数字印刷废纸纤维增强聚乳酸复合薄膜的性能研究

以数字印刷废纸、聚乳酸（PLA）为原料,采用熔融混炼、热压成形的工艺制备得到废纸纤维/PLA复合薄膜,探究了不同废纸纤维添加量和不同改性剂对复合薄膜性能的影响。分别加入硅烷偶联剂γ-缩水甘油醚氧丙基三甲氧基硅烷（KH560）、乙烯基三甲氧基硅烷（A171）、异丙基三（二辛基焦磷酸酰氧基）钛酸酯（TMC201）及木聚糖酶,对废纸纤维进行改性处理,研究了改性前后复合薄膜的力学性能、不透明度、化学结构及热稳定性等。结果表明,当废纸纤维质量分数为25%时,复合薄膜抗张强度最佳,达21.6MPa,相较于纯PLA薄膜提高了94.7%;当废纸纤维质量分数为20%时,其不透明度增加至95.5%;废纸纤维经改性处理后,复合薄膜抗张强度均有不同程度的提升,其中KH560的改性效果最佳,复合薄膜（废纸纤维质量分数25%）抗张强度达24.7 MPa,相较于改性前提升了14.4%;改性处理并未对复合薄膜的不透明度和热稳定性产生影响。     

芳纶纳米纤维/壳聚糖绝缘复合薄膜力学及绝缘性能研究

以芳纶纳米纤维（ANFs）为基体,壳聚糖（CS）为增强剂,采用真空辅助过滤技术制备了ANFs/CS复合薄膜,并通过热压法提高薄膜的致密性,以增强其力学和绝缘性能。结果显示,当壳聚糖负载量为0.02 g时,ANFs/CS复合薄膜的性能最优,其最大拉伸强度可达208 MPa,特征击穿强度62 kV/mm。对ANFs/CS复合薄膜进行热压处理后,复合薄膜的致密性明显提高,其最大拉伸强度和击穿强度分别为253 MPa和109 kV/mm,相较于热压前分别提升了21.6%和75.8%。     

纳米SiO_2改性聚丙烯薄膜的制备及力学性能研究

为了提高聚丙烯薄膜的力学性能,研制了一种纳米Si O2改性剂,采用熔融共混法将纳米改性剂填充到聚丙烯树脂中,流延、双向拉伸制备聚丙烯/纳米Si O2复合薄膜,并对其拉伸性能、穿刺性能等力学性能及阻隔性能(透湿)进行测试。结果表明,当纳米Si O2质量分数为0.8%时,改性薄膜的拉伸强度较未改性薄膜提高18%,杨氏模量提高58%,断裂伸长率提高65%。     

仿贝壳层状MTM/PVA/ANF复合薄膜的制备及其性能研究

通过水蒸发诱导自组装（A）和真空辅助抽滤（F）及其与离心处理（C）组合4种不同方法制备仿贝壳层状结构的蒙脱土/聚乙烯醇/芳纶纳米纤维（MTM/PVA/ANF）复合薄膜,并采用扫描电子显微镜（SEM）、原子力显微镜（AFM）、热重分析仪（TGA）、紫外分光光度计、动态接触角测试仪和拉伸测试仪对复合薄膜的微观结构、热稳定性、透光率、亲水性和力学性能进行表征。结果表明,不同方法（A、CA、F和CF）制得的复合薄膜都呈明显的层状结构,但复合薄膜的透光率、亲水性和力学性能不同。通过F法制备的复合薄膜具有更高的透光率和更好的疏水性;通过CF法制备的复合薄膜具有最优的力学性能,拉伸强度可达132.4 MPa,而通过A法制备的复合薄膜韧性最佳,断裂伸长率可达11.3%。     

增强剂对大豆蛋白/聚乙烯醇复合薄膜性能的影响

以薄膜拉伸强度、断裂伸长率、透光率、吸水率为评价指标,通过隶属度函数综合评分方法,研究了增强剂对大豆蛋白/聚乙烯醇复合薄膜性能的影响。实验结果表明:与对照组相比,添加可溶性淀粉,薄膜吸水率显著降低,透光率明显增大,但薄膜拉伸强度和断裂伸长率略有减小;添加羧甲基纤维素钠(CMC-Na),薄膜拉伸强度和吸水率明显增大,断裂伸长率明显减小,透光率几乎没有变化;加入明胶,薄膜的拉伸强度增大不明显,断裂伸长率和透光率均有显著提高,吸水率明显减小,当明胶浓度为0.200%时,薄膜综合性能最佳,拉伸强度为4.69MPa,断裂伸长率为45.65%,透光率为13.78%,吸水率为47.21%。     

PA6/纳米二氧化硅复合薄膜制备及力学性能

为了提高PA6纳米纤维薄膜的力学性能,以纳米二氧化硅为增强填料,配制PA6的甲酸溶液,采用静电纺丝法制备PA6/纳米二氧化硅薄膜,研究不同纳米二氧化硅添加量对复合薄膜的表面形貌、晶体结构、热行为和力学性能的影响。结果表明:纳米二氧化硅含量较低时在纤维中分散均匀,纤维表面光滑,而含量高时,发生团聚现象,纤维表面粗糙;纳米二氧化硅的添加诱导PA6由γ晶型向α晶型转变,且除了在223℃出现熔融峰外在230℃附近还出现肩缝;随着纳米二氧化硅含量的增加,PA6/纳米二氧化硅薄膜的结晶温度先升高后降低;与纯PA6薄膜相比,当纳米二氧化硅质量分数为0.5%时,拉伸强度和弹性模量分别增加了4.35倍和4.82倍。     

MgO纳米颗粒增强壳聚糖复合薄膜及其抗菌性能研究

采用聚甲基丙烯酸甲酯（PMMA）/碳酸镁预聚物原位合成方法制备球形氧化镁（MgO）纳米颗粒,与壳聚糖复合制备壳聚糖/MgO复合薄膜,研究其力学性能、热稳定性、阻隔性能及抗菌性能。MgO纳米颗粒添加量为5 wt%时,壳聚糖/MgO复合薄膜获得最佳的力学性能,拉伸应力及弹性模量分别较壳聚糖薄膜提高64%及50%。傅里叶红外光谱（FT-IR）结果表明,壳聚糖/MgO复合薄膜力学性能的提升主要是由于壳聚糖的羟基和胺基与MgO形成了氢键。此外,添加5 wt% MgO纳米颗粒后,复合薄膜的氧气透过常数降低了约18%,该薄膜在12 h内可使46%的大肠杆菌结构破坏或死亡,具有优异的抗菌效果。     

木质素基聚乳酸复合膜的物理老化性能研究

本研究合成了3种基于辛酰氯、十二酰氯和十八酰氯酯化改性的木质素酯（LEs）,并将其用于聚乳酸（PLA）的复合增韧改性。通过溶剂浇铸法制备了LEs/PLA复合膜,系统研究了不同LEs及不同添加量对LEs/PLA复合膜力学性能的影响以及物理老化过程中力学性能的变化特性。结果表明,物理老化时间的延长会显著降低复合膜样品的断裂伸长率,并提高其拉伸强度。但LEs/PLA复合膜的断裂伸长率老化后仍高于同老化条件下纯PLA,添加质量分数10%木质素十八烷基酯（LE18）的复合膜经84天物理老化后断裂伸长率仍有30.7%,为同老化条件下纯PLA断裂伸长率的6.27倍,拉伸强度为42.1 MPa。     

响应面法优化KGM-TiO_2复合薄膜的拉伸性能

以魔芋葡甘露聚糖(KGM)和纳米TiO2为原料,制备KGM/TiO2复合薄膜,研究制备工艺对复合薄膜性能的影响。以拉伸强度、断裂伸长率为评价指标,探讨了KGM溶胶浓度、甘油用量、pH、干燥温度对KGM薄膜特性的影响,在单因素实验的基础上,采用响应面分析法,优化了KGM薄膜的制备工艺,在此基础上,制备KGM/TiO2复合薄膜并考察TiO2掺杂比对复合薄膜性能的影响。建立了拉伸强度、断裂伸长率的回归模型,优化后的制备工艺条件为:KGM浓度1%、甘油添加量0.45%、pH10、干燥温度71℃。TiO2的掺入能有效提高KGM薄膜的断裂伸长率,对薄膜的力学性能有所改善,当TiO2掺杂比为0.003%时,复合薄膜性能良好。     

CMC/木质纤维复合纸的制备及性能

以羧甲基纤维素(CMC)和桉木浆为原料,将桉木浆抄造成纸张后浸渍CMC溶液制备CMC/木质纤维复合纸。探讨了CMC的浸渍量对复合纸的光学性能(透光率和雾度)、力学性能(拉伸强度和耐折度)的影响规律。结果表明:当CMC的浸渍量为65%时,CMC/木质纤维复合纸具有优异的光学性能和力学性能,其透光率为91%,雾度为82%,拉伸强度达142 MPa,耐折次数为1516次。     

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.     

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.