ISSN:0272-8397    

DOI:10.1002/pc.750060402

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe matrix/reinforcement interphase in aramid fiber/epoxy and carbon fiber/epoxy composites were modeled by coating an internal reflection spectroscopy (IRS) element with a thin layer of an aramid or of carbonized poly(acrylonitrile) (PAN). The coated element was then used as a substrate on which the curing of an epoxy resin took place. Infrared (IR) spectroscopy was used to demonstrate that the simulated reinforcement surfaces modified the crosslinking chemistry in the first 200–400 nm of epoxy matrix adjacent to the surfaces, producing an interphase of matrix material with properties different from those of the bulk of the epoxy matrix. This hypothesis was confirmed by the fabrication and testing of a series of unidirectional aramid fiber/epoxy and carbon fiber/epoxy composite

ISSN:0272-8397    

DOI:10.1002/pc.750060403

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe dispersion behavior of calcium carbonate (CaCO3), of mica and of sized sand fractions in poly(vinyl chloride) (PVC) and polypropylene (PP) has been evaluated using fillers with various surface treatments. Mechanical properties of the compounds were also studied in order to question the role of interfacial forces in the context of dispersion and property parameters. Surface characteristics of polymers and fillers were obtained from inverse gas chromatography data. It has been shown that in the acidic PVC matrix, rapid dispersion of fillers is favored when strong acid‐base interactions exist at polymer filler contacts. Similarly, mechanical properties at large extension are improved by acid‐base interactions. In contrast, for polypropylene (PP), a van der Waals force material, fillers without pronounced acid or base surface characteristics tend to disperse more rapidly and produce mechanically stronger compounds. The importance of filler surface properties and thus, apparently, of acid‐base interfacial forces varies directly with increasing particle size of the dispersed

ISSN:0272-8397    

DOI:10.1002/pc.750060404

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractMost rheological and rheo‐optical properties of suspensions such as viscosity and light‐scattering intensities can be expressed in terms of the average orientation and/or the average concentration distribution of the suspended particles. In general one can distinguish several distinct regimes: (i) infinitely dilute, (ii) dilute, (iii) semi‐dilute or moderately concentrated, and (iv) concentrated suspensions. Cases (i) and (ii) are regimes in which particle interactions are either absent or only two‐body interactions are important. These cases can, in general, be well described theoretically. Regime (iii) is characterized byn‐body (n≥ 2) interactions and is the least understood. Regime (iv) can often be described in terms of a cell model in which the motion of a reference particle, or the fluid motion around it, i

ISSN:0272-8397    

DOI:10.1002/pc.750060405

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractExperiments to determine the influence of calcium carbonate and titanium dioxide on flow patterns in die entrance regions are reported. The addition of loadings of calcium carbonate and tatanium dioxide of 5 volume percent and more is found to suppress the development of vortices in low density polyethylene at the entrance of a 180° entrance angle die. Vortex suppression was found in more complex entrance regions as well. Similar behavior has been found for carbon black compounds

ISSN:0272-8397    

DOI:10.1002/pc.750060406

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractA theoretical model of the dispersive mixing process in roll‐mills is proposed. The model is based on the assumption that intensive mixing is dominated by agglomerate rupture in the narrow nip high shear flow field between the rolls. The dynamics of agglomerate size distribution and its dependencies on a number of variables and parameters are presente

ISSN:0272-8397    

DOI:10.1002/pc.750060407

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe objective was to study the fiber length degradation during compounding of glass fiber with polypropylene. The effect of parameters such as viscosity, total work, concentration on fiber length and dispersion was studied using an automatic particle size analyzer. The length degradation is most severe during the very first stage of the process, i.e., when fiber bundles are being filamentized. The mode of glass fiber incorporation into the melt (fiber addition to the molten resin versus to polypropylene powder prior to compounding) was found to have no effect on the final fiber length. Matrix resin viscosity affects the fiber length significantly. Concentration dependencies of fiber length for different times of compounding suggest that the degradation results from both fiber‐fiber and fiber‐melt interacti

ISSN:0272-8397    

DOI:10.1002/pc.750060408

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe interface between the fibers and the polymer matrix controls the properties of fiber composites and has been the subject of much study. Recently, special techniques have been developed for single fiber pull‐out experiments on production fibers, which make it possible to obtain data on the frictional forces which govern sliding after the interface has fractured, as well as the adhesion strength of the interface. Tests on glass in polyester and epoxy resins show that the work of fracture of the interface is much smaller than that of the resin, and that the shrinkage pressures of these matrices, when fully postcured, are approximately the same (about 20 MPa). Coefficients of friction at the interface are 0.6 for the polyester and 1.0 to 1.6 for the epoxy. The carbon‐epoxy interface yields at shear stresses as high as 60 MPa, instead of fracturing, and the coefficient of friction during sliding is about

ISSN:0272-8397    

DOI:10.1002/pc.750060409

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractConcepts of post‐yield fracture mechanics were used to characterize the crack initiation and propagation resistances of mica‐reinforced polypropylene containing different mica concentrations. Although mica addition leads to an apparently brittle composite, the crack initiation resistance is slightly increased with mica concentration up to 10 percent by weight; and significant improvement in crack propagation performance was found for polypropylene reinforced by up to 20 percent of mica in comparison to that of virgin polypropylene. The debonding of the interface between mica flakes and the matrix leads to a micro‐ductility ahead of the crack tip in which the matrix is able to pull‐out from mica particles and to stretch. This micro‐ductility also prevents the brittle, unstable crack propagation, which is due to the coalescence of voids in pure polypropylene. Above 20 percent of mica, the reduction of the effective amount of the matrix material results in a substantial drop in the resistance to crack growth of mica‐reinforced po

ISSN:0272-8397    

DOI:10.1002/pc.750060410

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractWood fibers of aspen in the form of chemithermomechanical pulp (CTMP) has been used as reinforcement in polyethylene (PE). The secant modulus, tensile strength, energy, and elongation at yield were measured. It was found that the mechanical properties of the composite were higher than those of PE by a factor of 2.6 for modulus, 2.3 for stress, and 2.1 for energy at yield. Compared to glass fiber composites, the CTMP composites showed higher elongation, about 100 percent higher energy, 106 percent higher stress, and 75 percent higher modulus. Note that the cost of treated wood fibers is several times lower than that of treated glass fibers.

ISSN:0272-8397    

DOI:10.1002/pc.750060411

出版商:Society of Plastics Engineers, Inc.    

年代:1985

数据来源: WILEY