Preparation of sorbitol-based polyurethanes and their semiinterpenetrating polymer networks

Sorbitol is a useful agro-based substance that is inexpensive and commercially available. In the interest of adding value to bio-based raw materials, we have synthesized polyurethanes from sorbitol and toluene-2,4-diisocyanate (TDI) through both conventional heat and microwave processes. Relative to conventional heat, the microwave process achieved the same reaction at a faster rate, thereby saving time and energy. The nature of the resulting polyurethane products depended on the stoichiometry of the reaction. At increasing TDI levels, a viscous liquid, a soft gel, or a hard thermoset could be obtained. The polymers were fully characterized with ¹³C-NMR, Fourier transform infrared, size exclusion chromatography, and thermogravimetric analysis. The polyurethanes obtained near the gel point could be used to make semiinterpenetrating polymer networks (semi-IPNs) with a second polymer, thereby imparting some of the properties of the second polymer onto the sorbitol-based polyurethane. For illustration, the sorbitol-based polyurethane semi-IPNs were made in combination with poly(vinyl pyrrolidone) and poly(lactic acid). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47602.     

复合增塑剂改性PBAT/淀粉薄膜的性能

以玉米淀粉、聚己二酸/对苯二甲酸丁二酯(PBAT)为主要原材料,甘油为主增塑剂,山梨醇、聚乙烯醇200(PEG200)、二甲基甲酰胺等为辅增塑剂,通过挤出机造粒再吹塑方法制成淀粉填充PBAT薄膜。研究对比了不同增塑剂在淀粉填充PBAT材料中的塑化效果,同时探究了不同塑化剂对复合薄膜力学性能、表面粗糙度、吸水率、溶出率及熔体流动速率的影响。结果表明:山梨醇与甘油组成的复合增塑剂的塑化效果要优于PEG200和二甲基甲酰胺,淀粉在PBAT薄膜中的粒径最小、分散最均匀,且薄膜的拉伸强度、断裂生产率、摆锤冲击强度得到明显提高。PEG200和二甲基甲酰胺与甘油的复合增塑剂对淀粉的塑化未起到作用,但二甲基甲酰胺能与淀粉分子形成较为稳定的氢键,可以大幅度降低薄膜中淀粉的溶出率。薄膜的吸水性主要取决于淀粉的吸水性。熔体流动速率在一定程度上也能体现淀粉的塑化情况。     

Optimizing the mechanical and physical properties of thermoplastic starch via tuning the molecular microstructure through co‐plasticization by sorbitol and glycerol

Nowadays, environmental hazards caused by plastic wastes are a major concern in academia and industry. Utilization of biodegradable polymers derived from renewable sources for replacing common petroleum‐based plastics is a potential solution for reducing the problem. In this regard, starch has become one of the most promising alternatives to non‐biodegradable polymers for depleting plastic waste thanks to its low expense, abundance, renewability and biodegradability. However, the main drawbacks of starch are its poor processability, weak mechanical properties and severe hydrophilicity. In this work, thermoplastic starch (TPS) samples have been prepared using glycerol and sorbitol as co‐plasticizers in a laboratory co‐rotating twin screw extruder. Based on the mechanical test results, glycerol caused higher elongation to break but had lower tensile strength and elastic modulus compared to sorbitol plasticized starch. Fourier transform infrared spectroscopy and DSC results indicated that the hydrogen bond interaction between starch chains and plasticizers could be improved by replacing glycerol by sorbitol, which resulted in higher resistance against retrogradation proved by XRD results. TGA illustrated that the higher the sorbitol to glycerol ratio was, the more stable was the TPS. Using a proper amount of plasticizers (42 wt% total plasticizer, sorbitol to glycerol ratio 2:1) led to the preparation of a TPS sample with optimized properties including enhanced mechanical properties, high thermal stability, strong hydrogen bond formation and high resistance against retrogradation. © 2017 Society of Chemical Industry     

Effect of Sorbitol Plasticizer on the Structure and Properties of Melt Processed Polyvinyl Alcohol Films

Poly (vinyl alcohol) (PVA) possesses wide applications as food packaging materials, but is difficult to melt process for its strong inter/intra hydrogen bonding. In this work, flexible PVA films with different content of sorbitol plasticizers were prepared by melt processing with the assistance of water. And the influence of sorbitol plasticizer content on the crystallinity, optical transparency, water‐retaining capability, mechanical properties, thermal stability and oxygen and water permeability were investigated. The results indicated that sorbitol dramatically improved the melt processing ability of PVA. Sorbitol could interact with PVA to form strong hydrogen bonding interactions, which would decrease the original hydrogen bonding of the matrix, resulting in the decrease of crystallinity degrees. The glass transition, melting and crystallization peak temperatures decreased with the increase of sorbitol. All the films exhibited fine optical transparency. The water retaining capability were improved with the increase of sorbitol. Especially, an increase in elongation at break and decrease in Young's modulus and tensile strength were observed indicating good plasticizing effect of sorbitol on PVA films. In addition, the PVA films prepared in this work exhibited fine barrier properties against oxygen and water, suggesting wide application potential as packaging materials.     

新一代聚丙烯成核剂的合成及应用

介绍了二(3,4-二甲基二苄叉)山梨糖醇(DMDBS)的合成路线和作用机理,并以山梨糖醇和3,4-甲基苯甲醛为原料,在固体酸的作用下,不用分离水就能直接合成出新一代聚丙烯透明成核剂DMDBS.结果表明,在醇醛物质的量比2.1、催化剂加量4.5％(质量分数,以醇醛质量总和为基准,下同)、反应温度25℃、反应时间5h、溶剂...