The increased awareness of the environmental effects of petroleum based plastics has stimulated the coffee price emergence of biodegradable polymers such as polylactic acid (PLA). In a bid to increase the sustainability of PLA agricultural residues of animal feeds (corn stover, rice straw, and soybean hulls) have been explored and examined as reinforcing fillers to PLA composites. The consideration of such applications is suitable to the goals of the circular economy as it recycles low-value agricultural products. The current review critically evaluates lately carried out life cycle assessment (LCA) studies on PLA composites that have implemented such waste fillers with the full focus being on their environmental performance as well as methodological consistency. The review shows that these fillers have a potential of reducing the amount of greenhouse emission, energy usage, and other environmental effects, compared to pure PLA. However, unevenness in LCA methodology, especially in functional units, the system boundaries, and impacts categories obstructs direct LCA comparisons. The 1997 State of the Market report also has limited options of feedstocks and the lack of appraisals in the socio-economic front, so the overall sustainability analysis is restricted. Some of the remaining limitations that can be critical are to have generalized LCA frameworks, extended exploration of waste-based fillers, as well as combination of techno-economic analysis and social impact. Future inquiries ought to devise design considerations that would optimize both the functional characteristics and the performance of the environment and improve the reliability of sustainability measures. This review is evidence to the potential of agricultural waste reinforced PLA composites in the progress towards environmentally friendly materials and the need of integrative evaluation in the sustainable maturation of bioplastics.
The history of organic polymers is a remarkable journey from the discovery of natural materials like rubber and silk to the development of sophisticated synthetic polymers that have transformed industries and modern life. This comprehensive review article presents a detailed account of the evolution of organic polymers. It begins with the early uses of natural polymers and explores key breakthroughs, including the invention of Bakelite, nylon, and neoprene. The theoretical foundations of polymer science, laid by Hermann Staudinger, are discussed, and the post-war surge in polymer development is examined, including the introduction of polyethylene, polypropylene, and PVC. Notable advances in polymer chemistry, such as isotactic polypropylene and silicone polymers, are highlighted. The article also delves into the development of high-performance polymers like Kevlar and carbon-based materials, offering insights into their applications. Moreover, it discusses the current trends in polymer science, emphasizing sustainability and biodegradability. As the world continues to rely on polymers for numerous applications, this review provides a historical perspective and a glimpse into the future of organic polymers, where innovations are expected to shape various aspects of technology, healthcare, and environmental protection.
The present article reports the applications of Caputo-Fabrizio time-fractional derivatives. This article generalizes the idea of unsteady MHD free convective flow in a Walters.-B fluid with heat and mass transfer study over an exponential isothermal vertical plate embedded in a porous medium. The governing equations are converted into dimensionless form and extended to fractional model. The generalized Walters-B fluid model has been solved analytically using the Laplace transform technique. From the general solutions we reduce limiting solutions when to the similar motion for Newtonian fluid. The corresponding expressions for and Nusselt and Sherwood numbers are also assessed. Numerical results for velocity, temperature and concentration are demonstrated graphically for various factors of interest and discussed. As a result, we have plotted the influence of fractional parameter on fluid flow and drawn comparison between fractional Walters’-B and fractional Newtonian fluid and found that fractional Newtonian fluid is faster than fractional Walters’-B fluids.
Research into electro-conductive textiles based on conductive polymers like polypyrrole has increased in recent years due to their high potential applications in various fields. Conductive polymers behave like insulators in their neutral states, with typical electrical conductivity in the range 10–10 to 10–25 Scm–1. These neutral polymers can be converted into semi-conductive or conductive states with conductivities ranging from 1 Scm–1 to 10–4 Scm–1 through chemical or electro-chemical redox reactions. By applying these polymers to a textile surface, we can obtain novel composites that are strong, flexible, lightweight, and highly electroconductive. These textile composites are suitable for applications such as heating pads, sensors, corrosion-protecting materials, actuators, electrochromic devices, EMI shielding, etc. The methods of application of conductive polymers onto the textile surface, such as in-situ chemical, in-situ electrochemical, in-situ vapor phase, in-situ polymerization in a supercritical fluid, and solution coating processes, are described here briefly. The merits and demerits of these methods are mentioned here. The reaction mechanisms of chemical and electrochemical polymerization proposed by the different researchers are described. Different factors affecting the kinetics of chemical and electrochemical polymerization are accounted for. The influence of textile materials on the kinetics of chemical polymerization is reviewed and reported.
Energy shortages and environmental damage have become serious problems facing the society today. Biomass can be a renewable energy source, which large-scale development and utilization are of great significance to industry and social life. Biomass pyrolysis technology can achieve effective utilization of biomass energy. It is necessary to optimize the pyrolysis reaction technology and device for realize the industrialization and large-scale production of biomass energy.
Quartz sand was used as bed material in a small fluidized bed reactor with 1 kg/h feed. Corn straw powder with particle size of 20–40 mesh, 40–60 mesh, 60–80 mesh and 80–120 mesh was used as raw material for rapid pyrolysis at reaction temperatures of 400 °C, 450 °C, 500 °C and 550 °C. The bio-oil obtained after liquefaction of pyrolysis gas was analyzed. The variation trend of bio-oil composition in pyrolysis of corn straw powder with different reaction temperatures and raw material sizes was compared. The results show that: (1) the content of 3-hydroxyl-2-phenyl-2-acrylic acid in bio-oil increases with the decrease of raw material particle size, but it is less at 450 °C; (2) with the increase of reaction temperature, the content of hydroxyacetaldehyde in bio-oil increases at first and then decreases: the content of hydroxyacetaldehyde in bio-oil is the highest at 500 °C when the particle size is 20–40 mesh, and the highest at 450 °C with the other three particle sizes. Compared with other particle sizes, raw material with the particle size of 60–80 mesh is not conducive to the formation of aldehyde compounds; (3) the reaction temperature of 500 °C and the particle size of 60–80 mesh of raw materials are more conducive to the formation of phenolic compounds in bio-oil; (4) the ester compounds with particle size of 20–40 mesh in bio-oil is 20% higher than that of other particle sizes; (5) the reaction temperature and the particle size of raw materials had no significant effect on the formation of ketones, alcohols and alkane compounds in bio-oils.
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