摘要:

AbstractThis paper reviews various common methods for studying fiber‐matrix interaction with specific evaluation of the critical fiber length method. Commonly accepted methods are often shown to be unsatisfactory because interfacial results may not be independent of fiber tensile strength properties. A new concept for measuring fiber‐matrix interaction in a single filament, or in a single uniaxially reinforced thin layer, sandwiched between two relatively thick unreinforced layers is proposed. This method relies upon variable curvature bending jigs introducing continuously changing longitudinal shear profiles across the fiber surface by clamping the sandwiched specimen onto the jig surface and also upon the availability of physical detection methods of debonding fro

ISSN:0272-8397    

DOI:10.1002/pc.750090402

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractGraft polymers were prepared by copolymerization of double bond terminated long chain poly(vinylpyridine), endowed with polar units interacting with glass, and butylacrylate (BA) having short groups interactive with polyethylene. These polymers were used to coat A glass beads which were mixed with polyethylene (PE) to obtain glass‐PE‐composites. Good adhesion due to the presence of the adhesive polymer, and to a glass hydrolyzing pretreatment, permits higher elastic moduli and higher tensile strengths than in their absence. The adhesive composition has some influence especially on the yield stress which is higher when using the g‐polymer endowed with longer BA branches. Theoretical predictions of the moduli are discussed and do not give satisfactory results when compared with the experimental values, except at low concentrations. Failure is observed to begin in the polar zone and its mechanism appears to be dependent on the presence or absence of adhesive.The experimental stress and strain at the beginning of failure are lower for untreated fillers. The specific volume variation\documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{\Delta V}}{{V_O }} $\end{document}during the tensile test appears to be an important index of adhesion. Both the critical strain at which detachment begins and the slope of the\documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{\Delta V}}{{V_O }} $\end{document}curve can be assumed as effective adhesion in

ISSN:0272-8397    

DOI:10.1002/pc.750090403

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractComparison of tensile characteristics (modulus, strength) measured for bought‐in laminates and also laminates manufactured in‐house with published data has proved the testing procedure to be sound and compression molding to give composites of good quality. In the theoretical domain, the micromechanical approach was used to predict engineering constants such as the longitudinal, transverse and shear moduli that characterize the laminate in its principal directions. For the off‐axis loading, macro‐mechanical abstraction was applied and the angular dependencies of the above composite parameters were further supplemented by those for the Poisson ratio and the ultimate strength. Regardless of the theoretical approach used, the error of the predictions relative to the experimental data does not exceed 10

ISSN:0272-8397    

DOI:10.1002/pc.750090404

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractNon‐isothermal crystallization kinetics of poly(ether‐etherketone), PEEK, in the presence of carbon fibers has been studied for APC‐2 composites. Samples of APC‐2 PEEK composite were cooled from the melt at rates ranging from −1 to −20°C/min. A differential scanning calorimeter was used to monitor heat flow during the non‐isothermal crystallization. Effects of cooling rate on crystallization temperature, degree of crystallinity, and conversion rate were studied. We show that the Ozawa analysis fails to provide an adequate description of the non‐isothermal crystallization process in composite PEEK. A modified Avrami analysis was used to describe crystallization kinetics. For the composite material, the change from the primary kinetics of free crystal growth to slower secondary kinetics occurred at about 50 percent relative conversion for all cooling rates. Non‐isothermal crystallization in APC‐2 composite PEEK can be characterized by higher initiation temperature, higher heat flow maximum temperature, and greater relative conversion by primary processes when compared to 450G neat resin

ISSN:0272-8397    

DOI:10.1002/pc.750090405

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe impact strength and rigidity of polypropylene composites can be significantly improved by application of short glass fibers instead of mineral fillers in elastomer‐modified polypropylene. The properties of such composites are strongly dependent on the adhesive forces at the fiber‐matrix interface. Poor adhesion results in interfacial fracture solely by fiber‐matrix debonding, as evidenced by scanning electron microscopy on the fracture surfaces. This is accompanied by relatively low impact strengths. By contrast, increased adhesion leads to fracture not only by fiber‐matrix debonding, but also by crack propagation through the elastomeric phase at the fiber surface. This mechanism is thought to be responsible for a remarkable increase of the impact strength. Appropriate compositions of polypropylene, glass fiber, and elastomer resulted in composite properties similar to, or even better than, those of a typical acrylonitrile‐butadiene‐styrene copolymer. The lengths of the fibers recovered from the test specimens were somewhat smaller than the critical fiber lengths as calculated by simple shear lag theory. The properties of the present composites should thus be regarded as minima, rather than as potential maxima. This suggests that current composites may be suitable for engineering a

ISSN:0272-8397    

DOI:10.1002/pc.750090406

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractSingle‐fiber pullout tests are frequently used to characterize the interfacial adhesion between resin and fiber in reinforced composites. In this report, a fiber pullout experiment in which a drop of thermoplastic resin is sheared from a single fiber is described. Specialized apparatus, developed and constructed in our laboratory, as well as the techniques for sample preparation are discussed in detail. The interfacial shear strength of polybutylene terephthalate (PBT) in contact with silane‐treated E‐glass fibers is measured quantitat

ISSN:0272-8397    

DOI:10.1002/pc.750090407

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe melt rheological properties of nickel powder filled polypropylene composites were investigated. The effect of filler concentration on shear stress‐shear rate data, melt viscosity and melt elasticity parameters were determined by using a capillary rheometer. The study shows that the materials follow a power law in viscous behavior over the entire range of shear rates investigated and that the viscosity increases and elasticity decreases as filler concentration is increased up to a critical value. However, beyond the critical filler content melt viscosity decreases while melt elasticity increases. The effect of temperature on the viscoelastic properties of filled polypropylene was also investigate

ISSN:0272-8397    

DOI:10.1002/pc.750090408

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractA computer based measuring strategy to determine spatial orientation of short glass fibers from the cross‐section of single fibers is presented. A practicable way of correcting the inclination‐dependent probability of hitting a fiber is shown as well as the correction of fiber‐end intersections. The latter is done by pattern recognition and application of a set of FORTRAN subroutines. A simple model allows the approximate calculation of thermal expansion as a function of volume content and fiber orientation. This serves as an applicability test for the measuring s

ISSN:0272-8397    

DOI:10.1002/pc.750090409

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

ISSN:0272-8397    

DOI:10.1002/pc.750090401

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY