摘要:

AbstractThis paper presents new experimental data on the viscosity of ferrite‐filled polymers at high levels of loading. The choice of matrix and the choice of filler and filler loading has direct relevance to commercially important systems of magnetic plastics and rubbers. The effect of shear rate, concentration, and temperature on the rheological behavior of such highly loaded systems has been discussed in detail. The differences in the relative viscosities between the filled and unfilled systems for various matrices have been explained on the basis of polymer filler affinity and filler‐filler interact

ISSN:0272-8397    

DOI:10.1002/pc.750070402

出版商:Society of Plastics Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractThe performance of an electrodeposited interphase of poly(butadiene‐co‐maleic anhydride) (BMA) in carbon‐fiber composites is investigated. Carbon fibers are electrocoated with BMA from an aqueous solution and the coated fibers are fabricated into composite bars for evaluation of mechanical properties. These composites show superior impact strength, but lower interlaminar shear strength, compared to composites made from commercially treated fibers. It is suggested that unsaturation in the butadiene segments of the interphase polymer leads to the formation of a crosslinked layer during electrodeposition and subsequent drying. Inadequate penetration of this interphase by bulky epoxy molecules leads to a weak interphase/matrix interface which is the locus of failure, generating the observed mechanical properties. These conclusions are supported by examination of the fracture surfaces by Scanning Electron Microscopy. Further evidence of lack of matrix penetration into the interphase comes from electron microprobe line scans for bromine performed on cross‐sections of single‐filament composites, the bromine being introduced into the matrix via a brominated epoxy resin. Appropriate control of the chemical structure and physical characteristics of the interphase polymer is thus indicated, for acieving simultaneous improvements in impact and interlaminar shear

ISSN:0272-8397    

DOI:10.1002/pc.750070403

出版商:Society of Plastics Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractThe effects of such factors as flake size, orientation, and surface treatment on the fracture mechanism of mica‐reinforced polypropylene were investigated. Concepts of post‐yield fracture mechanics were used to characterize the crack initiation and propagation resistances of the composite. It was found that better flake alignment slightly increases the yield strength but does not affect the crack growth resistance of the material. Flake size degradation during processing leads to an increased crack initiation resistance but reduces the tearing capacity and the maximum crack growth resistance of the composite, due to a reduction of the extent of matrix deformation. In the same manner, the use of a coupling agent diminishes the effect of matrix drawing and the total energy dissipated during the fracture process, even though the crack initiation resistance can be increa

ISSN:0272-8397    

DOI:10.1002/pc.750070404

出版商:Society of Plastics Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractIn 1982 Paluski Boats with the assistance of the National Research Council of Canada, embarked on a project to design a reinforced plastic oar. The problems to be solved involved not only the construction of a shaft of sufficient strength, but also the development of a light and durable F.R.P. blade, as well as fixing to the pole a suitable strong and adjustable pivot point. The shaft was manufactured, borrowing techniques developed for ski poles and windsurfing masts, in the form of a tapered epoxy and carbon‐fiber pole. The blade was formed with an outer shell of epoxy and fiberglass laminate which was then filled with a two‐part structural foam. The pivot point, or ‘collar/sleeve assembly’ was made by molding around the shaft a solid section of polyurethane. The new plastic oars are lighter, less‐expensive, need no regular maintenance and are practically impossible

ISSN:0272-8397    

DOI:10.1002/pc.750070405

出版商:Society of Plastics Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractFT‐IR spectroscopy was used to collect spectra of γ‐aminopropyltriethoxy silane (γ‐APS) coupling agent deposited on KBr plates, modeling the silane interphase of composites, to study the effects of heating the γ‐APS film under various environmental conditions. This coupling agent is used in fiber‐reinforced epoxy composites. An aminebicarbonate salt forms when the sample is dried in a moist carbon dioxide environment giving rise to a series of bands from 2800 to 2000 centimeter−1(cm−1) and bands at 1637 cm−1, 1330 cm−1, 696 cm−1, and 663 cm−1. The primary amine group is split into two bands at 1572 cm−1and 1486 cm−1in the NH3+form. Heating removes the aminebicarbonate salt at temperatures above 95°C and condenses the γ‐APS polymer to a polysilsesquioxane film. The aminebicarbonate salt partially reforms if the γ‐APS film is stored in a moist CO2environment. At temperatures above 120°C the primary amine of γ‐APS is oxidized in air to imine groups. In the process of evolving the CO2the polymer is further condensed and the amine groups can be converted to imines if the temperatures exceeds 120°C. Both processes reduce the reactivity of the coupling agent with the epoxy resin. The structure of the silane interphase must be controlled during the processing of the composite to

ISSN:0272-8397    

DOI:10.1002/pc.750070406

出版商:Society of Plastics Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractA series of differential scanning calorimetry (DSC) and molding experiments were carried out to measure the effect of curing agents, namely initiators and inhibitor, on the SMC reaction. Results showed that the induction time, the reaction rate, and the limiting conversion of sheet molding compounds can be modified through the change of curing agents. The SMC resin with a higher concentration of low temperature initiator and molded at higher temperature may cure in a shorter period of time and reach a higher conversion. The shortened scorch time and shelf life can be balanced by adding small amount of inhibitor. Surface quality of molded SMC parts measured by solvent extraction process showed that limiting conversion is an important factor in SMC molding.

ISSN:0272-8397    

DOI:10.1002/pc.750070407

出版商:Society of Plastics Engineers    

年代:1986

数据来源: WILEY

摘要:

AbstractA mechanistic kinetic and heat transfer model is used to describe the cure of sheet molding compounds (SMC). Kinetic parameters such as rate constant of initiator decomposition and rate constant of propagation are estimated from the induction time and the time to reach the peak exotherm of isothermal reaction curves measured by the differential scanning calorimetry (DSC). Temperature and conversion profiles inside plate sections of SMC parts during molding are measured. The predicted results compare well with the experimental data except the limiting conversion. A set of predictive parameters are proposed from this model as guidelines for the optimal molding of SMC. Several moldability diagrams are also constructed which can be easily used to design the optimum SMC recipe for a given processing condition.

ISSN:0272-8397    

DOI:10.1002/pc.750070408

出版商:Society of Plastics Engineers    

年代:1986

数据来源: WILEY

ISSN:0272-8397    

DOI:10.1002/pc.750070401

出版商:Society of Plastics Engineers    

年代:1986

数据来源: WILEY