Biopolymers are an emerging class of materials being widely pursued due to their ability to degrade in short periods of time. Understanding and evaluating the recyclability of biopolymers is paramount for their sustainable and efficient use in a cost-effective manner. Recycling has proven to be an important solution, to control environmental and waste management issues. This paper presents the first recycling assessment of Solanyl, Bioflex, polylactic acid (PLA) and PHBV using a melt extrusion process. All biopolymers were subjected to five reprocessing cycles. The thermal and mechanical properties of the biopolymers were investigated by GPC, TGA, DSC, mechanical test, and DMA. The molecular weights of Bioflex and Solanyl showed no susceptible effect of the recycling process, however, a significant reduction was observed in the molecular weight of PLA and PHBV. The inherent thermo-mechanical degradation in PHBV and PLA resulted in 20% and 7% reduction in storage modulus, respectively while minimal reduction was observed in the storage modulus of Bioflex and Solanyl. As expected from the Florry-Fox equation, recycled PLA with a high reduction in molecular weight (78%) experienced 9% reduction in glass transition temperature. Bioflex and Solanyl showed 5% and 2% reduction in molecular weight and experienced only 2% reduction in glass transition temperature. These findings highlight the recyclability potential of Bioflex and Solanyl over PLA and PHBV.

Synthetic polymers are ubiquitous materials widely used in construction, automotive, electronics, and countless commercial products. With the growing trend of polymer applications in everyday life, upholding the rigorous fire safety regulations has become a matter of concern. In this regard, numerous studies have been conducted for improving the fire retardancy of polymers, mainly through incorporating a diverse group of fire‐retardant compounds into polymer‐based composites. This review article aims to present a comprehensive overview of recent advances in the fire‐retardant categories for polymeric materials especially emphasizing the nanosized fire retardants. Along with an attempt to focus attention on the consumption of conventional and possibly harmful fire retardants, potential eco‐friendly alternatives are represented. A detailed discussion on the flame retardation mechanisms and conventional fire characterization techniques are also discussed.

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Cortical bone quality, which is sexually dimorphic, depends on bone turnover and therefore on the activities of remodeling bone cells. However, sex differences in cortical bone metabolism are not yet defined. Adding to the uncertainty about cortical bone metabolism, the metabolomes of whole bone, isolated cortical bone without marrow, and bone marrow have not been compared. We hypothesized that the metabolome of isolated cortical bone would be distinct from that of bone marrow and would reveal sex differences. Metabolite profiles from liquid chromatography-mass spectrometry (LC-MS) of whole bone, isolated cortical bone, and bone marrow were generated from humeri from 20-week-old female C57Bl/6J mice. The cortical bone metabolomes were then compared for 20-week-old female and male C57Bl/6J mice. Femurs from male and female mice were evaluated for flexural material properties and were then categorized into bone strength groups. The metabolome of isolated cortical bone was distinct from both whole bone and bone marrow. We also found sex differences in the isolated cortical bone metabolome. Based on metabolite pathway analysis, females had higher lipid metabolism, and males had higher amino acid metabolism. High-strength bones, regardless of sex, had greater tryptophan and purine metabolism. For males, high-strength bones had upregulated nucleotide metabolism, whereas lowerstrength bones had greater pentose phosphate pathway metabolism. Because the higher-strength groups (females compared with males, high-strength males compared with lower-strength males) had higher serum type I collagen cross-linked C-telopeptide (CTX1)/procollagen type 1 N propeptide (P1NP), we estimate that the metabolomic signature of bone strength in our study at least partially reflects differences in bone turnover. These data provide novel insight into bone bioenergetics and the sexual dimorphic nature of bone material properties in C57Bl/6 mice.

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The material properties of bone tissue depend on the activity of remodeling bone cells, but the impact of bone cell metabolism on bone tissue is uncertain. To date, the metabolome of bone has not been evaluated for cortical bone, bone marrow, or whole bone including both tissue types. Furthermore, it is of particular interest whether the cortical bone metabolome reflects the sexual dimorphism observed in cortical bone material properties. We hypothesized that the metabolome of cortical bone differs from that of bone marrow, and that the cortical bone metabolome is sexually dimorphic. We first evaluated the metabolic profiles of isolated cortical bone, bone marrow, and whole bone for 20-week female C57Bl/6 mice (n = 10). We then compared metabolic profiles for isolated cortical bone from a separate group of 20-week female and male C57Bl6/mice (n = 10 / sex). Femurs from the same mice were evaluated for flexural material properties. Strength groupings (high strength males, high strength females, low strength males) were utilized to inform comparisons in the isolated humerus cortical bone metabolome. The metabolome of isolated cortical bone, bone marrow, and whole bone are distinct. The isolated cortical bone metabolome is also distinct between males and females. The female mice show evidence of lipid metabolism, whereas male mice show evidence of amino acid metabolism. Finally, 12 metabolic pathways were differentially regulated between bones that differed in strength. High-strength bones from both male and female mice included metabolites associated with tryptophan and purine metabolism. Taken together, these data demonstrate the power of metabolomics to provide insight into the effects of metabolism on bone physiology. These data add to an intricate picture of bone as an organ that is sexually dimorphic both in material and metabolomic profiles.

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