Alkali–methanol–anthraquinone pulping of Miscanthus x giganteus for thermoplastic composite reinforcement

Abstract

ABSTRACT:The potential of pulp fiber-reinforced thermoplastics is currently not fully explored in composites. One of the main reasons is that pulp fibers are extracted for the use in papermaking and are thus not optimized for use as reinforcements in thermoplastics. Furthermore, currently used processing methods constitute several severe thermomechanical steps inducing premature degradation of the fibers. A systematic development of these composite materials requires the study of both these aspects. The goal of this work was to optimize fiber extraction against properties relevant to the reinforcement of thermoplastics. To this end, thick-walled Miscanthus x giganteus pulp fibers were selected. The fibers were pulped by the alkaline-methanolanthraquinone process. An unreplicated factorial design was applied to determine the effect of key operating variables on fiber thermal stability and mechanical properties. The thermomechanical properties of pulp fibers depend primarily on the morphology and chemical composition of the fiber resource in terms of the respective amounts of lignin, hemicellulose, and cellulose, all strongly influenced by the choice of pulping conditions. Optimal pulping parameters were identified, allowing production of fibers thermally stable up to 255°C with an aspect ratio of 40, a straightness of 95%, and tensile strength as high as 890 MPa. , respectively.

Thermal and dynamic mechanical characterization of miscanthus stem fragments: Effects of genotypes, positions along the stem and their relation with biochemical and structural characteristics

“…These values are similar to the modulus of 10 GPa measured on stem fragments by nano-indentation by Bourmaud and Pimbert (2008). Of course, the moduli are much lower than the tensile modulus value of 55 GPa reported by Lundquist et al (2003) for individual fibres extracted from miscanthus stems by a pulping process and mostly composed of cellulose originating from cell walls. Besides, these values are close to tensile moduli of other stem fragments as bamboo, 11−36 GPa (Bourmaud et al, 2018;Gurunathan et al, 2015).…”

Sustainable biocomposites based on autohydrolysis of lignocellulosic substrates

“…To our knowledge, only Georgopulos et al [27] employed autohydrolysed samples of wood and brewery spent grains for reinforcing polypropylene-based composites, and Okuba et al [28] used steamexploded bamboo for improving the properties of PLA-based composites. Other reinforcers have been derived from LCM by physicochemical treatments, including thermomechanical pulping and acid hydrolysis [10], pulping with alkali-methanol-anthraquinone solutions [29], extraction with alkaline solutions [30,31], esterification [8] and carboxymethylation [26].…”

Variability of stem solidness among miscanthus genotypes and its role on mechanical properties of polypropylene composites

“…Composites reinforced with miscanthus stems are being increasingly studied due to attractive mechanical properties associated with their light‐weight compared to glass fibers (Girones et al 2016). The first such study was conducted on Miscanthus × giganteus and centered on the preparation of composites by incorporating fibers that were pulped by the alkaline–methanol–anthraquinone process (Lundquist et al, 2004). Johnson et al (2005) directly included stem fragments of Miscanthus × giganteus into a starch‐based polymer.…”

“…Few studies related the initial miscanthus stem properties with the biochemical characteristics of the plant. Lundquist et al (2004) used the smallest units and highest quality cellulose fibers from Miscanthus × giganteus stems thanks to an alkali–methanol–anthraquinone pulping process (Lundquist et al, 2004). They showed that cellulose fibers were thermally stable up to 255°C and had an aspect ratio of 40, a tensile strength of 890 MPa and a Young's modulus of 60 GPa.…”