Development of bioplastic materials: From rapeseed oil industry by products to added-value biodegradable biocomposite materials

Rapeseed crops are mainly harvested due to its high oil content. Production of oil from rapeseed generates a significant amount of by-products like presscake or meal. The high protein content (similar to 35%) of these rapeseed byproducts makes them an interesting plant-derived alternative for the development of bioplastic materials. The generation of bioplastics from a rapeseed meal by injection moulding was studied herein at different mould temperatures (80, 100, 120 degrees C). Further processing of the meal (pelletizing, milling, sieving) on the bioplastics produced was also analysed using dynamic mechanical thermal analysis (DMTA), tensile tests and water uptake capacity. In all cases, strengthening of the samples occurred when moulding at high temperatures (120 degrees C), which might be related to thermally promoted protein cross-linking. This effect was reflected by an increase of 50% in the viscoelastic properties of the bioplastics when increasing the mould temperature from 80 to 120 degrees C. Biocomposites of rapeseed meal and polycaprolactone (PCL) at different PCL contents (0-20 wt. %) were also produced. The viscoelasticity of the biocomposites depended on PCL concentration. When PCL content was 20 wt.%, viscoelastic moduli (E' and E '') increased around 200%, which may be associated either to its role as a filler or to its integration into the protein matrix. These results indicate that rapeseed meal is a suitable alternative for the generation of bioplastic materials adding value to a by-product of the rapeseed oil industry.