Processing and structure–property relationships of natural rubber/wheat bran biocomposites

Abstract

In this work, wheat bran was used as cellulosic filler in biocomposites based on natural rubber. The impact of wheat bran content [ranging from 10 to 50 parts per hundred rubber (phr)] on processing, structure, dynamic mechanical properties, thermal properties, physico-mechanical properties and morphology of resulting biocomposites was investigated. For better characterization of interfacial interactions between natural rubber and wheat bran, achieved results were compared with properties of biocomposites filled with commercially available cellulosic fillers-wood flour and microcellulose. It was observed that wheat bran, unlike commercial cellulosic fillers, contains high amount of proteins, which act like plasticizers having profitable impact on processing, physical, thermo-mechanical and morphological properties of biocomposites. This is due to better dispersion and distribution of wheat bran particles in natural rubber, which results in reduction of stiffness and porosity of the biocomposites. Regardless of cellulosic filler type, Wolff activity coefficient was positive for all studied biocomposites implying reinforcing effect of the applied fillers, while tensile strength and elongation at break decreased with increasing filler content. This phenomenon is related to restricted strain-induced crystallization of NR matrix due to limited mobility of polymer chains in the biocomposites. Furthermore, this explains negligible impact of particle size distribution, chemical composition and crystallinity degree of applied cellulosic filler on static mechanical properties of highlyfilled NR biocomposites. The conducted investigations show that wheat bran presents interesting alternative for commercially available cellulosic fillers and could be successfully applied as a low-cost filler in polymer composites.

The Influence of Bleached Jute Fiber Filler on the Properties of Vulcanized Natural Rubber

“…The vulcanization times obtained for all compositions were similar. As reported 15,17,31 , the torque values of natural rubber increased with the fiber addition, indicating an increase in the stiffness of the vulcanized compounds. This is due to the restriction in the mobility of the rubber molecules caused by the fibers 31 .…”

“…Natural rubber composites containing natural fibers have been prepared using a variety of methods, for example, using a laboratory two-roll mixing mill 15,16 and a Brabender batch mixer 17 , and the properties of these composites have been analyzed. Pittayavinai et al 15 studied the effect of the manipulation of the crosslinking density of the fiber-containing natural rubbers.…”

“…For some formulations, there was an increase in the tensile strength compared to natural rubber. Formela et al 17 studied the properties of natural rubber and wheat bran biocomposites. This study reported an increase in the tensile modulus with the addition of fillers, explaining that the fibers can cause strain-induced crystallization in natural rubber.…”

Reactive extrusion of bio-based polymer blends and composites – Current trends and future developments

“…Furthermore, the lack of DCP effectiveness to improve matrix/filler adhesion could be related to complexity of chemical reactions between used components (natural fibers, PLA matrix and DCP). Especially taken into account that, diversity of physico-chemical properties of natural fibers/fillers has significant impact on the interfacial interactions in biocomposites [153][154][155]. Sajna et al [156] evaluated the impact of nanoclay and glycidyl methacrylate grafted poly(lactic acid) (PLA-g-GMA) on the thermal and flammability properties of PLA/banana fiber biocomposites.…”

Influence of peroxide modifications on the properties of cereal straw and natural rubber composites

“…Therefore, the maximum of the tan d peak height can be used to determine interfacial adhesion between the fiber and the polymer matrix. For better understanding the interfacial interactions between NR and used fillers, the adhesion factor (A) was calculated from DMA data according to literature (Wei et al 2013;Formela et al 2016;Akindoyo et al 2017) using Eq. (5):…”