空心锭包覆纺纱包缠捻度及其分布的影响因素分析

为探讨影响空心锭包覆纺纱包缠捻度及其分布的因素及影响程度,分析了外包缠纱退绕及芯纱在包缠张力作用下扭转产生的附加捻度,以及影响附加捻度大小和波动的因素;对采用不同芯纱速度、线密度、张力以及粗细不匀芯纱纺制的包覆纱进行了捻度测试与比较分析。结果表明:外包缠纱退绕产生的附加捻度的捻向与包缠捻向相同,而芯纱扭转产生的附加捻度的捻向与包缠捻向相反;随纺纱工艺的不同,二者的共同作用决定了包缠捻度的偏差大小和分布均匀度;包缠捻度具有纱线加捻的类似捻回分布特征,芯纱粗细不匀显著影响短片段捻回分布均匀度,粗节处捻回少,细节处捻回多。     

自捻纱纺纱速度对自捻捻度的影响

自捻纱由交替的 Z 捻段和 S 捻段以及无捻区段 3 个区段组成.对比观察自捻纱和相同支数环锭单纱和股线的纵截面,结果显示:自捻纱 Z 捻段和 S 捻段的纵截面特征和环锭股线近似.自捻纱的无捻区由分离的 2 根须条组成,是影响纱线性能的关键区段.纺制 2 种纺纱线密度,5 种纺纱速度自捻纱,测量其 Z 捻段和 S 捻段自捻捻度及无捻区长度,结果表明:自捻纱的 Z 捻段和 S 捻段的自捻捻度随纺纱速度增加而下降.在周期长度和自捻罗拉往复动程固定的前提下,自捻捻度不仅和纺纱线密度有关,还与纺纱速度有关.自捻纱无捻区长度随着纺纱速度的增加而增加.纺纱线密度越低,无捻区长度越大.     

粗梳毛纺中的捻缩与捻差

粗梳毛纺中的捻缩与捻差董桂香捻缩在纺纱过程中是普遍存在的。如捻缩率较小，一般只考虑它对合股纱线细度的影响。在粗梳毛纺系统纺低支纱肘，抢缩率较大，对粗纱定重、细纱牵伸及成纱捻度都产生了不可忽略的影响，要修正粗纱定重并降低几档选择捻度变换齿轮。这种修正和...     

捻度对聚酰亚胺纱线拉伸性能及可织性的影响

为提高聚酰亚胺(PI)长丝的可织性，选取3种线密度的PI长丝，分别设计制备5种捻度的PI纱线。通过测试纱线捻度表征指标、拉伸性能和织造损伤性能，探讨捻度对3种线密度PI纱线拉伸性能与织造损伤情况的影响，并对PI纱线的可织性进行上机评价。结果表明：线密度越小，纱线结构越紧密，纱线的捻回角和捻缩率越大。不同捻度作用下，22.22、55.56和166.67 tex PI纱线的临界捻度分别为16、16和12捻/(10 cm),拉伸强度相比相同线密度未加捻PI长丝的分别增加24.28%、27.37%和20.83%;捻度为12捻/(10 cm)的22.22 tex PI纱线抵抗综眼和筘齿的织造损伤性能更好；结合上机织造试验发现，12捻/(10 cm)的PI纱线更有利于上机织造。     

精纺细纱的捻缩规律——双股正常纱(Z×S,S×Z)

本文在实践的基础上总结出双股正常纱捻缩规律的算式，使捻缩考虑由经验插值转为科学计算，从而揭示了捻缩与纱支，捻度、捻系数等的内在规律     

涤/棉混纺纱的直径和毛羽

巴雷利亚、卡斯特罗与哈特等人合作,最近对环锭和气流纺所纺的涤/棉(50/50)混纺纱,在成纱直径和毛羽两个方面,与纯棉、纯涤纶纱进行了比较、研究。试验用纱为25毫克/米,捻度:环锭纱574～814捻/米,气流纱766～1244捻/米。结果发现,对于相同线密度与捻度的环锭纱,棉纱横截面的直径大于涤纶纱,混纺纱的介于二者之间。对于气流纱,在临界加捻区附近时,纱的直径随着捻度的增加而增加。同时,从整个试验来看,棉纱的毛羽     

经验交流

经验交流无捻毛巾的开发与生产无捻毛巾具何普通达不到的待柔软手感，我们采用棉纱与聚乙烯醇纤维捻入手，进行无捻毛巾的开发，获得了成功。１无捻毛巾的特点无捻毛巾的毛纱为没有捻度纱或者低捻度纱（在１～２个捻度以下），这种无捻纱手感特别柔软，织成毛巾洗脸、擦手...     

雪尼尔线捻度设计的研究

雪线加捻的目的主要是将茸纱夹紧，防止脱茸并具一定强度和绒感。通过分析雪线加捻结构模型，探讨了茸纱密度、茸纱和芯纱的线密度、纺纱纤维以及雪线的加捻方式与雪线捻度的关系。导出了雪线捻度的设计公式，并以实例说明其应用。论述雪线四种加捻方式的特点及对雪线捻幅的变化，提出雪线芯纱合适的加捻设计；导出ZZS加捻方式时芯纱单纱、初捻、复捻捻度的设计公式。     

网格圈负压式集聚纺集聚区须条半自由端加捻机制

网格圈负压式集聚纺纱实践表明,在相同工艺条件下,纺制相同线密度的纱线,集聚纱捻度比环锭纱捻度高5％左右.为揭示此现象的形成机制,采用高速摄影技术,对直线形集聚斜槽集聚区须条的集聚情况进行拍摄,发现存在类似卷捻的现象.通过纺纱实验,对采用相同工艺纺制的相同线密度的集聚纱和环锭纱捻度进行对比,结果表明集聚区须条的附加捻度是...     

自捻纱半周期捻度测量仪

一、概况由于自捻纱半周期的实际捻度与设计捻度往往偏差很大,影响成纱质量,因之迫切需要有快速测量自捻纱半周期捻度的仪器,以代替手工测量。该仪器的试制成功,大大加快了测试速度,减轻了试验人员的劳动强     

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.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

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.     

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.     

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.     

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.     

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.