A dialdehyde starch-based adhesive for medium-density fiberboards

Abstract

Bio-based adhesives have gained considerable attention in the last years as more sustainable and healthier alternatives to the formaldehyde-based adhesives used today in wood-based panel manufacturing. In this study, dialdehyde starch (DAS) with various aldehyde contents was prepared by using sodium metaperiodate as an oxidizing agent. Characterizations were performed by employing Fourier-transform infrared spectroscopy, nuclear magnetic resonance, and thermal stability analysis. Different adhesive compositions were used for making medium-density fiberboard (MDF) panels. They were based on DAS (12 wt% based on fiber), emulsifiable diphenylmethane diisocyanate (eMDI, 2-4 wt% based on DAS), and microfibrillated cellulose (MFC, 0.5-1.0 wt% based on DAS). Fibers and the adhesive components were mixed with a combination of dry mixing and wet spraying. The physical and mechanical properties of MDF panels bonded with different DAS-based adhesives were compared with those of melamine urea-formaldehyde (MUF) adhesive and sole eMDI. The results showed that the MDF panels made with DAS-MFC-eMDI of 99.52% bio-based content showed comparable properties to standard panels with a commercial MUF adhesive. It was implied that DAS in the presence of small amount of eMDI can create strong bonds with wood fibers, while an additional positive effect on bonding was due to the contact surface enlargement of MFC.

Effect of press temperature on oat husk particleboards bound with a dialdehyde starch adhesive

“…Likewise, a brown discolouration of the panels (Fig. 1c) increased from a pressing temperature of 160°C, which was not noticeable when the adhesive was integrated into breboards in a previous study (Neitzel et al, 2023). The DAS-based adhesive, in combination with a brous material, resulted in breboards with comparable properties to those bonded to a melamine urea-formaldehyde resin (Neitzel et al, 2023).…”

Recent Developments in Eco-Friendly Wood-Based Composites II

“…For this reason, growing ecological and environmental consciousness drives efforts for the development of new eco-friendly wood-based composites for various end-use applications. In recent years, significant efforts have been made to reduce formaldehyde emissions from wood-based composites via: (i) the reduction of formaldehyde content in resin formulation [4,5]; (ii) the use of scavengers such as tannins, lignin, starch, wheat and hemp flour, and pulp and paper sludge [6][7][8][9][10][11][12][13][14] or other compounds (starch derivatives, charcoal, pozzolan, zeolites, and urea) [15][16][17][18][19] that scavenge formaldehyde; (iii) the post-treatment or surface treatment of the wood-based products [18,20]; (iv) the use of natural resins, including soy protein, tannin, lignin, and starch adhesives [21][22][23]; (v) and the thermal pre-treatment of veneer before bonding [24][25][26]. Comprehensive information on the reduction of formaldehyde emissions in various ways can be also found in several published reviews [4,20,[27][28][29][30].…”