UHMWPE复合纱的纺制及性能测试

UHMWPE纤维具有较高的比强度和比模量,但纤维吸湿性差。文章以黏胶短纤维为外包纤维,UHMWPE短纤纱(14.75 tex)及长丝(16.67 tex)为芯丝分别纺制34 tex包芯纱。以黏胶短纤维为中间纤维,UHMWPE短纤纱(14.75 tex)及长丝(16.67 tex)为包缠纤维分别纺制34 tex赛络菲尔纱。通过改变UHMWPE短纤纱或长丝与须条的间距优化赛络菲尔纱的性能,并对成纱性能进行测试和对比分析。结果表明:相同线密度纱线,以UHMWPE长丝为芯丝或包缠纤维所纺的包芯纱和赛络菲尔纱除断裂伸长率外,在强度、条干及毛羽方面均优于以UHMWPE短纤纱为芯丝或包缠纤维所纺的包芯纱和赛络菲尔纱。在纺制赛络菲尔纱时,UHMWPE短纤纱与须条的间距以8 mm为较优,UHMWPE长丝与须条的间距以6 mm为较优。     

数据驱动与有限元仿真融合的纱线断裂强力分析方法

为揭示机器人运动速度等参数对纱线性能的影响规律,考虑纱线夹持长度与拉伸速度对断裂强力分布的影响,分析了动态环境下环锭纺细纱断裂强力的分布特征。首先设计拉伸实验对环锭纺细纱性能进行分析,并构建了环锭纺短纤纱本构模型表征其强伸性能。其次建立有限元仿真模型模拟短纤纱的断裂过程,揭示了纤维间载荷传播的规律和纱体结构演化的4个阶段模型。最后对纱线强力数据的统计特征进行分析,建立了其分布参数模型。结果表明,分布检验与威布尔分布相比,对数正态分布的拟合误差最小,残差平方和为0.000 6,进一步提高了动态环境下环锭纺细纱强力预测的可靠性。     

加捻方向对双股线性能的影响

加捻是制备短纤纱、股线及绳索的必备工序。加捻对纱线有两方面作用,一是通过加捻增加纤维间的抱合力,从而赋予纱线足够的强度。二是加捻增加了纤维间的螺旋角并使纤维集聚在一起,从而增加纱线的强度。采用意大利Savio公司的Sirius倍捻机制备不同捻向的双股线试样。尝试验证不仅捻度对纱线性能有重要的影响,而且纱线捻向也有很大的影响。测试结果表明,捻向与单纱捻向相同的双股线(单向捻合双股线)具有更好的断裂强力、断裂伸长率、摩擦因数与耐磨性。研究还给出了捻向对双股线及由双股线制成的织物拉伸性能的影响。     

经编织造过程对短纤纱力学性能的影响

为扩大短纤纱在经编领域的应用以及经编面料的研发,对短纤纱在经编织造过程中的损伤因素进行了探讨。以73．8 dtex紧密赛络纺涤纶短纤纱为原料,测试不同导纱部件以及编织速度、织物组织延展线长度对短纤纱力学性能的影响。结果表明：纱线编织行进路径中,经过的每个器件都会使短纤纱断裂强度和断裂伸长率下降,经过导纱梳后的纱线断裂强度和断裂伸长率的下降幅度明显大于经过分纱梳后的纱线;随着机速的提升,短纤纱断裂强度和断裂伸长率不断下降,并呈现明显的线性关系;随着织物组织延展线的增长,短纤纱断裂强度和断裂伸长率有增加的趋势。     

材料受破坏的机理和未来检测仪器

在实验的基础上对《纺织材料学》中“纤维,纱线断裂机理,测量指标”等观点提出置疑,指出了测量指标被误用的事实,揭示了纤维,纱线断裂机理的实质,并把这一实质性指标确认为所有材料的属性之一。     

双股线捻向对纱线/织物拉伸性能的影响

加捻是加工短纤纱、合股纱、线与绳的一道重要工序。加捻通常被定义为纱线两端相对回转,产生螺旋状变形的过程。捻度通常用单位长度内纱线的捻回数(如每米纱线上的捻回数)表示。短纤维加捻可使纤维聚集在一起,从而使纱线具有足够的强度,同时具有一定的连续长度。加捻工序对纱线具有双重作用:一是加捻增加了纱线的横向压力,使纤维间的抱合力增强,为纱线提供足够的强度;二是加捻增大了纤维的螺旋角,并为纱线提供最大的纤维强度。采用意大利Savio公司的Sirius倍捻机制备不同捻向的纱线,并尝试验证不仅捻度在双股线力学性能方面起着重要作用,而且捻向也起着重要作用。测试结果表明,具有与单纱相同捻向的双股线(即单向捻合双股线)具有更好的断裂强力、断裂伸长率、摩擦因数与耐磨性。研究还证实捻向对双股线与由双股线制成的织物拉伸性能的影响。     

短纤纱动态拉伸性能

短纤纱的拉伸强力通常是评定纱线质量的重要指标。纱线拉伸强力在纺纱后道的大部分工序中(如整经、机织和针织)起着重要作用,因此对其精确的评定方法在工业生产中很重要。通过分析动态拉伸性能的定义和所用到的拉伸仪器,以环锭纺、转杯纺、喷气纺和摩擦纺的短纤纱的动态拉伸性能测试为例,做了几项有关理论和实验的工作,探讨了研究短纤纱动态拉伸性能在工业生产中的重要性,同时也总结出影响动态拉伸性能的因素有材料、纺纱参数和测试方法等,得出短纤纱静态和动态强力的关系。     

基于临界滑脱长度的短纤纱断裂强力计算

为得到一种更加合理的短纤纱断裂强力的近似计算方法,根据短纤纱结构的理想化假设和临界滑脱长度的概念,推导出短纤纱断裂过程中纤维临界滑脱长度的近似计算表达式以及发生断裂和滑脱的纤维对短纤纱断裂强力的实际贡献。鉴于短纤纱截面纤维根数的不匀,根据计算得到的临界滑脱长度采用纤维在短纤纱中随机排列的模拟对短纤纱断裂强力进行计算。通过纺制不同线密度下具有不同捻系数的粘胶纱与涤纶纱并测试其断裂强力对该计算方法进行验证。计算和验证结果表明：临界滑脱长度的计算值随着捻系数的增加而减小,且当捻系数增加时,短纤纱断裂强力的计算值随着捻系数的增加升高至最高值而后发生下降,这是与实测短纤纱强力值的变化趋势是一致的。     

Siro纱的空气变形

膨松度是纱线的一个重要特性,它决定了织物的保暖性、柔软性和舒适性,同时还提高了布面丰满度,因而可生产出丰满度均等的轻薄织物。短纤纱的膨松度一般要比长丝纱好,在短纤纱中,粗梳纱的膨松度要比精梳纱好。膨松度主要取决于纱线中纤维的排列。在短纤纱中,纤     

纤维勾接强力对纱线强力的影响

纱线强力是衡量纱线性能优劣的重要指标.但在实践中采用高强纤维纺纱有时却纺不出高强纱线.文章通过理论分析发现,纱线中纤维不但受到轴向拉力的作用,还受到垂直于纤维轴向的剪切力以及剪切力所产生的弯曲力矩、加捻所产生的扭转力矩的作用,因而纱线强力与纤维的耐弯曲破坏性能有关.用实验得到的数据进行线性回归分析证明,用来表示纤维耐弯曲破坏性能的勾接强度和单纱强度之间存在着较高的相关性,而纤维的轴向拉伸强度与其单纱强度之间的相关性较小,说明纤维的勾结强度比拉伸强度对纱线强度的影响程度要大.因此,在确定纱线捻度等纺纱工艺参数时,对于勾接强度较低的脆性纤维,应采用较小的捻系数.     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.