Chemical modification of natural fibers and optimizing the processing of thermoplastic composites by compressing molding method

Natural fibers are being extensively used to make composite material due to them being more environmentally friendly compared to conventional synthetic fiber. However, their use is hindered because of the drawback of being hydrophilic in nature. This, in turn, lower their mechanical performance due to the low adhesion to the hydrophobic thermoplastic polymer. Moreover, there is a high chance of mechanical failure of natural fiber reinforced thermoplastic composites (NFRTC) during their service life due to moisture absorption through the fibers. Hence different fiber surface modification methods are utilized to improve the hydrophobicity of the natural fibers. Film stacking done in the compression molding machine is one of the most popularly used methods in composite making of woven fabric reinforced thermoplastic composites. An abundance of research reports the utilization of maleic anhydride grafted polypropylene (MAPP) as coupling agent for short natural fiber reinforced composites based on polypropylene (PP) made by melt compounding method. The objective of this research is to use MAPP to reduce the hydrophilicity of woven flax fabric intended to be used in composite production. It is also assumed that the modification of flax by MAPP may also improve the mechanical properties of the composites made by film stacking method. The MAPP dissolved in xylene at three different concentrations and three different reaction times were used to modify the woven flax fabric. The effectiveness of the hydrophobization of fabric is determined by ATR-FTIR and moisture absorption tests. The modified flax fabrics were used to produce PP based composites by film stacking method after optimizing the hot-pressing parameters. The result from this study shows that the usage of MAPP increases the hydrophobicity of the fiber. The appearance of carbonyl peak at 1735 cm-1 in the modified fiber indicates that the chemical reaction has occurred between the MAPP and the flax fabric. The results from the moisture absorption test show that fabric treated with highest MAPP concentration of 1.5 % for a longest duration of 10 minutes reduces its moisture uptake to 4.50 % from 7.14 % of untreated flax fiber. However, tensile strengths of the materials produced with the modification do not show positive outcome