ABSTRACT
Advancements in polymer science and engineering have helped the scientific community to shift its attention towards the use of environmentally benign materials for reducing the environmental impact of conventional synthetic plastics. Biopolymers are environmentally benign, chemically versatile, sustainable, biocompatible, biodegradable, inherently functional, and ecofriendly materials that exhibit tremendous potential for a wide range of applications including food, electronics, agriculture, textile, biomedical, and cosmetics. This review also inspires the researchers toward more consumption of biopolymer-based composite materials as an alternative to synthetic composite materials. Herein, an overview of the latest knowledge of different natural- and synthetic-based biodegradable polymers and their fiber-reinforced composites is presented. The review discusses different degradation mechanisms of biopolymer-based composites as well as their sustainability aspects. This review also elucidates current challenges, future opportunities, and emerging applications of biopolymeric sustainable composites in numerous engineering fields. Finally, this review proposes biopolymeric sustainable materials as a propitious solution to the contemporary environmental crisis. © 2022 Elsevier Ltd.
ABSTRACT
With respect to the explosion of single-use plastic packaging consumption during the COVID-19 pandemic, environmentally friendly substitutes are critically needful for sustainable development. Therefore, the present work focuses on the functional properties of bioplastic blends prepared through hot compressing molding of thermoplastic starch (TPS) and spent coffee grounds (SCG) in different ratios (0%–20% SCG) as the potential features of SCG were extensively employed in biocomposites for the first time. The insertion of dark brown SCG into TPS hindered UV transmission by 100% at 320 nm and 99.2% at 400 nm. Moreover, the samples with 15% and 20% SCG induced a surge in radical scavenging activity from 7.95% to over 92% at a concentration of 0.1 g/ml owing to the rich source of antioxidants in SCG. The lignin component and high carbon content also improved the thermal performance of TPS/SCG blends, enhancing thermal stability, delaying onset and maximum degradation temperatures, and achieving the HB rating in the UL-94 test. Compared to a pure TPS matrix, TPS blends incorporating up to 10% SCG exhibited improvement in elastic modulus without deterioration of tensile strength. © 2022 Society of Plastics Engineers.
ABSTRACT
Fogging on transparent surfaces such as goggles causes a series of hazards to users. To fabricate antifogging and low-haze transparent renewable polymer materials, intrinsic hydrophilicity with high water adsorption capability of thermoplastic starch (TPS) had been adopted. Strikingly, when benzoic acid (BA) was blended with thermoplastic starch (TPS-BA), the haze of TPS-BA was only 7.8% when it suffered the cold and warm method of antifogging measurement with 87% transmittance. Simultaneously, TPS-BA achieved an 18 mm inhibition zone for Staphylococcus aureus. To reveal the antifogging mechanism of TPS-BA films, the surficial and interior structure features were evaluated by three-dimensional optical scanner, scanning electron microscopy (SEM), contact angle testing, small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), temperature-dependent Fourier transform infrared (FTIR), dynamic mechanical analysis (DMA), and so on. The incorporation of BA resulted in the roughness (Rq), water contact angle (WCA), and crystallinity of the TPS-BA film decreasing from 6.5 to 0.68 μm, 65.1 to 39.9°, and 13.6 to 6.3%, respectively. The amorphous matrix and smooth surface reduced the scattered light, allowing the TPS-BA film to achieve low haze performance and high transmittance. Importantly, the diversified and weakened hydrogen bonds formed among starch, BA, and glycerol could inhibit the formation of starch crystalline regions and allowed hydroxyl groups to quickly bond with water. Thus, when TPS-BA is placed in a high-humidity surrounding, an "expressway"is constructed for water molecules diffusing into the TPS-BA matrix. This novel low-haze, antifogging, sustainable, and facilely fabricated TPS with antibacterial properties is a promising candidate in disposable medical goggles to fight against COVID-19. © 2021 American Chemical Society. All rights reserved.