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Cottonseed protein has been shown to have promising adhesive properties as an eco-friendly and effective polymeric wood adhesive. In this work, we adopted the biomimetic concept from mussel adhesio...

The interests in biobased wood adhesives have been steadily increasing in recent years. Cottonseed protein isolate has shown potential as a renewable biobased adhesives. For a better understanding ...

In order to decrease the usage of formaldehyde and petroleum-derived raw materials, there has been a lot of interest in using protein-based wood adhesives as more eco-friendly and less hazardous al...

Recently, there has been an increasing trend toward replacing conventional fossil-based plastics with bioplastics that are eco-friendly and biodegradable. In this work, blends of polycaprolactone (...

There is increasing interest in agro-based, biodegradable and eco-friendly wood adhesives as partial replacements for petroleum-based adhesives. In this work, we studied the adhesion of cottonseed ...

Acylation of polysaccharides is a commercially important reaction and is usually performed in a process involving the polysaccharide, an acid anhydride, and an inorganic acid. As an alternative to inorganic acid, many catalysts, including some metal chlorides, have been previously reported as catalysts. In this work, we took a more comprehensive look at several metal chlorides to observe trends and reactivities among them, particularly relating to reaction temperature, time, and amount of acetic anhydride used. Iodine was also included for comparison. Almost all the metal chlorides studied were found to be active as catalysts for the acetylation of starch under suitable reaction conditions. However, each metal chloride had a somewhat different reactivity with a different optimal temperature needed for satisfactory reactions to take place. The molecular weight of the starch acetate products decreased in all cases observed. The reactivity trends among the metal halides seemed to correlate both with ...

Most commercial wood adhesive use either formaldehyde-based resins or polyurethanes, both of which include potentially toxic chemicals in their formulations. As a result, proteins are being considered as greener and more sustainable wood adhesives. While most of the protein adhesive studies focus on soy proteins, there is also interest in exploring alternatives. In this work, testing of the adhesive performance of cottonseed protein isolate was undertaken in the presence of protein denaturants, i.e. guanidine hydrochloride (GuHCl), sodium dodecyl sulfonate (SDS), urea, and alkali. For comparison, soy protein isolate was also included in the study. At optimal dosage levels, the dry adhesive strength of cottonseed protein isolate could be enhanced by 38, 25, or 47% with SDS, GuHCl, or urea, respectively. The dry adhesive strength and hot water resistance of cottonseed protein isolate was generally superior to that of soy protein isolate, with or without the denaturants. Thus, the combination of cott...

Water-washed cottonseed meal (WCSM) has been shown as a promising bio-based wood adhesive. In this work, we tested the bonding strength of WCSM slurries with high solid contents and low press temperatures per industrial input for non-structural applications as European Standard Class D1 wood adhesives. Increasing the WCSM content from 11 to 20% and 30% did not substantially change the adhesive strength but increased the viscosity of WCSM slurries dramatically. The shear strength at break of the maple wood pairs bonded at 40 and 60 °C was lower than that of maple pairs bonded at 100 °C. However, the shear strength of the pairs bonded at lower temperatures (40 and 60 °C) could be improved by extending the press time from 20 to 120 min. Addition of citric acid (CA) improved the viscosity of the WCSM adhesive at 20% solid content, but lowered the adhesive strength. The addition of denaturing reagent sodium dodecyl sulfate (SDS) showed reverse impacts on the adhesive strength and viscosity, compared to...

Xylan is a hemicellulose, which is found abundantly in nature. In this work, a novel polyurethane was developed involving xylan and tolylene-2,4-diisocyanate (TDI). Polymer synthesis was achieved through conventional heat or microwave-assisted reaction in dimethyl sulfoxide. Because xylan has multiple OH groups on each polymer chain, the TDI/xylan molar ratio had to be adjusted to produce a soluble polymeric product. The reaction products were characterized by 13C NMR, FTIR, thermogravimetric analysis, and differential scanning calorimetry. The xylan polyurethane was shown to exhibit improved thermal stability over xylan.

The interest in natural product-based wood adhesives has been steadily increasing due to the environmental and sustainable concerns of petroleum-based adhesives. In this work, we reported our research on the utilization of water-washed cottonseed meal (WCM) as wood adhesives. The adhesive strength and water resistance of WCM adhesive preparations on poplar, Douglas fir, walnut, and white oak wood veneers were tested with press temperatures of 80, 100, and 130 °C. Our data indicated that raising the hot press temperature from 80 to 100–130 °C greatly increased the bonding strength and water resistance of the WCM adhesives. The general trend of the adhesive strength of WCM on the four wood species was Douglas fir > poplar ≈ white oak > walnut. The rough surface of Douglas fir with tipping features could enhance the mechanical interlocking between the wood fibers and adhesive slurry, contributing to the high adhesive strength. The dimensional swelling of the bonded wood pairs due to water soaking was...

In this work, a microwave-assisted method was developed to prepare polyurethanes from starch or maltodextrin and tolylene-2,4-diisocyanate (TDI). As compared to conventional heating, this new synthetic procedure saves energy, significantly reduces reaction time, and yet entails product yields that are comparable to those of the conventional heating procedure. The reaction products were characterized with NMR, FT-IR, thermogravimetric analysis, and scanning electron microscopy. From these analyses, the polyurethanes made with the conventional and microwave methods are shown to be similar in chemical structure and physical morphology. Furthermore, the 1H and 13C NMR spectra of the starch polyurethanes have been fully assigned for the first time.

Many polysaccharides are allowed for direct food use, where they serve a number of useful functions including dietary fiber, bulking agent, thickener, encapsulant, gelling agent, foam and emulsion stabilizer, protective colloid, emulsifier and suspending agent, adhesive and binder, flocculant, swelling agent, film/coat former, or syneresis inhibitor. Many of these polysaccharides have complex structures or are mixtures with different components. Over the years, NMR has been a premiere technique for characterizing these materials. NMR characterization can help identify the materials in question, quantify the different functional groups present, and detect minor components and impurities. Above all, the high resolution achieved in solution NMR can provide detailed structural information on composition, sequence distribution, substitution pattern, and molecular weights (in some cases) for individual polysaccharides. Concurrent application of other analytical techniques, such as methylation, esterification, f...

The NMR spectral assignments of polystyrene are reviewed and re-examined using various NMR techniques. Revised 13C-NMR assignments are obtained of the backbone methylene carbon; furthermore, the tacticity sequences of backbone methine carbon are assigned for the first time. The observed spectral intensities are fitted to a reaction probability model using curve deconvolution and a computer-assisted analytical approach. In addition, through the two-dimensional 1H-13C shift-correlated experiment, 1H-NMR assignments are obtained. A spectral simulation approach, using a statistical model and observed 13C shifts, is devised.