Steam‐exploded wheat straw fibers as reinforcing material for polypropylene‐based composites. Characterization and properties

Abstract

Composites of wheat straw fibers with polypropylene (iPP) and maleic anhydride modified polypropylene (iPPMA) were prepared.Before being mixed with polypropylene matrices, the wheat straw fibers were subjected to a steam explosion process that induces morphological and structural changes in lignocellulosic materials. Such changes are able to enhance the interactions with the thermoplastic matrix.Compared with iPP, the modified matrix (iPPMA) has shown higher mechanical performances (tensile and impact behavior) and a remarkable decrease of water absorption, that is one of the main drawbacks of natural fiber composites.Finally, the presence of covalent bonds between maleic anhydride and steamexploded (STEX) fibers, by means of an esterification reaction, produced during the melt-mixing process, can explain the resulting good interfacial adhesion found in iPPMA-based composites. ZUSAMMENFASSUNG: Aus Weizenstrohfasern und Polypropylen (iPP) bzw. mit Maleinsaureanhydrid modifiziertem Polypropylen (iPPMA) wurden Composite hergestellt . Die Weizenstrohfasern wurden vor dem Einmischen in die Polypropylenmatrix einem Dampfexplosions-prozeB unterworfen, der bei Lignocellulosematerialien morphologische und strukturelle Veraderungen bewirkt, die zu einer Verbesserung der Wechselwirkungen mit der thermoplastischen Matrix fuhren kdnnen. Die modifizierte iPPMA-Matrix weist im Vergleich zur iPP-Matrix bessere mechanische Eigenschaften (Zug-und Schlagverhalten) und eine bemerkenswerte Verringerung der Wasseraufnahme, einer der Hauptnachteile von Compositen mit Naturfasern, auf. Die gute Grenzflachenhaftung in den iPPMA-Compositen kann mit den beim Mischen der Fasern mit der Polymerschmelze gebildeten kovalenten Esterbindungen zwischen den Maleinsaureanhydrid-Segmenten und den dampfbehandelten Fasern erklart werden.

Poly(lactic acid)‐based biocomposites reinforced with kenaf fibers

“…To confirm this assumption, the adhesion parameter A of the fiber-matrix interface was also evaluated. 43,44 The parameter A is defined by the following equation: 45…”

“…To confirm this assumption, the adhesion parameter A of the fiber‐matrix interface was also evaluated 43, 44. The parameter A is defined by the following equation:45 where V F is the volume fraction of the filler in the composite, and tan δ C ( T ) and tan δ M ( T ) are the values of tan δ, measured at the temperature T , of the composite and the pure matrix, respectively.…”

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)‐based biocomposites reinforced with kenaf fibers

“…To confirm this assumption, the adhesion parameter A of the fiber-matrix interface was also evaluated. 33,34 The parameter A is defined by the following equation 35 :…”

Preparation and Characterization of Lemongrass Fiber (Cymbopogon species) for Reinforcing Application in Thermoplastic Composites

“…straw, flax, and Luffa cylindrica fibers have been studied as reinforcements or fillers in polymer composites (Avella et al 1995;Dogherty et al 1995;Wambua et al 2003;Frounchi et al 2007;Bledzk et al 2010;Maneesh et al 2012;Zhang et al 2016). These fiber reinforcements improve the mechanical strengths and thermal stability of the composites (Panthapulakkal et al 2006;Alemdar and Sain 2008;Zou et al 2008;Mominul et al 2009;Ravindra et al 2010;Arrakiz et al 2013).…”