Wang Shen, Li Yanhui, Zhang Jingxian, Man Jia, Nie Yanyan, Ji Maocheng, Chen Heyu, Li Fangyi, Zhang Chuanwei
College of Mechanical and Electrical Engineering, Qingdao University, Qingdao 266071, China.
Key Laboratory of High Efficiency and Clean Mechanical Manufacture (M of E), School of Mechanical Engineering, Shandong University, Jinan 250061, China.
Carbohydr Polym. 2024 Feb 1;325:121574. doi: 10.1016/j.carbpol.2023.121574. Epub 2023 Nov 11.
Unlike thermoplastic petroleum-based materials, starch-based materials rely on aqueous systems but are incapable of hot melting, resulting in low processing efficiency and limited large-scale industrial applications. In this study, the combination of α-amylase liquefaction and urea plasticization was used for the first time to obtain enzymatic thermoplastic starch (ETPS) for hot melting by changing the molecular chain of starch. ETPS showed an apparent hot melting phenomenon when heated below 200 °C. Differential scanning calorimetry revealed that heat absorption peaks were obviously reduced, and the hot melting phenomenon occurred easily depending on the combination of enzymatic hydrolysis and plasticization. Dynamic mechanical analysis indicated that the combined modification effectively increased the number of freely movable chains. The red shift of -OH stretching vibration peaks indicated the formation of strengthened hydrogen bonds in ETPS. X-ray diffraction showed that the crystallinity of ETPS was reduced to 5.68 %, effectively reducing the regenerative phenomenon. Gel permeation chromatography revealed that the molecular weight of ETPS decreased, and the entanglements between molecular chains were reduced. A tensile test showed that the elongation at break of ETPS was as high as 235.29 %, which was much higher than those of enzymatic hydrolysis starch and thermoplastic starch.
与热塑性石油基材料不同，淀粉基材料依赖于水性体系，但无法热熔，导致加工效率低下且大规模工业应用受限。在本研究中，首次使用α-淀粉酶液化和尿素增塑相结合的方法，通过改变淀粉的分子链来获得可热熔的酶促热塑性淀粉（ETPS）。ETPS在低于200°C加热时表现出明显的热熔现象。差示扫描量热法显示吸热峰明显降低，且取决于酶解和增塑的组合，热熔现象容易发生。动态力学分析表明，复合改性有效地增加了自由活动链的数量。-OH伸缩振动峰的红移表明ETPS中形成了强化的氢键。X射线衍射表明，ETPS的结晶度降低至5.68%，有效减少了再生现象。凝胶渗透色谱显示ETPS的分子量降低，分子链之间的缠结减少。拉伸试验表明，ETPS的断裂伸长率高达235.29%，远高于酶解淀粉和热塑性淀粉。
