Determination of conditions of infiltration in infusion method of glass fibers laminates
Jerzy Myalski
Quarterly No. 2, 2009 pages 138-143
DOI:
keywords: polymer matrix composite, laminate, glass fiber composite, technology, infusion
abstract The paper presents the results of investigations introducing possibilities of manufacturing of FRP composites using infusion technology. The investigations focused on evaluation of an influence of technological parameters, particularly applied un-derpressure, on efficiency of infiltration process and on a flow of resin through the reinforcing fibers. An effect of kind and form of fiber reinforcement, its basis weight, and amount of layers on flow speed of a resin was also evaluated, as well as the basic mechanical proprieties of the laminate and volume fraction of the reinforcement. As the composite matrix a low viscosity vinylester resin was used. The composite reinforcement were glass fibers in the form of: mat, satin weave fabric, roving fabrics and fabric-mat cloth. An investigation was also conducted on sandwich construction in order to determine an effect of a sandwich foam-core on the infiltration process. It was found that laminate quality and duration of the process depend first of all on the pressure value. Values of pressure 0.4, 0.6, and 0.75 bar were applied within the investigations. The pressure value decides how fast the reinforcing layers soak. By 0.4 bar pressure the infiltration time is even 6 times longer that by 0.6 bar. It was considered that the laminate composites of better mechanical proprieties and the enlarged volume fraction of reinforcement were obtained by comparatively low pressure. Flexural and tensile strength of composite laminates manufactured by 0.4 bar pressure were of about 30% higher than of those manufactured by 0.75 bar. However, lower value of pressure extends considerably the time of filling of the preform. Increase in the pressure shortens time of the process, but it can bring deterioration in mechanical properties of the laminate, producing areas devoid of resin. To shorten the process duration we can apply a special arrangements introduced between the layers of reinforcement giving additional channels distributing the resin. In the case of sandwich constructions we may introduce special cross incisions in material of foam-core. It was found that infusion technology gives high volume fraction values in composites, even by large basis areal weight of reinforcing layers. In laminates formed by contact method, the volume fraction of reinforcement is usually much lower. It is impossible to impregnate the fabric and mats of large basis weight using contact method because impossibility of infiltration of the resin through reinforcement. Infusion technique enables manufacturing of strong, good quality and good repeatability composite materials.