Review of the pretreatment methods for wheat straw building materials

Abstract

This paper reviews the pretreatment methods for wheat straw building materials and classifies the main methods according to their characteristics. The results indicate that the steam cooking and steam explosion treatment methods are relatively better than other methods and that particleboard and medium-density fiberboard manufactured using pretreated wheat straw possess correspondingly superior physical and mechanical properties. However, deficiencies in internal bonding, tensile strength, dimensional instability (swelling) and high moisture absorption remain. Thus, the present study proposes improving the pretreatment method and measurement and suggests a future development direction for the pretreatment of wheat straw building materials.

Wheat straw pre-treatments using eco-friendly strategies for enhancing the tensile properties of bio-based polylactic acid composites

“…Several methods have been developed in order to improve the surface compatibility of the natural reinforcements by additive incorporation as well as employing a variety of pre-treatment processes to produce a high-performance bio-based composites. Physical pre-treatment methods, including steam cooking, steam explosion, liquidplasma, and ozonation (Ghaffar et al, 2017b;Putra et al, 2020), as well as chemical pre-treatments such as mercerization, acetylation, enzymatic, and alkaline pre-treatments (Ghaffar and Fan, 2015a;Hýsek et al, 2018;Hýsková et al, 2020;Li et al, 2007b), have been shown to be beneficial in terms of (i) modifying the surface of straw with the partial removal of extractives, waxes, and silica which made it more hydrophilic and more compatible with water-based resins, (ii) expanding the microcellular structure of straw and hence improving the penetration of matrix into cell lumens, leading to intimate bonding quality between substrate and matrices (Elbashiry et al, 2018;Oushabi, 2019). Wang et al (2018) employed an alkaline pre-treatment using 4 wt % sodium hydroxide (NaOH) solution for bamboo fibers, which led to an increase in the elongation at break and tensile strength of the polylactide composites filled with alkaline treated fibres by 84 % and 49 %, respectively (Wang et al, 2018).…”

Key advances in development of straw fibre bio-composite boards: An overview

“…NaOH and H 2 SO 4 treated fibres achieved the most prominent surface modification [47]. Contrarily, it was found out that the steam cooking and steam explosion fibre treatment methods which were not considered in the previous work performed better than the other fibre treatments [48]…”

High‐strain‐rate mechanical performance of particle‐ and fiber‐reinforced polymer composites measured with split Hopkinson bar: A review

“…This is due to considerably higher mechanical properties of epoxy and CF compared with their counterparts PP and WSF. [164,165] Vinyl ester (VE)/GF shows great compressive strength (Figure 15) not only because of the high-fiber content but also because the unidirectional alignment of GF, with superior strength, [166] within the matrix, enhanced the variation in stress propagation within the VE polymer. [167] Besides, when introduced at high-enough concentrations, straight and aligned fibers participate as load-bearing components, which greatly reinforces the polymer matrix.…”