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Bio based polyurethane nanocomposites (renewable thermosets) show a diverse range in properties, processing components and production of smart materials for health, food, and energy sectors. In this work, polyurethane nanocomposites based on isophorone diisocyanate (IPDI), and hydroxyl terminated-polybutadiene (HTPB) incorporating clay were modified using hydroxyethyl cellulose (HLAC) to be further assessed for thermal and mechanical properties. Elastomers samples were prepared by blending clay suspension and PU prepolymer to attain clay contents of 0.3, 0.5, and 1% (weight on dry basis) along with butane diol and HLAC chain extenders. Effect of nanofiller aggregation and dispersion on the thermal degradation and surface morphology of the bionanocomposites were studied. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray (SEM/EDX) and thermal gravimetric (TG) techniques were used to investigate the interactions among PU matrix, clay nanofillers, and HLAC. Mechanical testing indicated an increase in tensile strength and a decrease in elongation at break (%) by just adding 0.3 wt% clay. The thermal stability of the bionanocomposites was improved with the addition of clay. The results of the thermal and mechanical studies demonstrated the feasibility of the bionanocomposites as strong and thermally stable elastomers with low filler loading., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Bionanocomposites is an emerging class of biohybrid materials, have a significant impact in environmental and biomedical fields owing to their high performance, lightweight, unique, and ecofriendly properties. A major challenge in the multiphase bionanocomposites system is to subtle control over the performance by managing the individual properties of reacting components. Herein, we presented the preliminary investigation on bionanocomposite system based on graphene nanoplatelets (GNPs) and hydroxyethyl cellulose graft poly(lactic acid) copolymer-polyurethane (HLAC-PU) with the aim to understand the structure property correlation for proposed applications in electronics and medical areas. The HLAC was fabricated by graft copolymerization of hydroxyethyl cellulose (HEC) and lactic acid (LA) with dibutyltin dilaurate. The HLAC was used to get a bio-functionalized PU matrix reinforced with GNPs by step-growth polymerization method. The structural, surface, and thermal properties of the HLAC and GNPs-HLAC-PU bionanocomposites were studied. The spectroscopic techniques confirmed the structure of bionanocomposites by the identification of related bands. The SEM/EDX results demonstrated that the 0.3 wt% of GNPs dispersed well in the HLAC-PU matrix and offered higher crystallinity. The reinforcement of the 0.3 wt% of GNPs has meaningfully enhanced the thermal stability producing higher residue contents. The reinforced GNPs filler increased the water resistance of bionanocomposites by reducing their water vapor permeability., (Copyright © 2020 Elsevier B.V. All rights reserved.)

2-Hydroxyethyl cellulose graft polylactic acid copolymer (HLAC) was prepared by graft copolymerization of lactic acid (LA) and 2-hydroxyethyl cellulose (2-HEC), initiated by dibutyltin dilaurate (DBTDL) catalyst in aqueous media. Halloysite nanotubes (HNTs)/polyurethane (PU) bionanocomposites were prepared using the HLAC as chain extender in the step-growth polymerization. HNTs were dispersed in HLAC based PU matrix at different weight ratios of 0.30, 0.50, 1.00, and 3.00. Chemical structure and morphology of the graft copolymer and bionanocomposite elastomers were characterized using solid state 1 H NMR, ATR-FTIR, XRD, and SEM-EDX, while thermal degradation behavior was studied by TGA and DSC techniques. Surface morphology of the HNTs reinforced HLAC/PU bio-nanocomposites demonstrated the homogeneous dispersion of HNTs with little wavy rough surface at low contents which turned to be brittle at higher contents due to agglomerated HNTs. It is observed that the lower contents of HNTs were completely exfoliated in the HLAC/PU matrix. Crystalline pattern of the elastomers improved at lower contents of HNTs that enhanced the thermal stability of the bionanocomposites. The mechanical testing suggested that HNTs/HLAC/PU bionanocomposites have higher values of tensile strength and % elongation with only 0.3-0.5 wt% contents of HNTs that suggested the potential applications of elastomers at economic cost., (Copyright © 2020 Elsevier B.V. All rights reserved.)