Main-chain poly(phosphoester)s: History,syntheses, degradation,bio-and flame-retardant applications

Nature on planet earth is dominated by poly(phosphoester)s (PPEs). They structure and determine life in the form of deoxy- and ribonucleic acid (DNA & RNA), and, as pyrophosphates, they store chemical energy in organisms. Polymer chemistry, however, is dominated by the non-degradable polyolefins and degradable polycarboxylic esters (PCEs) produced on a large scale today. Recent work has illustrated the potential of PPEs for future applications beyond flame-retardancy, the main application of PPEs today, and provided a coherent vision to implement this classic biopolymer in modern applications that demand biocompatibility and degradability as well as the possibility to adjust the properties to individual needs. This comprehensive review summarizes synthetic protocols to PPEs, their applications in biomedicine, e.g., as biodegradable drug carrier or in tissue engineering, and their flame retardant properties. We highlight recent developments that may make phosphorus-based polymers attractive materials for various future applications.     

绿色包装材料——生物降解塑料

对绿色包装材料-生物降解塑料的降解机理、特点，国内外研究现状和进展及存在的问题和发展前景进行了介绍。     

Effects of Nd on microstructures and properties of extruded Mg-2Zn-0.46Y-xNd alloys for stent application

The microstructures, mechanical and corrosion properties of three extruded Mg-2Zn-0.46Y-xNd alloys (x = 0.0, 0.5, 1.0 wt%) were studied by optical microscopy, scanning electronic microscopy (SEM), electrochemical measurements and tensile tests. Microstructural observations indicated that Nd led to the uniformity and the variation of morphology of major second phase; tensile tests showed that Nd can improve the ductility at moderate amount (0.5 wt%) and will be detrimental up to 1.0%; Mg-2Zn-0.46Y-0.5Nd alloy exhibited excellent mechanical properties (σ_b, 269.0 MPa, σ_0.2, 165.6 MPa and elongation, 24%); electrochemical tests revealed that Nd can enhance the corrosion resistance and Mg-2Zn-0.46Y-1.0Nd alloy had lowest corrosion current density, which was reasoned that the line-shape and rodlike NdZn₂ phase might serve as corrosion barriers and the dissolved Nd can raise the electrode potential of the matrix.     

Modification of polylactide upon physical properties by solution-cast blends from polylactide and polylactide-grafted dextran

Polylactide (PLA)-grafted polysaccharides with various lengths and numbers of graft chains were synthesized using a trimethylsilyl protection method. The properties of the cast films prepared from graft-copolymers were investigated through thermal and dynamic mechanical analyses. The graft-copolymer films exhibited a lower glass transition temperature (T_g), melting temperature, and crystallinity, and higher viscosity properties compared to PLA films. Moreover, the usefulness of graft-copolymer as a plasticizer was investigated with 1:4 blend films prepared from the graft-copolymers and PLA. The blend films showed lower T_g and crystallinity, and higher viscosity properties compared to PLA films.     

全淀粉塑料流变性能的研究

对研制的全淀粉塑料的流变性能进行了研究，分析讨论了淀粉种类、增塑剂、基它助剂及熔融温度对全淀粉塑料流变行为的影响。     

Property improvement of thermoplastic mung bean starch using cotton fiber and low‐density polyethylene

Due to high water uptake and low mechanical properties of biodegradable thermoplastic starch, thermoplastic starch prepared from mung bean starch (TPMBS) was modified by the incorporation of cotton fiber and low‐density polyethylene (LDPE). The effect of different ratios of cotton fiber/LDPE, i.e., 10:0, 7:3, 5:5, 3:7, and 0:10, on water uptake, mechanical, thermal, and biodegradable properties of TPMBS was examined. Different TPMBS samples were prepared using internal mixer for compounding and compression molding machine for shaping samples. It was found that the TPMBS incorporated with 10:0, 7:3, and 3:7 cotton fiber/LDPE showed an increase in the stress at maximum load and Young's modulus. Moreover, the water absorption of all of the modified TPMBS samples tended to decrease as compared to the pure TPMBS. Morphological, thermal, and biodegradable properties of different TPMBS samples were also investigated.     

Physico-chemical and film-forming properties of bovine-hide and tuna-skin gelatin: A comparative study

A bovine-hide gelatin and a tuna-skin gelatin, both characterized on the basis of their amino acid composition and molecular weight distribution, were used to prepare edible films by casting with glycerol and sorbitol added as plasticizers. The molecular weight distribution of the tuna-skin gelatin exhibited appreciably higher quantities of β-components (covalently linked α-chain dimers), whereas bovine-hide gelatin showed a certain degradation of α₁-chains being indicative of a greater proteolysis. Intrinsic differences in the gelatin attributes affected in diverse manner some of the physical properties of the films. Thus, water vapour permeability was higher in the bovine-hide gelatin film, whereas deformability was considerably higher (10 times higher) in the tuna-skin gelatin film. In contrast, breaking force and water solubility were basically unaffected by gelatin origin. Analysis of the thermal properties revealed both films to be wholly amorphous with similar glass transition temperature values thanks to the plasticizing effects of the glycerol and sorbitol and the low moisture contents.