Study on Properties of Poly(urethane-ester) Synthesized from Prepolymers of ε-Caprolactone and 2,2-Dimethyl-1,3-Propanediol Monomers and Their Biodegradability

Poly(urethane-ester) was prepared by polymerization of 4,4′-methylenebis(phenyl isocyanate) (MDI) and prepolymers of ε-caprolactone and 2,2-dimethyl-1,3-propanediol monomers P(CL-DP) with various chain lengths as polyol sources. Characterizations of poly(urethane-ester) were carried out by analysis of functional groups (FTIR), thermal properties (DTA/TGA), mechanical properties (Tensile tester), crystallinity (XRD), and biodegradability. The chain length of prepolymers used in polymerization has a significant effect in properties of poly(urethane-ester) as well as their biodegradability. The formation of poly(urethane-ester) was indicated by the presence of new absorption peaks at wave number of 3,348.2 and 1,596.9 cm^?1 for urethane (–NH–) and aromatic groups in chain of polymers, respectively. The increase chain length of prepolymer used in polymerization with 4,4′-methylenebis(phenyl isocyanate) was observed the increase thermal property and crystallinity of poly(urethane-ester). However, the maximum mechanical property and also biodegradability in activated sludge were observed in poly(urethane-ester) prepared by polymerization of 4,4′-methylenebis(phenyl isocyanate) (MDI) and P(CL-DP) prepolymers with DP/CL ratio of 1/20. Apparently, the amorphous parts of polymers are rapidly decomposed by enzymes of microorganisms, so the crystallinity on the whole of poly(urethane-ester) increases after incubation time of 30 days.     

The wild ancestors of domestic animals as a neglected and threatened component of biodiversity

Domestic animals have immense economic, cultural, and practical value and have played pivotal roles in the development of human civilization. Many domesticates have, among their wild relatives, undomesticated forms representative of their ancestors. Resurgent interest in these ancestral forms has highlighted the unclear genetic status of many, and some are threatened with extinction by hybridization with domestic conspecifics. We considered the contemporary status of these ancestral forms relative to their scientific, practical, and ecological importance; the varied impacts of wild–domestic hybridization; and the challenges and potential resolutions involved in conservation efforts. Identifying and conserving ancestral forms, particularly with respect to disentangling patterns of gene flow from domesticates, is complex because of the lack of available genomic and phenotypic baselines. Comparative behavioral, ecological, and genetic studies of ancestral-type, feral, and domestic animals should be prioritized to establish the contemporary status of the former. Such baseline information will be fundamental in ensuring successful conservation efforts.     

A systematic study on the fabrication of transparent nanopaper based on controlled cellulose nanostructure from oil palm empty fruit bunch

Journal of Polymers and the Environment - Cellulose nanopaper (CNP) is a new potential candidate for flexible biopolymer substrate made of nanocellulose (NC). We systematically studied the effect...