Effect of Enzymatic Pretreatment on the Preparation and Properties of Soy-Based Adhesive for Plywood

Abstract

Response surface methodology was employed to determine the effects of enzymatic pretreatment temperature, time, and pH on the reducing sugar content and bonding strength of soy-based adhesives (SBAs). Plywood specimens bonded by the SBAs with Pinus massoniana veneer were then produced. A significant positive correlation was observed between reducing sugar content and the bonding strength of SBAs. The effects of pretreatment temperature and time on bonding strength were also significant, but insignificant with respect to reducing sugar content; the effects of enzymatic pretreatment time on response values were the smallest. The optimal enzymatic pretreatment conditions of SBA were a pretreatment temperature of 54 °C, a pretreatment time of 20.0 min, and a pretreatment pH of 5.1. Under these conditions, the reducing sugar content and bonding strength (boiling-water test) of SBAs were 2.93% and 0.62 MPa, which were higher than the control by 113.9% and 30.6%, respectively. X-ray diffraction (XRD) indicated that the ordered degree of soy protein decreased, but the ordered structure had no variation when defatted soy flour was treated by enzymes with combination of acid, salt, and alkali. The SBAs contain more active functional groups and have better water resistance after curing.

Controllable crosslinking system of soy protein‐based adhesives via soybean polysaccharide for wood composites

“…Its backbone was composed of homogalacturonan and rhamnogalacturonan, and its branched chains was composed of galactan and arabinan 28 . Moreover, SPS was the major carbohydrate component in the commercial DSF, it mainly contributed to the weak water resistance of the soy protein‐based adhesives 29 . To quantitative analysis the effect of SPS on the crosslinking adhesive, it will be used as the carbohydrate additive model in the following research.…”

“…28 Moreover, SPS was the major carbohydrate component in the commercial DSF, it mainly contributed to the weak water resistance of the soy protein-based adhesives. 29 To quantitative analysis the effect of SPS on the crosslinking adhesive, it will be used as the carbohydrate additive model in the following research. The bond strength of plywood may be modulated by controlling the contents of SPS in the soy protein-based adhesive.…”

Evaluation of Starch as an Environmental-Friendly Bioresource for the Development of Wood Bioadhesives

“…After acid hydrolysis at a temperature of 60 • C, the grafting process proceeds, using (NH 4 ) 2 SO 4 as the initiating agent. The monomers that bind to the starch structure in the polymerization process are polyvinyl alcohol (PVA), which binds through hydrogen bonds [39], vinyl acetate and butyl acrylate, which bind through the free hydroxyl radicals of amylose and amylopectin [40]. After this first polymerization, a second one is carried out in the pursuit to improve the thermogravimetric properties of the starch bioadhesive.…”

Investigation of an environmentally friendly incense consisting of soy-based adhesive and wood powder

“…Soy protein is one of the widely studied vegetable proteins for the preparation of soy-based adhesives that were used in the production of plywood in the early 20 th century, but were replaced by urea-formaldehyde adhesives that had better water resistance (Chen et al 2018). Through the persistent efforts of many researchers, the water resistance of soy-based adhesives has continuously improved, and great progress has been made in the bonding of wood (Chen et al 2012). Previous research has found that alkali-modified soy protein isolate adhesives applied to bonded plywood displayed improved water resistance (Hettiarachchy et al 1995).…”