摘要:

AbstractThe Combination of reaction injection molding and pultrusion has resulted in a new processing technique, RIM‐Pultrusion, Which has been used to produce a thermoplastic epoxy prepreg. This prepreg has been used to produce a long‐fiber injection molded phenoxy/carbon fiber composite with near‐Zero void content. A heat‐activated curing system has been developed, which allows injecton molding of the prepreg to form a thermostet long‐finer epoxy/carbon finber composite. The RIM‐ pultrusion conditions for producing an injection moldable prepreg are described. Capillary rheomety is used to study the epoxy resin to determine the proper molar ratio for RIM‐Pultrusion. The long‐fiber epoxy compostie is analyzed with dynamic mechanical analysis (DMA) and Fourier transform infrared spectroscopy (FTIR). Also., the impact strength and solvent resistance of the long‐fiber composite are examined. The properties of the thermoset long‐fiber epoxy xomposite are compared to those of a thermoplastic injection molded long‐fi

ISSN:0272-8397    

DOI:10.1002/pc.750150202

出版商:Society of Plastics Engineers    

年代:1994

数据来源: WILEY

摘要:

AbstractThe mechanisms of void formation and elimination during the stamping process of a polypropylene/glass fiber composite have been infestigated as a function of temperature, pressure, and time. Experiments were performed in a temperature and pressure controlled chamber, equipped with a rapid cooling facility. Samples of the composite as well as model polypropylene specimens containing calibrated voids were held at 200°C at different levels of hydrostatic pressure (1,10,100, and 300 bars), for a period of either 1 or 10 min. The speciments were subsequently characterized by denstiy measurements and morphologival observation. It was shown that: i) the expansion of the composite observed during the heating at 200°C under atmospheric pressure is largely induced by the gases previously dissolved in the polymeric matrix, ii) the rapid increase of the pressure during the stamping process leads to the closing of voids and, iii) the final holding under high calculation of void growth and shrinkage is in agreement with the morphological observation

ISSN:0272-8397    

DOI:10.1002/pc.750150203

出版商:Society of Plastics Engineers    

年代:1994

数据来源: WILEY

摘要:

AbstractThe goal of this work was to investigate the effect of two stage pressure molding on the compression molding of a sheet molding compound (SMC). It has been shown in previous studies that a rapid drop in pressure during SMC curing significantly reduced severity of sink marks. This study concentrated on a method of predicting the optimum time during curing to release pressure by examining material behavior through process data from in‐mold sersors. A simple control scheme was them applied for automatic pressure release at the optimum time corresponding with the peak of the material expansion and the onset of the reaction exother

ISSN:0272-8397    

DOI:10.1002/pc.750150204

出版商:Society of Plastics Engineers    

年代:1994

数据来源: WILEY

摘要:

AbstractThe manufacture of polymer composites through the process of resin transfer molding (RTM) involves the impregnation of the reactive polymer resing into a mold with preplaced fibrous reinforcements. Determination of RTM processing conditions requires the understanding of various parameters, such as material properties, mold geometry, and mold filling conditions. Modeling of the entire RTM process provides a tool for analyzing the relationship of the important parameters. This study developed a nonisothermal 3‐D computer simulation model for the mold filling process of RTM based on the control volume finite element method. The model will be able to simulate mold filing in molds with complicated 3‐D geometry. Results of some numerical studies in RTM show the applications of the proposed mo

ISSN:0272-8397    

DOI:10.1002/pc.750150205

出版商:Society of Plastics Engineers    

年代:1994

数据来源: WILEY

摘要:

AbstractThe molecualr dynamics of a semicrystalline polyimide were studied by13C nuclear magnetic resonance (NMR) spectroscopy. The T1spin lattice relaxation times were observed over a temperature range of 24°C to 94°

ISSN:0272-8397    

DOI:10.1002/pc.750150206

出版商:Society of Plastics Engineers    

年代:1994

数据来源: WILEY

摘要:

AbstractThis work is and anyalysis of the performing process of a thermoformable glass fiber mat. Important processing variables associated with the preforming operations were extracted from stamping experiments. From the study of deformation modes, we may conclude that the defects found in fiber mat preforming are closely related to these deformation modes. Stretching causes finer thinning and re‐orientation. Bending results in mat springback and thickness reduction, while in‐plane compression induces wrinkles through buckling. Each defect may be reduced by specific adjustments. These adjustments, however, tend to interact with each other, and make the preforming control a challenging t

ISSN:0272-8397    

DOI:10.1002/pc.750150207

出版商:Society of Plastics Engineers    

年代:1994

数据来源: WILEY

摘要:

AbstractThe single filament composite (SFC) test has been uses to investigate the adhesion of carbon and glass fibers to thermoplastic matrices. A new modification of the test is proposed, consisting of SFC specimens stretched until the neck formation is complete. This makes the measuring of fiber fragment lengths much easier and allows a wider class of matrices to be investigated. The adhesion between fiber and thermoplastic matrix is strongly dependent on the contact forming conditions. With increased time of thermal treatment, interfacial bonding is improved and the failuere mode is changed. In the case of por fiber‐mitrix adhesion, interfacial failure occurs. With an increase in interfacial shear strength, the martix cracks perpendicular to the fiber at the fiber break

ISSN:0272-8397    

DOI:10.1002/pc.750150208

出版商:Society of Plastics Engineers    

年代:1994

数据来源: WILEY

摘要:

AbstractIn this paper, we model the elastic modulus ofin‐situcomposite fibers from polymer blends where a fibrous liquid crystalline polymer (LCP) phase is induced by drawing. We propose a composite model to account for the change of the elastic moduli of the reinforcing LCP phase with the draw ratio of the composite fibers. We envisage the LCP phase as a composite of a perfectly oriented chain aggregate and a randomly oriented chain aggregate which are connected in series. We then derive equations for the longitudinal and the transverse elastic moduli of the composite fibers based on the well‐known Halpin‐Tsai equation and the composite model of the reinforcing LCP phase. Using this approach, we are able to make a number of predictions including the transverse elastic modulus and mechanical anisotropy. Our results show that theoretical predictions of the longitudinal elastic modulus agree fairly well with experimental results for polycarbonate/Vectra composites. The proposed modulus equations will be useful in providing guidelines for fabrication and applications of this new class of polymeric mate

ISSN:0272-8397    

DOI:10.1002/pc.750150209

出版商:Society of Plastics Engineers    

年代:1994

数据来源: WILEY

ISSN:0272-8397    

DOI:10.1002/pc.750150201

出版商:Society of Plastics Engineers    

年代:1994

数据来源: WILEY