This work presents a facile, solvent-free approach for the fabrication of PLA biocomposites, followed by melt extrusion process to prepare stereocomplex PLA films with excellent thermomechanical and gas barrier properties. The presence of stereocomplex crystallites improves the thermal properties of polylactic acid (PLA); however, the formation of stereocomplex crystallites is predominantly lesser compared to homocrystallites in case of high molecular weight poly(L-lactic acid) and poly(D-lactic acid) blend. Grafting of biofillers with polymer matrix chains may help in homogeneous dispersion and formation of stereocomplex crystallites. Henceforth, stereocomplex PLA was fabricated with cellulose microcrystals (CMC) as filler, after chemical modification by in situ ring opening polymerization of D-lactide. The stereocomplexation in the blend system was found to be enhanced by the extended molecular surface area provided by grafted CMC. As confirmed by morphological analysis, the modification of CMC drives the homogeneous dispersion into the matrix and reduction in the size of CMC in the range of ∼200 nm diameter. Increased melting temperature (∼209 °C) with no evidence of homocrystallites confirm the role of grafted CMC in the formation of stereocomplex crystallites by suppressing the development of homocrystals. The fraction of stereocomplex crystallites was found to be 100% when analyzed using X-ray analysis. The enhanced stereocomplexation in the composites resulted ∼96% improvement in the tensile strength in comparison to pristine PLLA/PDLA blend. Interestingly, the oxygen permeability and water vapor permeability were reduced by ∼25% and ∼35%. The improved thermomechanical properties of the biocomposites through enhanced stereocomplexation may comply with the requirement for high temperature engineering and packaging applications.

The inherent capability to deform and reform in a predefined environment is a unique property existing in shape memory polyurethane. The intrinsic shape memory ability of the polyurethane is due to the presence of macro domains of soft and hard segments in its bulk, which make this material a potential candidate for several applications. This review is focused on manifesting the applicability of shape memory polyurethane and its composites/blends in various domains, especially to human health such as shielding of electromagnetic interference, medical bandage development, bone tissue engineering, self-healing, implants development, etc. A coherent literature review highlighting the prospects of shape memory polyurethane in versatile applications has been presented.

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In this study, we successfully demonstrate single-step industrially scalable reactive extrusion of polylactic acid (PLA)/ cellulose nanocrystal (CNC)-based cast films which leads to reduced necking, improved processability, melt strength, and rheological behavior. PLA chains grafted onto CNCs, formed cross-linked gel-like structures of high molecular weight (M w ≈ 150−245 kDa), with varying grafting efficiency (14%−67%) or gel-fraction yield (16%− 69%), depending on the type of compatibilizers used. The reactively processed films show reduction in both oxygen properties (20%− 65%) and water vapor barrier properties (27%−50%), along with improved thermomechanical properties. These films finds potential applications for the storage of oil-and dairy-based products, which show shelf lives of ∼5 months and ∼2 weeks, respectively, and are within the standard migration limits, as per the set legislations. Therefore, the present study provides a novel, easily processable extrusion-based approach for manufacturing sustainable PLA/ CNC-based green and eco-friendly films with improved recyclability, biodegradability, and nontoxicity for potential applications as food packages on a commercial scale.

Ending the fossil fuel era towards a sustainable future will require high-performing renewable materials with a low environmental impact. Carbon black, produced by partial combustion or thermal decomposition of petroleum...