Thermoplastic polymers reinforced with fibrous agricultural residues

The scope of the present paper is to study the perspectives of using lignocellulosic fibrous plant residues as fillers of thermoplastic polymers. Those natural fibres are low-cost by-products, environmental-friendly and practically sustainable raw materials. The lignocellulosic materials used in this study were both untreated and pre-treated residues from eucalyptus wood, ground corncob, and brewery's spent grain. Polymer matrices of low-density polyethylene (LDPE) and PVC plastisol were used, to prepare composite specimens with different amounts (10-50 phr) of lignocellulosic fillers. These specimens were tested for their mechanical properties, and additional assessment was made via measurements of their surface hardness and observations by stereoscopic optical microscopy. The results of this study show that loading of LDPE with natural fibres leads to a decrease in tensile strength of the pure polymer. On the other hand, the Young's modulus increases due to the higher stiffness of the fibres. Although the properties of some blends are acceptable for some applications, further improvement will be necessary, mainly by optimising fibre-polymer interface characteristics.