恒定内压下热老化对PE管材性能的影响检测

PE材料是当前管道行业中运用最多的管道材质,因其优异的力学性能、易加工性质获得市场的广泛好评。加上PE材料化学稳定性能好,能够降低管道对运输物质,例如自来水的影响,同时PE材料相比其它管道材料,耐低温性更强,应用范围更加广泛。本文主要介绍恒定内压下热老化对PE管材性能的影响检测。     

可焚烧可降解聚乙烯薄膜的光--生物降解性能研究

借助人工加速老化实验箱、自然土壤填埋坑等实验方法，采用力学性能测试、扫描电镜等测试方法对可焚烧可降解聚乙烯(PE)塑料包装材料的可环境消纳性能进行探讨。实验结果表明，以PE为主材料，添加无机粉体，生物活性剂，FeSt3-MnSt2复合光敏剂，研制出高填充可降解的PE塑料薄膜，具有良好的光——生物降解性能，并可适用于焚烧处理。     

汽车内饰用涤纶针刺布/聚乙烯淋膜复合材料研究

对两种用于针刺布淋膜复合材料的聚乙烯(PE)母粒进行了测试,包括热学和结晶性能、熔体流动性能和流变性能,并对其制备的两种汽车内饰用涤纶针刺布/PE淋膜复合材料的拉伸、撕裂性能进行了评价。结果表明:两种PE熔点接近(约120℃),黑色PE母粒的熔融重结晶现象明显,且淋膜加工后的结晶度下降更显著;黑色PE母粒的熔体流动速率大于原色PE母粒,二者总体介于1~5g/10min;两种PE均属于"切力变稀"熔体,在同一剪切速率和温度下,原色PE母粒的表观粘度明显大于黑色PE母粒;两种PE淋膜复合材料的拉伸延展性和撕裂性能均优于未淋膜材料,原色PE淋膜复合材料的纵、横向的拉伸强力和断裂伸长率,以及平均撕裂强力均最佳,其最大值分别可达到1572.1N、71.8%和250.5N。     

淀粉基可食膜性能及其影响因素的研究进展

淀粉基可食膜是以淀粉或改性淀粉为主要原料，添加填充物和少量功能成分(抗菌剂/抗氧化物)通过干法或湿法等工艺制成的高分子薄膜，具有生物可降解性和可食性等优点。然而，由于淀粉膜力学性能、阻隔性能等相比传统塑料更差，因此探究淀粉膜性能的影响因素及优化工艺将成为重点研究方向。本文综述了淀粉基可食膜的性能、淀粉的结构性质、加工助剂、淀粉改性等对其性能的影响及机制，并概述了淀粉基可食膜应用前景及存在的问题，展望了其发展前景，为进一步开发具备优良性能的淀粉基可食膜提供参考。     

防紫外线、防电磁辐射PAN复合纳米纤维膜的制备及性能分析

为制备具有防紫外线、防电磁辐射双重功能的纳米纤维膜,在纯聚丙烯腈(PAN)溶液中加入二氧化钛(TiO_2)与纳米银颗粒(AgNPs),利用静电纺丝方法制备纯PAN和PAN/TiO_2、 PAN/AgNPs、 PAN/TiO_2/AgNPs复合纳米纤维膜,分析纳米纤维膜的微观形貌、紫外线防护性能、紫外线吸收性能和防电磁辐射性能。结果发现:当在纯PAN溶液中加入质量分数为0.50%的TiO_2及1.20%的AgNPs时,制备的PAN/TiO_2/AgNPs复合纳米纤维膜具有极好的紫外线防护功能和防电磁辐射功能,可用于开发具有防紫外线和防电磁辐射双重功能的纳米纤维纺织品。     

壳聚糖与水性聚氨酯的复配及其性能研究

采用较低分子量的改性壳聚糖与水性聚氨酯复配,通过自乳化聚合法制备了一系列不同配比的共混膜,研究了共混膜的力学性能、生物降解性、热稳定性等,利用红外光谱(FTIR)、扫描电子显微镜(SEM)研究了共混膜的结构及表面形态,并且通过吸湿性、溶胀性和接触角实验进行了共混膜的亲水性测试.在成膜实验的基础上,通过羊毛织物防毡缩整理研究复配液的防毡缩性能,测试了羊毛织物的毡缩率、抗菌性以及力学性能,利用SEM研究了纤维整理前后表面结构的变化.结果表明,低分子量壳聚糖与水性聚氨酯的复配液具有良好的成膜性和防毡缩性,在防毡缩的同时能赋予织物一定的吸湿性、抗菌性和生物降解性.     

用于纸质文档保护的原位静电纺废旧聚对苯二甲酸乙二醇酯膜

针对纸质文档易受潮、易撕裂、易老化等保护难题，以回收废旧聚对苯二甲酸乙二醇酯(rPET)为原料，通过原位静电纺丝工艺将rPET纳米纤维直接沉积到纸质文档表面形成纤维保护膜。分析了原位静电纺处理前后纸质文档的形貌、表面润湿性、力学性能以及防紫外线性能。结果表明：制备的rPET纤维膜不会遮盖字迹，纤维膜的孔径为(5.53±0.38)μm,可阻挡常见灰尘和霉菌；最优条件下制备的rPET纤维膜可将纸质文档的水接触角提高到135.1°;沉积rPET纤维膜后纸质文档的拉伸强度和撕裂强度较未处理文档分别提高了129.1%和161.1%,紫外线防护系数可达到71.4。研究发现原位静电纺rPET纤维膜到纸质文档表面达到了较好的保护效果，该方法为矿泉水瓶的回收再利用及纸质文档保护提供了新途径。     

涤纶篷盖织物热老化后的力学性能研究

对聚氨酯涂层的涤纶篷盖织物,在不同温度下进行热老化处理,并对热老化处理后该织物进行力学性能测试。结果表明:在175℃热老化处理后,织物力学性能开始有明显降低;在200℃热老化处理后,力学性能有十分显著的降低,撕裂强力尤为显著;在225℃热老化处理后,织物力学性能在开始阶段急剧下降,此后下降趋于平缓。聚氨酯篷盖织物,在相同条件下热老化处理后,其撕裂性能降低最大,顶破性能降低最小,拉伸性能的降低介于两者之间。     

柚皮果胶-海藻酸钠可食复合膜对草莓的保鲜

以自制柚皮果胶和海藻酸钠为基材制备的柚皮果胶-海藻酸钠可食复合膜具有良好的阻隔性能、力学性能。以柚皮果胶-海藻酸钠可食复合膜为保鲜包装材料,考察不同包装处理对草莓的感官品质、营养成分、MDA含量及SOD活性的影响。结果表明,以该复合膜托盘包装和以复合膜液涂抹+PE膜托盘包装的保鲜效果极显著于其他各处理组,能有效降低草莓的失水率、腐烂率和MDA含量的增加,减少草莓果实的可溶性蛋白质、可溶性固形物、Vc含量和SOD活性的降低,在短期内有效保持草莓的感官品质和营养成分,延长贮藏时间。以复合膜液涂抹+PE膜托盘包装方式的保鲜效果最好,可替代传统PE膜的托盘保鲜方式。     

PPTA纤维的光老化机制及其防紫外改性研究进展

聚对苯二甲酰对苯二胺(PPTA)纤维具有高强高模、耐高温及轻质等优点，广泛应用于国防安全、航天航空、交通运输和光纤光缆等领域。但PPTA纤维极易发生紫外光老化降解，对其进行防紫外改性可提高其在户外环境下的使用寿命。综述了PPTA纤维的光老化机制，并着重介绍了PPTA纤维的防紫外改性研究进展，其中化学改性方法易使PPTA纤维力学性能下降，物理改性方法则对设备要求较高，尚需探究无损化、低成本的防紫外改性产业化方法。     

基于山梨醇酐单棕榈酸酯防雾膜制备与性能研究

为研究山梨醇酐单棕榈酸酯的防雾效果,以山梨醇酐单棕榈酸酯为主要防雾材料,通过造粒得到防雾母料,三层吹塑共挤得到防雾聚烯烃薄膜,并对防雾母料造粒加工性能、薄膜防雾性能、光学性能、力学性能进行测试。结果表明,随着防雾剂在母料中含量的增加,母料熔点降低,融熔指数提高,流动性得到提升,利于母料的加工;当防雾剂在薄膜中含量为时,水滴在薄膜表面接触角为9.72°,薄膜的防雾等级在水浴热雾与急速热雾法测试条件下可到达1级;防雾剂含量在薄膜中含量为1.5%高温测试环境下的持久性达到168 h;随着防雾剂含量继续增加,薄膜的力学性能与光学性能均不同程度的下降,防雾剂在薄膜中的含量在达到防雾要求时应控制在适当水平。     

镜面防雾剂微胶囊的制备与应用

解决生活中常见的镜面起雾问题,以密胺树脂为壁材,采用原位聚合法制备了具有压敏性的雾剂微胶囊,将其用漫轧法整理在基布上制成擦镜布,并探讨了防雾剂的浓度,芯壁比和整理工艺对防雾效果的影响,用该擦镜布擦拭镜面防雾效果良好。     

PGFE/BOPP防雾薄膜的制备与性能研究

用表面活性剂聚甘油脂肪酸酯(PGFE)对BOPP薄膜进行表面改性,降低薄膜表面张力,使其具有防雾作用。以聚甘油脂肪酸酯为防雾剂,采用涂布法制备得到PGFE/BOPP防雾薄膜,通过试验测定分析了薄膜的防雾性能,机械性能、光学、透氧、透湿等性能。结果表明:涂布PGFE后,薄膜拉伸强度增大、雾度增大,透光率降低,对氧气、水蒸气的阻隔性提高,其中2%浓度的PGFE涂布后,BOPP薄膜防雾效果,机械性能较好,可以作为防雾包装薄膜使用。     

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.     

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.