摘要:

AbstractThe Tensile strength of sheet molding compounds containing circular coutouts is investigated. The results show that sheet molding compounds contain inherent voids making the material unaffected by notches smaller than a certain size, The results show a reasonable fit with a three parameter model.

ISSN:0272-8397    

DOI:10.1002/pc.750020402

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractVarious models that have been proposed to predict the properties of particulate filled systems are reviewed and compared with experimental data. At filler volume fractions less than ∼0.2‐∼0.3, these models give essentially equivalent predictions that are within the scatter of experimental measurements. At higher volume fraction of inclusions, significantly different results are obtained from the various models. These predictions either overestimate or underestimate observed properties. New, theoretical combining rules are presented to predict the Young's modulus, Poisson's ratio shear modulus, bulk modulus, and coefficient of thermal expansion in terms of the properties of the matrix and inclusion and the volume fraction concentration of the inclusion. The predictions of these combining rules are in good agreement with experimental data that cover the feasible concentration range of inclusions for a variety of composite materials, ranging from particulate filled thermosetting resins to thermoplastic

ISSN:0272-8397    

DOI:10.1002/pc.750020403

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe effect of the absorption of water and isooctane on the rate of fatigue crack propagation of sheet molding compounds (SMC‐R30 and SMC‐R65) was investigated. A crack extension gage was used to measure the crack length. Results show that the absorption of water decreases the rate of fatigue crack propagation in the initial cycles but increases the rate of propagation in the final cycle. The absorption of isooctane into SMC‐R65 tends to decrease the rate of fatigue crack propagation. Microscopic observation shows considerable swelling of the polyester matrix due to the absorption of water and no significant apparent effect due to the absorption of isoo

ISSN:0272-8397    

DOI:10.1002/pc.750020404

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe absorption of water, isooctane, methanol and ethanol into a sheet molding compound (SMC‐R30) at room temperature is studied. The absorption behaviors are shown to be Fickian, with constant diffusion coefficients. Desorption of methanol and ethanol soaked specimens causes considerable surface crackin

ISSN:0272-8397    

DOI:10.1002/pc.750020405

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractEleven light weight polymeriozed composite materials derived from waste products were investigated. These waste materials after impregnation with a polymer were found to lhave better physico‐mechanical properties than ordinary cement concrete. Such impregnation, combined with fine sand and epoxy hardener, takes advantage of the optimum properties of the composites. The use of such polymerized composites for building constriction on a large scale can be undertaken, economizing on cemen

ISSN:0272-8397    

DOI:10.1002/pc.750020406

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractA series of sheet molding compound (SMC) materials have been prepared in which the only variable was the polyester resin used as the matrix. The polyester resins were all synthesized from maleic anhydride, propylene glycol and 1,2 propane diol. Systematic variations were made in the molar ratio of maleic of to phthalic anhydride used, and also in the hydroxyl values of the polyesters. The resins were also separately crosslinked with styrene, and the fracture toughness of the cast sheets measured. The toughness of the SMC was assumed to be measurable by linear elastic fracture mechanics (LEFM) methods. Results indicated that the resin matrix toughness was inversely related to polyester unsaturation but the SMC toughness was directly related to it. The hydroxyl values of the resins were determined by nuclear magnetic resonance (NMR) of the silyated derivatives. The tensile properties of the SMC were investigated. Modulus increased steadily with resin hydroxyl value, but tensile strength showed a maximum at 50 mg. These observations indicate the importance of hydroxyl value in SMC resin formulation, arising from its effect on fiber‐resin bond strengt

ISSN:0272-8397    

DOI:10.1002/pc.750020407

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractA simple circular pultruded rod was used to evaluate the mechanical and economic performance of four commercially available hollow spherical fillers (microbubbes). The incorporation of such glass or silicate microbubbes in a pultruded rod produced a decrease in density, strength and modulus. However, the loss of strength and modulus was more than compensated for by the decrease in density so that a 50 percent material cost saving was possible without any sacrifice in flexural or torsional properties. Thus for simple profile (rods, bars. Panels) the use of hollow spherical fillers can be economically advantageous in reducing material costs. The syntactic pultrusions posses many of the desirable properties of wood such as toughess, low density, high strength and stiffness plus the ability to accommodate nails and screws. The operating conditions of the pultruder wee normal with the exception that half as much force was needed on the puller and the pultruder would only operate satisfactorily when the resin/glass fiber/microbubble concertrations were within specified boundaries. Pyrex type glass bubbles were found to be less prone to damage during processing and performed better than silicate type microbubbles.

ISSN:0272-8397    

DOI:10.1002/pc.750020408

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractFourier transform infrared spectroscopy (FT‐IR) has been utilized to investigate the interfacial chemical bonding at the interfaces of the aminosilanes and the nedic methyl anhydiride cured epoxy matrix in fiber‐reinforced composites. It is found that the nedic methyl anhydride can react with γ‐aminopropyltriethoxysilane (APS) and N‐methylaminoproplytrimethoxysilane (MAPS). In comparing the relative reactivities of two coupling agents to the epoxy resin, the secondary aminosilance has a higher reactivity than the primary aminosilance. An elevated temperature is required for the copolymerization to take place between the silane and the epoxy resin. The results indicate that covalent bonds form at the coupling agents. The molecular structure of the interface in MAPS treated fiberglass reinforced composites is different from that of the APS treated fiber composites. In addition, an accelerated copolymerization initiated by the coupling agent treated surface is also found in the resin interphase which may be important in determining the mechanical properties of the co

ISSN:0272-8397    

DOI:10.1002/pc.750020409

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractK‐calibration procedures were performed with a glass fiber‐reinforced epoxy angleply plate, a skin a sandwich structure. Different K‐calibration functions were obtained for various notch tip relative locations within the composite. In view of these observations and of the previously seen anisotropy of those functions it was concluded that the selection of an appropriate K‐calibration function depends on both the reinforcement geometry and on the notch tip l

ISSN:0272-8397    

DOI:10.1002/pc.750020410

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThis paper presents some of the important results obtained from a series of studies on cohesive fracture in adhesively bonded joints. Due to the complex nature of the adhesive joint fracture, an accurate and efficient numerical method particularly suitable for the present problem has been developed, based on a hybrid‐stress finite element formulation. Fracture characteristics in adhesively bonded joints are described in terms of local crack‐tip deformation and stress fields in the polymeric adhesive layer. Effects of material properties, joint geometry, and bond‐line thickness on the crack behavior are studied for classical lap‐shear and currently used double‐cantilever‐beam joints. Of particular interest are the crack‐tip stress intensities in the adhesive layer; their values are obtained for several cases of practic

ISSN:0272-8397    

DOI:10.1002/pc.750020411

出版商:Society of Plastics Engineers, Inc.    

年代:1981

数据来源: WILEY