060207

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractExperiments utilizing charges constructed of black and white sheet molding compound (SMC) reveal the basic kinematic mechanisms controlling the flow of the fiber‐filled compound in compression molding. The experimental results show that SMC deforms in uniform extension within individual charge layers, with slip occurring at the mold surface and, for slower closing speeds, also between the layers of SMC. When the mold closes rapidly, the charge extends uniformly through its thickness, with all slip concentrated at the mold surfac

ISSN:0272-8397    

DOI:10.1002/pc.750060208

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractAn efficient and economical experimental apparatus has been designed and built which delivers a known radiant heat flux and simultaneously measures the in‐depth temperature profiles in polymeric materials. Test samples are maintained in a controlled environment and are heated radiantly by a silicon carbide heating element capable of producing heat fluxes up to 7.0 cal/cm2‐sec. The experimental data produced by this device are extremely accurate and therefore are suitable for use in verification of numerical models. The utility of the apparatus was demonstrated by measuring temperature profiles to approximately 1000°C in a glass‐filled phenol‐formaldehy

ISSN:0272-8397    

DOI:10.1002/pc.750060209

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe increased utilization of reinforced polymeric blend composite materials has prompted renewed interest in mathematical models which can explain or predict the characteristics of processing and the properties of composite materials in terms of the properties and concentration of the components. As a first step toward developing the rules for multicomponent systems we restrict our attention to the Lee‐Nielsen's model and concepts of two‐component systems with particulate inclusions embedded in a continuous matrix. The following property‐mixing relationships are then discussed: (1) reinforcement of uncured and cured rubber composites; (2) thermal expansion of polymer composites; (3) elastic modulus, and thermal conductivity of (reinforced) polymeric foam materials; and (4) heat buildup of rubber composites. Some important concepts and principles which have evolved from our experimental attempts at correlating the behavior of heterogeneous multiphase polymer materials are also disc

ISSN:0272-8397    

DOI:10.1002/pc.750060210

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractWe present a thermoelastic analysis of the composite cylinder model for a undirectional composite including anisotropic fibers and an interphase region. We have found the magnitude of the residual thermal stresses on the micromechanics level induced by differential shrinkage between the anisotropic fibers and the matrix. For typical composites the largest residual stress is tension along the fiber direction, and a simple lower bound expression for this stress is given. Prediction of the magnitude of the thermal stresses requires knowledge of the thermal and physical properties of the matrix. The relevant properties for epoxy and thermoplastic matrices are discussed. The magnitude of the residual stresses can be reduced by tailoring the interphase region, but only if the interphase region serves to reduce the temperature for the onset of stress buildup. The volume fraction dependence of the longitudinal and transverse thermal expansion coefficients of the composite is compared to analogous expressions in the literature which do not include anisotropy of the fibers.

ISSN:0272-8397    

DOI:10.1002/pc.750060211

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY