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Using the melt polycondensation of five bio-based aliphatic monomers (succinic acid, sebacic acid, fumaric acid, 1,3-propanediol, and 1,4-butanediol), we first synthesized the more flexible and biodegradable polyester diols (BPD) with an average molecular weight of 3825. Then, the BPD was polymerized with excessive 4,4′-diphenylmethane diisocyanate (MDI). Finally, the molecular chain extender of 1,4-butanediol (BDO) was used to fabricate the biodegradable thermoplastic polyurethane elastomer (BTPU), comprising the soft segment of BPD and the hard segment polymerized by MDI and BDO. Atomic force microscope (AFM) images showed the two-phase structure of the BTPU. The tensile strength of the BTPU containing 60% BPD was about 30 MPa and elongation at break of the BTPU was over 800%. Notably, the BTPU had superior biodegradability in lipase solution and the biodegradation weight loss ratio of the BTPU containing 80% BPD reached 36.7% within 14 days in the lipase solution.

Using melt polycondensation of bio-derived dicarboxylic acids and diols, followed by polyester emulsification and radiation, we fabricate the bio-based elastomer nanoparticles with controllable biodegradability, which can be used in biomedical fields.

The Yellow River "River Bed Blowing up" phenomenon is a special phenomenon that river sediment stirred up in bulk under the function of hyper concentration floods. It is a complex dynamic process. In this paper, based on the investigation and analysis of the large number of prototype, according to the theoretical analysis and repeated experiments, the author successfully simulated the whole process of the phenomenon in the room, and set up a clear and correct physical graphics of it. All of which laid a solid foundation for people to deeply research into the hydrodynamic conditions and the formation mechanism that caused the phenomenon.