High-performance natural fiber composites made from technical flax textiles and manufactured by resin transfer moldingDonnerstag (06.07.2017) 16:00 - 16:20 Uhr Bestandteil von:
In the present work it is shown that the resin transfer molding (RTM) technique is a beneficial technique to manufacture natural fibers into a high-performance natural fiber composites. Due to the pressure in the mold, the RTM technique provides the opportunity to produce laminates having natural fibers with much higher fiber volume fractions, vf, than other techniques. At first, three different types of weaves (weave #1 and #2 is a plain weave and weave #3 is a twill weave) were produced by using low-twist flax yarns and standard-twisted flax yarns. Laminates based on technical flax fabrics and a petrochemical derived epoxy thermoset were fabricated by RTM process. For each laminate different numbers of plies (4, 5, 6, and 7) were used to achieve a broad range of vf (from 32 % up to 55 %) which are having a pore volume fraction, vp, as low as possible (min. 0.7 % - max. 2.7 %). From laminates flexural properties in warp and weft direction were determined (ISO 14125) and the effect of respective yarn type on flexural properties was investigated. The best properties were achieved for the laminates based on weave #2 with vf = 55 % (strength=303 MPa, modulus=19.3 GPa). The laminates were immersed into a water bath (ASTM D570) to test the influence of vf and vp on the water absorption behavior. The maximum water uptake (4-7 wt.-%) and the maximum thickness swelling (3-12 %) were observed for the samples with higher vf. Laminates based on weave #1 were immersed again into the water bath to investigate the extent of deterioration of flexural properties with respect to water absorption at various time intervals. The laminates were tested immediately after removing from the water bath and after re-drying. Difference in flexural properties for the wet and re-dried laminates was observed.