半纤维素薄膜研究新进展

针对半纤维素薄膜在食品包装材料、生物医用和可食薄膜的三个主要应用方向,分析和概述了近年来半纤维素薄膜方面的最新研究进展,侧重对比了薄膜的力学性能和阻隔性能。重点总结了当前半纤维素薄膜基材以及半纤维素薄膜改性的研究热点,并展望了半纤维素薄膜材料的发展前景。     

农林生物质残余物的高值化利用:半纤维素的提取、改性及应用研究进展

综述了生物质半纤维素的提取、改性及其在水凝胶、膜材料等领域的应用研究进展;着重介绍了半纤维素薄膜的塑化、化学改性和增强体增强改性;重点关注其作为包装材料的阻隔性能;展望了半纤维素膜材料可能的发展前景。     

CVD法氮化硅薄膜制备及性能

氮化硅薄膜是一种重要的薄膜材料,具有优秀的光电性能,钝化性能和机械性能,将在微电子,光电和材料表面改性领域获得广泛应用,本文着重评述了制备氮化硅薄膜的几种化学相沉积方法和一些性能。     

高导热聚酰亚胺/氮化硼复合材料的制备与表征

聚酰亚胺(PI)是综合性能优良的一类聚合物。本文利用钛酸酯偶联剂对六方氮化硼(h-BN)进行改性,制备了改性前后不同h-BN含量的复合薄膜,并对其性能进行研究。结果表明:随着h-BN含量的增加,复合材料热导率、热稳定性提高,吸水率下降;相同填料含量下,改性后的h-BN制备的复合薄膜性能皆优于未改性h-BN制备的复合薄膜。     

五层共挤阻隔薄膜的结构、性能、工艺及表征

介绍了以聚乙烯、聚丙烯、尼龙6、乙烯-乙烯醇共聚物四种聚合物原料作为多层共挤复合膜的材料进行挤出成型制备高阻隔性的薄膜,其中以PA6和EVOH作为阻隔薄膜的阻隔层材料,将聚乙烯作制备阻隔薄膜的热封层材料。分别通过热重分析、流变性能测试详细讨论了各种聚合物原料的热稳定性、热流变性能等,并在此基础上探讨了五层共挤流延膜的加工工艺,而后又对制备得到的六种五层共挤流延膜的力学性能及阻隔性能进行了详细表征。     

LDHs基气体阻隔薄膜材料的研究进展

透明且具有柔性的气体阻隔材料在电子器件封装、食品和药品保存等方面显示出广阔的应用前景。本文从材料的结构设计、制备方法和性能强化途径几个方面综述了层状双金属氢氧化物（LDHs）基气体阻隔薄膜材料的研究发展现状。研究指出,以绕道理论模型为理论支撑展开的主体、客体及主客体间的相互作用设计是材料性能提升的关键。首先,主体LDHs纳米片具有可调节的长径比,这对于调控气体阻隔性能来说是一种理想的填充材料;其次,聚合物客体的种类多样性赋予了LDH/聚合物气体阻隔薄膜独特的力学、光学和电化学特性,为气体阻隔薄膜的实际应用提供了更广阔的空间,同时对聚合物基体的物理化学特性的调节可提升阻隔性能;再者,调节LDHs和聚合物之间的相互作用力可进一步减小主客体间的自由体积,使得气体阻隔特性进一步提升,同时,有序的2D结构赋予了LDHs纳米片的高取向,可以延长气体分子的扩散路径而提高薄膜材料的非渗透性。最后,提出LDHs基气体阻隔薄膜材料性能强化将成为LDHs基气体阻隔薄膜材料发展的新方向。     

中国专利

聚合物改性聚烯烃锂离子电池隔膜及其制备方法本发明涉及的聚合物改性聚烯烃锂离子电池隔膜由聚烯烃微孔膜一面或双面复合一层薄膜,复合薄膜厚度为1～20μm,经溶胶状聚合物涂布而成。本发明改善了聚合物对隔膜的润湿性及界面性质,电池隔膜具有良好的润湿性、热关闭效应和热收缩小的特性。用本发明所制隔膜组装的电池具有良好的充、放电循环性能,改善了正负极材料与隔膜间的界面性质。     

生物降解聚酯降解性能调控研究进展

综述了聚合物分子结构设计、聚合物共混改性以及复合材料配方设计等生物降解聚酯降解速率调控方法,分析了生物降解聚酯降解性能调控面临的问题并展望其前景,以期为制备具有高性能、时控性和完全降解性的生物降解聚合物材料提供理论基础。     

聚合物改性水泥基材料的研究进展

普通混凝土与水泥砂浆具有许多优点,但其抗渗性差,在腐蚀性介质的作用下其使用寿命缩短.加入聚合物是解决这一问题的一种有效途径,并且聚合物能够显著改善水泥材料的性能.论文介绍了用于改性水泥砂浆和水泥混凝土的聚合物的种类,探讨了聚合物水泥基材料的改性机理,介绍了聚合物水泥基材料的应用及存在的问题,并据此对聚合物水泥基材料的研究进行了展望.     

疏水性可再分散聚合物乳胶粉的研究进展

对可再分散聚合物乳胶粉进行疏水性改性是提高其应用性能的重要方法。本文概述了疏水改性的可再分散聚合物乳胶粉的制备技术,对脂肪酸及其衍生物、硅烷等疏水改性的可再分散聚合物乳胶粉的特性和应用进行了论述,指出了疏水性可再分散乳胶粉用于水泥砂浆、新型内外墙干粉涂料等建筑材料可赋予材料良好的疏水性,从而提高其性能和使用寿命。     

Design and mechanism of controllable respiration polyamideamine-epichlorohydrin modied sugarcane bagasse pith hemicellulose film

The major challenge in hemicellulose blend films for food packaging is to overcome the inferior wet strength and hydrophilic properties of hemicellulose-based films. Inspired by the principle of wet strength of paper, novel bio-based packaging film with high barrier and strength properties was designed via bagasse pith hemicellulose as main substrate materials and polyamideamine-epichlorohydrin (PAE) as strengthening agent. The chemical characterization showed that the mechanical and barrier properties of the blend films were found to be strongly dependent upon the amount of PAE added in the films. Compared with the film without PAE, the tensile strength of PAE-containing film with optimal amount of 1% PAE increased by 100.25%, the water vapor permeability decreased by 23.25%, and the oxygen permeability decreased by 87.18%. The results showed that the new ester bond formed between PAE and hemicellulose caused the more excellent mechanical and barrier properties of films.     

Characteristics of soy protein isolate‐montmorillonite composite films

Soy protein isolate/montmorillonite (SPI/MMT) nanocomposite films were prepared in which MMT was used as a nanofiller at 0, 3, 6, 9, 12, and 15 wt % relative to SPI dry weight. Effects of MMT on film properties including tensile strength, elongation at break, total soluble matter, water vapor permeability, and oxygen permeability were assessed. X‐ray diffraction patterns were determined, and morphologies of SPI and the SPI‐MMT composite films were visualized by scanning electron microscopy. Mechanical and barrier properties were improved by evidenced increases in tensile strength and modulus, and decreases in permeability to water vapor and oxygen. MMT concentrations of 3%–12% were optimal for improving functional properties of the composite films. X‐ray diffraction and scanning electron microscopy examinations revealed the formation of an intercalated and exfoliated structure on the addition of MMT into the SPI matrix. We conclude that intercalated and exfoliated MMT silicates enhance mechanical and barrier properties of SPI films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Physical and mechanical properties of nanocomposite barrier film containing encapsulated nanoclay

Waterborne poly(styrene‐co‐butyl acrylate) was prepared via miniemulsion polymerization in which nanoclay (Cloisite® 30B, modified natural MMT) in different concentrations was encapsulated. Scanning electron microscopy, X‐ray diffraction, and transmission electron microscopy confirmed the encapsulation and intercalated‐exfoliated structure of Cloisite® 30B within poly(styrene‐co‐butyl acrylate). The effect of nanoclay content on water vapor permeability, water uptake, oxygen permeability, thermal, and mechanical properties of thin films containing 1.5, 2.56, 3.5, and 5.3 wt % encapsulated Cloisite® 30B in poly(styrene‐co‐butyl acrylate) was investigated. The presence of encapsulated Cloisite® 30B within the polymer matrix improved tensile strength, Young's modulus, and toughness of the nanocomposites depending on the nanoclay content. Water vapor transmission rate, oxygen barrier properties, and thermal stability were also improved. The results indicated that the incorporation of Cloisite® 30B in the form of encapsulated platelets improved physicomechanical properties of the nanoclay‐polymer composite barrier films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanical and barrier properties of poly(lactic acid) films coated by nanoclay–ink composition

In this study, poly(lactic acid) (PLA) films were coated by an ink formulation containing nanoclay dispersed with ultrasonic homogenization for 20 min. Mechanical and barrier properties of the coated films were evaluated according to clay type and concentration. PLA films coated by ink formulations containing Cloisite 30B displayed the best mechanical and barrier properties in six types of nanoclays. PLA films coated by Cloisite 30B‐containing ink varying in clay concentration were investigated. Tensile strength and elongation at break of these coated films were improved in 1% Cloisite 30B. Oxygen permeability decreased significantly upon the addition of clay levels up to 1% and slightly decreased with further increases in the amount of the clay. The value of water vapor permeability also decreased depending on the increases of clay (0%–20%). When the clay content in the sample was 2.0%, the surface of coated PLA films displayed aggregation visible using film emission scanning electron microscopy. X‐ray diffractometry and transmission electron microscopy indicated that a mixture of exfoliated and intercalated structure was formed with addition of 1% (w/w) Cloisite 30B to the ink after ultrasonication. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effects of the incorporation of saturated fatty acids on the mechanical and barrier properties of biodegradable films

The effects of saturated fatty acids at a concentration of 1.5% on the mechanical and barrier properties of starch‐based films were evaluated in films prepared with two concentrations of glycerol, 20 and 25%. The water vapor permeability (WVP) was determined at three ranges of relative humidity, RH, (0–33, 33–64 and 64–97%). In all cases, an increase in WVP values was observed with increasing RH. SEM images showed a more homogeneous and compact structure in the films with caproic and lauric acids. The films with fatty acids showed higher elongation and maximum stress, and they had Young's modulus values close to those of the control; thus, the addition of fatty acids did not impair the mechanical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Surface and barrier properties of hybrid nanocomposites containing silica and PEO segments

Hybrid organic–inorganic nanocomposites containing PEO segments linked to a methacrylate network were prepared through a dual‐curing process, which involved photopolymerization and condensation of alkoxysilane groups. A system based on an α,ω‐dimethacrylate PEO oligomer (BEMA 1400) added with methacryloyl‐oxypropyl‐trimethoxysilane (MEMO) and tetraethoxysilane (TEOS) was used. The surface properties of the obtained films were investigated through XPS analyses and contact angle measurements. A selective enrichment of the MEMO additive towards the outermost layers of the films was evidenced either in the presence or in the absence of TEOS. SEM analyses were performed on the cross section of the films coated on PET substrates, determining the film composition at different depth by EDS analysis. The Si content was found constant, moving from the PET surface towards the air–surface of the films. The barrier properties, with respect to oxygen, of the hybrid films coated on a PET substrate were measured. A decrease of the permeability and of the oxygen transmission rate using hybrid coatings was observed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 4107–4115, 2007     

Interactions between PLA,organo-montmorillonite and plasticizer: Synergistic effect on the barrier and mechanical properties of PLA nanocomposites blown films

In this study, the impact of incorporating a plasticizer on the compatibility between organo-montmorillonite (OMMt) and polylactic acid (PLA) is investigated, and the resulting barrier and mechanical properties are reported. Four polymers were chosen as plasticizers to prepare the PLA nanocomposite blown films: poly(ethylene glycol), poly(ethylene oxide), polycaprolactone (PCL), and random ethylene-methyl acrylate-glycidyl methacrylate terpolymer. Firstly, 5 wt% of each plasticizer and 3 wt% of OMMt (Dellite® D43B) were mixed simultaneously with PLA in a twin-screw extruder and then introduced into the hopper of a single screw extruder to produce D43B-PLA/plasticizer nanocomposite films. The compatibilization effect was examined based on microstructure observations and thermodynamic predictions. Crystallinity was evaluated using DSC and XRD measurements. The results obtained for permeability and mechanical testing showed that the improvement of barrier and mechanical properties depends directly on the degree of compatibility between plasticizer, OMMt, and PLA. Indeed, the interfacial properties, XRD diffraction, and TEM images showed that a synergistic effect can result from high interfacial interactions between different compounds.     

Physical properties and morphology of films prepared from microfibrillated cellulose and microfibrillated cellulose in combination with amylopectin

Two types of microfibrillated cellulose (MFC) were prepared using either a sulfite pulp containing a high amount of hemicellulose (MFC 1) or a carboxymethylated dissolving pulp (MFC 2). MFC gels were then combined with amylopectin solutions to produce solvent‐cast MFC‐reinforced amylopectin films. Tensile testing revealed that MFC 2‐reinforced films exhibited a more ductile behavior and that MFC 1‐reinforced films had higher modulus of elasticity (E‐modulus) at MFC loadings of 50 wt % or higher. Pure MFC films had relatively low oxygen permeability values when data were compared with those for a variety of other polymer films. MFC 1 and MFC 2 films had similar opacity but differences in appearance which were attributed to the presence of some larger fibers and nanofiber agglomerates in MFC 2. Field emission scanning electron microscopy (FE‐SEM) and atomic force microscopy (AFM) were used to illustrate the morphology of MFC nanofibers in pure films and in an amylopectin matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of mica modification with ethylene-vinyl acetate wax on the water vapor barrier and mechanical properties of poly-(butylene adipate-co-terephthalate) nanocomposite films

Poly-(butylene adipate-co-terephthalate) (PBAT) is one of the most popular raw materials for degradable plastic films because of its good biodegradability, ductility, and processability. However, the application of this material is limited by its unsatisfactory water vapor barrier property. This study aims to improve the water vapor barrier and mechanical properties of PBAT films by introducing mica modified by ethylene-vinyl acetate copolymer waxes (EVA-mica). The EVA-mica nanosheets showed a more uniform dispersion in the PBAT films than the mica nanosheets. The PBAT/EVA-mica films containing 2% EVA-mica demonstrated outstanding crystallinity, water vapor barrier, and mechanical properties compared with the pure PBAT films. Results showed a 20.23% increase in crystallinity, an 80.09% reduction in water vapor permeability, a 26.82% increase in tensile strength, and a 9.10% increase in tear strength. The enhanced water vapor barrier and mechanical properties of the PBAT/EVA-mica nanocomposite films are favorable for their future application as biodegradable films.