改性蒙脱土/PVA/淀粉复合膜的制备及其抗菌性能

采用高温灼烧法制备纳米氧化铜蒙脱土(MMT-CuO),然后用十四烷基二甲基苄基氯化铵(1427)进行蒙脱土的阳离子改性。以聚乙烯醇(PVA)、红薯淀粉为基材,甘油为塑化剂,蒙脱土为抑菌剂和强化剂,制备改性蒙脱土/PVA/淀粉复合膜。结果表明,随着未改性蒙脱土的含量增加,复合膜的抗拉强度也逐渐增加,添加量为8%时,膜的抗拉强度为(7.132±0.201)MPa,断裂伸长率为(145.747±5.039)%;季铵盐改性MMT-CuO的添加量的增大,膜的拉伸强度变化不显著,但是断裂伸长率、水溶性和水蒸气透过性均降低,改善了膜的水溶性和水蒸气透过性;改性蒙脱土可以提高膜的抗菌性,尤其对金黄色葡萄球菌,这种复合改性蒙脱土在抗菌包装上具有潜在应用价值。     

水溶性高分子/蒙脱土纳米复合浆料

以钠基蒙脱土、丙烯酸类单体和聚乙烯醇为原料,通过溶液原位聚合法和溶液插层法分别制备出不同蒙脱土含量的丙烯酸系共聚物/蒙脱土纳米复合浆料和聚乙烯醇/蒙脱土纳米复合浆料。用X射线衍射(XRD)法测定纳米复合材料中蒙脱土的层间距,并测定纳米复合浆料对纤维的黏附性和浆纱强力。试验结果表明,当蒙脱土含量较少时,形成了剥离型纳米复合材料,随着蒙脱土含量的增加,形成插层-剥离型和插层型纳米复合材料;丙烯酸系纳米浆料有利于提高对纯棉纤维的黏附性,并提高浆纱的断裂强力,而聚乙烯醇纳米浆料可提高对涤/棉的黏附性,对浆纱强力的影响不大。     

有机改性蒙脱土对改性淀粉复合膜性能的影响

为了获得高性能的淀粉/蒙脱土纳米复合材料,选取3种改性淀粉为成膜基材,3种有机改性蒙脱土(OMMT)为增强剂,采用溶液流延法制备了复合膜。X-射线衍射说明改性剂和淀粉分子进入蒙脱土片层间发生插层反应。红外光谱结果表明双十八烷基二甲基氯化铵改性蒙脱土(D1821MMT)与氧化酯化淀粉(OAS)、深度氧化淀粉(HOS)具有较强的氢键作用;而十八烷基二甲基苄基氯化铵改性蒙脱土(1827MMT)与羟丙基交联淀粉(HPDSP)存在较强的氢键作用。OAS/D1821MMT复合膜具有较高的抗拉强度(5.80 MPa)和透光率(86.83%);HOS/1827MMT复合膜具有较高的断裂伸长率;HPDSP/1831MMT复合膜水蒸气渗透系数最低(1.30×10-10g·m·m-2·s-1·Pa-1)。研究证实,OMMT与改性淀粉能够形成性能更加优良的纳米复合膜,该膜在食品包装领域具有广泛应用前景。     

壳聚糖-蒙脱土与壳聚糖-高岭土纳米复合涂料流变性及其对纸张阻隔性能的影响

分析了不同的硅酸盐用量和搅拌速度对壳聚糖-蒙脱土和壳聚糖-高岭土纳米复合涂料流变性的影响;借助原子力显微镜(AFM)观察了涂覆这2种纳米复合涂料后白卡纸的表面形貌,并探讨了这2种涂料对纸张阻隔性能的影响。结果显示,随蒙脱土用量的增加,壳聚糖-蒙脱土纳米复合涂料的黏度增大,但当蒙脱土用量为12%时,涂料黏度下降;蒙脱土的搅拌速度越大,表观黏度对剪切速率的依赖性越大,壳聚糖-蒙脱土纳米复合涂料属于典型的非牛顿假塑性流体,表现出典型的“剪切变稀”现象。随高岭土用量的提高,壳聚糖-高岭土纳米复合涂料的黏度增加,其非牛顿性要大于壳聚糖-蒙脱土纳米复合涂料;随高岭土搅拌速度的提高,壳聚糖-高岭土纳米复合涂料出现了典型的“剪切增黏”现象。相同工艺条件下,壳聚糖-高岭土纳米复合涂料的黏度高于壳聚糖-蒙脱土纳米复合涂料。AFM结果显示,经纳米复合涂料涂布后纸张的粗糙度较原纸显著降低,且壳聚糖-蒙脱土纳米复合涂料对纸张阻隔性能的影响优于壳聚糖-高岭土纳米复合涂料。     

蒙脱土的改性方法及应用现状

由于天然蒙脱土颗粒层间距小,层间化学微环境不利于单体插入,从而和单体的相容性差,为了提高其使用性能并扩大应用领域,就要求对蒙脱土进行改性.改性的方法有有机改性、无机改性和有机/无机复合改性三种,同时列举了各种改性蒙脱土在纳米复合材料、废水处理和催化材料等领域的应用现状.最后,提出要切实加强蒙脱土的层间域微环境和化学改性等基础理论的研究.     

淀粉蒙脱土复合浆料的制备及性能测试

探讨淀粉蒙脱土复合浆料的浆纱性能.采用溶液插层法制备了淀粉基蒙脱土复合浆料,测试了其浆液黏度、黏附性、浆膜的强伸性和耐磨性,并采用所制备出的淀粉蒙脱土复合浆料进行了上浆试验.结果表明:淀粉蒙脱土复合浆料浆膜的断裂伸长率和耐磨性较普通淀粉浆料有明显改善,且对涤棉有较好的黏附性.认为通过蒙脱土的改性处理可改善淀粉的脆硬性,提高淀粉浆的上浆效果.     

蒙脱土杂化硅溶胶整理织物的热性能

采用溶胶-凝胶法制备蒙脱土纳米复合材料杂化硅溶胶,并将其应用于棉织物阻燃整理。通过红外(FT-IR)和X射线衍射(XRD)分析,研究了杂化硅凝胶的化学结构及插层后蒙脱土的层间距变化;通过热失重分析(TGA)及垂直燃烧测试,探讨了蒙脱土纳米复合材料对织物热稳定性和阻燃性能的影响。结果表明,蒙脱土纳米复合材料与硅溶胶发生物理作用,复合材料被包覆在凝胶薄膜中。杂化硅溶胶的成膜性较好,可在织物表面形成一层致密薄膜,提高了织物的热稳定性和阻燃性能,且耐洗性良好。     

蒙脱土对水溶性聚合物基蒙脱土纳米复合材料性能的影响

通过自由基水溶液聚合制备了聚二烯丙基二甲基氯化铵-丙烯酰胺-丙烯酸(PDM-AM-AA),将PDM-AM-AA分别与钠基蒙脱土、十六烷基三甲基氯化铵改性蒙脱土(1631-MMT)和二烯丙基二甲基氯化铵改性蒙脱土(DM-MMT)进行复合,制备系列纳米复合材料,采用FT-IR和XRD对其结构进行了表征,并将其分别配合2%铬粉应用于皮革鞣制工艺中,对坯革的耐湿热稳定性和物理机械性能进行了测试。XRD结果表明:PDM-AM-AA/1631-MMT和PDM-AM-AA/DM-MMT纳米复合材料中蒙脱土的衍射峰消失,PDM-AM-AA/Na-MMT纳米复合材料中蒙脱土的层间距为1.5125nm;与聚合物PDM-AM-AA相比,蒙脱土的引入使得纳米复合材料的结晶度不同程度地降低。应用结果表明:PDM-AM-AA/DM-MMT配合2%铬粉应用于制革工艺中,坯革的各项性能较好,能够符合服装用皮革QB/T1872-2004的标准。     

蒙脱土的改性及其在制革工业中的应用进展

由于蒙脱土特殊的结构,其在纳米复合材料领域起着举足轻重的作用,并被广泛地应用于轻工、石油、橡胶、冶金、污水处理、药品等行业。本文简要地概述了蒙脱土的结构组成和基本性质,并对蒙脱土的无机改性,有机改性及无机-有机复合改性进行综述,然后重点总结了近年来蒙脱土及改性蒙脱土在皮革加脂剂,皮革鞣剂,皮革涂饰剂,皮革抗菌、防霉剂及制革污水处理等领域的研究及应用现状,最后对蒙脱土在皮革领域的发展趋势进行了展望。     

响应面法优化纳米SiO_2改性大豆蛋白/聚乙烯醇复合薄膜工艺

为增强大豆蛋白/聚乙烯醇复合薄膜的综合性能,以纳米SiO2含量、分散剂聚乙烯基吡咯烷酮(PVPK-30)的含量、膜液pH值为影响因子,以薄膜拉伸强度、断裂伸长率、透光率、吸水率为主要评价指标,通过响应曲面试验确定纳米SiO2改性大豆蛋白/聚乙烯醇复合膜的最佳工艺条件。试验结果表明:当加入1.75%的SiO2纳米粒子(占大豆蛋白和PVA干重),1.20%的PVP(占纳米粒子干重),膜液的pH值控制在5.50时,复合薄膜的综合性能最好;与原大豆蛋白/PVA复合膜相比,改性后薄膜的抗张强度由4.61 MPa增加到9.76 MPa,断裂伸长率由64.98%提升到92.76%,透光率由15.54%升到24.12%,而吸水率由46.37%略降到45.28%。本试验为大豆蛋白/聚乙烯醇复合薄膜性能的改善以及生产应用提供理论和试验基础。     

Effect of PLA lamination on performance characteristics of agar/κ-carrageenan/clay bio-nanocomposite film

Multilayer films composed of PLA and agar/κ-carrageenan/clay (Cloisite® Na⁺) nanocomposite films were prepared, and the effect of lamination of PLA layers on the performance properties such as optical, mechanical, gas barrier, water resistance, and thermal stability properties was determined. The tensile strength (TS) of the agar/κ-carrageenan/clay nanocomposite films (67.8 ± 2.1 MPa) was greater than that of PLA films (43.3 ± 3.6 MPa), and the water vapor permeability (WVP), water uptake ratio (WUR), and water solubility (WS) of the nanocomposite films were higher than those of PLA films. The film properties of the multilayer films exhibited better properties of the component film layers. Especially, the WVP and water resistance of the bionanocomposite film were improved significantly, while the OTR of the PLA film decreased profoundly after lamination with PLA layers. Thermal stability of the bionanocomposite also increased after lamination with PLA layers.     

Chitosan/clay films' properties as affected by biopolymer and clay micro/nanoparticles' concentrations

Blends of chitosan (from Cuban lobster) and clay micro/nanoparticles were prepared by dispersion of the clay particles in the film matrix and the films obtained were characterized in terms of water solubility, water vapor, oxygen and carbon dioxide permeability, optical, mechanical and thermal properties using an Instron universal testing machine, differential scanning calorimetry, thermogravimetric analyses and scanning electron microscopy (SEM). The water vapor barrier properties of the films were significantly improved by incorporation of clay in their composition, while the water solubility decreased as the clay concentration increased (for a constant chitosan concentration). The tensile strength of chitosan/clay films increased significantly with increasing chitosan and clay concentrations, while the values of elongation decreased slightly for high values of chitosan concentration. T_m increased with the increase of chitosan concentration, but the changes in T_m with the addition of clay were not significant.Polynomial models were fitted to the experimental data in order to facilitate future design of chitosan/clay film systems.     

Study of physical and mechanical properties of polypropylene nanocomposites for food packaging application: Nano-clay modified with iron nanoparticles

Polypropylene (PP) nanocomposites were prepared via melt interaction of clay in a twin screw extruder. The evaluation of PP nanocomposites containing montmorillonite (OMMT) with or without iron nanoparticles modification was studied for food packaging applications. The nanocomposites were investigated by thermal, mechanical, morphological and gas barrier analyses. The X-ray diffraction patterns of all nanocomposites revealed an increment in d-spacing of the OMMT layers and proved the compatibility of neat PP and clay, along with the intercalation and partial exfoliation of the layers. Addition of nanoparticles had reverse effect on the intercalation and exfoliation of the clay to some extent. Transmitting optical and scanning electron microscopy revealed certain homogeneity with uniform distribution of OMMT and nano-particles in the PP matrix. According to the acquired thermal properties, a tendency for the melting temperatures increased with the clay concentration. Also, crystallization temperature and crystallinity decreased with the clay concentration; however, nanoparticles compensated the effect of clay. Despite of no significant change in the ultimate tensile strength and elongation properties were observed in nanocomposites, the yield strength presented a substantial enhancement and the rigidity as well. Melt flow index (MFI) examination revealed decreasing melt viscosity of nanocomposite through increasing OMMT and iron nanoparticles. Besides, OMMT showed a high capacity to improve oxygen and water vapor barrier properties of PP. The use of clay increased the mobility distance of the gas molecules, led to oxygen permeability of neat PP being reduced whereas nanoparticle acted as an active oxygen scavenger and was capable of intercepting and scavenging oxygen by undergoing a chemical reaction with. Migration test also showed no restrictions in the use of nanocomposite films in food packaging.     

Preparation and properties of polypropylene/clay nanocomposites for food packaging

Polypropylene (PP)/clay nanocomposites based on PP, organic clay (montmorillonite; MMT), and maleated polypropylene (MAPP) were prepared by melt compounding. The mechanical, thermal, morphological, and gas barrier properties of the resulting PP/clay nanocomposites were investigated at varying concentrations of the components for food packaging. The results revealed that the mechanical strengths, including tensile, flexural, and Izod impact strength, were increased for PP/clay nanocomposites compared to neat PP. The thermal properties showed a tendency for the melting and degradation temperatures to increase with the clay concentration. The effect of the compatibilizer was observed using scanning electron microscopy (SEM). The X-ray diffraction pattern of the nanocomposites revealed increased d-spacing of the MMT layers, indicating that the compatibility of neat PP and clay was improved by the addition of MAPP, and the intercalation and partial exfoliation of the layers. The use of clay increased the mobility distance of the gas molecules, leading to the oxygen permeability of neat PP being reduced by 26% to 55%.     

Structure and properties of nylon-6/amino acid modified nanoclay composite fibers

Biodegradable amino acid modified nanocaly was applied to produce nylon-6/nanoclay composite fibers using melt blending and melt spinning processes. Field emission scanning electron microscopy images showed that the surface of composite fibers was uniform and free from defects. Layer spacing of modified nanoclay was increased due to the penetration of polymer molecules into clay layers. Crystallinity, γ crystalline percentage and total molecular orientation of composite fibers were higher in comparison to neat nylon-6 fibers, as revealed by WAXD and birefringence measurements. Tensile strength of composite fibers was lower when compared to neat nylon-6 fibers. This may be attributed to some aggregation of nanoclay and its weakening effect. Melting and glass transition temperature of composite fiber was decreased due to the addition of modified nanoclay, indicating the formation of γ crystals and also breaking of some hydrogen bonds between the polymer molecules and the formation of new hydrogen bonds between the modified clay and the polymer molecules.     

Effect of clay content on the physical and antimicrobial properties of whey protein isolate/organo-clay composite films

Whey protein isolate (WPI)/Cloisite 30B organo-clay composite films with different amounts of the clay (0, 5, 10, and 20 g/100 g WPI) were prepared using a solution casting method and their properties were determined to assess the effects of clay content on film properties. The resulting films had an opaque appearance, which depended on the amount of clay added, and a similar gloss. However, the composite films were slightly less transparent compared to the transparent neat WPI films. Film properties, such as surface color and optical properties, varied depending on clay content. The haze index of the WPI/clay composite films as assessed by surface reflectance decreased indicating that the surface of the films was more smooth and homogeneous. The tensile and water vapor barrier properties of the composite films were also influenced by the amount of incorporated clay. In addition, WPI/Cloisite 30B composite films showed a beneficially bacteriostatic effect against Listeria monocytogenes.     

Effect of montmorillonite clay and biopolymer concentration on the physical and mechanical properties of alginate nanocomposite films

Alginate-based nanocomposites at different montmorillonite clay (MMT) loadings were produced by solvent casting method. The combined effect of biopolymer and MMT content on the mechanical and physical properties of the obtained nanocomposites was investigated. The MMT weight percent relative to alginate was varied from 1% to 5% and polymer concentration was 1 and 1.5% w/v. Films containing 5% (wt/wt) of MMT show, with respect to neat alginate, reduced water permeability of about 19% and 22% and an increased water solubility of about 36% and 40%, for 1% and 1.5% alginate films, respectively. The tensile strength of neat alginate films increased significantly with increasing alginate concentration (about 36%) but slightly increased with increasing clay content up to 3%. The values of elongation decreased with increasing the both of clay content and polymer concentration. Results on X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed well developed exfoliated nanocomposite films especially at low level of nanoclay addition.     

热处理温度对明胶-魔芋粉复合膜性质的影响

为考察热处理温度对明胶-魔芋粉复合膜理化性质的影响,测定和比较了复合膜的溶解性、接触角、微观结构和热稳定性等指标。结果发现,未经热处理的复合膜在30?℃温水中的膜溶解率（film solubility,FS）和蛋白溶解率（protein solubility,PS）分别为45.62%和28.83%,而在90?℃热水中分别为74.32%和71.44%。当复合膜经热处理后,膜的FS和PS随着热处理温度的升高逐渐下降。30?℃温水中溶出的α和β链蛋白条带浓度随热处理温度升高逐渐降低,而90?℃热水中溶出的蛋白受热处理温度影响不明显。复合膜明胶侧的接触角为107.14°,而魔芋粉侧的接触角为88.53°,经过热处理后均出现上升的趋势。伴随热处理温度的升高,膜的水蒸气透过率出现一定程度的下降,而b*值和透明度均出现上升的趋势。根据扫描电子显微镜分析和差示扫描量热法检测的结果,可以发现随热处理温度的升高,复合膜的明胶层和魔芋粉层逐渐融合在一起,而且膜的热稳定性逐渐上升。以上结果表明,提高热处理温度可以改善明胶-魔芋粉复合膜的耐水性、表面疏水性、阻水性和热稳定性。     

Green Nanocomposites from Renewable Resources: Effect of Plasticizer on the Structure and Material Properties of Clay‐filled Starch

Nanocomposites of starch were prepared via different addition sequences of plasticizer and clay by the solution method. The extent of dispersion of the filler was evaluated by wide angle X‐ray diffractometry (WAXD) in the resulting composites. Thermal stability, mechanical properties and water absorption studies were conducted to measure the material properties whereas FT‐IR spectroscopy was used to study the microdomain structure of composites. The sequence of addition of components (starch /plasticizer (glycerol) / clay) had a significant effect on the nature of composites formed and accordingly properties were altered. Glycerol and starch both have the tendency to penetrate into the silicate layers but penetration of glycerol is favored owing to its smaller molecule size. The filler dispersion becomes highly heterogeneous and the product becomes more brittle when starch was plasticized before filling with clay due to the formation of a bulky structure resulting from electrostatic attractions between starch and plasticizer. It was concluded that best mechanical properties can be obtained if plasticizer is added after mixing of clay in the starch matrix.     

Effect of randomly methylated beta-cyclodextrin on physical properties of soils

The application of cyclodextrins in several soil remediation technologies has been increasingly studied, but little is known about their effects on soil physical properties. One of the popular soil remediation additives, randomly methylated beta-cyclodextrin (RAMEB), was found to significantly alter surface and pore properties of soil clay minerals. Therefore, in this paper we studied the effect of various RAMEB doses on physical properties of selected soils, representing a wide range of clay content (3-49%). The results showed that soil physical properties were greatly modified by RAMEB treatment. Analysis of water vapor adsorption isotherms revealed that RAMEB increased water adsorption and surface area in sandy soils and decreased them in clayey soils. An increase in adsorption energy of water in RAMEB-treated soils indicated that desorption of nonpolar pollutants can be enhanced. Water vapor desorption isotherms showed that the volumes and radii of micropores (nanometers range) increased above 1% RAMEB concentration. The micropores became more rough and complex after RAMEB treatment as deduced from an increase in fractal dimensions. The volume of soil mesopores measured by mercury intrusion porosimetry (micrometers range) gradually decreased in most soils with an increase in RAMEB concentration whereas the average mesopore radius increased, indicating that finer mesopores were blocked by RAMEB. Measurements of the granulometric composition of soils by sedimentation analysis showed that the amount of coarse-size soil fractions increased on the expense of finer fractions due to aggregation of smaller particles. Behavior of the studied soils after RAMEB treatment depended on their clay content and the dose of cyclodextrin. In clay-rich soils, strong interactions of cyclodextrins with the soil solid phase governed the resulting soil properties. In clay-poor soils, the cyclodextrin excess (not interacted with clays) played a dominant role. Modification of surface, pore, and aggregation properties of soils by RAMEB can have a significant effect in soil remediation technologies.