Micro-sized cellulosic materials are promising reinforcements for thermoplastic composites. In this study, a new type of microcellulose – cellulose oxalate (COX) was used as reinforcement for polypropylene-based composites and its reinforcing effect was evaluated. COX and microcrystalline cellulose (MCC), which was used for comparison, were subjected to ball milling process for different times to obtain milled cellulose powders. Ternary composites consisting of 60 wt% polypropylene (PP) as the matrix, 10 wt% maleic anhydride grafted polypropylene (MAPP) as the coupling agent and 30 wt% milled or non-milled cellulose powder as reinforcement were prepared by melt-extrusion and injection molding. Tensile test results showed that 1 h milled COX-containing composite exhibited the best tensile properties (e.g., tensile strength and Young’s modulus are 16.1% and 106.0% respectively higher than those of neat PP) and MCC generally exhibited a poorer reinforcing effect than COX with same milling time. On the other hand, COX was reacted with oleic acid, as coupling agent instead of MAPP, to prepare hydrophobic fillers in a catalyst-free esterification for different times and MCC was also selected for comparation. The success of esterification of COX and oleic acid was confirmed but little esterification occurred when MCC was used. After reacting COX with oleic acid for 18 and 48 h, the products showed stable water contact angles of about 130°. Composites of polypropylene with COX or MCC were prepared. Tensile tests showed that for a given reaction time, the COX-based composites exhibited higher values of both Young’s modulus and tensile strength than those of MCC-based composites.

Cellulose oxalate as reinforcement in polymeric composites

ACS Spring Meeting 2021

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