Sugarcane bagasse fibers at high contents in thermoplastic composites: A novel approach using agro‐industrial residue via thermokinetic mixing

Abstract

Agro-industrial residue from sugarcane cultivation in Brazil generates more than 200 million tons of bagasse per year, which is rich in plant fibers that can be potentially applied in polymer composites. New processing routes are required to process composites with fiber contents above 50% wt. The objective of this work was to incorporate sugarcane bagasse fibers to polypropylene at high contents (50%-80% wt) in the development of composites via thermokinetic mixture. Composites with 50% and 60% fibers showed a traditional composite morphology, while those with 70% and 80% resembled agglomerated composites. The water absorption varied between 5% and 34%, increasing with fiber content, while the bulk density remained relatively constant, close to 1 g/cm 3 . The flexural strength and the flexural modulus reached 31 MPa and 2.4 GPa, respectively, tending to decrease with fiber content. In summary, the present work showed the viability of the proposed processing route, with only two starting materials, to produce cheap, relatively lightweight composites with mechanical properties close to and water absorption much lower than wood composites (medium-density fiberboard and medium-density particleboard) used in similar applications, such as furniture, construction, and automobile industry.

Comparison of the Physico-Mechanical and Weathering Properties of Wood–Plastic Composites Made of Wood Fibers from Discarded Parts of Pomelo Trees and Polypropylene

“…Nevertheless, the strength of WPC B20 was comparable to that of commercial wood-PP composites (36.5-42.7 MPa flexural strength) reported by Klyosov [43], and it also met the strength requirement (exceeding 20 MPa) of exterior WPCs (types EX I and II) in accordance with the Chinese National Standard CNS 15,730 [44]. Meanwhile, the flexural properties of WPC B20 were higher than that reported by Lazarini and Marconcini [21] for PP-based composites containing 50 wt% bagasse fibers (25 MPa of MOR and 2.0 GPa of MOE). Generally, the strength was lower for juvenile wood, and the fibers were shorter for juvenile wood than mature wood [42], which might cause the flexural strength of WPC B20 to be less than that of WPC R20 and WPC S20 .…”

“…Therefore, compared with inorganic fillers (e.g., mineral fillers and glass fibers) used in reinforced composites, WPCs show many advantages such as reducing the proportion and cost of the plastic matrix, increasing the stiffness of the plastic matrix, improving the physico-mechanical properties and processability of wood materials, renewability, low maintenance requirements, and environmentally friendliness [11][12][13][14][15][16][17][18][19]. In addition to wood particles or fibers, various agricultural wastes, such as bagasse [20,21], bamboo [16,18], cotton [11], coconut [22], hemp fiber [12], kenaf fiber [23], pineapple leaf [11], palm [9,24], rice husk [25], red pepper fruit stem [26], and straw [27], were also used as reinforcements or fillers for the thermoplastic composites. However, little information is available regarding the recycling and reuse of the pomelo waste.…”