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Microwave Curing (microwave + curing)
Selected AbstractsMicrowave and conventional curing of thick-section thermoset composite laminates: Experiment and simulationPOLYMER COMPOSITES, Issue 2 2001Erik T. Thostenson In conventional processing, thermal gradients cause differential curing of thick laminates and undesirable outside-in solidification. To reduce thermal gradients, thick laminates are processed at lower cure temperatures and heated with slow heating rates, resulting in excessive cure times. Microwaves can transmit energy volumetrically and instantaneously through direct interaction of materials with applied electromagnetic fields. The more efficient energy transfer of microwaves can alleviate the problems associated with differential curing, and the preferred inside-out solidification can be obtained. In this work, both microwave curing and thermal curing of 24.5 mm (1 inch) thick-section glass/epoxy laminates are investigated through the development of a numerical process simulation and conducting experiments in processing thick laminates in a conventional autoclave and a microwave furnace. Outside-in curing of the autoclave-processed laminate resulted in visible matrix cracks, while cracks were not visible in the microwave-processed laminate. Both numerical and experimental results show that volumetric heating due to microwaves promotes an inside-out cure and can dramatically reduce the overall processing time. [source] Epoxy nanocomposites curing by microwavesPOLYMER ENGINEERING & SCIENCE, Issue 8 2006Nurseli Uyan In this work, chemically modified sodium montmorillonite and epoxy monomer were used to prepare nanocomposites in two consecutive stages. In the first stage, dodecylamine, octadecylamine, hexadecylamine, and hexadecyltrimethyl ammonium bromide were used to prepare various organophilic clays. In the second stage, the bisphenol-A based epoxy monomer and predetermined amounts of organoclay were mixed together and then cured by an aliphatic polyamine for 20 min under microwave at 400 W. Furthermore, ,-, diacrylate poly(dimethylsiloxane) was added to the mixture before the curing process to modify the toughness of the samples. The mixture was poured into the poly(tetrafluoroethylene) mold; the epoxy resin/curing agent ratio was maintained as 2/1. The clear films formed after microwave irradiation were removed from the mold, cooled, and then stored in a cool and dry medium until characterization. The samples were analyzed by wide angle X-ray diffraction, differential scanning calorimetry, and mechanical tests. Surfaces of the cold fractured samples were also observed under the scanning electron microscope. The results revealed that microwave curing of the samples of 5% organoclay and 5% siloxane showed improvement in mechanical properties. POLYM. ENG. SCI. 46:1104,1110, 2006. © 2006 Society of Plastics Engineers [source] Numerical investigation of the influence of material properties and adhesive layer thickness on the heating efficiency of microwave curing of an adhesive-bonded jointPOLYMER ENGINEERING & SCIENCE, Issue 8 2004H. W. So In the process of microwave curing of an adhesive-bonded joint, both the adhesive layer and the adherends affected the heating efficiency of the joint. As an extension of previous studies, the influences of changing the properties of the components of the joint on the heating efficiency were predicted by simulations that were based on the numerical model developed previously. The influence of adhesive thickness was also studied. The properties that directly affected power dissipation and heat loss of the adhesive layer were found to be important to the heating efficiency of the process. The heating rate was also sensitive to the thickness of the adhesive layer. Polym. Eng. Sci. 44:1414,1418, 2004. © 2004 Society of Plastics Engineers. [source] Comparative study of continuous-power and pulsed-power microwave curing of epoxy resinsPOLYMER ENGINEERING & SCIENCE, Issue 10 2000Bao Fu Three epoxy reaction systems, diglycidyl ether of bisphenol A (DGEBA) with curing agents meta phenylene diamine (mPDA), diaminodiphenyl methane (DDM), and diaminodiphenyl sulfone (DDS), were cured with both pulsed-power and continuous-power microwave curing systems. Isothermal curing was conducted at three different temperatures for each reaction system with both pulsed-power and continuous-power microwave curing systems. Extent of cure was measured with Fourier Transform Infrared Spectroscopy (FTIR). The temperature characteristics, incident and reflected power patterns, and the reaction rates were compared between the two curing approaches. The incident power and reflected power of both curing processes were observed to reveal reaction status. Continuous-power microwave curing produced noticeably higher reaction rates than pulsed-power microwave curing. [source] | ||||||||||