Preparation and properties of unmodified ramie fiber reinforced polypropylene composites

Abstract

Ramie fiber (RF) was used to reinforce the polypropylene (PP). The composites were prepared with a melting hybrid technology. Tests had been performed on PP and composites with different RF contents (10 wt%, 20 wt%, and 30 wt%). By using SEM, DSC, TGA, electronic universal testing machine, HDT-VICAT tester and coefficient of linear expansion tester, the effects of the RF loading were assessed on the basis of morphologies, mechanical and thermal properties as well as vicat softening temperature and CTE of the resulting composites. The results show that the thermal degradation temperature of the PP/RF composites becomes lower with higher fiber content. The crystallization rate of the PP matrix is accelerated by the unmodified RF. Because of the inferior interfacial bonding strength between RF and PP, the tensile strength of composites decreases by the presence of RF. And the RF used is relatively long compared with the diameter, the impact strength of the composites is improved by the unmodified RF. The vicat softening temperature of composites can be increased by about 5 °C in the presence of RF compared with PP. The CTE is reduced significantly in the presence of RF. Generally speaking, impact strength, crystallization rate, vicat softening temperature and CTE of PP/RF composites could be improved in the presence of RF. The tensile strength is decreased and thermal degradation temperature of composites becomes lower, but these should not affect most subsequent normal uses of the composites. As the unmodified RF is used directly, no hazardous waste is produced during the fabrication process, combined with the low price, so, a facile and economic preparation pathway is given by using unmodified natural fiber to reinforce polymer and composites with good performance obtained.