A new article out of Ning Yan’s lab has been published in ACS Sustainable Chemistry and Engineering written by Nicole Tratnik, Pei-Yu Kuo, Nicolas R. Tanguy, Pitchaimari Gnanasekar, and Ning Yan. In this article studies the effect on amylopectin and amylose content in corn starches on modification through epoxidization and adhesion properties to wood
Formaldehyde-free, water-resistant, and environmentally friendly wood adhesives were prepared from starches via a simple one-step epoxidation reaction followed by cross-linking using diethylenetriamine. This study focused on the effect of amylose/amylopectin ratio of starch (high amylose, low amylose, and amylopectin) on the epoxidation reaction and on the bonding performance of the prepared epoxidized starches. The epoxidation of starches altered the fluid behavior of the resins, from Newtonian for pristine epoxy to shear thinning, that corroborated the successful integration of starch chains as part of the epoxy resin. Epoxidized amylopectin had the highest viscosity, 114 Pa.s, and a high degree of substitution, 2.33 ± 0.10, among the starches that indicated that amylopectin is more favorable for the grafting of epoxy groups and for the integration of starch chains in epoxy resins compared to the starches with high amylose content. Bonding strengths were determined by lap shear tests on yellow birch specimens in dry, wet, and boiled conditions. High amylopectin epoxidized starch showed the highest lap shear bonding performance under wet conditions (5.50 ± 0.451 MPa). Under boiled conditions, all three epoxidized starches showed equally better performance than the unreacted starch-filled epoxy blends. This study provides fundamental insights into the effect of starch molecular structure on epoxidation reaction and adhesion properties and suggests a promising approach for developing strong formaldehyde-free sustainable biobased wood adhesives.
Facile Synthesis of a Phosphorus-Containing Sustainable Biomolecular Platform from Vanillin for the Production of Mechanically Strong and Highly Flame-Retardant Resins Pitchaimari Gnanasekar, Martin Feng, Ning Yan* ACS Sustainable Chem. Eng. 2020, Publication Date: November 18, 2020
A novel chemical architecture, vanillin based phosphorus containing flame-retardant building block (VP) was successfully synthesized as a sustainable platform biomolecule to be converted into fire-retardant epoxy (VPE) and polyurethane (VPU) resins for application as environmentally-friendly adhesives. Structural characterizations confirmed the successful functionalization through their molecular structures. A series of VPU and VPE blends were prepared that showed excellent dry and wet bonding strengths and superior self‐extinguishing fire‐retardancy. The highest bonding strength of VPE80 for dry, cold and hot water treatment were noted about 3.64, 3.62 and 3.35 MPa respectively and the best fire‐retardant properties with the maximum LOI value of 29.6% and the lowest heat release rate according to cone calorimetry tests, due to the strong synergistic interpenetrating networks formed between the epoxy and PU macromolecules. The GC-MS analysis of the char residues indicated that the mechanisms for fire-retardancy were a combination of the quenching effect from the phosphorus-containing free radicals and the diluting effect of the non-flammable gases in the gas phase, plus the formation of phosphorus-rich char layers in the condensed phase. This study showcased a highly promising approach to develop environmentally-friendly high-performance fire-retardant chemicals using non-toxic vanillin as the starting material.
A new article out of Ning Yan’s lab has been published in ACS Sustainable Chemistry + Engineering written by Heyu Chen, Pitchaimari Gnanasekar, Sandeep S. Nair, Wenbiao Xu, Prashant Chauhan, and Professor Ning Yan
In this article, lignin-containing cellulose nanofibrils (LCNFs) were used in polymeric diphenylmethane diisocyanate (pMDI) wood adhesives as a functional compound to significantly reinforce bonding properties.
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Lignin as a Key Component in Lignin-Containing Cellulose Nanofibrils for Enhancing the Performance of Polymeric Diphenylmethane Diisocyanate Wood Adhesives Heyu Chen, Pitchaimari Gnanasekar, Sandeep S. Nair, Wenbiao Xu, Prashant Chauhan, and Ning Yan ACS Sustainable Chemistry & EngineeringArticle ASAP DOI: 10.1021/acssuschemeng.0c05642