4种改性淀粉与明胶共混膜的制备与性质比较

该研究对4种改性淀粉（羟丙基二淀粉磷酸酯、羟丙基淀粉、氧化淀粉、氧化羟丙基淀粉）的溶解度、膨胀势、糊化特性、老化值进行了分析和比较。溶解度高、膨胀势小、糊化特性好、老化值低的淀粉，较适宜作为制备共混膜的原料。在此基础上加入甘油或聚乙二醇400（Polyethylene Glycol，PEG400）作为增容剂，并对配方中水和甘油加入量进行了初步摸索，运用紫外、扫描电镜和拉伸试验机测定共混膜的透光性、透水气性、微观形貌和机械性能。结果表明：羟丙基淀粉溶解度最高，为86.42%；膨胀势最低，为0.086%，稳定性更好；黏度较低，老化值较大，流动性高，易于成膜。为4种改性淀粉中最适宜和明胶共混的原料。利用紫外分光光度计进行全波长扫描测量透光率；利用不同时间水保留质量反应透水汽性；用扫描电镜放大500~6 000倍对微观形貌观察，用拉伸材料试验机对机械性能进行测试。通过比较，发现以羟丙基淀粉为原料的共混膜，具有较好的透明度（优于纯明胶样品的透光度），良好的透水汽性和机械性能。微观形貌也是呈现出相容性较好的形态（SEM显示），相较于PEG400，甘油作为增容剂时共混膜的微观形貌横截面均匀光滑，内容物相容性好。明胶:甘油:水质量比为1:9:3:13制得共混膜透光性、透水气性、机械性能最佳，具有较好的实际应用价值。

Preparation and Property Comparison of Four Modified Starches and Gelatin Blended Films

Gelatin-blend films with four modified starches (hydroxypropyl distarch phosphate, hydroxypropyl starch, oxystarch, and oxidized hydroxypropyl starch) were analyzed in terms of solubility, swelling potential, pasting characteristics, and aging value. Starch with high solubility, low swelling potential, good gelatinization characteristics, and low aging value is more suitable for preparing blend films. For this, glycerol or polyethylene glycol 400 (PEG400) was addedas bulking agent to prepare starch-gelatin blend films, and the proportions of water and glycerol in the formula were tested. Ultraviolet (UV) spectroscopy, scanning electron microscopy (SEM), and tensile testing were used to determine the light transmittance, water vapor transmission, microscopic morphology, and mechanical properties of the blend films. The results showed that hydroxypropyl starch had the highest solubility (86.42%). Its swelling potential of 0.086% was the lowest, compared to those of the other three starches, while the stability was higher. Its low viscosity provided good fluidity and enabled easier film formation. It had a larger aging value as well. All these properties indicate that among the four modified starches, hydroxypropyl starch is the most suitable for blending with gelatin. Specifically, we report that the blend film with hydroxypropyl starch has higher transmittance than pure gelatin, good water vapor permeability, and mechanical properties. The micromorphology, as shown by SEM, shows good compatibility. Compared to PEG400, glycerol provides a more uniform and smoother cross-section for the blend film. The gelatin: glycerol: water mass ratio of 1:9:3:13 produced a blend film with the highest light transmittance, highest water vapor permeability, and best mechanical properties. Hence, this blend film has good potential for practical applications.