摘要:

AbstractA family of casting composites, epoxy resins with mineral fillers, having a range of electrical properties, are being developed. In such composites, the dielectric constant is controlled primarily by varying the filler material in composition and proportions. The present work reports on the mechanical properties of composites made with two types of filler, an alumina powder (XA3500 from ALCOA) and a BaTiO3/TiO2ceramic powder (ATD‐50 from Ampex). Dependence of mechanical properties on curing agents was also determined. Filler contents from 0 to 40 percent volume were used. Epoxy systems contained single epoxy resin with both amine and anhydride hardeners. Processing of the anhydride‐cured systems was easier than that of the amine‐based systems because of their lower viscosity and longer gel time of the former. However, the anhydride‐cured systems required higher processing temperatures. Curing kinetics and molecular bonding were investigated using a combination of differential scanning calorimetry, dynamic mechanical thermal analysis, and scanning electron microscopy. Activation energies of 11.2 kcal/mole and 12.1 kcal/mole were obtained for the curing of the amine‐based and the anhydride‐based composites respectively, and a small difference in the glass transition temperature was also observed. These effects can be attributed to the difference in the structure of the curing agents. The epoxy resin cured with NMA is less ductile compared with those cured with MTHPA or MHHPA due to slight chemical modification on the ring structures. This dependence of ductility on curing agent was observed in specimens with different filler contents. Although the presence of the filler materials was found to enhance the mechanical properties of the epoxy, the fracture mode in these materials is st

ISSN:0272-8397    

DOI:10.1002/pc.750100402

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThe specific interaction characteristics and the inherent agglomeration of variously surface coated rutile pigments have been assessed, respectively, by inverse gas chromatographic and powder rheological methods. Standardized methods were used to disperse the pigments in polyethylene and chlorinated polyethylene. Measurements were made of energy requirements for dispersion and of the quality of dispersion attained. It was found that in the non‐polar polyethylene matrix, dispersion processes depended on the strength of pigment agglomerates, but not on the specific interaction potential of the solids. Conversely, in the acidic chlorinated polyethylene, acid/base interactions influenced dispersion but the process was independent of inherent pigment agglomeratio

ISSN:0272-8397    

DOI:10.1002/pc.750100403

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThis paper explores the possibility of using X‐ray micro‐analysis for studying the morphology of the polymer blend composite PPS(GF)/HDPE (glass‐filled poly(phenylene sulfide)/high density polyethylene) system and the characterization of filler and polymer dispersion in the s

ISSN:0272-8397    

DOI:10.1002/pc.750100404

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThe failure of the interface in a carbon fiber‐epoxy system was studied for six different epoxy blends using the single‐filament‐composite technique. The blends were formulated to yield a wide range of stiffnesses, and their effect on interfacial failure was examined. Specimens were made from Hercules IM6‐G carbon fiber and the different blends of epoxy, and then strained to obtain a distribution of fiber fragment lengths. Birefringence patterns near the fiber breaks were observed and recorded. Some of the specimens were strained until they failed and the resulting fracture surfaces were observed under a scanning electron microscope to determine fracture patterns and the existence of debonding. The fragment length distributions were interpreted using a Monte‐Carlo simulation of a Poisson/Weibull model for fiber strength and flaw occurrence. The results were used to calculate an effective interfacial shear strength. From this analysis we conclude that one cannot accurately predict the interfacial properties of a composite based solely upon conventional single fiber and bulk matrix properties. Local matrix properties and fiber/matrix interactions, on a microscale, play a key role in composite

ISSN:0272-8397    

DOI:10.1002/pc.750100405

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractSuspensions, which are filled at loading levels approaching their maximum packing fractions, present special processing challenges. The flow and deformation behavior of such highly filled suspensions are dominated by strong slip effects. Furthermore, during pressure driven flows of these suspensions, the polymer matrix can filter out, giving rise to demixing and unstable flows. In this study, the capillary flow and extrusion of highly filled suspensions of ammonium sulfate and other salt fillers in a poly(butadiene acrylonitrile acrylic acid), PBAN matrix were investigated. The experimentally observed instabilities were elucidated in conjunction with a proposed mechanism, involving slip and filtration rates. This mechanism suggested greater affinity to unstable flows with relatively lower matrix shear viscosity, greater particle size of the filler, and greater convergence ratio; all of which were experimentally verified.

ISSN:0272-8397    

DOI:10.1002/pc.750100406

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThe creep and creep rupture response of a chopped fiber composite material (SMC‐R50) were investigated experimentally and analytically. The goal of this research was to use the short time laboratory data to predict long time creep and creep rupture behavior. The creep response data up to 200 min duration were obtained at various constant temperature and stress levels. The short time creep data were then modeled using a modified power law equation. The modified power law equation contains the parameters of the so‐called accelerated characterization procedure. Using this power law equation, the short time creep response at the elevated temperatures were able to successfully predict the long time creep response at a lower temperature and stress level. To predict the creep rupture behavior, the modified power law equation was then coupled with a strain energy based failure criterion. It was found that the same parameters that were used in the prediction of the long‐time creep response can also be used to predict the creep rupture. At a given temperature level, the strain energy density related to creep rupture was found to be a constant. Furthermore, this strain energy density was found to increase with an increase in temperature. With a limited amount of data, it was found that the strain energy based failure criterion coupled with the modified power law equation can be used to predict long time creep rupture beh

ISSN:0272-8397    

DOI:10.1002/pc.750100407

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThis paper analyzes the effects of the addition of a three‐component dry type adhesive system on the properties of composite SBR (styrene‐butadiene rubber) material containing 20 percent short polyamide (5 mm length and 60 μm diameter). The curing times are extended and green strength is doubled. The replacement of the silica component in the system by a natural silicate is not only feasible, but proves to be favorable for certain properties, such as the storage modulusE′, which becomes less sensitive towards temperature changes. Dynamic property measurements provide evidence of an additional dispersion corresponding to the matrix‐fiber interface located around 40 to 50°C, which does not occur in the composites without adhesive. The activation energies of the main relaxation process of these materials are determined, amounting to 175 KJ/mol for the matrix and 250 KJ/mol for adhesive‐containing composites, as a consequence of the formation of strong bonds between

ISSN:0272-8397    

DOI:10.1002/pc.750100408

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

摘要:

AbstractThe recent growth in the use of polymer composites has resulted in the need for higher productivity manufacturing processes than are currently used in most thermoset composite production. One of the ways to provide increased productivity in composite manufacturing is to use thermoplastic matrix sheet composites. In this investigation the part forming characteristics of several thermopolastic composites were investigated. Glass fiber reinforced composites based on polypropylene, nylon 12, poly(butylene terephthalate), poly(ethylene terephthalate), poly(phenylene sulfide), and poly(etheretherketone) were examined. The processing conditions required for solid‐state stamping of these composites were determined. A temperature process window for stamping each of these composites was determined, and found to correlate with the melting and re‐crystallization peaks from differential scanning calorimetry (DSC) sc

ISSN:0272-8397    

DOI:10.1002/pc.750100409

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY

ISSN:0272-8397    

DOI:10.1002/pc.750100401

出版商:Society of Plastics Engineers    

年代:1989

数据来源: WILEY