ISSN:0272-8397    

DOI:10.1002/pc.750050102

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

ISSN:0272-8397    

DOI:10.1002/pc.750050103

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractPhysical properties of composites as a function of filler content have been described in the past through models requiring the solution of macroscopic equations of motion for an elastic continuum or, on a more empirical level, by the assumption of various compositional averaging schemes. We discuss a model drawn from our molecular mixture theory. This allows us to avoid the formal problems attending concentrated suspensions and introduces molecular filler‐medium interaction parameters. Comparisons with experimental material and empirical equations involving bulk modulus and thermal expansivity will be given. The theory opens the possibility of determining interfacial strengths from appropriate mechanical and thermal measurements and of predicting one set from another set of dat

ISSN:0272-8397    

DOI:10.1002/pc.750050104

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe interaction of very dilute solutions of a cationic vinylbenzyl silane (CVBS), a methacrylate functional silane (γ‐MPS), and an isopropyl‐tri‐(dioctylpyrophosphato) titanate (IDT) with a mica surface has been studied by carbon analysis. For all three coupling agents the dependence of adsorption with time of treatment follows a step‐like curve, where each step corresponds to a monolayer coverage on the mica. Under the operating conditions used it was noted that a particular monolayer is always completed before the next is started. The adsorption of γ‐MPS was found to be very sensitive to the time allowed for hydrolysis of the silane, while the adsorption of CVBS was relatively independent of the hydrolysis time when it is varied from 0 to 5400 s. The results indicate that γ‐MPS and CVBS near the mica surface form a dense structurally regular multilayer phase with the silane molecules oriented normal to the surface. IDT molecules occupy a surface area on mica which is characteristic of their b

ISSN:0272-8397    

DOI:10.1002/pc.750050105

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe molecular structure of γ‐methacryloxypropyltrimethoxysilane (γ‐MPS) deposited on the surfaces of particulate mineral fillers was modeled by adjusting the pH of an aqueous alcoholic solution of the silane in absence of a substrate. Hydrolyzates obtained from the solution were studied by gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FT‐IR) and found to be polymethacryloxypropylsilsesquioxanes whose configuration and molecular‐weight distribution were dependent on the solution pH. In acidic environments (below pH 4) the polycondensation mechanism appeared to proceed in a selective manner to form polycyclic blocks which resemble a beaded chain following condensation between blocks. Under more neutral and basic conditions (at or above pH 4) the polycondensation mechanism, resulted in polymethacryloxypropylsilsesquioxanes with the more equilibrated double chain ladder configuration. The molecular weight distribution of these structures was dependent on the stability of the silanol or the silanolate ion. Extremely high‐molecular‐weight and polydisperse polymethacryloxypropylsilsesquioxanes were generated at near neutral pH due to the formation of the double chain ladder configuration and the high silanol instability in this pH range. The two different polymethacryloxypropylsilsesquioxane configurations were also observed on γ‐MPS modified metal oxide substrates. The structures help explain some of the previously observed trends with respect to γ‐MPS adsorption on particulate mineral fillers. In strongly basic environments the methacrylate function of γ‐MPS partially hydrolyzes to form sodium carboxylate, and carbon dioxide is absorbed from the air and reacts to

ISSN:0272-8397    

DOI:10.1002/pc.750050106

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe Rheometrics mechanical spectrometer has been employed in the parallel plate mode to study the rheological behavior of pure polypropylene resin and melts filled with 10, 20, 30, and 40 percent by weight glass fibers. Steady‐state shear data show that, for loadings above 20 percent fiber, increasing fiber loading leads to an increase in viscosity of the melt. The effect of increasing fiber content becomes smaller at higher shear rates. For the same loading range, fiber addition increases the first normal stress difference, and the effect of fiber loading becomes smaller with increasing shear rate. At 10 percent loading, the viscosity of the filled polymer melt is lower than that of the pure resin melt. These results require further confirmation.Strain sweeps employing dynamic measurements in conjunction with the parallel plate mode of the Mechanical Spectrometer were carried out. In general, it was found the dynamic properties are strain dependent. Steady shear data employing the cone‐and‐plate mode were not repea

ISSN:0272-8397    

DOI:10.1002/pc.750050107

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractSeven samples of HDPE containing 0, 2, 5, 10, 25, 40 and 60 weight percent of mica were prepared on a roll mill at 200°C. The samples were tested atT= 150, 170, 190 and 210°C for a wide range of rate of deformation from 10−2to 2 × 104s−1. Both capillary and rotational rheometers were used. The samples were found to be thermally stable. The results indicate that η,G′, andG″ increase with mica content for the whole range of deformation rates. The relaxation time spectrum for the sample containing 60 weight percent of mica showed a particulate contribution. The zero shear viscosity was discussed in terms of suspensi

ISSN:0272-8397    

DOI:10.1002/pc.750050108

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractExtensional flow of mica‐filled high density polyethylene was studied at 150°C in a Rheometrics elongational rheometer. The constant strain‐rate mode at a rate of 10−3to 1.0 s−1, and the constant stress mode were used. The mica content was 0, 25, 40, and 60 weight percent. In both testing modes, the steady state elongational viscosities were obtained; those for the filled samples were about ten to twenty times larger than the shear viscosity at corresponding (low) rates of def

ISSN:0272-8397    

DOI:10.1002/pc.750050109

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe flow mechanism of particulate polymers during processing is reviewed. The extrusion of starch‐g‐poly(methyl acrylate) polymers is a good example of this type of processing, since graft copolymers retain their granular appearance and do not melt, even at high temperature, due to the rigid starch matrix. The formation of a continuous plastic by extrusion is accomplished by the sintering of heat‐deformed granules in the high‐pressure zone of the extruder die. Photomicrographs confirm this mode of formation. Plots of flow rate through the extruder die versus pressure in the die are presented. Tensile strengths and percent elongation of extruded specimens are not greatly affected by variations in flow rate. The equilibrium moisture content (about 5 percent) of starch‐g‐poly(methyl acrylate) plasticizes the starch component and thus reduces the operating pressure in the die. Tensile strengths, however, are unaffected by the presence of equilibrium moisture. Final traces of residual acid (resulting from initiator solution) are difficult to remove from starch‐g‐poly(methyl acrylate), and prolonged heating of the graft copolymer in the presence of this acid results in poly

ISSN:0272-8397    

DOI:10.1002/pc.750050110

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe mechanical properties of plastics and elastomers reinforced by short fibers are generally dictated by the selection of matrix and reinforcement. However, the high tensile properties attainable in these systems through laboratory processing techniques are frequently not obtained in conventional fabrication operations. To gain a wider latitude in meeting economic and performance constraints, the control of composite structure in the fabrication step should not be overlooked. Tool geometry and processing conditions can be manipulated specifically to control the fiber orientation distribution in the product. A study of fiber orientation in composite compounds during flow through runners, gates, and dies leads to recommendations for optimizing the directional strength and stiffness according to a kinematic model. Performance data on parts fabricated from various short‐fiber composite materials bear out these projection

ISSN:0272-8397    

DOI:10.1002/pc.750050111

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY