PVC膜材料的光氧老化性能

以PVC膜材料为对象,采用不同辐射强度的紫外线人工加速老化实验对其光氧老化过程进行研究。对老化过程中试样的黄度指数进行测试,并进行红外光谱和紫外光谱分析。测试结果表明：不同辐射强度下试样的老化机制没有发生变化,但当累积紫外线辐射能相同时,试样的老化程度并不一致,这是因为试样在不同辐射强度下的光氧老化速度与辐射强度不成比例关系,因此,互易定律不适用于PVC涂层膜材料寿命预测模型的建立,而根据Schwarzschild定律可很好地建立不同辐射强度下试样老化结果的相关性。     

PVC涂层膜材料老化性能研究的进展

对PVC涂层膜材料热氧老化、光氧老化、化学降解等机理进行了简单说明,并讨论了应力对高分子材料老化的影响;系统地介绍了PVC涂层膜材料自然气候老化和人工加速老化的试验方法及相关标准,特别是光氧老化的试验方法和相关标准,以及各种宏观和微观的老化检测、分析方法,并对这些方法和相关标准加以总结和分类;分析了PVC涂层膜材料的人工加速老化试验与自然老化结果间的相关性研究现状以及存在问题;最后,对PVC涂层膜材料老化性能研究的重点方向进行了展望。     

聚氯乙烯膜结构复合材料的光氧老化行为及评价

为探究经编和机织涂层膜结构复合材料的光氧老化行为,以涤纶经编和机织聚氯乙烯(PVC)涂层膜结构复合材料为对象,选取6种织物试样,研究其在紫外光辐射下的老化现象,同时与涤纶纱线力学性能的老化效应进行对比;同时研究了老化实验过程中复合材料的光氧老化行为及力学性能变化,并分析了其微观损伤机制。结果表明:涂层膜对基布纱线起到了很好的保护作用;经编织物膜结构材料老化后的初始模量均高于机织物膜结构材料,断裂强力保持率则反之;在辐射能为82.08×10³ kJ/m²时,织物的横密和纵密均为24根/(5 cm)的单面经编膜结构复合材料断裂强力保持率仅为62.4%,且其涂层对基布的保护作用已失效,涂层膜表面严重粉化和黏结;另外5种双面膜结构试样断裂强力保持率均在85%以上,在此辐射能范围内涂层面变粗糙,但仅出现少量沟槽,表现出良好的抗光氧老化性能。     

热湿条件对PVC膜结构材料拉伸性能的影响

分别在热和热湿复合两种条件下,对PVC膜结构材料进行了加速老化实验,测试了材料的拉伸性能.结果表明,在热湿条件下老化结束后,材料的断裂应力、初始模量和断裂比功的损失率分别大于44%、65%和51%;而在热条件下老化结束后,材料对应指标的损失率分别小于31%、27%和36%.同时比较拉伸特征值可得出,在热老化作用下,断裂应变对材料断裂比功的变化起主导作用;在热湿老化作用下,断裂应力是影响材料断裂比功的主要因素.     

芳纶紫外线辐照老化失效的无损检测评估

探讨抗荷服和抗浸服(芳纶材料)老化程度的无损检测方法。采用紫外线辐照模拟自然紫外线损伤过程,系统研究了常用的抗荷服和抗浸服在紫外线辐照下的微观形貌、微结构、色度以及断裂强力变化,分析了此类芳纶材料色度特征变化与断裂强力之间的对应关系。结果表明:紫外线辐照会破坏材料纤维微结构,导致其出现老化现象;抗浸服和抗荷服在不同紫外线辐照时间下色度特征值与断裂强力均呈现出明显规律。认为:建立起基于色度检测的材料老化损伤无损检测和评估技术,可以实现此类特种纺织材料剩余寿命的预测。     

羟基锡酸锌/Sb_2O_3对聚氯乙稀复合建筑膜材的协同阻燃性能

为提高聚氯乙烯(PVC)复合膜材的阻燃性能并降低Sb2O3的使用量,制备了羟基锡酸锌(ZHS);利用X射线粉末衍射仪、傅里叶红外光谱仪和场发射扫描电镜对制备的样品进行了测试。结果显示,制备的样品为边长1μm左右的立方体ZHS。将ZHS等助剂添加到PVC糊料中制备了具有阻燃作用的膜材涂层材料,通过测试极限氧指数、热重分析及扫描电镜对炭渣形貌分析等方法,探讨了PVC复合涂层材料的阻燃作用。结果表明:添加ZHS的PVC材料的残炭量高于添加Sb2O3的PVC材料且炭渣表面更致密;而添加ZHS/Sb2O3的PVC材料的极限氧指数(LOI值)高于二者单独使用,即ZHS和Sb2O3对PVC涂料存在协同阻燃效应,从而降低Sb2O3在阻燃PVC涂层材料中的使用量。     

紫外线辐射强度对聚丙烯长丝光氧老化的影响

 以聚丙烯长丝为研究对象,采用不同紫外线辐射强度的人工加速老化试验对其光氧老化过程进行研究。对老化过程中试样的断裂强力进行测试,并进行红外光谱分析。测试结果表明：采用2根和4根紫外荧光灯管的老化结果之间相关性较好,而与8根灯管老化结果之间的相关性较差。造成这种差别的原因在于,2根和4根灯管老化条件下的降解产物与8根灯管老化条件下的降解产物有所不同,即过高的紫外辐射强度会导致聚丙烯长丝光氧老化动力学过程的改变。     

表面涂层产业用纺织品的老化

本文采用对实际环境进行模拟的人工加速老化方法对表面涂有丙烯酸酯、PVDF（聚偏氟烯）以及PTFE的六种不同的膜材料的老化性能进行了研究。环境模拟的方法由两套具有高度加速老化效果的处理系统组成。在为期20天的加速老化周期内，每种样品周期性的受到紫外线、雨水、空气中的热湿有害气体以及霜冻的作用。与实际情况相似的是，在这种人工模拟环境的作用下，膜材料样品也会泛黄并失去光泽。结果显示：采用新胭脂红－TA方法染色的样品最初的表面涂层不均匀，并且样品老化后发生剥离和化学变化，对于PVDF涂层来说这一现象更为明显。这一快速测试方法很明显地显示出不同膜材料成分系统和不同的老化环境的判别。老化引起的化学变化由ATR红外光谱仪监控，这些化学变化或许是由于表面涂层中的酯基团不同的水解敏感性导致的。     

应力回复对PVC涂层膜材料蠕变性能的影响

为深入研究建筑膜材料的蠕变性能,对PVC涂层膜材料在应力回复条件下的蠕变性能进行了测试和分析,阐述了非寻常蠕变性能的产生机理.结果 表明,PVC涂层膜材料的蠕变性能与应力回复阶段的最大应力、蠕变应力及加、卸载速率密切相关.无应力回复和应力回复量较高时,PVC涂层膜材分别表现出寻常蠕变与逆蠕变行为特征,加、卸载速率仅影响...     

聚氨酯涂层长丝织物耐紫外光性能研究

以涤纶长丝为基布的聚氨酯涂层织物,在紫外光的照射下会发生“老化”现象,利用扫描电镜(SEM)、红外光谱仪(FTIR)对老化前后涂层织物的表面形貌和内部结构进行表征,并采用回归方程来预测涂层织物的力学性能变化趋势.结果表明:随着照射时间的延长,涂层织物力学性能下降,色差增大,聚氨酯的C-o和C-N发生断裂,涂层膜出现固结...     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press