Microwave pultrusion of unidirectional reinforced epoxy composites using single-frequency and variable-frequency processing techniques.

摘要

The pultrusion process is a continuous manufacturing method, which can be used to produce reinforced plastics with a constant cross-sectional area through the length of the product. The continuous microwave processing technique is highly desired for processing large composite materials, which need even and fast heating such as long pipes or panels. The general advantages of using microwave technology include: decreased processing times, better control of temperature profiles within the composite material, and enhanced mechanical properties.;The objective of this project was to obtain experimental data for microwave pultrusion processing. Heating and curing profiles of the pultruded material were studied at different processing conditions. The fixed frequency pultrusion tests were accomplished using the best heating mode for the prepreg system at a certain processing speed and input power. The relation between microwave processing rate, input power, and extent of cure was studied by finding the optimum operating conditions. Mechanical tests, such as flexural and tensile strength measurements, were conducted. A variable frequency power source was used to achieve a more even temperature distribution across the prepreg. The effects of fiber reinforcement on the efficiency of microwave heating were studied. Concepts for an on-line monitoring system were explored.