TOCNs、聚丙烯酰胺对羧甲基纤维素钠膜性能的影响

为改善羧甲基纤维素钠（sodium carboxymethyl cellulose,CMC）薄膜的机械性能,利用2,2,6,6-四甲基哌啶氮氧化物氧化法制备的纳米纤维素纤丝（2,2,6,6-tetramethyl-1-piperidinyloxy-oxidized cellulose nanofibrils,TOCNs）增强CMC膜的拉伸强度,利用阳离子聚丙烯酰胺（cationic polyacrylamide,CPAM）在水溶液中电解形成的阳离子与其他两者在水中形成的COO－之间的静电作用及化学反应增强其断裂伸长率,从而制备强度及韧性两者兼优的生物可降解薄膜。研究发现,按照m（CMC）∶m（TOCNs）∶m（CPAM）为50∶10∶1配比制备的复合膜较纯CMC膜拉伸强度增加约177%,断裂伸长率增加约36%,透光率、热稳定性均有提高,但阻氧性略有下降,结果表明,TOCNs的添加能明显提高CMC膜的拉伸强度、热稳定性,CPAM的加入能提高CMC膜的断裂伸长率和透光性,三者之间存在着相互作用和良好的相容性,三者共混能明显改善CMC膜的性能。     

Alkali treatment on nettle fibers

This work deals with alkali treatment on nettle fibers. The first part of this work examines structure and properties of alkali-treated nettle fibers, while the second part reports on optimization of alkali treatment to improve tensile properties of nettle fibers. In this part, the alkali-treated nettle fibers were examined for their chemical, structural, physical, and mechanical characteristics and compared to untreated fibers. The alkali treatment appeared to remove lignin from the fiber, thereby resulting in increase in its crystallinity, improvement in its appearance, and decrease in its width and linear density. The untreated fiber was quite strong but less flexible and less extensible. A mild alkali treatment resulted in increase in tensile strength and elongation at break, without much changing initial modulus. On the other hand, a severe alkali treatment resulted in reduction in fiber strength as well as initial modulus without much change in elongation at break.     

Effect of Chemical Treatment on the Tensile Strength Behavior of Coir Geotextiles

ABSTRACT

The present study investigates the effects of chemical treatment on the tensile strength behavior of the two woven and two nonwoven coir geotextiles. The results reveal that tensile elongation at failure for the untreated and treated woven and nonwoven coir geotextiles was higher in the warp direction in comparison to the weft direction. The tensile elongation at failure for the untreated and treated woven coir geotextiles were influenced by the stiffness and the opening of kinks in the coir yarn whereas the tensile elongation at failure of the untreated/treated nonwoven coir geotextiles was influenced by the presence of the polyethylene (PE) yarn used in stitching along with PE netting and diameter of the yarn used in PE netting. The chemical treatment decreased and increased the tensile strength of both the woven and nonwoven coir geotextiles, respectively. The mass per unit area of woven coir geotextile decreased whereas it increased for both the nonwoven coir geotextiles after the chemical treatment. The chemical treatment modifies the surface characteristics of both the untreated woven and nonwoven coir geotextiles due the removal of impurities and filling up the voids present on the surface.     

竹浆纤维含量及纬密对棉/竹浆纤维交织物力学性能的影响

对15种不同规格的棉与棉/竹浆纤维交织物面料的拉伸断裂强度、断裂伸长率、撕破强度、磨损牢度等力学性能进行测试比较,研究竹浆纤维含量及纬密对其力学性能的影响。结果表明：随着竹浆纤维含量增加,织物的经纬向拉伸断裂强力之和下降,纬向断裂伸长率上升,经向断裂伸长率先上升而后下降再上升;纬向撕破强力先下降而后上升,经向撕破强力变化不大;织物的质量减少率快速增加,织物磨损牢度变差,竹浆纤维含量为30%时,织物的磨损牢度最好;竹浆纤维含量达到70%时,交织物的断裂伸长率、撕破强力、摩损牢度均为最低,在实际生产应用中应尽量避免选用。当经密保持不变,纬密增加时,织物的断裂强力增加,断裂伸长率逐渐增大,撕破强力减小,耐磨性能提高。     

微晶纤维素的醚化改性及其在淀粉膜中的应用

为改善微晶纤维素（microcrystalline cellulose,MCC）在淀粉膜中的分散性,通过对MCC进行阳离子醚化改性,制得改性微晶纤维素（modified-microcrystalline cellulose,MD-MCC）,并对其化学结构、结晶性、热稳定性和微观形貌进行表征。采用溶液流延法制得淀粉-微晶纤维素复合膜（淀粉-MCC,淀粉-MD-MCC）,分别研究MCC和MD-MCC添加量对淀粉膜结构和性能的影响。结果表明,与MCC相比,MD-MCC的基本化学结构未改变,仍然保持纤维素的基本结构,但其结晶度和热稳定性略有降低,表面呈多孔结构。随着MCC和MD-MCC添加量的增加,淀粉膜的表面粗糙度增大,透光率和断裂伸长率降低,水接触角、水分含量和厚度增大,抗拉强度和水蒸气渗透系数先增加后减小。MD-MCC在淀粉膜中的分散性优于MCC,淀粉-MD-MCC复合膜的力学性能和阻水性能优于淀粉-MCC复合膜,其中MD-MCC添加量为5%时,复合膜具有最大的抗拉强度和阻水性能。     

艾草改性竹浆纤维的形态结构及其性能研究

采用不同浓度的H2SO4和Na OH溶液对艾草改性竹浆纤维和竹浆纤维进行处理,研究酸、碱处理对纤维的回潮率和拉伸性能的影响。结果表明:艾草改性竹浆纤维的回潮率大于竹浆纤维,但其断裂强度和断裂伸长率均小于竹浆纤维;2种纤维的回潮率均随H2SO4体积分数的增加而增大,而随Na OH体积分数的增加而减小;断裂强度和断裂伸长率均随H2SO4和Na OH体积分数增加而呈现下降趋势;回潮率和断裂强度受Na OH体积分数的影响较大,耐碱性较差,因此2种纤维应当尽量避免碱处理。     

Coir Fiber–Process and Opportunities

Abstract

Growing environmental awareness throughout the world has triggered a paradigm shift towards designing materials compatible with the environment. Coira lignocelluosic natural fiberhas emerging importance as an engineering material due to its high tensile strength and elongation properties. The advantages of natural lignocellulosic fibers include acceptable specific strength properties, low cost, low density and biodegradability. This work is intended to present an overview of the main results presented in literature on this topic, focusing the attention on the fiber properties in terms of physical and chemical structure. Some aspects related to the traditional uses of coir fibers are also presented. Coir, as an ecofriendly fiber, has tremendous potential in India as well as the rest of the World for mattresses, fabric and other novel applications. Research and development efforts have been underway to find new use areas for coir.     

Effects of Coir Fiber and Maleic Anhydride Modification on the Properties of Thermoplastic Starch/PLA Composite Laminates

Coir fiber reinforced composite laminates made of poly(lactic acid) (PLA) with a thermoplastic starch (TPS) were fabricated. Modified thermoplastic starch (MTPS) was prepared by reactive blending of TPS with maleic anhydride (MA). The effect of coir fibers was of our main interest. The tensile properties, water absorption, and morphological properties of the fabricated composite laminates were investigated. The composite laminates between PLA and starch TPS were prepared using coir fiber as reinforcing core, and the physical, mechanical, and morphological properties were studied. The results suggested that the optimum fiber contents for maximum tensile strength for TPS/PLA and MTPS/PLA composites were 20 and 30 wt%, respectively. Using MA for chemical modification of TPS for PLA composites could reduce the PLA content of about 10 wt%, and improve the tensile about 20%. The volume swelling for the MTPS/PLA composites was much lower than that for the TPS/PLA composites, and the swelling reduced with increasing coir fiber content. Based on compressive strength, the pallets produced using MTPS/PLA composites showed a high potential to replace the commercial urea-formaldehyde/PLA composites. It clearly appeared that MA modification to TPS not only improve the mechanical properties of fiber reinforced PLA composites, but also made the PLA composites bio-degrade more quickly.     

明胶-聚乙烯醇-羧甲基纤维素三元复合肥料缓释膜及其性能研究

以明胶、羧甲基纤维素、聚乙烯醇为原料,通过戊二醛交联和溶液共混制备了缓释肥料包膜,采用红外光谱(FT-IR)、X-射线衍射、扫描电镜、透光率测试等,测试了包膜的抗张强度、断裂伸长率、耐水性,并考察了原料明胶、羧甲基纤维素、PVA含量和交联剂戊二醛、增塑剂甘油用量对力学性能和吸水率的影响,同时对包膜进行了差示量热扫描和热重分析。结果表明该条件下原料之间具有较强的相互作用,形成了一个较稳定的复合体,包膜具有良好的力学性能和热稳定性,在农业领域有潜在利用价值。     

麦麸纤维/小麦麸质蛋白复合膜碱性乙醇成膜体系影响因素研究

将小麦麸质蛋白(wheat gluten,WG)和麦麸纤维(wheat-bran cellulose,WC)通过溶液共混于碱性乙醇系统,采用流延成膜法制备复合膜。探讨成膜体系中料液比、麦麸纤维含量、甘油添加量、乙醇浓度、体系pH值及黄原胶添加量对复合膜物理性能抗拉强度(tensile strength,TS)、断裂伸长率(elongation at break,EAB)、水蒸气透过系数(water vapor permeability,WVP)、水溶性和透光性等的影响。结果表明:添加麦麸纤维能明显增强小麦麸质蛋白膜的抗拉强度,降低其水蒸气透过系数和水溶性,抗拉强度最高为20.44 MPa,比纯小麦麸质蛋白膜(TS=8.65 MPa)提高了140%;成膜体系各因素对复合膜各物理性能都存在不同程度的影响,其中甘油添加量影响最大,其次为麦麸纤维含量,黄原胶添加量影响最小。该研究可为进一步制备性能优异的小麦麸质蛋白复合膜提供技术参考。     

戊二醛添加顺序对胶原蛋白肠衣膜品质的影响

为了缩减胶原蛋白肠衣膜的制备工序，提高食品行业包装材料的质量，考察了戊二醛的添加顺序对胶原蛋白肠衣膜品质的影响。分别通过制胶时、成胶后以及成膜后3种添加方式，以抗拉强度、断裂延伸率、热收缩率、溶胀率、色泽及变性温度等为指标进行了研究。结果表明：在任一添加方式下，戊二醛都可促进胶原蛋白肠衣膜机械性能和表面疏水性的提高，导致溶胀率和热收缩率的下降；其中，通过FTIR和DSC分析表明，采用成膜后浸入戊二醛方式交联获得的肠衣膜交联效率最高，热稳定性最高，且对肠衣膜性能的提升最为显著；进一步，随着戊二醛添加量的提高，肠衣膜的色泽逐渐变黄，而当添加量超过100 mg/L时，戊二醛交联对肠衣膜品质并无进一步显著提升作用。     

Effects of drawing process on crimp formation-ability of side-by-side bicomponent filament yarns produced from recycled,fiber-grade and bottle-grade PET

In this study, side-by-side bicomponent filaments from recycled poly(ethylene) terephthalate (R-PET) from post-consumer bottles, fiber-grade PET (FG-PET) and bottle-grade PET (BG-PET) successfully were extruded. The bicomponent fibers in the forms of FG/R, BG/R and FG/BG were produced in a spinning machine and drawn by a thermal drawing process to improve their mechanical properties using draw ratios between ‘2.5 and 2.8’. The effects of conditions on the fiber structure, physical properties and crimp formation of resultant fibers were evaluated. The birefringence, shrinkage and mechanical properties, such as tensile strength and tensile modulus, increased and elongation at break decreased for the drawn fibers, and this was attributed to the fiber orientation. Distinct crimp formation was observed from drawn bicomponent fibers after thermal treatment. There were significant birefringence and shrinkage difference between two components in drawn bicomponent fibers caused to severe crimp formation.     

环境条件对大豆生物解离纤维素可食性膜性能的影响

以大豆生物解离纤维素为基料,辅以柠檬酸及丙三醇制备可食性膜,探究环境条件对大豆生物解离纤维素可食性膜性能的影响。结果表明:随着环境温度的升高,可食性膜的拉伸强度、断裂伸长率、溶水时间逐渐增加,但是环境温度对可食性膜的水蒸气透过率和色泽影响较小;随着环境相对湿度的增加,可食性膜的拉伸强度逐渐降低,断裂伸长率、水蒸气透过率、溶水时间增加,色泽无明显变化,亮度略微增加;随着储藏期的延长,拉伸强度、溶水时间增加,断裂伸长率、水蒸气透过率逐渐降低,可食性膜整体变黄。     

Gelatin–pectin composite films from polyion-complex hydrogels

Preparation and properties of composite films from gelatin and low-methoxyl pectin from simultaneous reversible and permanent polyion-complex hydrogels are presented. Ionic interactions between positively charged gelatin and negatively charged pectin produce reversible physical hydrogels with homogeneous molecular arrangement that improve both mechanical and water resistance but do not alter thermal stability relative to single polymer gels. Subsequent addition of 0.3 weight percent (wt.%) glutaraldehyde crosslinks gelatin heterogeneously, due to the presence of domains with non-uniform crosslinking, as revealed by the structural analysis. Resulting interspersed permanent chemical hydrogel showed a decreased swelling attitude by nearly 10 fold relative to films from gelatin alone and further improved mechanical performance (tensile strength and elongation at break). Results demonstrate that simultaneously exploiting the specific reactivity provided by the functional groups of both biopolymers can be used to create unique new structures with improved properties and offer potential for tailoring these to a wide range of targeted applications.     

改性纳米TiO2对纤维素包装膜性能及结构的影响

本文利用氯化锂/N,N-二甲基乙酰胺(LiCl/DMAc)溶解纤维素,并与改性、未改性的纳米TiO2进行共混,采用溶胶-凝胶法制备可降解纤维素包装膜.通过红外光谱对改性前后纳米材料的结构进行表征,测试纤维素包装膜的拉伸强度及断裂伸长率,并进行热失重分析;使用扫描电镜和原子力显微镜观察其表面结构.结果表明:改性纳米TiO2比未改性纳米材料在纤维素膜中的分散更均匀,当改性纳米TiO2与纤维素混合比例为0.5∶100时,纤维素包装膜的拉伸强度和断裂伸长率分别为25.6MPa和125％,较加入未改性纳米TiO2的纤维素膜拉伸强度提高了1.45倍,断裂伸长率是原来的1.35倍.     

脱乙酰改性对魔芋葡甘聚糖/黑米膳食纤维复合膜特性的影响

目的 对比脱乙酰魔芋葡甘聚糖/黑米膳食纤维复合膜与魔芋葡甘聚糖/黑米膳食纤维复合膜, 探究脱乙酰对魔芋葡甘聚糖复合膜的影响。方法 以魔芋葡甘聚糖为原料, 对魔芋葡甘聚糖进行脱乙酰改性, 再与黑米膳食纤维、甘油、蛭石共混, 采用流延法制备两种复合膜, 以复合膜拉伸强度、断裂伸长率、水蒸气透过率、溶水率为考察因素, 确定最优配方, 并通过傅里叶变换红外光谱和扫描电镜进行表征。结果 。脱乙酰改性使复合膜抗拉强度提高12%、断裂伸长率降低17%、溶水率降低12%、水蒸气透过系数降低41%, 红外光谱与扫描电镜结果表明脱乙酰魔芋葡甘聚糖黑米膳食纤维复合膜具有更高的稳定性。结论 脱乙酰改性处理改善了复合膜微观结构, 提高了复合膜的物理性能。脱乙酰魔芋葡甘聚糖/黑米膳食纤维复合膜制备以期为新型复合膜的开发提供理论参考, 并为魔芋葡甘聚糖与黑米膳食纤维的开发利用提供参考。     

Evaluation of Structural,Tensile and Thermal Properties of Banana Fibers

Recognizing the importance of properties of the plant fibers for their use in polymeric composites and nonavailability of data on tensile, thermal, and other properties of banana fibers of Karnataka (India), a study was undertaken with the objective of determining some of these properties. This article presents determination of structural aspects of the fibers by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques; obtaining stress-strain curves and tensile properties by tensile testing; finally, thermal properties by differential scanning calorimetry and thermogravimetric analysis. FTIR spectrum of banana fibers showed aromatic character, while XRD results indicated the fiber to have mainly the cellulose I structure and crystallinity index of 52%. Thermal-degradation details of fiber samples were revealed by thermal studies. Stress-strain curves of banana fibers suggested their brittle nature with moderate values of tensile strength, but low percentage elongation. Weibull analysis of obtained tensile strength values revealed variation of “characteristic strength” values from 3800 MPa at 99% reliability to 22,700 MPa with 0.01% reliability. Morphology studies revealed the number of defects along the length of the fiber, while fractured surface exhibited flat surface with intracellular fractures clearly indicating brittle nature of the fiber.     

Micron- and nano-cellulose fiber regenerated from ionic liquids

In this research, two types of ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl) and ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIMAc), were used as recyclable solvents for dissolving raw cellulose in the spinning of micron- and nano-scale regenerated cellulose fiber. The approach for preparing the cellulose solution using these ionic liquids is described. A comparative study was also conducted on cellulose solubility, the spinning method, and cellulose fiber properties produced with each solvent. The experimental fibers are characterized in terms of fiber diameter, strength, thermal property, crystallinity, and content of solvent residual, using tensile test, thermogravimetric analysis, scanning electron microscopy, X-ray diffraction, and mass spectrometry. The study concluded that there was a significant difference in the tensile strength, but not in the elongation and modulus of the fibers regenerated from BMIMCl and EMIMAc. For crystal size, crystal orientation, and crystallinaty index, the BMIMCl-generated fiber had higher values than the EMIMAc-regenerated fiber. For the thermal property, EMIMAc fiber was more stable at higher temperatures than BMIMCl fiber. It was also revealed that the EMIMAc fiber had significantly less solvent residual content than the BMIMCl fiber.     

EVALUATION OF CERTAIN PHYSICAL PROPERTIES OF MEAT USING A UNIVERSAL TESTING MACHINE

ABSTRACT— The Instron tester served to evaluate physical properties of uncooked rabbit and beef muscle including work of rupture, breaking strength, break elongation elasticity and stress relaxation. These methods measure variations in muscle type, aging and post-mortem treatments comparably with shearing instruments. Shank showed higher tensile properties than tenderloin, less elasticity and lost more applied stress. With rabbit, the breaking force of longissimus dorsi unrestrained during rigor was .237 Ib/g ± 7.5% for samples 5.0 cm by 0.2–0.5 cm² while restrained muscle gave .168 ± 9.9% and also exhibited higher elasticity and break elongation. Post-mortem aging decreased tensile properties and elasticity. Psoas muscle, characterized by more coextensive fibers, had higher tensile properties than longissimus dorsi.     

Preparation and Properties of Cellulose/Tamarind Nut Powder Green Composites

Using biopolymer cellulose as the matrix and tamarind nut powder (TNP) obtained from agricultural waste of tamarind nuts as the filler, the green composites were made. Cellulose was dissolved in environmental friendly solvent of aq. 8 wt. % Lithium hydroxide and 15 wt. % urea which was precooled to ?12 ° C. To the cellulose solutions, TNP was added in 5 wt. % to 25 wt. % of cellulose separately. Each solution was evenly spread on glass plates and the wet composites were prepared by regeneration method using ethyl alcohol coagulation bath. The wet films were dried in air at room temperature. The dried composite films were characterized by FTIR spectroscopy, X-ray diffraction, thermogravimetric analysis and also tested for their tensile properties. The tensile strength and the % elongation at break of the composites were higher than those of the matrix and increased with TNP content. While the matrix had a tensile strength of 111.8 MPa, the cellulose/TNP composite loaded with 25 wt.% TNP possessed a tensile strength of 125.4 MPa (12% increase). Though the thermal stability of the composites was lower than cellulose matrix, all the composites were stable up to a temperature of 350 °C.