摘要:

AbstractShear viscosity and die swell ratio of acrylonitrile‐butadiene‐styrene filled with glass beads and glass fibers were measured. The relative viscosity of the composites increased with filler content, but decreased with shear rate. At low shear rates, fiber filled systems had higher relative viscosities than bead filled systems. At high shear rates, the opposite was observed. The die swell ratio of the unfilled material increased linearly with the logarithm of the shear rate. Systems highly filled with glass beads or fibers showed a maximum in the die swell ratio at medium shear rates. The magnitude of the maximum in the die swell ratio increased with the filler content and the die length, up to a certain length, in a series of dies that had the same radius. The presence of a maximum in the die swell ratio of the filled melts is explained by an order‐disorder phenomenon observed earlier

ISSN:0272-8397    

DOI:10.1002/pc.750100102

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThe reduction in fiber length during extrusion and injection molding of two commercial glass fiber‐reinforced polypropylene products containing 30 percent by weight of glass fibers was studied. The first product had very small fibers of average length around 0.5 mm and also contained a coupling agent. The second product contained relatively longer glass fibers of 9 mm length and no coupling agent. In both cases, fiber attrition occurs predominantly at the solid‐melt interface in the meiting zone of the extruder. However, in the short fiber granules, the maximum of the length distribution, which for the initial sample is around 0.5 mm, moved to shorter fiber lengths along the screw channels further from the hopper. In the long fiber granules, a bimodal length distribution was obtained in the intermediate channels; the first maximum was around the original length of 9 mm and the second centered around 0.5 mm. Thus, the forces at the solid‐melt interface result in fiber breakage to lengths which are predominantly around 0.5 mm. The fiber attrition was observed to be more severe in injection molding apparently because of higher shear rates and also because the fibers had to pass through narrow channels. The measured distributions of fiber length along the screw channels for the two products are presented, and the possible mechanisms of fiber breakage are discussed. The mechanical properties of samples containing different fiber length distributions and the effects of fiber length and interfacial adhesion on properties are presented and discussed in Pa

ISSN:0272-8397    

DOI:10.1002/pc.750100103

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractTwo commercial grades of glass fiber‐reinforced polypropylene granules, one containing short fibers of average length around 0.5 mm with a coupling agent and the other containing relatively much longer fibers mostly around 9 mm, but no coupling agent, were injection‐molded into dumbbells and tested in tension between −43 and 90°C. There is considerable fiber attrition during injection molding; the fiber lengths are reduced to average values of 0.4 to 0.8 mm for thses two samples. Also during injection molding of the test sample, partial molecular alignment of the matrix (polypropylene) occurs which supplements the reinforcement of the matrix due to the aligned glass fibers (30 percent by weight) present in the composite sample. The stiffness and strength of these samples do not reflect the effects of fiber lengths since most of the fibers are of very small length in the molded specimen and also since the sample with longer fibers has a non‐uniform distribution of fibers. While the interfacial shear strength does not appear to play a significant role in determining stiffness, it turns out to be extremely important in controlling strength, particularly at the higher test temperatures. The room temperature impact strength is high for the sample containing relatively longer fibers of average length around 0.8 mm in which fiber dispersion is non‐uniform and fiber agglomerates are present. Acoustic emission data shows that debonding and fiber pull‐out are the main contributors to sample toughness; this observation is supported by scanning electron micrographs of the fract

ISSN:0272-8397    

DOI:10.1002/pc.750100104

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractIn this paper, a simple theoretical model for elastic properties of short fiber‐reinforced thermoplastic (SFRTP) composite systems is described, which considers the effect of two important structural parameters, viz., fiber aspect ratio distribution and fiber orientation distribution. An experimental technique for producing SFRTP samples featuring a fairly uniform fiber orientation is described, and a broad set of experimental results on the mechanical properties of SFRTP systems based on polystyrene (PS) and polyethylene (PE) resins with several fiber loadings is presented. The use of the simple theoretical model to analyze the experimentally‐determined elastic properties is discus

ISSN:0272-8397    

DOI:10.1002/pc.750100105

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThe strength and fracture properties of a polypropylene filled with ultrafine calcium carbonate (0.07 μm) have been studied in the composition range of 0 to 40 percent by volume. Untreated and surface treated (with stearic acid and a titanate coupling agent) grades have been considered. The untreated filler caused a decrease of toughness whereas a maximum, at ∼10 percent, was observed for the treated filler. The fracture energy was analyzed in terms of the crack pinning model. Due to the very small size of particles the pinning contribution proved to be negligib

ISSN:0272-8397    

DOI:10.1002/pc.750100106

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractSeveral commercially available glass fiber reinforcements were analyzed to determine the amounts (“loadings”) and types of coatings applied by their manufactures. Loadings were determined by solvent extraction and pyrolysis and ranged from 0.54 to 4.22 weight percent with the heaviest amounts on random mats and the least amounts on rovings intended for filament winding and weaving. The major components of the solvent‐extracted coatings were identified by infrared (IR) and proton nuclear magnetic resonance (NMR) spectroscopies. All of the coatings analyzed could be sorted into three classes of coatings which matched the matrix types recommended by the glass manufacturers. In each case, the coating consisted primarily of a mixture of two separate materials, designated as the “unreacted resin” and the

ISSN:0272-8397    

DOI:10.1002/pc.750100107

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractIn this paper the electromagnetic inductance (EMI)‐shielding of metal‐and ferroelectric‐particle filled polymers is described. The composite, containing only metallic fillers, has a shielding effectiveness comparable to conventional products. The addition of a few percent of ferroelectric material to this composite enhances the shielding behavior by several orders of magnitude—without increasing its electrical conductivity. In this three component composite the shielding effectiveness reaches a maximum close to the ferroelectric/paraelectric transition temperature. The synergetic effect, obtained by the addition of ferroelectrical particles, is related to the high dielectric losses of ferroelectric material close to its transition temp

ISSN:0272-8397    

DOI:10.1002/pc.750100108

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractA model is presented that simulates on a microcomputer the fiber distribution in a planar arrangement applicable to thin sheets of composites. Although it does not take into account spatial fiber interference, the software allows one to investigate a number of important design parameters. The inputs used in the simulation are: thickness of the composite sheet, diameter and volume fraction of fibers along with fiber length, and angular position which can be specified in a number of ways. The program utilizes the internal random function to depict each fiber, as it is generated, in a “simulation window” of the monitor while the mathematics of the system are being done simultaneously within the smaller “valid window”. The procedure prescribes that the center of gravity of all fibers be uniformly distributed over the simulation window area. For that reason and because the 2D model is extended to simulate a three‐dimensional sheet, results will represent the ideal configuration or upper bonds of a corresponding practical case. Graphical representations and statistics are thus produced to quantify the geometric pattern of the system. One use of the model is, for instance, to see how the geometric patterns and their associated statistical parameters compare at a given volume fraction when the fiber length is fixed or when fiber length can be modeled as a normal, a uniform, or another specific dis

ISSN:0272-8397    

DOI:10.1002/pc.750100109

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractEdge notched samples of polypropylene (PP) and high‐density polyethylene (HDPE) containing different mica concentrations were tested in mode I tensile loading. Crack growth was approximated by a non‐linear regression of exponential form using statistical software (SAS). Characterization of fatigue crack propagation (FCP) was made using the Paris‐Erdogan law. The crack front in PP was preceded by a wide plastic zone in which craze developed, leading to a discontinuous crack growth. Using spline functions, a margin between maximum and minimum FCP rates, recorded during the crack progression, is presented along with the average FCP rates. It is shown that mica‐reinforced PP samples exhibit higher FCP rates than unfilled PP. In HDPE, mica reduces FCP rates resulting in a higher resistance to fatigue crack propagation. Effect of test frequency is presented for unfilled polymers and 10 percent mica concentration by weight in both matrices. An increase in the test frequency has no significant effect on FCP rates for both raw and mica‐reinforced PP. Unfilled and mica‐filled HDPE show noticeable decrease in FCP rates with increasin

ISSN:0272-8397    

DOI:10.1002/pc.750100110

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

ISSN:0272-8397    

DOI:10.1002/pc.750100101

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY