可食性淀粉/壳聚糖复合膜的制备与性能研究

目的 利用壳聚糖对淀粉改性制备可食性复合膜,研究复合膜的结构与性能。方法 通过溶液共混法将壳聚糖的乙酸溶液与淀粉糊化液均匀混合,然后流延成膜,分析壳聚糖、甘油、Na Cl含量对复合膜的力学性能、水蒸气透过率的影响,通过X-射线衍射、扫描电镜和热重分析对复合膜的结构和性能进行表征分析。结果 复合膜中淀粉与壳聚糖两组分具有良好的相容性;甘油和Na Cl的添加有利于促进淀粉的塑化,改善复合膜的柔性,同时影响其力学强度和水蒸气透过率。结论 当淀粉与壳聚糖质量比为5∶3、甘油质量分数为25%、Na Cl质量分数为5%时,所制备的膜具有优异的综合性能。     

玉米磷酸酯双淀粉基可食性包装膜综合性能研究

目的以玉米磷酸酯双淀粉为基材,甘油为增塑剂,制备可食性包装膜。方法通过改变玉米磷酸酯双淀粉添加量,测试可食性包装膜的厚度、定量、力学性能、透湿性和透CO2性等指标,从而确定最佳配比。结果实验发现,随着玉米磷酸酯双淀粉添加量的增大,可食性包装膜的厚度和定量增大,拉伸强度、拉伸率和透湿性先增大后减小,透CO2性下降。结论在80℃条件下搅拌40 min、烘干温度为60℃时,淀粉的质量分数为7.5%、甘油的体积分数为5%的薄膜综合性能较好。     

甘油对壳聚糖-淀粉复合可食性膜力学性能的影响

目的以壳聚糖-淀粉复合膜为研究对象,加入不同质量分数的甘油作为增塑剂,研究甘油对复合膜性能产生的影响。方法将壳聚糖溶液和玉米淀粉溶液以6∶4的体积比混合,再添加一定量甘油,流延成膜,利用万能试验机测定膜的力学性能,用扫描电镜观察膜的形貌特征,并对膜进行红外扫描和X-衍射分析。结果甘油与淀粉壳聚糖具有良好的相容性,当甘油质量分数为35%～55%时,随着甘油含量的增加,膜的抗拉强度下降,断裂伸长率增加,抗拉强度最高可达33.57 MPa,断裂伸长率最高可达80.39%。结论甘油作为一种增塑剂,能够改善膜的力学性能,为可食性膜的广泛应用提供了可能性。     

可食性干酪包装膜的制备及性能研究

目的研究酪蛋白酸钠、壳聚糖、甘油添加量对可食膜性能的影响。方法以酪蛋白酸钠和壳聚糖为原料,甘油作为增塑剂,制备可食性干酪包装膜,以膜的水溶性及力学性能为指标,通过单因素及正交试验,确定各成膜成分的最佳配比。结果当用质量分数为5%的酪蛋白酸钠水溶液、质量分数为2%的壳聚糖冰乙酸溶液和质量分数为2%的甘油混合液进行成膜,所得可食膜的综合性能较优,其水溶性为35.8%,断裂伸长率为75.4%,拉伸强度为10.58 MPa,弹性模量为13.47 MPa。结论随着酪蛋白酸钠含量的增加,膜的水溶性变化不大,膜的断裂伸长率先增大后减小,拉伸强度和弹性模量均随之增大;随着壳聚糖含量的增加,膜的水溶性逐渐下降,膜的断裂伸长率、拉伸强度、弹性模量均随之增大;随着甘油含量的增加,膜的水溶性逐渐减小,膜的断裂伸长率逐渐增大,拉伸强度和弹性模量逐渐减小。     

壳聚糖-葡甘聚糖共混改性的研究

对壳聚糖-葡甘聚糖共混改性进行了研究,并对共混膜的力学性能、透气性、透过率进行一系列的性能测试.实验结果表明:壳聚糖与葡甘聚糖在共混膜中存在强烈的相互作用及良好的相容性;共混膜的力学性能随葡甘聚糖含量的增加而得到明显提高,当壳聚糖/葡甘聚糖的体积比为7/3,甘油添加量为15%(质量分数,后同)时,共混膜的各项性能达到最优.     

挤出法制备生物质包装材料

目的在挤出工艺条件下,以废纸纤维和农作物秸秆为主要原料制备生物质包装材料,研究影响其试样力学性能的主要因素并确定较优配方。方法在废纸和农作物秸秆原料中加入一定量的淀粉、甘油、PVA,经搅拌混合均匀后,通过单螺杆挤出机连续挤出,以实现环保生物质包装材料的连续生产。在单因素实验的基础上,通过正交实验探讨秸秆含量、淀粉含量、PVA含量、甘油含量对材料力学性能的影响。结果在85℃下水浴加热15 min时,混合物料和淀粉之间具有良好的相容性。试样抗压性能的影响因素及主次顺序为淀粉含量PVA含量基材比例甘油含量,试样抗弯性能的影响因素及主次顺序为淀粉含量基材比例PVA含量甘油含量。结论物料分散的均匀性和粘度是以废纸、农作物秸秆为主要原料通过挤出法制备生物质包装材料的关键。当基材比例(秸秆与废纸的质量比)为2︰3,PVA质量分数为2.5%,淀粉质量分数为9%,甘油质量分数为5%时,可获得较优的力学性能。     

聚乙烯醇-魔芋葡甘聚糖包装膜透光率与雾度

目的研究影响聚乙烯醇-魔芋葡甘聚糖包装膜透光率和雾度的因素。方法以甘油、山梨醇为复配增塑剂,将纯化过的魔芋精粉和聚乙烯醇按一定质量比混合后水浴恒温共混,流延干燥制备包装膜,研究共混温度、共混时间、基料配比、复配增塑剂配比对包装膜透光率和雾度的影响。结果魔芋精粉和聚乙烯醇按质量比为1∶10混合,在水浴温度80℃下恒温共混3 h,加入质量分数为10%的复配增塑剂,复配增塑剂中山梨醇和甘油的质量比控制在1∶2~1∶3时制备的包装膜透光率和雾度达到最佳。结论各因素对包装膜的透光率和雾度有较大影响,原因是它们能促使魔芋葡甘聚糖分子和聚乙烯醇分子形成强烈的协同作用。     

壳聚糖基抗菌复合膜的制备与性能

目的制备一种以壳聚糖为主要成分的抗菌薄膜,并研究其性能。方法壳聚糖、聚乙烯醇(PVA)、纳米二氧化钛和甘油等通过流延法制成膜,将壳聚糖与聚乙烯醇的质量比、纳米二氧化钛用量、甘油用量以及干燥温度等4个因素作为试验因素,通过正交试验,以抗菌性、水溶性和力学性能作为指标,对其性能进行评价。结果当壳聚糖与PVA质量比为8∶2,纳米TiO_2质量分数为0.75%,甘油质量分数为0.5%,干燥温度为70℃时,抗菌复合膜的综合性能最好。结论加入聚乙烯醇和纳米二氧化钛并以壳聚糖为主要成分的抗菌薄膜具有较好的抗菌性、水溶性和力学性能,且具有抗菌缓释性。     

壳聚糖-淀粉-聚乙烯醇共混改善壳聚糖膜性能的研究

以溶液共混的方法,制备了壳聚糖-淀粉-聚乙烯醇共混膜,并对薄膜的抗拉强度、断裂伸长率和气体阻隔性进行了测试.实验表明:壳聚糖含量为40%(质量分数,后同),聚乙烯醇和淀粉质量比例2:1,甘油含量15%时,共混体系具有较好的相容性、较理想的机械性能和气体阻隔性,共混膜的抗拉强度和断裂伸长率分别达到62MPa和118%,透氧系数仅为12.1×10-15 cm3·cm/cm2·s·Pa.     

四种多元醇增塑剂对淀粉-壳聚糖复合膜的性能研究

目的探究多元醇作为增速剂对淀粉-壳聚糖薄膜材料性能的影响,评估4种多元醇的增塑效果,并选出最优。方法将4种不同的多元醇作为增塑剂,通过流延法制备壳聚糖-淀粉薄膜,分析增塑剂含量对材料力学性能的影响,并通过扫描电镜、傅里叶红外、X-射线衍射、静态接触角对复合膜的结构和性能进行表征。结果将单一多元醇作为增塑剂加入淀粉-壳聚糖溶液,当添加质量分数为15%的甘露醇时,拉伸强度为最大值,为53.39 MPa;当添加质量分数为60%的甘油时,断裂伸长率最大,为45.11%。当甘油质量分数为50%时,综合效果较好,拉伸强度为21.36 MPa,断裂伸长率为35.33%。结论复合膜中淀粉与壳聚糖具有良好的相容性,添加增塑剂有利于改善复合膜的力学性能。多元醇增塑剂处于低浓度或中等浓度范围时,不具有有效的增塑作用。在4种多元醇增塑剂中,甘油的综合效果最好,所制备的膜具有较优的综合性能。     

醋酸对明胶-壳聚糖膜性质的影响及应用

目的制备基于不同醋酸质量分数的明胶-壳聚糖基可食复合膜,以期探究醋酸质量分数(1%、1.5%、2%和2.5%)对复合膜性质及应用的影响。方法利用透湿仪、透氧仪、拉伸仪、扫描电镜、热重、红外和拉曼光谱探究可食性复合膜的理化性质,并进行机理解析。结果低醋酸浓度制备的复合膜具有较低透湿性和透氧性,且其抗拉强度和断裂伸长率较高;同时醋酸浓度较低时,可以提高复合膜表面的光滑度,改善复合膜的热稳定性。红外测试与拉曼测试表明,明胶、壳聚糖、醋酸之间主要是通过氢键进行相互作用并结合,从而形成了稳定致密的薄膜。结论以质量分数为1%醋酸制备得到的明胶-壳聚糖基复合膜,其性质表现得更加优异,同时该系列薄膜可以制备成包装袋并能有效包装花生,对明胶-壳聚糖复合膜在食品包装领域的应用具有一定的参考作用。     

2-噻吩乙酸的HPLC分析测定

建立了一种2-噻吩乙酸的反相高效液相色谱-紫外检测法.研究了流动相的组成、流速及色谱柱温度等因素对测定的影响.采用色谱柱为VARIAN C18(250 mm×4.6 mm,5μm)反相色谱柱,流动相为甲醇-水(V∶V=70∶30),流速1.0 mL/min,柱温为室温,紫外检测波长235 nm,在6 min内可完成分析.该方法的回收率为98.4%~99.8%,RSD<1%.其优点为2-噻吩乙酸与其同分异构体3-噻吩乙酸得到较好的分离,明显不重叠,且操作简单、快速和准确可靠,用于2-噻吩乙酸产品的纯度测定,结果令人满意.     

Morphology and antibacterial properties of plasticized chitosan/metallocene polyethylene blends

In this work, plasticized chitosan-based materials were produced through a molten process. A thermo-mechanical treatment was used to achieve chitosan plasticization in the presence of water, acetic acid, and glycerol. Water and glycerol acted as plasticizers, while acetic acid was used as a solvent and plasticizer for chitosan. The influence of acetic acid total content, chitosan/acetic acid solution ratio, and chitosan/glycerol ratio were examined in this study. The various plasticized compounds were blended with a metallocene polyethylene (mPE) and the morphology, rheological, and antibacterial properties of this novel blend system were examined. It was found that an increase in acetic acid content allowed better chitosan dissolution, while a higher glycerol concentration resulted in improved dispersion of the plasticized chitosan phase in the mPE. Following thermo-mechanical treatment, blends presented good antibacterial properties with a reduction of the number of bacteria (non-pathogenic Escherichia coli) by 2 log(CFU/mL) for the chitosan-containing systems with respect to neat mPE. Mechanical properties of the mPE/plasticized chitosan blends were improved by compatibilization with ethylene vinyl acetate, while antibacterial properties were not affected.     

醋酸分子印迹电化学传感器的制备

基于循环伏安电化学聚合方法,以30mmol/L醋酸作为模板分子,5mmol/L苯酚作为功能单体,0.1mol/L氯化钾和0.05mol/L磷酸盐缓冲溶液(pH=5.4)作为聚合底液,聚合电位为-0.8~1.2V,扫描圈数为20,以0.1mol/L碳酸氢钠溶液作为洗脱液进行洗脱20min,最终制得性能较佳的醋酸分子印迹电化学传感器。对该传感器进行循环伏安(CV)表征、阻抗表征、扫描电镜的形貌表征、差分脉冲表征,探索了不同pH磷酸盐缓冲溶液作为聚合底液、不同浓度洗脱液和不同洗脱时间对该传感器性能的影响。发现在以0.05mol/L磷酸盐缓冲溶液(pH=5.4)作为最佳底液条件下,醋酸分子印迹电化学传感器与0~45×10^-9 mol/L浓度范围内醋酸分子二者呈现出良好的线性关系,其检出限为2.85×10^-9 mol/L,同时研究了该传感器的重现性和稳定性。     

TiO2纳米薄膜的微结构控制

通过有机酸修饰的水基so1-gel法，分别制备了由层状、针形和球形纳米粒子构成的纳米二氧化钛薄膜，采用SEM、XRD、红外光谱进行了表征.研究发现，调节水解过程中钛酸四丁酯：醋酸的摩尔比，可以控制薄膜的微结构，并对其机理进行了分析.该方法可以应用于sol-gel法制备其他纳米薄膜过程中的材料微结构控制.     

提取剂对紫薯花青素提取效果的影响及pH响应

花青素,是一种天然水溶性色素,因其对环境友好、安全无毒,且对pH变化敏感的特点,在智能包装领域展现了独特的研究价值。以紫薯为原料,通过保持提取剂的总体积不变,改变提取剂中冰醋酸和无水乙醇的体积比的方法,研究了提取剂中不同冰醋酸和无水乙醇的体积比对花青素提取效果的影响,并分析了不同pH值下花青素溶液的显色反应。结果表明,不同配比的提取剂对紫薯中提取花青素有较大影响。在冰醋酸和无水乙醇体积一定的条件下,通过紫外-可见吸收光谱、pH示差法等分析发现,冰醋酸和无水乙醇的体积比为1:1时提取的花青素含量最高,显色效果明显。     

TiO2纳米薄膜的微结构控制

通过有机酸修饰的水基sol-gel法,分别制备了由层状、针形和球形纳米粒子构成的纳米二氧化钛薄膜,采用SEM、XRD、红外光谱进行了表征。研究发现,调节水解过程中钛酸四丁酯:醋酸的摩尔比,可以控制薄膜的微结构,并对其机理进行了分析。该方法可以应用于sol-gel法制备其他纳米薄膜过程中的材料微结构控制。     

Preparation and character of textured ZnO:Al thin films deposited on flexible substrates by RF magnetron sputtering

ZnO:Al thin films deposited on transparent TPT substrates by magnetron sputtering were etched in acetic acid solution. The effects of etching solution concentration and etching time on the structure and properties of ZnO:Al films were investigated. The obtained films had a hexagonal structure and a highly preferred orientation with the c-axis perpendicular to the substrate. The ZAO film etched in 1% acetic acid solution for 10 s had a pyramidal structure and an enhanced light scattering ability, the average transmittance and reflectance in the visible region were 72% and 26% respectively, the sheet resistance was 260 Ω/□. Both transmittance and reflectance of the films decreased as the etching solution concentration and etching time increasing. Etching had a negative effect on the conductive properties of ZAO films. The lowest sheet resistance was 120 Ω/□ for the ZAO film without etching.     

Cross-linking regulators in one-step synthesis of macronet ion-exchangers

Hydrophillic macronet resins were prepared via a route which includes simultaneous sulphonation and cross-linking of styrene-acrylonitrile copolymer and polystyrene foam. Chlorosulphonic acid was employed as both the sulphonating reagent for the introduction of the sulphonic acid group on styrene units and the medium for the formation of sulphone-type cross-links. Controlled cross-linked structures were achieved by the parallel participation of acetic acid or acetic anhydride as sulphone cross-bridging regulators. The reaction yield, as well as the properties of the formed gels, were studied in respect to the cross-linking regulator concentration and the chlorosulphonic acid flow rate. Both strongly and weakly acidic ion-exchangers on the same substrate were achieved when styrene-acrylonitrile copolymer was used as a raw material. The synthesized macronet ion-exchangers were found to exhibit high swelling abilities and intermediate ion-exchange capacities while scanning electron microscopy (SEM) revealed their morphology.     

Thermodynamic studies on solvent effects in molecularly imprinted polymers. 2. Concentration of the organic modifier

The effects of the organic modifier concentration on the isotherm parameters of the two enantiomers of Fmoc-tryptophan (Fmoc-L,D-Trp) on an Fmoc-L-Trp-imprinted polymer were investigated over a wide concentration range (0.005-100 mM), using frontal analysis. The modifier was acetic acid; concentrations of 0.2, 0.9, 1.7, and 3.7 M in an acetonitrile-based mobile phase were studied. At each concentration, adsorption isotherm data were acquired for each enantiomer. From these data, the isotherm parameters of each compound were derived from nonlinear isotherm fitting and the affinity energy distributions were calculated independently. We found that three types of sites coexist for Fmoc-L-Trp but only two types of sites for Fmoc-D-Trp, except at the lowest acetic acid concentration (0.2 M), at which three types of sites coexist. Increasing the acetic acid concentration decreases the selectivity and the overall affinity of both enantiomers. The overall affinity of Fmoc-L-Trp is dominated by the contribution of the low-density highest energy sites while that of Fmoc-D-Trp is dominated by the most abundant, low-energy sites. For the low-energy sites, increasing the acetic acid concentration affects the association constant of the enantiomers more than the number of corresponding sites. In contrast, for the highest energy sites (sites that exist only for Fmoc-L-Trp), increasing the concentration of acetic acid affects significantly the number of sites but hardly changes the association constant.