纳米纤维素/聚乳酸复合包装薄膜的制备及表征

目的添加适量的纳米纤维素改善聚乳酸的脆性,以适应产品的包装。方法将聚乳酸(PLA)与纳米纤维素(CNFs)共混制备复合包装材料,测试该复合材料的力学性能、透光率、红外谱图,并用扫描电子显微镜(SEM)观察了复合包装材料的表面形貌。结果纳米纤维素添加到聚乳酸中增加了其力学性能,当纳米纤维素质量分数为2%时,拉伸强度和冲击强度都达到最大;随着添加CNFS比例的增大,CNFs/PLA复合薄膜材料的透光率随之降低,雾度随之升高,但是该薄膜作为包装材料对商品的可视性影响不大。结论纳米纤维素(CNFs)是具有一定长径比的纳米级线状材料,对材料的拉伸强度具有增强作用。     

纳米纤维素晶/醋酸纤维素共混超滤膜材料的研究

采用浸没沉淀相转化法制备了纳米纤维素晶(CNC)/醋酸纤维素(CA)完全环境友好的共混膜材料,考察了在铸膜液中添加不同质量分数的CNC对共混膜各方面性能的影响。通过超滤装置测定了共混膜的水通量、截留率、含水率和孔隙率;通过万能试验机、环境扫描电子显微镜(SEM)、热重分析仪(TGA)对超滤膜进行了力学性能、形貌结构和热稳定分析。结果表明,随着CNC含量增加,共混膜的孔隙率呈增长趋势,由40.8%提高到66.4%,大孔由原来的规则圆形漏斗状变为狭长椭圆状且互相连通,水通量和拉伸强度呈先上升后减小的趋势。当CNC添加量为0.5%时,共混膜综合性能最优,相比纯CA膜,水通量提高64.7%,拉伸强度提高70%,热稳定性也得到增强。     

玉米秸秆微晶纤维素/聚乳酸复合膜的制备与性能

采用玉米秸秆微晶纤维素(CSCMC)作为增强材料, 生物可降解材料聚乳酸(PLA)作为基体, 制备了CSCMC/PLA复合膜材料, 并对复合膜的结晶度、热稳定性能、力学性能进行了测试。结果表明, 复合膜材料的热稳定性能和力学性能优于纯聚乳酸膜。当CSCMC的质量分数为10%时, 复合膜的热稳定性能和力学性能达到最佳, 与纯PLA膜相比, 起始分解温度提高了34.38 ℃, 拉伸强度提高了58.3%, 断裂伸长率提高了31.1%。      

丙烯酸原位聚合改性纤维素纳米晶体/聚乙烯醇复合膜的制备及性能

利用丙烯酸原位聚合和纤维素纳米晶体与聚乙烯醇复合制备聚乙烯醇-聚丙烯酸-纤维素纳米晶体(PVA-(PAACNC))复合膜。通过傅里叶变换红外光谱、扫描电子显微镜分析、接触角测试、拉伸试验和透光率测试考察了CNC和PAA的共同添加对复合膜结构形态、耐水性、力学性能和透明性的影响。结果表明,与纯PVA膜相比,改性复合膜仍然保持较高的透光率,在可见光低波段最低只降低5.6%;表面疏水性得到改善,接触角提高了40°以上;只用CNC改性时,所得的PVA-CNC复合膜中CNC的团聚现象比较严重,且力学性能对环境湿度非常敏感;同时用PAA和CNC改性时,所得复合膜中CNC的团聚现象得到明显抑制,在100RH%湿态环境下仍保持较好的力学性能,且断裂伸长率大幅提高。     

丙烯酸原位聚合改性纤维素纳米晶体/聚乙烯醇复合膜的制备及性能EI北大核心CSCD

利用丙烯酸原位聚合和纤维素纳米晶体与聚乙烯醇复合制备聚乙烯醇-聚丙烯酸-纤维素纳米晶体(PVA-(PAACNC))复合膜。通过傅里叶变换红外光谱、扫描电子显微镜分析、接触角测试、拉伸试验和透光率测试考察了CNC和PAA的共同添加对复合膜结构形态、耐水性、力学性能和透明性的影响。结果表明,与纯PVA膜相比,改性复合膜仍然保持较高的透光率,在可见光低波段最低只降低5.6%;表面疏水性得到改善,接触角提高了40°以上;只用CNC改性时,所得的PVA-CNC复合膜中CNC的团聚现象比较严重,且力学性能对环境湿度非常敏感;同时用PAA和CNC改性时,所得复合膜中CNC的团聚现象得到明显抑制,在100RH%湿态环境下仍保持较好的力学性能,且断裂伸长率大幅提高。     

聚乳酸/醋酸纤维素共混膜的制备及性能研究

采用浸没沉相转化法制备聚乳酸/醋酸纤维素(PLA/CA)共混膜,通过SEM、红外光谱、热重分析、吸水率、透气率、接触角和力学性能实验考察了PLA含量对PLA/CA共混膜结构和性能的影响。红外分析表明,PLA的添加并没有破坏CA本身的基团和氢键结构;SEM分析表明,在PLA低含量的条件下,PLA与CA相容性较好,形成的共混膜的表面光滑,排列十分紧密;PLA的引入改善了CA膜的抗水性和综合力学性能,但热稳定性有所下降;当PLA含量为15%时,共混膜质地较为密实,拉伸强度、断裂伸长率综合性能较好,透气率低。     

羧甲基纤维素增强膜的制备及性能

目的为了获得一种可用于食品包装的羧甲基纤维素增强膜。方法以羧甲基纤维素(CMC)为成膜基底,甘油为增塑剂,分别将质量分数为1%,3%,5%和10%的纳米纤维素(NCC)添加到CMC中,共混流延制备羧甲基纤维素增强膜(CMC-NCC)。结果 NCC的加入,提高了CMC的力学性能和对水蒸气的阻隔性能,还提高了CMC的热性能。FT-IR分析结果表明,CMC与NCC两者间形成了分子间氢键;XRD分析结果表明,NCC可以改变CMC的结晶排列。当添加质量分数为5%的NCC时,CMC-NCC的拉伸强度比纯CMC膜提高了25.6%,断裂伸长率降低了21.3%,透湿量降低了9%,热稳定性提高了2%,透光率维持在87%以上。结论 CMC增强膜具有力学性能高、阻湿性能好等优点,NCC提高了CMC的成膜品质。     

纤维素纳米晶/环氧树脂复合材料的制备及性能研究

以过硫酸铵氧化微晶纤维素得到纤维素纳米晶(CNC),与二乙烯三胺在N,N-二甲基甲酰胺(DFM)中发生缩合接枝反应,制备胺化纤维素纳米晶(ACNC)。采用溶液共混法,分别将CNC和ACNC与环氧树脂复合得到纤维素纳米晶/环氧树脂复合膜,纤维素纳米晶不仅起到增强剂的作用,还起到固化交联剂的作用,进而改善环氧树脂的性能。利用万能力学试验机、动态热机械性能、环境扫描电子显微镜、热重分析等对复合材料的性能加以表征分析。结果证明,当CNC和ACNC的添加量均为0.1%时,环氧树脂复合膜的机械强度最大;纤维素纳米晶的加入不仅能够提高环氧树脂的力学性能,还能显著改善其柔韧性,ACNC对环氧树脂复合膜的增强作用高于CNC,CNC的增韧作用强于ACNC。     

聚氨酯弹性体/纤维素纳米晶体复合材料的制备及性能研究

通过浓硫酸水解脱脂棉制备纤维素纳米晶体(CNC),并用3-氨基丙基三乙氧基硅烷(APTS)对其进行表面修饰。以4,4-二苯基甲烷二异氰酸酯(MDI)、聚四氢呋喃(PTMG)、CNC、1,4-丁二醇(BD)为原料制备聚氨酯弹性体/纤维素纳米晶体(PUE/CNC)复合材料,研究了CNC用量对PUE/CNC复合材料性能的影响。结果表明:当CNC用量达到1%(wt,质量分数,下同)时,复合材料的拉伸强度和断裂伸长率分别提高了178%和97.5%,热性能也有所提高;但CNC用量超过1.5%后,复合材料的力学性能下降,热性能仍保持提升。     

微纤化纤维素/聚乳酸薄膜的制备及性能分析

目的将微纤化纤维素(MFC)和聚乳酸(PLA)共混成膜,以提高薄膜的透湿、透氧、阻光等性能,满足果蔬等食品的包装要求。方法采用酶解法与机械处理的方法制备MFC,使用硅烷偶联剂KH560对MFC进行疏水改性处理,再将改性处理的微纤化纤维素(MFC-S)与PLA共混制成薄膜。结果当MFC-S的质量分数为0.75%时,MFC-S/PLA共混包装膜的拉伸强度比纯PLA膜增加了13.3%,当MFC-S的质量分数为2%时,MFC-S/PLA共混包装膜的透氧系数为纯PLA膜的1.43倍,透湿系数为纯PLA膜的1.26倍,透光率降低了60%,阻光效果较好。结论 MFC-S的质量分数为0.75%时,包装膜的拉伸强度较好;MFC-S的质量分数为2%时,透氧、透湿、阻光性较好。     

Plasticized polylactic acid nanocomposite films with cellulose and chitin nanocrystals prepared using extrusion and compression molding with two cooling rates: Effects on mechanical,thermal and optical properties

Triacetate citrate plasticized poly lactic acid and its nanocomposites based on cellulose nanocrystals (CNC) and chitin nanocrystals (ChNC) were prepared using a twin-screw extruder. The materials were compression molded to films using two different cooling rates. The cooling rates and the addition of nanocrystals (1 wt%) had an impact on the crystallinity as well as the optical, thermal and mechanical properties of the films. The fast cooling resulted in more amorphous materials, increased transparency and elongation to break, (approx. 300%) when compared with slow cooling. Chitin nanocomposites were more transparent than cellulose nanocomposites; however, microscopy study showed presence of agglomerations in both materials. The mechanical properties of the plasticized PLA were improved with the addition of a small amount of nanocrystals resulting in PLA nanocomposites, which will be further evaluated for film blowing and thus packaging applications.     

聚乳酸/茶多酚抗氧化膜的制备及其性能研究

以聚乳酸（PLA）为基材,茶多酚（TP）为抗氧化剂,通过流延法制备了具抗氧化活性的可降解PLA/TP共混膜,并研究了茶多酚添加量对共混膜包装性能及抗氧化性能的影响。研究结果表明：茶多酚与聚乳酸基质间发生了相互作用,茶多酚在聚乳酸基质中具有较好的分散性。天然抗氧化物茶多酚的添加使共混膜的拉伸强度、断裂伸长率以及透光率降低,但显著提高了共混膜的热封强度、透湿系数、透氧系数、溶解度和自由基清除率。当茶多酚的质量分数为0.9%时,共混膜的热封强度为3.31 N/(15 mm),透湿系数和透氧系数分别是纯PLA膜的1.68倍和6倍,透光率为88.1%,自由基清除率为89.18%,是一种具有应用潜力的环境友好型食品活性包装材料。     

纳米纤维素增强淀粉食品包装材料的研究进展

目的 为了解决纯淀粉材料力学性能低、脆性大等缺点,探索纳米纤维素对淀粉膜材料的影响,为食品包装材料领域和替代传统石油基的高分子材料方向提供新的思路。方法 通过跟进国内外纳米纤维增强淀粉相关研究和应用进展,概括3种纳米纤维素的性能,介绍淀粉食品包装材料未来将面临的挑战和机遇,重点分析纳米纤维素对淀粉膜性能的影响。结论 纤维素纳米纤维（CNF）、纤维素纳米晶（CNC）和微晶纤维素（MCC）对淀粉进行增强后,淀粉复合材料的力学性能、阻隔性能和热学性能均得到改善,纳米纤维素增强淀粉食品包装材料在未来食品包装领域将得到扩展。     

Chitosan nanocomposite films incorporating cellulose nanocrystals and grape pomace extracts

Chitosan nanocomposite films incorporating grape pomace extract (GPE), either Cabernet Franc (CF; a red variety) or Viognier (a white variety), and cellulose nanocrystal (CNC) were prepared using a solvent casting method. Mechanical properties, water vapour permeability, color and opacity, crystalline structure, thermal properties, total phenolic content, and antioxidant activity of the films were characterized. Incorporating CNC alone significantly (P < .05) increased tensile strength of the films and decreased their percent elongation at break and water vapour permeability. Grape pomace extract had an opposite effect on mechanical properties by decreasing tensile strength but increasing percent elongation at break. Film color was mainly influenced by the presence and type of GPE. Films containing CF extract exhibited the darkest appearance with increased reddish and bluish hues. Addition of CNC significantly increased film opacity and the alignment of chitosan chains, while the effect of GPE was not significant. Thermal analysis showed that chitosan and CNC were partially miscible and that the addition of CNC did not significantly change decomposition temperature of the films. Incorporation of GPE significantly (P < .05) increase total phenolic content and antioxidant activity. Films containing CF had higher DPPH? radical scavenging capacity than their counterparts with Viognier. Film incorporating both CNC and CF shows greater potential for food packaging application because of a combination of improved physical properties and high antioxidant activity.     

天然抗氧化羟丙基甲基纤维素水溶性包装薄膜

将竹叶抗氧化剂(AOB)添加到羟丙基甲基纤维素(HPMC)制膜液中,采用流延法制得具有抗氧化性能的AOB/HPMC复合水溶性包装薄膜。并通过红外吸收光谱、X射线衍射、热重分析等对复合薄膜的官能团变化、结晶情况等进行了表征,测定了样品薄膜的透光率和雾度,利用DPPH自由基清除实验分析了薄膜的抗氧化性能。研究了AOB的添加量对复合包装薄膜的抗氧化性能、水溶性、力学性能和光学性能的影响。实验结果表明:AOB的添加没有破坏HPMC本身的基团,仅扰乱了分子链的排列,导致AOB/HPMC复合薄膜的结晶度下降,热分解温度提高,热稳定性能加强,具有抗氧化性的功能特性;且随着AOB添加量的不断增加,复合水溶性包装薄膜的水溶性不断提高,力学性能和光学性能有所下降,但下降幅度不大,抗氧化性能先增大后降低,当AOB的添加质量分数为0.03%时,复合薄膜对DPPH自由基的清除率达最大值,为89.34%。     

Anisotropic,Transparent Films with Aligned Cellulose Nanofibers

Transparent films or substrates are ubiquitously used in photonics and optoelectronics, with glass and plastics as traditional choice of materials. Transparent films made of cellulose nanofibers are reported recently. However, all these films are isotropic in nature. This work, for the first time, reports a remarkably facile and effective approach to fabricating anisotropic transparent films directly from wood. The resulting films exhibit an array of exceptional optical and mechanical properties. The well‐aligned cellulose nanofibers in natural wood are maintained during delignification, leading to an anisotropic film with high transparency (≈90% transmittance) and huge intensity ratio of transmitted light up to 350%. The anisotropic film with well‐aligned cellulose nanofibers has a mechanical tensile strength of up to 350 MPa, nearly three times of that of a film with randomly distributed cellulose nanofibers. Atomistic mechanics modeling further reveals the dependence of the film mechanical properties on the alignment of cellulose nanofibers through the film thickness direction. This study also demonstrates guided liquid transport in a mesoporous, anisotropic wood film and its possible application in enabling new nanoelectronic devices. These unique and highly desirable properties of the anisotropic transparent film can potentially open up a range of green electronics and nanofluidics.