交联羧甲基纤维素-藕粉复合膜的制备与表征

以羧甲基纤维素和藕粉为基材,辅以添加甘油、茶多酚、蜂蜡制备可食复合膜,通过单因素和正交分析各组分对膜水蒸气透过系数、过氧化值、抗拉强度等指标的影响,确定复合膜的最佳配方:羧甲基纤维素与藕粉的质量比为2/0.3,甘油的添加量0.05%,茶多酚添加量为0.04%,蜂蜡的添加量为0.08%。以氯化钙对复合膜进行交联改性,当氯化钙浓度1%、交联时间8min,制备的交联羧甲基纤维素-藕粉复合膜抗水性能显著提高。以FTIR测定膜的红外光谱,以扫描电镜观察了膜表面和界面层的形态,以TG作膜的热重分析。研究结果表明,羧甲基纤维素经共混复合、氯化钙交联改性,有利于提高膜的阻隔性能、机械性能及抗水性能,该交联羧甲基纤维素/藕粉复合膜可替代传统塑料薄膜,是一种价格适中又具有营养价值的可食性内包装材料。     

纳米ZnO/HDPE复合膜的制备和性能研究

本文通过熔融共混和模压技术制备得到纳米氧化锌/高密度聚乙烯(纳米-ZnO/HDPE)复合膜,并考察了该膜的微观形态、机械性能、结晶性能以及阻隔性.结果发现,复合膜中改性纳米ZnO的含量较低(0.5wt%)时,纳米ZnO在HDPE中具有较好的分散性.随着改性纳米ZnO含量的增加,复合膜的拉伸强度和撕裂强度先增大后减小,ZnO含量为0.5wt%时,综合力学性能最佳.此外,改性纳米ZnO的添加能提高HDPE的结晶度,并能增强复合膜的阻隔性能.     

脱脂棉纳米微晶纤维素的制备及其作为海藻酸盐-淀粉复合薄膜增强剂的应用

探究了纳米微晶纤维素对海藻酸盐-淀粉复合薄膜的增强效果。以脱脂棉为原料,采用化学预处理结合超声破碎法制备纳米微晶纤维素(NCC);以马铃薯淀粉与海藻酸钠为成膜基材,以甘油为增塑剂,将NCC作为增强组分,通过流延法制备复合薄膜。微观形貌观察表明,脱脂棉NCC呈棒状,直径30 nm左右,长径比约为8;对复合膜的机械性能、阻隔性能、光学性能、水溶性、热稳定性和红外光谱检测表明,当NCC的添加量为5%(w/w)时,可以有效提高复合膜的拉伸强度、水溶时间和热稳定性,降低复合膜的透湿系数,而对复合膜的透光性影响不大。     

海藻酸钠-果胶改性复合膜的制备及表征

以海藻酸钠(SA)和柚皮果胶(PEC)为基材,辅以添加甘油和不同种类脂质制备复合膜,通过分析各组分对膜水蒸气透过系数、过氧化值、抗拉强度等指标的影响,确定复合膜的适宜配方:SA与PEC的质量比为10/2,甘油的添加量0.3%,石蜡添加量为0.12%。以CaCl_2、BaCl_2、FeCl_3、Al_2(SO_4)_3不同交联剂对该复合膜进行改性,以CaCl_2为交联剂,CaCl_2浓度3%、交联时间3min条件下制备的海藻酸钠-果胶改性复合膜各项性能提高。以FTIR、SEM、XRD、接触角测定膜的表面结构形态和性质进行表征和测试。研究结果表明海藻酸钠-果胶复合膜各组分间的相容性好,经CaCl_2交联后显著改善膜的阻隔性能、机械性能及抗水性能,海藻酸钠-果胶改性复合膜是一种具有良好发展前景的可降解复合包装膜。     

Fe~(3+)掺杂纳米TiO_2改性水性聚氨酯的制备及性能研究

以过氧钛酸水溶液为前驱体,在100℃下回流4 h,制备了透明的Fe~(3+)掺杂纳米二氧化钛(TiO_2)溶胶,可见光下的催化性能测试表明Fe~(3+)的最佳掺杂浓度为0.1%。将该掺杂浓度的纳米TiO_2溶胶与水性聚氨酯乳液通过简单共混制备了Fe3+掺杂纳米TiO_2改性水性聚氨酯复合膜。采用SEM、UV-Vis、TG等测试方法对复合膜进行表征,结果表明,纳米粒子均匀分散于复合膜中,并赋予了水性聚氨酯良好的紫外吸收能力。机械性能测试表明复合膜的抗张强度得到明显提高,并且在添加量为1%时达到最强(43 MPa),相对增强了13%。可见光下复合膜对亚甲基蓝(MB)的去除实验表明,Fe~(3+)掺杂纳米TiO_2的添加使得水性聚氨酯膜具有光催化自清洁能力。     

低温碱脲溶解制备再生纤维素复合膜及其应用

采用低温碱脲体系溶解棉浆纤维素,并复配以纯丙或苯丙乳液,利用乙醇再生制备纤维素复合水凝胶,再热压诱导高分子聚集态结构转变,构建复合改性纤维素膜材料。结果表明,树脂复配制得的纤维素复合膜比纯纤维素膜在尺寸稳定性、拉伸性能、表面疏水性、溶胀性等方面均有所改善。当树脂复配率为10%时,复合膜的拉伸性能最好,且纯丙改性比苯丙改性的效果更优,纯丙改性纤维素膜的断裂强力较纯纤维素膜的提升94.4%,断裂伸长率提高33.7%。改性纤维素膜的表面疏水性能随树脂复配率增大而增强,溶胀率随复配率提高而降低,其中纯丙改性膜的性能改善幅度比苯丙改性膜更高。当纯丙树脂复配率为50%时,所成膜材料的表面水滴接触角达79.3°,水溶胀率降至40.8%。无论改性与否纤维素膜的表观物理结构均较为紧密,其中10%纯丙改性复合膜的表面更为光滑、致密。     

纳米TiO_2抗菌复合膜的制备及其在枇杷保鲜中的应用

为制备出综合性能较好的抗菌绿色包装材料用于枇杷保鲜。以明胶、羧甲基纤维素钠为成膜基材,添加具有抗菌活性的纳米TiO_2对复合膜进行改性处理,研究纳米TiO_2添加量对复合膜机械性能、阻隔性能和抑菌性能等方面的影响。通过膜的性能测试,确定最佳的纳米TiO_2添加量并将其应用于枇杷保鲜。研究表明:纳米TiO_2添加量为2%时,复合膜的机械性能、成膜特性及抗菌活性相对最好。该处理组枇杷的呼吸强度、失重率,木质化含量显著低于对照组(P0.05)。冷藏至35 d时,处理组枇杷的菌落总数、腐烂率及MAD含量显著低于对照组(P0.05)。该研究可为纳米TiO_2抗菌复合膜的制备及枇杷保鲜提供新参考。     

海藻酸钙/纳米晶纤维素复合膜的制备及性能研究

采用硫酸水解脱脂棉制备纳米晶纤维素,并以浇注法制备海藻酸钙/纳米晶纤维素复合膜。通过对复合膜的机械性能、吸水性能、透湿性能和光学性能进行检测,结果表明,以此法制得的纳米晶纤维素呈棒状,直径20~40nm,长径比约为7。将纳米晶纤维素添加入膜中,复合膜的抗拉强度和断裂伸长率显著增大,而吸水性、透湿性和透光率显著减小。     

纳米纤维素添加量及干燥温度对海藻酸钠可食用膜性能的影响

为研究纳米纤维素对海藻酸钠可食用膜的影响,首先通过改变纳米纤维素添加量制得海藻酸钠复合膜液,研究成膜溶液静态流变性能,随后在不同干燥温度下制得复合膜,研究其透光率、水溶性、水蒸气透过率、氧气透过率及红外光谱特性。结果表明:所有膜液均为假塑性流体,且随着纳米纤维素添加量增加,膜液的假塑性程度升高,黏度变大。在相同干燥温度下,随着纳米纤维素含量增加,复合膜的透光率降低,水溶时间变长;50℃干燥制得的膜阻隔性能最佳,纳米纤维素添加量为15%的复合膜比纯海藻酸钠膜的水蒸气透过率下降了28.7%,添加量为5%的复合膜比纯海藻酸钠膜的氧气透过率下降了22.1%;红外光谱表征发现,在加入纳米纤维素后,复合膜官能团吸收峰发生位移,这可能是两者之间发生了氢键相互作用,从而改善了海藻酸钠膜的阻隔性能。     

4 种改性方式对明胶膜性能的影响

研究了共混改性、增塑改性、交联改性和乳化改性对明胶膜性能的影响。结果表明,明胶分别与壳聚糖、海藻酸钠共混溶解性较好,成膜均匀透明,同时具有较低的水蒸气透过率和透氧率,阻隔性增强;添加甘油作为增塑剂可提高明胶膜的断裂伸长率,机械性能增强;与柠檬酸钠交联改性后降低了明胶膜的水蒸气透过率,增强阻隔性能,提高抗拉强度,增强力学性能,但是膜的透光率下降;添加质量分数为0.1%的乳化剂吐温-80可以降低可食膜的水蒸气透过率,增强膜的阻隔性能,同时增大抗拉强度,改善机械性能。研究认为,共混、增塑、交联、乳化4 种改性方式均能不同程度地影响明胶膜的阻隔性能和机械性能,改善明胶膜的综合性能以满足其在不同领域的应用。     

GEO添加量对PLA/GEO复合膜性能及双孢蘑菇保鲜效果的影响

本文研究了不同浓度（0%、5%、7.5%、10%和12.5%）的葡萄柚精油（GEO）对聚乳酸(PLA)/葡萄柚精油复合膜的热性能,结构性能,机械性能,气体阻隔性能和抗菌性能等方面的影响。GEO通过减少聚合物链段的分子间作用力,从而改善复合膜的柔韧性,对复合膜起到一定的增塑作用。GEO的添加降低了PLA相的结晶性。随着GEO浓度的增加,复合膜的水蒸汽阻隔性能显著降低。但是,复合膜的抗菌活性因GEO的加入得以提高。将聚乳酸/葡萄柚精油复合膜应用于双孢蘑菇保鲜。结果表明,聚乳酸/葡萄柚精油复合膜与纯聚乳酸膜、低密度聚乙烯膜相比较,更能有效地保持蘑菇的硬度,阻止微生物生长,维持较好的总体接受度。因此,聚乳酸/葡萄柚精油复合膜可作为一种有效的包装材料,用于延长双孢蘑菇的货架期。     

纳米二氧化钛抗菌食品包装复合膜的研究进展

纳米二氧化钛具有较好的抗菌作用,且在传统包装材料中有较好的分散性,添加了纳米二氧化钛的食品包装薄膜具有较好的抗菌效果,能在一定程度上延长食品的保质期。目前,有较多关于纳米二氧化钛食品包装复合膜的研究,主要是围绕抗菌性,机械性能和安全性等方面展开,研究表明：纳米二氧化钛复合膜的抗菌性受光照影响;复合膜的机械性能、热力学性能和阻隔性等随纳米二氧化钛的加入有所改变;复合膜中的纳米二氧化钛可能会迁移到包装的食品中,造成食品安全隐患;制备复合膜时需综合考虑以上因素。本文主要对纳米二氧化钛的抗菌机理、纳米二氧化钛抗菌食品包装薄膜的制备和应用、纳米二氧化钛的迁移研究进展进行概述,旨在扩展纳米二氧化钛复合膜更好更安全地应用于食品包装。     

纳米纤维素的制备及其在食品包装材料中应用的研究进展

纳米纤维素作为包装材料的填充成分,可以提高材料的力学性能和阻隔性能,并可改善复合材料的热学性能及降解性能.本文简要介绍了纤维素及纳米纤维素,重点阐述了纳米纤维素的制备方法(化学法、生物法和物理机械法等)及其在食品包装材料中的应用(保鲜及抗菌包装材料、活性包装材料和高阻隔包装材料等).最后,对纳米纤维素在食品包装材料领域...     

Development and characterisation of polylactic acid–gliadin bilayer/trilayer films as carriers of thymol

Biodegradable food packaging promises a more sustainable future. Poly(lactic acid) (PLA) is a promising alternative for petroleum‐derived polymers. However, PLA films suffer from poor barrier properties compared with petroleum‐derived ones. To address this issue, we designed bilayer and sandwich‐architectured trilayer films based on PLA and gliadin. We reported firstly the direct formation of PLA–gliadin bilayer/trilayer films without surface modification on PLA film. The films were compact and uniform, and double/triple layers were combined firmly, preventing delamination. This strategy enhanced mechanical resistance, ductility and moisture barrier of gliadin films and concomitantly enhanced the oxygen barrier for PLA films. Thymol loadings endowed bilayer/trilayer films with antimicrobial activity and antioxidant activity. The antimicrobial activity of the films depended on film types, and gliadin layer presented larger inhibition zone than PLA layer, hinting that the films possessed directional releasing role. This study opens a promising route to fabricate bilayer/trilayer architecture helping to create synergism of the biopolymers.     

金属或金属氧化物对聚乳酸薄膜性能影响的研究进展

聚乳酸（polylactic acid, PLA）是一种以植物资源为原料合成的聚酯,可用于包装材料,对环境不产生任何污染。但聚乳酸耐热性差、脆性大限制了在行业中的实际应用,将PLA膜同金属及金属氧化物纳米粒子复合是一种可以有效改善聚乳酸膜性能的方式,本文概括了聚乳酸薄膜制备方法及特点,介绍了Ag、TiO₂、ZnO、SiO₂纳米粒子和聚乳酸复合膜,主要综述了这些纳米粒子对聚乳酸膜性能的影响及机制,最后对此类复合膜存在问题和未来发展进行展望。     

转谷氨酰胺酶对乳清浓缩蛋白-纳米微晶纤维素复合膜性能的影响

为了研究转谷氨酰胺酶(TG)对乳清浓缩蛋白(WPC)-纳米微晶纤维素(NCC)复合膜性能和结构的影响,本研究以WPC和NCC为原料,利用TG酶处理对WPC-NCC复合膜的机械性能和屏障性能进行优化,并探究TG酶的交联作用对乳清蛋白分子二级结构和复合膜成膜微观结构的作用情况。结果表明,在TG酶的添加量达到12 U/g_蛋白时,WPC-NCC复合膜的抗拉强度达到2.25 MPa,断裂伸长率达到86.75%,水蒸气透过率为4.40×10-12 gmPa-1s-1m-2,有效改善了WPC-NCC复合膜的机械性能性和水蒸气屏障性能。经过TG酶的处理,乳清蛋白结构向稳定有序的方向转变,减少了复合膜的孔洞数量和孔径,使成膜表面结构更加致密,促进了复合膜的机械性能和水蒸气屏障性能的提升。     

Antioxidant migration resistance of SiOx layer in SiOx/PLA coated film

As novel materials for food contact packaging, inorganic silicon oxide (SiO_x) films are high barrier property materials that have been developed rapidly and have attracted the attention of many manufacturers. For the safe use of SiO_x films for food packaging it is vital to study the interaction between SiO_x layers and food contaminants, as well as the function of a SiO_x barrier layer in antioxidant migration resistance. In this study, we deposited a SiO_x layer on polylactic acid (PLA)-based films to prepare SiO_x/PLA coated films by plasma-enhanced chemical vapour deposition. Additionally, we compared PLA-based films and SiO_x/PLA coated films in terms of the migration of different antioxidants (e.g. t-butylhydroquinone [TBHQ], butylated hydroxyanisole [BHA], and butylated hydroxytoluene [BHT]) via specific migration experiments and then investigated the effects of a SiO_x layer on antioxidant migration under different conditions. The results indicate that antioxidant migration from SiO_x/PLA coated films is similar to that for PLA-based films: with increase of temperature, decrease of food simulant polarity, and increase of single-sided contact time, the antioxidant migration rate and amount in SiO_x/PLA coated films increase. The SiO_x barrier layer significantly reduced the amount of migration of antioxidants with small and similar molecular weights and similar physical and chemical properties, while the degree of migration blocking was not significantly different among the studied antioxidants. However, the migration was affected by temperature and food simulant. Depending on the food simulants considered, the migration amount in SiO_x/PLA coated films was reduced compared with that in PLA-based films by 42–46%, 44–47%, and 44–46% for TBHQ, BHA, and BHT, respectively.     

Effect of banana and plasticizer types on mechanical,water barrier,and heat sealability of plasticized banana‐based films

Unripe banana flour and starch were used to formulate plasticized banana‐based films (flour film, PBF; starch film, PBS) with two types of plasticizers (glycerol, Gly; sorbitol, Sor) and a mixture of Gly‐Sor on film properties. PBS showed greater water barrier, elongation at break, toughness, and transparency, but lower efficiency in heat sealability than PBF. However, the easier and a higher yield in the preparation process of PBF lead to higher UV and visible light barrier than PBS which could be due to its protein content and the presence of phenolic compounds in PBF. Both banana films plasticized with Sor showed high glossiness, high efficiency in heat sealability, and mechanical and water barrier properties; however, the undesirable recrystallization of white crystals resulted in lower film flexibility. Thus, Gly‐Sor was preferred without change of water barrier but strengthened heat sealability. Therefore, banana‐based film might be considered as a green food packaging material.

Practical applications

Banana flour and starch from unripe bananas can be used as safe food ingredients for food products and as green biodegradable packaging materials. Banana flour film showed similar mechanical properties as banana starch film but involved easier processing and higher yield in the preparation of banana flour. Moreover, banana flour films had higher efficiency in heat sealability with the potential to protect the packed food from UV–visible light deterioration. Furthermore, an easier way to modify proper film properties is by the proper selection of the plasticizer. A mixture of plasticizers (glycerol and sorbitol) showed high potential to improve long‐term physical stability such as through UV–visible light prevention, and improved mechanical properties and heat sealability of plasticized banana‐based films. Briefly, plasticized banana flour film with a mixture of plasticizer will be potential, alternative biodegradable packaging material to reduce the use of nonbiodegradable synthetic plastic materials in food applications.     

柚皮纳米微晶纤维素的制备及其用于改进羧甲基淀粉膜性能的研究

以柚皮纤维素为原料,采用硫酸酸解法制备柚皮纳米微晶纤维素,对纳米微晶纤维素的形貌、结晶结构进行表征分析,以复合膜表面形貌、力学性能、水蒸气透过率和透光率为指标,研究不同添加量柚皮纳米微晶纤维素对羧甲基淀粉膜性能的影响。研究发现：柚皮纳米微晶纤维素为长度为60~180 nm,直径为3~15 nm的棒状晶体;X-射线衍射表明其仍为纤维素I型结构;复合膜电镜图光滑平整;纳米微晶纤维素添加量为5%时,复合膜的拉伸强度较原膜提高最大（52.22%）;而随着纳米微晶纤维素的添加,复合膜的断裂伸长率呈下降趋势;当添加量为7%时,复合膜水蒸气透过率降低最大（23%）;纳米微晶纤维素的添加量大于3%时显著降低复合膜的透光率,但未改变原膜在不同波长下的透光率。因此,添加柚皮纳米微晶纤维素能有效改善复合膜的性能,制备出综合性能优良的羧甲基淀粉复合膜。     

Natural antimicrobials and antioxidants added to polylactic acid packaging films. Part I: Polymer processing techniques

Currently, reducing packaging plastic waste and food losses are concerning topics in the food packaging industry. As an alternative for these challenges, antimicrobial and antioxidant materials have been developed by incorporating active agents (AAs) into biodegradable polymers to extend the food shelf life. In this context, developing biodegradable active materials based on polylactic acid (PLA) and natural compounds are a great alternative to maintain food safety and non-toxicity of the packaging. AAs, such as essential oils and polyphenols, have been added mainly as antimicrobial and antioxidant natural compounds in PLA packaging. In this review, current techniques used to develop active PLA packaging films were described in order to critically compare their feasibility, advantages, limitations, and relevant processing aspects. The analysis was focused on the processing conditions, such as operation variables and stages, and factors related to the AAs, such as their concentrations, weight losses during processing, and incorporation technique, among others. Recent developments of active PLA-based monolayers and bi- or multilayer films were also considered. In addition, patents on inventions and technologies on active PLA-based films for food packaging were reviewed. This review highlights that the selection of the processing technique and conditions to obtain active PLA depends on the type of the AA regarding its volatility, solubility, and thermosensitivity.