壳聚糖/纤维素硫酸钠复合膜性能的研究

为了研究以壳聚糖和纤维素硫酸钠(NaCS)为材料制备的聚电解质复合膜在药物控制释放上的应用,考察了壳聚糖相对分子质量、NaCS相对分子质量和取代度对该复合膜机械性能(强度、韧性等)和溶胀性能的影响。结果表明,壳聚糖相对分子质量、NaCS相对分子质量和取代度对壳聚糖/NaCS复合膜的机械性质和溶胀性能都有显著的影响。壳聚糖相对分子质量越高,该复合膜的断裂伸长率越大。而NaCS相对分子质量和取代度的增大则会导致该膜的溶胀率降低。此外,溶液pH值对壳聚糖/NaCS复合膜溶胀率也有明显的影响。     

胶原-聚乙烯醇水凝胶溶胀特性的研究

采用经化学改性的含羧基的聚乙烯醇、胶原为原料,经物理交联,即反复冻融法制备了胶原-聚乙烯醇水凝胶。研究了不同原料配比的胶原-聚乙烯醇水凝胶的溶胀动力学、pH敏感性及pH溶胀-消胀特性,并利用数学方程拟合的方法计算其平衡溶胀比,尽量减少了因样品溶胀不足或测量误差导致平衡溶胀比估算的不准确性,使所得数据更加科学准确。结果显示:制备的胶原-聚乙烯醇水凝胶具有很快的溶胀速率,如胶原含量为9.09%的4号水凝胶可在100min内达到90%的平衡溶胀率,且随着胶原含量的增加,溶胀速率随之加快;电解质可降低其平衡溶胀比;有一定的pH敏感性和pH溶胀-消胀特性,胶原含量的增加可使水凝胶的pH溶胀-消胀特性更加显著。     

羧甲基纤维素对可食性复合包装膜性能的影响研究

以小麦面筋蛋白为原料,与羧甲基纤维素复合制备可食性包装膜,探索羧甲基纤维素对于可食性复合包装膜性能的影响,为确定最佳成膜工艺创造条件。     

不同聚醚对聚氨酯成膜性能的影响研究

本文主要讨论了聚醚的品种和不同当量对水基聚氨酯成膜材料热力学性能和使用性能的影响。结果表明：在聚丙二醇、聚乙二醇、聚四氢呋喃二醇和聚己二酸丁二酯二醇等多种聚醚中，尤以聚四氢呋喃醚PTMG耐低温性、压花成型性和耐切割性最优。增加聚氨酯链段中硬段的浓度，可以提高涂层的离板性；将不同种类的聚醚共聚可显著提高成膜材料的综合性能。     

羧甲基纤维素作为纸板生产中湿部助剂的实验研究

在造纸工业中，羧甲基纤维素(CMC)多年来已广泛用于表面施胶剂和涂料的黏合剂。它具有成膜性、优良的保水性和其他一些有用的特性，这些都引起了造纸工作者的注意。     

聚丙烯酰胺凝胶电泳法对猪皮水解胶原蛋白的分离

胶原由于其独特的结构、化学及生物学性质，被人们广泛用于食品、化妆品、医药等工业领域。因此，人们对胶原和胶原蛋白的水解产物进行了广泛深入的研究。其中胶原蛋白的水解产物的分离、分析，对进一步揭示水解作用机理、控制水解产物分子量的大小及对水解产物中不同分子量大小的各个组分的分离纯化具有重要意义。本文利用SDS-聚丙烯酰胺凝胶电泳法对猪皮水解胶原蛋白进行分离，在选择恰当的缓冲溶液体系、凝胶体系的的基础上，对凝胶浓度、样品的浓度、进样量和染色的方法进行了大量的实验。结果表明采用SDS-聚丙烯酰胺电泳对胶原蛋白水解产物进行分离分析，在浓缩胶浓度3%，分离胶浓度10%的条件下，可达到较好的分离效果。     

羧甲基淀粉/玉米秸秆纤维素复合可食膜的研究

以羧甲基淀粉(CMS)为主要成膜基材,添加羧甲基纤维素钠(CMC)、山梨糖醇(Sorbitol, Sor)和玉米秸秆纤维素(CSC)制备复合可食膜。研究各成膜材料质量浓度对膜的抗拉强度和断裂伸长率的影响,通过响应面试验优化羧甲基淀粉基复合可食膜的最佳制备工艺。结果表明:当CMS质量浓度为3.95 g/100 mL, CMC质量浓度为0.92 g/100 mL, Sor质量浓度为1.64 g/100 mL, CSC质量浓度为0.79 g/100 mL时,膜的抗拉强度和断裂伸长率分别达到19.43 MPa和26.87%。扫描电子显微镜和傅里叶红外光谱分析表明各成膜材料各组分之间的相容性较好,分子间的氢键作用加强。     

水溶性羧甲基壳聚糖的制备及其应用

壳聚糖是甲壳素脱乙酰基的产物,由于独特的生物活性和生理功能,近年来己引起众多领域的关注。但是,壳聚糖不溶于水,这使壳聚糖的应用受到极大限制。通过化学改性,引入亲水基团,得到水溶性壳聚糖衍生物一直是人们研究的热点,其中,羧甲基化最常用和最有效的方法之一。羧甲基壳聚糖是一种两性聚电解质,能有效的与金属离子进行络合。它有优良的增稠性、分散性、乳化性、保湿性、成膜性、凝胶性等。,与壳聚糖相比,羧甲基壳聚糖的水溶性提高,并可以在广泛的PH值溶液内溶解,且无毒、无味、生物相容性好,可降解,这些丰富而独特的功能性质使羧甲基壳聚糖在诸多领域中得到了应用,如医用敷料、食品保鲜剂、化妆品保湿剂、水处理絮凝剂等。     

二元胶原基复合膜的制备

以聚乙烯醇和壳聚糖作为改性剂，选择不同的干燥方法及成膜器具制成的膜，对其进行力学性能检测、共混液稳定性检测、透光率检测、孔隙率和孔结构检测。研究结果表明，当聚乙烯醇／胶原干基质量比为8：2时，胶原-聚乙烯醇膜材料的力学性能最佳；当壳聚糖／胶原干重比为7：3时，胶原-壳聚糖膜材料的力学性能最佳。研究结果同时证实干燥方式是影响膜材料孔隙率和孔结构的决定性因素，且表面光滑的成膜器具可以提高膜材料的力学性能及透光率。     

POLYACRYLAMIDE GELS AS ELASTIC MODELS FOR FOOD GELS: FRACTURE PROPERTIES AFFECTED BY DEXTRAN AND GLYCEROL

Influence of dextran and glycerol on fracture properties of 10% polyacrylamide (PAAm) gels was studied as a representative model system for food gels. No direct relationship was found between the fracture properties and gel liquid‐phase viscosity. In general, addition of dextran and glycerol did not affect gel network crosslink density and chain length. With minimal dextran addition, fracture stress and strain experienced large increases. Increase of the fracture stress and strain was attributed to fracture mode transition from elastic to elasto‐plastic fracture, resulting from dextran addition. Plastic deformation at the crack tips, acting as fracture‐initiating points, prior to fracture propagation lowered stress concentration effect. Sensitivity of 10% PAAm gels, with/without dextran, to induced imperfections showed the fracture stress to be higher than expected based on Griffith's energy balance criteria, manifesting in a delayed fracture process. The plastic deformation was ascribed to the delayed crack nucleation resulting from dextran addition. The fracture stress and strain of 10% PAAm gels increased with glycerol addition. The increase in fracture properties was attributed to plastic deformation, caused by a delayed crack nucleation prior to fracture propagation. The mechanism of delayed crack nucleation remains unclear, but the results obtained from this investigation can be used to understand reasons for the change in fracture property of food gels created by additives.     

离子对壳聚糖/果胶聚电解质复合物溶胀性及微观结构的影响研究

本文将壳聚糖、果胶在含有六种不同离子的溶液环境中复合,考察离子种类及浓度对壳聚糖/果胶聚电解质复合物（PEC）得率、溶胀度（水及模拟环境中）、红外光谱及微观结构的影响。离子价态对PEC得率的影响为：三价离子〉二价离子〉一价离子;离子浓度低时,离子浓度促进PEC得率增加,离子浓度高时,离子浓度抑制PEC得率增加。离子种类不同,PEC的溶胀过程不同,复合环境中含有FeCl3和Fe2（SO4）3的PEC在水中具有最大、最小溶胀度,分别为56.87±0.63和9.21±0.13;含有MgSO4和Fe2（SO4）3的PEC在胃肠模拟液中具有最大、最小溶胀度,分别为361.74±6.21和28.01±0.66。红外光谱结果表明添加离子并未影响PEC中NH3＋/COO-键的形成。扫描电镜结果显示PEC呈海绵多孔状,添加离子后PEC孔壁厚度增加9.76±1.03%至334.19±5.12%不等,表面更加光滑,而孔隙状态因离子种类不同而不同。研究表明PEC得率、溶胀度及微观结构受到离子影响,但其交联方式不变。     

食品模拟体系中淀粉基膜材增塑剂的迁移

本文采用酯化淀粉以三乙酸甘油酯为增塑剂,经流延法制备了酯化淀粉薄膜,并利用傅里叶红外光谱衰减全反射技术(ATR-FTIR)和热重分析仪(TGA)分析了淀粉基膜材与不同食品模拟体系接触后其表层增塑剂和整体增塑剂的变化情况。结果表明,基于与淀粉基膜材、增塑剂之间的亲和性差异,食品模拟体系对淀粉基膜材产生不同的溶胀作用,导致不同程度的增塑剂迁移;与淀粉基膜材亲和性越高的食品模拟体系,对淀粉基膜材表层和内部的溶胀更迅速,并可溶解更多的增塑剂分子,从而导致淀粉基膜材中更大程度的增塑剂迁移;表层增塑剂和整体增塑剂的迁移情况差异表明,溶剂溶胀和增塑剂迁移由膜材表层向内部发生。基于以上结果可推断,在实际应用过程中,选择合适的应用领域、设计调整材料结构可主动抑制增塑剂迁移,实现这类新型包装材料的安全使用。     

Mechanical and water vapor barrier properties of tapioca starch/decolorized hsian-tsao leaf gum films in the presence of plasticizer

The objectives of this research were to examine the mechanical and water vapor barrier properties of the starch/decolorized hsian-tsao leaf gum (dHG) films as a function of dHG and glycerol concentration. Edible film-forming solutions were prepared by mixing tapioca starch with dHG at different starch/dHG ratios to make a total solid content of 2%. In total, 15–40% glycerol was then added based on the dry film matter. Starch/dHG films were obtained by casting. It was found that the puncture strength, tensile strength, and modulus as well as the inverse of relaxation coefficient of starch/dHG films pronouncedly increased with increasing dHG, accompanied with a decreasing tendency in puncture deformation and tensile strain at break. Such results implied that starch interacted with dHG synergistically, resulting in the formation of a new network to improve the mechanical properties of tapioca starch/dHG films. Mechanical strengths of starch/dHG films decreased and water vapor permeability (WVP) at 75% RH increased with increasing glycerol concentration. However, the plasticizing effect of glycerol became less significant at high dHG concentration, particularly for the puncture deformation and tensile strain at break of the films. Water sorption isotherm results indicated that significant water sorption would only occur at high water activity (about 0.75), and generally became more pronounced with increasing glycerol and dHG concentration, but to a lesser extent for the latter. Dynamic mechanical analysis revealed that the major glass transition of starch/dHG films occurred at about −50 °C.     

Genipin交联明胶/溶菌酶缓释抗菌膜材料的微结构与性能研究

针对亲水明胶膜材料对抗菌剂缓释能力较差的问题,采用生物交联剂(genipin)调节膜材料微结构,制备出新型控释明胶/溶菌酶复合膜材料。系统研究了复合膜材料的力学性能、水汽阻隔性能、膨胀性和热性质等物理性能,并用AFM研究了膜材料的表面微结构,探讨了其结构-性能之间的关系。结果表明:genipin交联显著改善复合膜材料的力学性能,TS值从9.72 MPa逐渐增加至18.80 MPa;复合膜材料的膨胀度(swelling)随genipin浓度增加急剧下降,从1316%降至~200%;genipin交联提升复合膜材料的热稳定性。复合膜材的表面粗糙度依赖于genipin浓度,在低浓度段(0~1.0%),膜材料呈现平整表面微结构;高浓度(2.0%)时,膜表面出现不规则的突起,变得粗糙。适度的genipin交联有助于形成有序的三维网络结构,改善复合膜材料的物理性能;高浓度的genipin过度交联明胶基质,形成团聚状聚集物,及弱化明胶分子间相互作用,进而弱化膜材料的水汽阻隔能力。     

Release Kinetics of Nisin from Chitosan–Alginate Complex Films

Understanding the release kinetics of antimicrobials from polymer films is important in the design of effective antimicrobial packaging films. The release kinetics of nisin (30 mg/film) from chitosan–alginate polyelectric complex films prepared using various fractions of alginate (33%, 50%, and 66%) was investigated into an aqueous release medium. Films containing higher alginate fractions showed significantly lower (P < 0.05) degree of swelling in water. Total amount of nisin released from films into an aqueous system decreased significantly (P < 0.05) with an increase in alginate concentration. The mechanism of diffusion of nisin from all films was found to be Fickian, and diffusion coefficients varied from 0.872 × 10^?9 to 8.034 ×10^?9 cm²/s. Strong complexation was confirmed between chitosan and alginate polymers within the films using isothermal titration calorimetry and viscosity studies, which affects swelling of films and subsequent nisin release. Complexation was also confirmed between nisin and alginate, which limited the amount of free nisin available for diffusion from films. These low‐swelling biopolymer complexes have potential to be used as antimicrobial packaging films with sustained nisin release characteristics.     

Vanillin cross-linked chitosan microspheres for controlled release of resveratrol

In this work, resveratrol (Res) was incorporated into chitosan microspheres for controlled release and stabilisation. The microspheres were prepared by emulsion chemical cross-linking method, and vanillin was used as the novel cross-linker. The microspheres showed a smooth surface with irregular small particles and internal voids with a size distribution between 53 and 311 μm. Interpenetrating network cross-linking mechanisms might account for the Schiff base reaction between chitosan and vanillin. The encapsulation efficiency of Res within microspheres was up to 93.68%. Res contained within microspheres was protected from light and heat compared with the free Res. In addition, release behaviours were governed by two distinct stages and dependent on pH of release media. Diffusion, swelling and erosion mechanisms might coexist for the full controlled release and Higuchi was the most suitable model for the whole release procedure. Thus, controlled release and stabilization of Res were achieved through incorporation of Res into cross-linked chitosan microspheres by vanillin.     

Mechanical and water vapour barrier properties of edible gellan films

Edible films based on gellan were developed. Of the plasticizers tested, glycerol was found to be the most suitable with respect to mechanical properties and transparency. The mechanical properties (tensile and puncture), water vapour permeability (WVP) and glass transition temperature (T_g) were examined for gellan films as a function of glycerol concentration. The lowest effective glycerol concentration was ∼60% (film dry weight basis); below this concentration, the films tended to be brittle and difficult to handle, whereas films with more than ∼75% glycerol tended to be sticky. Addition of glycerol to gellan films increased extensibility (tensile elongation and puncture deformation) moderately, but decreased tensile strength, elastic modulus and T_g, and increased WVP of the films. Increasing the a_w caused marked decreases in tensile strength and elastic modulus, but decreased tensile elongation only slightly. In general, tensile strength and elastic modulus appeared to be more sensitive to changes in glycerol content and a_w than puncture strength.