Thermal and thermomechanical properties of biocomposites made from modified recycled cellulose and recycled polypropylene

Abstract

ABSTRACT:Residual cellulose fibers from the paper industry have been used as reinforcements in recycled polypropylene (PP) composites. The main obstacle to obtaining good properties with this biocomposite is deficiencies in the compatibility between the nonpolar matrices and the polar cellulose fibers used as reinforcements. The aim of this work was to improve the compatibilization between these cellulose fibers and the PP matrix with four different methods: modification by the addition of polypropylene-maleic anhydride copolymer (PPgMA) during the process of blending, preblending modification of the cellulose with a solution of PPgMA, modification of cellulose by silanes (vinyltrimethoxysilane), and acetylation of cellulose. Blends with all of the differently modified celluloses were prepared with the cellulose content varied up to 40%, and then all of the blends were subjected to thermal (differential scanning calorimetry and thermogravimetric analysis) and thermomechanical (dynamic mechanical thermal analysis) analyses. The results showed that the addition of cellulose fibers improved the thermomechanical behavior of the PP, increasing the value of the log of the dynamic modulus, and affected the thermal and thermooxidative behavior. Moreover, an advantage of the use of a recycled PP containing a small quantity of ethyl vinyl acetate (EVA) as a prime material in the composition was the enhancement of mechanical properties. The use of these methods for the modification of cellulose led to more desirable thermal and thermooxidative stabilities.

Functionalization, Compatibilization and Properties of Polyolefin Composites with Natural Fibers

“…An increased thermal stability was found in PP composites with GMA modified hemp; moreover, marked changes in the morphology and overall crystallization rate of PP were observed in these composites due to the enhanced nucleating effect on the fiber surface. For all examined materials, the mechanical analysis showed that tensile modulus and elongation at break are significantly affected by the type and amount of fiber (aspect ratio: [10][11][12][13][14][15][16][17][18][19][20], as are affected by the structure (and concentration) of compatibilizer. In particular, the addition of functionalized polyolefins (PP-g-GMA, PS-co-MA) resulted in an increased stiffness owing to the improved fiber-matrix adhesion.…”

“…Polymer modification appears to be a quick, effective method to provide good interfacial adhesion, in contrast to fiber modification, which generally involves solvent based processes. Maleated PP (PP-g-MA) have been extensively used as compatibilizers in various polyolefin composites with natural fibers [12][13][14]; glycidyl methacrylate grafted PP (PP-g-GMA) has been employed in composites of PP with hemp fibers [15].…”

Characterization of Plastic Composite Based on HIPS Loaded with Bagasse

“…The improvement of Young`s modulus may be due to the high disaggregation of fibers with elevated elastic modulus. Meanwhile soaking the composite in oil for 24 h did not show any notable effect on the composite elasticity [33,34] as in Fig. 5a.…”

“…(4a, b). On the other side, fiber-reinforced HIPS composites had relatively higher Young's modulus compared to HIPS alone [33]. Since the natural fibers have higher Young's modulus than the thermoplastic polymers.…”

“…The second stage of weight loss occurred at temperature range 200-400°C, with a transition peak at 350°C due to the decomposition of cellulose [32]. The final products from the degradation of bagasse under an inert atmosphere are carbonaceous residues plus ungraded fibers since they did not remain after heating [33].…”