PLA针织产品的应用前景

1前言PLA纤维是目前独一无二的由熔纺工艺和从天然糖类植物中制得的纤维。作为一种纤维, PLA纤维兼有天然纤维(如羊毛、棉花和丝绸等)以及常规合成纤维最希望具有的物理特性,PLA的性能使其成为合成纤维和天然纤维间的“天然桥梁”。2 PLA 纤维产品性能特点PLA纤维的优异性能包括:可生物降解性、优异的触感、导湿性、回弹性、耐燃性和UV稳定性以及抗污性等。PLA纤维与聚酯、棉纤维性能的比较如表1所示。PLA纤维的性能特点分述如下。2.1PLA的可生物降解性能PLA纤维制品废弃后,在一定条件下可降解成二氧化碳和水,并且即使燃烧,燃烧…     

绿色环保纤维——聚乳酸纤维

叙述了聚乳酸(PLA)及其纤维的发展史、国内外生产现状,介绍了聚乳酸(PLA)纤维的原料———PLA聚合物的制备技术:丙交酯开环聚合法、直接聚合法及共同聚合法;以及聚乳酸(PLA)纤维的纺丝生产技术:溶液纺丝法与熔融纺丝法。同时对聚乳酸(PLA)纤维的物理性能、可生物降解性、安全性、耐气候性及其主要用途进行了叙述。     

PLA纤维及其制品的应用特性分析

PLA纤维是一种性能优异的聚酯纤维。本文综合分析了PLA纤维的生物降解性和可循环性、无毒性、低温染色性、回弹性和抗皱性、阻燃性、耐紫外线性,阐述了生产中应注意的问题,并对PLA纤维的应用前景作了论述。     

PLA纤维的特性分析及应用前景

文章综合分析了PLA纤维的生物降解性和可循环性、无毒性、低温染色性、回弹性和抗皱性、阻燃性、耐紫外线性，说明PLA纤维是一种性能优异的聚酯纤维，具有广阔的应用前景。     

PLA长丝的基本结构与物理性能

聚乳酸(PLA)纤维是一种可降解的生物质合成纤维。本文测定与分析了PLA长丝纤维的化学组成、结晶度和形态结构,并研究了PLA长丝的吸湿性、拉伸力学性能和热收缩性能。研究结果表明,PLA纤维具有明显的酯键结构,结晶度约为23.87%,纤维横截面近似圆形,纵向较为平直光滑,回潮率(0.79%)低,长丝的力学性能较佳,弹性回复性好,但是热收缩率大。     

湿处理条件下聚乳酸纤维的强度损伤特性

研究了温度为30~90℃、pH值在3.85~11.8的条件下聚乳酸(PLA)纤维的强度损伤特性。结果表明,微酸性虽然是对PLA纤维强度损伤较小的条件,但随着处理时间的延长和处理温度的升高,同样会对PLA纤维产生非常明显的强度损伤。在碱性条件下,随着pH值的升高、温度的增加和处理时间的延长,PLA纤维的强度损伤都将明显增加。     

蔗渣纤维增强聚乳酸复合材料的制备及性能分析

以造纸用蔗渣纤维和聚乳酸(PLA)为主要原料,制备了蔗渣纤维增强聚乳酸复合材料,研究了NaOH(蔗渣纤维处理剂)的质量分数、复合材料中蔗渣纤维添加量及热压温度对复合材料力学性能的影响。结果表明,蔗渣纤维添加量为30%时,蔗渣纤维与PLA混合较好,复合材料较均匀;采用质量分数为5%的NaOH处理蔗渣纤维,可以溶解蔗渣纤维中的半纤维素、果胶等,使纤维更细化,比表面积增大,从而有效改善复合材料力学性能;热压温度为170℃时,PLA的流动性有助于改善蔗渣纤维在PLA中分散的均匀性,且不会使蔗渣纤维和PLA降解。在此最优条件下,复合材料的拉伸强度和冲击强度分别达到最大值。     

PLA纤维载体染色工艺

为了解决PLA纤维染深性差的问题,选取肉桂酸甲酯为载体,分析染色工艺对C.I.分散红73上染PLA纤维的影响,并测试了载体染色对PLA纤维基本性能的影响.结果表明,在染色pH为4.8,染色温度为100℃,载体用量为3 g/L时,得色量较高;载体染色PLA纤维的耐日晒、耐汗渍、耐皂洗色牢度均能达到3～4级或以上;载体染色...     

聚乳酸/聚(3-羟基丁酸酯-co-3-羟基戊酸酯)共混纤维的结构及其织物染色性能

聚乳酸(PLA)与聚(3-羟基丁酸酯-co-3-羟基戊酸酯)(PHBV)共混纺丝是改善聚乳酸(PLA)纤维的耐热性和柔韧性的方法之一。为了揭示共混纤维结构对其织物染色性能的影响规律,借助热重分析仪、差示扫描量热仪、X射线衍射仪等手段分别对共混纤维和PLA纤维的微结构和热性能进行分析。采用高、中、低温3类分散染料,对2类纤维织物的染色升温速率曲线、提升性和各项染色牢度等性能进行了比较。结果表明：共混纤维中PLA与PHBV两相分离,PLA相具有与PLA纤维相似的晶型结构,其结晶度较高,而PHBV相中形成较低的结晶;与PLA纤维相比,共混纤维的熔点较高,玻璃化温度稍低,因此其能在较低的温度下达到上染平衡;在相同的染色条件下,共混纤维织物的表观染色深度几乎是PLA织物的2倍;2类纤维织物的耐皂洗色牢度性能均不够理想。     

不同整理条件对PLA纤维拒水拒油性能的影响

采用不同条件对PLA纤维进行整理,测试了PLA纤维的拒水拒油性能。结果表明,整理条件对纤维的力学性能、黏均分子质量和耐水洗性都有影响。当整理剂质量浓度为50g/L,150℃焙烘3 min后,PLA纤维拒水拒油性能良好,纤维强度保持率为86.84%,黏均分子质量保持率为88.6%。     

Encapsulation of food ingredients

Microencapsulation is a relatively new technology that is used for protection, stabilization, and slow release of food ingredients. The encapsulating or wall materials used generally consist of starch, starch derivatives, proteins, gums, lipids, or any combination of them. Methods of encapsulation of food ingredients include spraydrying, freeze‐drying, fluidized bed‐coating, extrusion, cocrystallization, molecular inclusion, and coacervation. This paper reviews techniques for preparation of microencapsulated food ingredients and choices of coating material. Characterization of microcapsules, mechanisms of controlled release, and efficiency of protection/ stabilization of encapsulated food ingredients are also presented.     

蒽醌助剂对乙二醇溶剂脱胶苎麻纤维性能的影响

为解决苎麻在乙二醇有机溶剂脱胶中纤维易被氧化而导致性能下降的问题,在乙二醇溶剂中添加助剂蒽醌对苎麻进行脱胶,并对蒽醌不同添加量下制得的纤维进行结构和性能表征。结果表明:纤维中半纤维素含量随蒽醌添加量的增加而升高,纤维的聚合度、结晶度、物理力学性能先升高后降低,纤维的残胶率和线密度先降低后升高;当蒽醌质量分数为0.3% 时,这些性能均达到最佳值,此时纤维的聚合度、结晶度、制成率、断裂强度、断裂伸长率、断裂功比不加蒽醌时分别提高了7.32%、20.53%、1.46%、9.55%、6.89%、33.33%,纤维的残胶率、线密度比不加蒽醌时分别降低了17.91%、7.24%。     

Evaluation of mycotoxin-contaminated cereals for their use in animal feeds in Hungary

In the period between December 5, 1991 and September 17, 1998, 760 maize, 367 wheat, 119 soybean, 222 barley, 85 bran, 32 triticale, 60 oat, 14 rye and 22 sunflower samples were investigated for the presence and concentration of seven fusariotoxins (T-2 toxin, zearalenone, deoxynivalenol, nivalenol, diacetoxyscirpenol, HT-2 toxin, fusarenone-X) and OTA. The comparison of analytical data with those of the relevant literature revealed that although the incidence rate and/ or concentration of Fusarium mycotoxins and OTA in Hungarian-grown cereals is occasionally considerable, the position of the country is not worse than the average of countries. Our findings indicate that soybean tends to be good substrate for trichothecene-producing fungi and the rate of contamination is regarded as substantial. The commodities were assorted into one of three quality categories. The proportion of objectionable samples was only 3.0, 2.2, 2.3 and 1.7% in maize, wheat, barley and soybean samples, respectively. However, this low rate of objection might still be a source of great economic loss. The proportion of objectionable samples was much higher in the case of bran, oat and triticale (7.1, 6.7, and 6.3%, respectively). The results of the present investigation indicate a need for regular screening for mycotoxins of importance and individual appraisal of each commodity from the point of their use in animal feeds.     

丹蒽醌对氧化脱胶苎麻纤维理化性能的调控

为解决苎麻氧化脱胶中纤维容易被过度氧化而性能受损的问题,在氧化脱胶液中添加了具有纤维素和半纤维素保护效果的试剂 1,8-二羟基蒽醌（丹蒽醌）,并通过调节1,8-二羟基蒽醌的用量实现了对苎麻纤维理化性能（强伸性能、聚合度、半纤维素含量、制成率等）的调控。结果表明,1,8-二羟基蒽醌用量越高,纤维中半纤维素含量、制成率越高;但纤维强伸性能随1,8-二羟基蒽醌含量先升高后降低;当1,8-二羟基蒽醌的用量为2 %时,脱胶的综合效果最佳,此时纤维的断裂功、聚合度、半纤维素含量、制成率比不使用1,8-二羟基蒽醌时分别提高了41.0%、2.0%、17.3%、7.0%;此外,使用1,8-二羟基蒽醌后,脱胶废水的COD值降低了40%,大幅度提高了氧化脱胶工艺的环保性。     

蛤蜊中金属营养元素的影响因素及来源

探讨产地、季节、品种对蛤蜊中金属营养元素含量的影响,解析蛤蜊中金属营养元素含量与养殖地淤泥和海水中相关元素含量间的关系。于2014年5月和9月在青岛市、南通市和大连市海岸采集花蛤、文蛤及养殖地淤泥和海水样品,测定样品中金属营养元素含量,分别进行方差分析和Pearson相关分析。结果显示,蛤蜊中Mg、K、Ca、Mn、Fe、Cu、Zn含量受产地的影响,Ca、Cu、Zn含量受季节的影响,Mg、Ca、Mn、Fe、Cu、Zn含量与品种有关;Na、Mg、Ca、Co、Cu含量与淤泥中相关元素的含量密切相关,而10 种金属营养元素含量与海水中相关元素含量相关性均不显著。本研究表明,蛤蜊中金属营养元素含量受产地、季节、品种的影响,其来源除淤泥、海水外,还有其他途径。     

Daily intake of trace metals through coffee consumption in India

The trace element contents of five varieties of instant coffee powder available in the Indian market have been analysed. Ca, Cr, Fe, K, Mg, Mn, Ni, Sr, Zn and Pb, Cd, Cu have been determined using atomic absorption spectrophotometry and differential pulse anodic stripping voltammetry, respectively. The metal levels in the coffee powders observed in this study are comparable with those reported for green coffee beans (Arabica and Robusta variety) reported worldwide with the exception of Sr and Zn, which were on the lower side of the reported values. Concentrations of these metals have been converted into intake figures based on coffee consumption. The daily intakes of the above metals through ingestion of coffee are 1.4mg, 1.58 mu g, 124 mu g, 41.5mg, 4.9mg, 17.9 mu g, 2.9 mu g, 3.8 mu g, 12.5 mu g, 0.2 mu g, 0.03 mu g and 15.5 mu g, respectively. The values, which were compared with the total dietary intake of metals through ingestion by the Mumbai population, indicate that the contribution from coffee is less than or around 1% for most of the elements except for Cr and Ni which are around 3% .     

Effects of process parameters on quality changes of shrimp during drying in a jet-spouted bed dryer

ABSTRACT:  The objective of the present study was to investigate the effects of various parameters, that is, concentration of salt solution (2%, 3%, 4%[w/v]), boiling time (3, 5, 7 min), drying air temperature (80, 100, 120 °C), and size of shrimp, on the kinetics of drying and various quality attributes of shrimp, namely, shrinkage, rehydration ability, texture, colors, and microstructure, during drying in a jet-spouted bed dryer. In addition, the effects of these processing parameters on the sensory attributes of dried shrimp were also investigated. Small shrimp (350 to 360 shrimp/kg) and large shrimp (150 to 160 shrimp/kg) were boiled and then dried until their moisture content was around 25% (d.b.). It was found that the degree of color changes, toughness, and shrinkage of shrimp increased while the rehydration ability decreased with an increase in the concentration of salt solution and boiling time. Size of shrimp and drying temperature significantly affected all quality attributes of dried shrimp. The conditions that gave the highest hedonic scores of sensory evaluation for small dried shrimp are the concentration of salt solution of 2% (w/v), boiling time of 7 min, and drying air temperature of 120 °C. On the other hand, the conditions that gave the highest hedonic scores of sensory evaluation for large dried shrimp are the concentration of salt solution of 4% (w/v), boiling time of 7 min, and drying air temperature of 100 °C. The quality attributes of dried shrimp measured by instruments correlated well with the sensory attributes, especially the color of dried shrimp.     

Soy Bioactive Components in Functional Perspective: A Review

Functional foods are the focus of attraction for well-being. The healthy living of Asians may be attributed to a diet enriched with soy isoflavones viz. genistein and daidzein which fills the gap of proteinaceous diet in vegetarians. Several factors, such as administration, dosage, metabolism, ingestion of other pharmacological substances, type of estrogen receptors, and presence or absence of endogenous estrogen, affect the activities and bioavailability of isoflavones. The mode of therapeutic action could be either through the stimulation of estrogen receptors or by the non-involvement of estrogen receptors. Soy, due to its isoflavones content, serves as a balanced and remedial substitute in combating various lifestyle disorders, like cancer prevention, by interruption of the breakdown of extracellular matrix that surrounds growing vessels and tumors, lowering of lipid and blood insulin levels by regulating lipid and glucose metabolism, alleviation of menopausal symptoms, and osteoprotective effects by modulating estrogen receptors, thus acting as a safer switch to hormone replacement therapy, anti-hypertensive effect which may also contribute to cardioprotective, anti-oxidative effect, regulation of cognitive functions, and many others. Therefore, it could be regarded as a valuable therapeutics. However, since soy isoflavones also act as endocrine disruptors, they also possess some negative effects. Concerns have been raised in relation to thyroid function abnormality. In view of the previously mentioned facts an attempt has been made to review the literature available on both beneficial as well as deleterious role of isoflavones, soy derived bioactive compounds.     

Avena sativa (Oat), A Potential Neutraceutical and Therapeutic Agent: An Overview

The aim of the present review article is to summarize the available information related to the availability, production, chemical composition, pharmacological activity, and traditional uses of Avena sativa to highlight its potential to contribute to human health. Oats are now cultivated worldwide and form an important dietary staple for the people in number of countries. Several varieties of oats are available. It is a rich source of protein, contains a number of important minerals, lipids, β-glucan, a mixed-linkage polysaccharide, which forms an important part of oat dietary fiber, and also contains various other phytoconstituents like avenanthramides, an indole alkaloid-gramine, flavonoids, flavonolignans, triterpenoid saponins, sterols, and tocols. Traditionally oats have been in use since long and are considered as stimulant, antispasmodic, antitumor, diuretic, and neurotonic. Oat possesses different pharmacological activities like antioxidant, anti-inflammatory, wound healing, immunomodulatory, antidiabetic, anticholesterolaemic, etc. A wide spectrum of biological activities indicates that oat is a potential therapeutic agent.     

Textural Modification of Processing Tomatoes

Knowledge of the textural properties of processing tomatoes is crucial to ensuing product acceptability; measurement, control, and optimization of these properties through judicious selection of varieties and control of unit operations results in products that the consumer prefers. It is important to first define the terms texture, rheology, consistency, and viscosity prior to discussing principles of their measurement. The textural properties of processing tomatoes may be measured using both sensory and objective tests, and the latter may be either destructive or nondestructive in nature. The unique anatomy of tomato fruit (peel, pericarp, columella, and locules) in part dictates the method of texture measurement. Numerous factors, including variety, maturity, genetic modification, cultural particles, and environmental conditions, processing conditions, and calcium addition affect the textural integrity of tomatoes. Textural properties of raw tomatoes and most processed tomato products are reviewed in this article.