In this study, a biobased thermoset resin was developed from a nonedible starch source obtained from mango processing industrial waste. Mango seed starch (MSS) was extracted from defatted mango seed kernels and cross-linked using a “green” cross-linker/catalyst system, 1,2,3,4-butane tetracarboxylic acid (BTCA)/sodium propionate (NaP), to obtain the thermoset resin. The tensile properties of the cross-linked MSS were found to be adequate to replace edible starch based thermoset resins, e.g., potato or corn or proteins such as soy. The cross-linking or the esterification reaction proceeds faster and at lower temperature in the presence of a suitable catalyst. Sodium hypophosphite (SHP), a widely used catalyst for esterification using poly­(carboxylic acid)­s and hydroxyl groups of starch or cellulose, contains phosphorus and the effluents containing SHP, i.e., phosphorus, are toxic to humans and can adversely affect the fauna in water. Also, SHP decomposes to toxic phosphine gas when heated. The results of the present study indicate that sodium propionate (NaP), used as a nonphosphorus green catalyst, is as effective and efficient as SHP. The cross-linking of starch was confirmed directly using ATR-FTIR spectra and the degree of substitution (DS) values obtained by chemical titrations as well as indirectly through an increase in the tensile properties. Higher modulus and strength and lower degree of swelling in water of films cross-linked using NaP confirmed that NaP acts as a better catalyst than the conventional SHP.

The present research focuses on developing nonedible starch‐based resin to replace the currently used edible starches (corn, potato, etc.), protein (soy) as well as some of the petroleum‐based resins for fiber‐reinforced composite applications. Starch was extracted from mango seeds, a waste source freely available in tropical countries. Micro fibrillated cellulose (MFC) obtained from kraft pulp was used to reinforce mango seed starch‐based resin in order to take advantage of the chemical similarity between the starch and the cellulose which results in good interfacial bonding. Uniform dispersion of MFC in starch was obtained using homogenizer. Further, this MFC/MSS mixture was crosslinked using an environment friendly crosslinker, 1,2,3,4‐butane tetracarboxylic acid (BTCA). Crosslinking was confirmed directly using ATR‐FTIR spectra. MFC/MSS biocomposite specimens were prepared by solution casting method. The characterization of MFC/MSS biocomposites showed that their tensile and thermal properties were comparable to the edible starch‐based composites. The thermoset resins obtained from agricultural mango seed waste can be used to replace currently available resins derived from the edible sources or even some petroleum‐based resins for packaging, coatings, mulches, and other applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43803.

This study presents the preparation and use of a “green” cross-linker derived from a waste soy flour sugar (SFS) mixture to cross-link keratin in wool fibers to increase their tensile properties. Earlier studies of keratin cross-linking involved chemicals such as glyoxal and glutaraldehyde that are toxic to humans. In addition, their effectiveness in improving tensile properties has been significantly lower than obtained in this study using modified SFS. Characterization of SFS using 13 C NMR revealed the presence of five sugars having different molecular lengths. Oxidation of SFS using sodium periodate resulted in multiple aldehyde groups, as confirmed by 1 H NMR and attenuated total reflection Fourier-transform infrared (ATR-FTIR). The oxidized SFS (OSFS) when used to cross-link the amine groups from the wool keratin resulted in 36 and 56% increase in the tensile strength and Young’s modulus of the fibers, respectively. These significant increases in strength and Young’s modulus were a result of having multiple aldehyde groups on each sugar molecule as well as different molecular lengths of sugars, which favored cross-links of multiple lengths within the cortical cell matrix of wool fibers. The cross-linking between the aldehyde groups in OSFS and amine groups in wool fibers was confirmed using ATR-FTIR and from the color change resulting from the Maillard reaction as well as decrease in moisture absorption by the fibers. Stronger wool fibers can not only increase the efficiencies of wool fiber spinning and weaving and reduce yarn and fabric defects but can also allow spinning finer yarns from the same fibers. Oxidized sugars with optimum molecular lengths can be used to cross-link other biological proteins as well, replacing the currently used toxic cross-linkers.

This study presents a cyclodextrin-based “green”, inexpensive cross-linker to enhance the wrinkle-recovery angle (WRA) of fabrics. Cyclodextrin (CD) was oxidized using hydrogen peroxide (H2O2) and carboxylated with malic acid to introduce multiple carboxylic acid groups. The presence of carboxylic acid groups on CD was confirmed using attenuated total reflectance Fourier transform infrared (ATR-FTIR) and 13C NMR. Carboxylated CD (C-CD) was used to cross-link cotton fibers via multiple ester bond formation. Cross-linking was confirmed using ATR-FTIR and an increase in WRA. The impact of cross-linking on color change and tensile properties such as strength, strain, and tear strength of the fabrics was characterized. The wrinkle resistance of the treated fabrics was found to be durable for up to 25 laundry washings. Shelf-life of C-CD was found to be stable for 6 weeks as it did not show a reduction in WRA of fabrics. C-CD would be an excellent green alternative for industrial scale-up to replace dimethylol dihydroxyethyleneurea or 1,2,3,4-butanetetracarboxylic acid finishing, which are toxic and expensive.

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