Papers by Keyword: Thermoset Resin

Abstract: A novel B-stage resin system is developed for the „Resin Transfer Pressing“ (RTP) process. This composite manufacturing technique makes use of nonwoven and recycled carbon fibres (rCF) that are oversaturated with a thermosetting resin. The new resin system is based on two different hardeners, allowing to easily impregnate the rCF, storing the semi-finished parts at room temperature and finally curing them via compression molding. It is shown that a commercially available resin system can be tailored to the required needs by the smart combination of state-of-the art, latent hardener systems.The present study focusses on the route for B-staging of the resin system. The viscosity for impregnation and oversaturation was adjusted to be in the range of 5 to 40 Pa·s at 60°C. The viscosity increases to above 50 Pa·s at room temperature, allowing storage and handling of the semi-finished parts and processing them whenever it is required. Choosing a proper processing temperature is important during the B-staging process to avoid any unintended activation of the second hardener, which is responsible for the final curing stage of the system.

Abstract: Polymer matrix plays a crucial role in the development of advanced light weight composite materials, and is mainly responsible for thermal and mechanical properties. These polymer matrices are usually thermosetting plastics due to their ease of processing. Thermoset resins were prepared using different compositions of dicyanate ester of bisphenol A and polyether imide and carbon fiber laminates were prepared by wet layup technique. Small amount of epoxy (diglycidyl ether of bisphenol A) was also added to the composites to improve the (interfacial) bonding between the carbon fiber and the resin. The Copper (II) oxalate with 1,5-pentanediol was used as a catalyst for the first time to reduce the curing time from eight hours to four hours. The catalyst has also reduced the curing temperature from 400°C to 250°C. The catalyst Copper (II) oxalate is commercially available. The plasticizer has improved the thermal and mechanical properties of the matrix significantly. The addition of epoxy to the thermoset resin improved the (interfacial) bonding between the resin and carbon fiber. FTIR results suggest that the polymerization reaction of dicyanate results in the formation of trizine ring with phenolic group. SEM results show the interaction of bisphenol A dicyanate (BPADCy) monomer to form polymer matrix. SEM images also represent a uniform anchoring of matrix on the individual carbon filament. It is clear from thermal analysis that sample having 85% BPADCy and 15% polyetherimide (BPR-2) shows the greater thermal stability which is due to the reaction of epoxy with cyanate matrix.

Abstract: Traditional description of the rate of the thermoset resin reaction by the Arrhenius relationship multiplied by a reaction function has been used in this study. The Kissinger method and ASTM E 698 procedure have been used for a determination of parameters of the Arrhenius relationship. N-th order, Prout-Tompkins and Kamal-Sourour models have been used and evaluated as the reaction functions to formulate the curing kinetic models of an epoxy resin.An engineering tool based on Microsoft Excel code has been developed by using the developed methodology. This tool has been successfully applied for a building of the curing kinetic model of vinyl ester resin with high microwave absorption properties to be used in the microwave assisted pultrusion processes.

Abstract: Unsaturated polyester resins are extensively used in the automotive industry as matrix for polymer based composite materials, but have poor impact resistance. Toughness can be improved dispersing a softer phase in brittle polymers. Scrap tyres constitute a significant waste problem and are a low-cost source for rubber. The objective of this work is the mechanical characterization of matrix systems containing solid rubber particles obtained from scrap tyres. Several pre-treatments were tested based on contact time and temperature. The flexural and Charpy impact behaviour of the modified resins showed a decrease in performance. Dynamic mechanical tests did not result in clear evidence of phase mixing. Optical microscopy showed the presence of contaminant particles, which were considered the cause for the low performance. Among the modified resins, a positive shift in flexural behaviour occurred when pre-heating was used. It is thought the strategy may prove effective in enhancing resin toughness, if the waste rubber is purified prior to its utilization.