羟丙基封端聚硅氧烷改性水性聚氨酯的制备及其性能研究

以异佛尔酮二异氰酸酯(IPDI)与聚醚(N210)为原料,采用自制羟丙基封端聚硅氧烷(HP-PDMS)替代部分聚醚(N210),制备羟丙基封端聚硅氧烷改性水性聚氨酯乳液,并用于涤纶织物涂层整理.研究改性剂HP-PDMS用量对乳液及胶膜性能的影响,测试涂层织物的应用性能.结果表明:随着HP-PDMS用量的增加,乳液粒径变大,稳定性变差,胶膜水接触角变大,吸水率变小.HP-PDMS用量为6%时,乳液稳定,胶膜水接触角为106.2°,吸水率为32.49%.与未改性的聚氨酯涂层织物相比,改性聚氨酯涂层织物静水压、柔软度均有所提高;与聚醚型聚硅氧烷改性水性聚氨酯涂层织物相比,羟丙基封端聚硅氧烷改性水性聚氨酯涂层织物的静水压和接触角均有所提高,尤其接触角提高显著,达到136.1°.     

阳离子型苯丙乳液的合成与应用

以阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)与非离子型表面活性剂复配作乳化剂,以苯乙烯(St)和丙烯酸丁酯(BA)为主要单体,用种子半连续法乳液聚合工艺制备阳离子型苯丙乳液施胶剂。探讨了非离子乳化剂种类对聚合物乳液性能以及浸胶后纸张性能的影响。采用激光粒度分析仪表征自制乳液的平均粒径,通过扫描电镜、表面张力仪对纸张浸胶前后的表面形貌、对水的静态接触角进行测试和表征。结果表明,当采用ER-10作为非离子乳化剂与阳离子乳化剂复配时,自制乳液对纸张的抗水性能和力学性能的提高最为显著,其中纸张对水的静态接触角可达115.9°。     

阳离子度对含氟丙烯酸酯共聚物乳液及其胶膜表面性能的影响

为研究阳离子度对含氟丙烯酸酯共聚物乳液及其胶膜表面性能的影响,添加DMC阳离子改性单体,制备了甲基丙烯酸十二氟庚酯(FM)、丙烯酸丁酯(BA)、N-羟甲基丙烯酰胺(NMA)共聚乳液.通过红外光谱(FT-IR)、透射电镜(TEM)、示差扫描量热仪(DSC)对其结构、形态和热性能进行了表征,考察了阳离子度对乳液粒径、稳定性、形貌及其胶膜的耐水接触角、表面张力、吸水率的影响.结果表明,随着阳离子单体的增加,乳液柱径减小,稳定性噌大;胶膜的耐水性减小,表面自由能增大.     

阳离子型聚丙烯酸酯浆内施胶剂的制备及应用

本研究选用甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸异辛酯为主要单体,与阳离子型丙烯酸酯单体—甲基丙烯酰氧乙基三甲基氯化铵(DMC)和功能单体G共聚制备新型阳离子型浆内施胶剂。研究中,采用马尔文粒度仪表征自制乳液的粒径及粒径分布;DSC和TGA表征共聚物的玻璃化转变温度及热分解行为。此外,通过表面张力仪、扫描电镜和Cobb值测定仪对乳胶膜对水的静态接触角、施胶前后纸页的表面形貌以及抗水性进行观察和表征后发现,聚合物乳胶膜对水的接触角有显著提高,并且共聚单体的组成会影响施胶后纸页对水的接触角大小。研究中探讨了功能单体DMC、引发剂AIBA用量等对纸张施胶度的影响,结果表明,采用浆内施胶的方法,自制乳液可赋予纸张良好的抗水性。当w(DMC)=5.0%、w(AIBA)=1.58%时,自制乳液对纸张抗水性的提高最为显著。     

蓖麻油改性水性聚氨酯及其性能

为提高水性聚氨酯涂层织物的拒水性,以蓖麻油(CO)改性水性聚氨酯乳液,并用于织物涂层。研究了CO和二羟甲基丙酸(DMPA)用量对乳液及胶膜性能的影响,测定了涂层织物的性能。结果表明:随着CO用量的增加,乳液粒径变大,分布变宽,稳定性变差,外观由半透明变为乳白色;胶膜的水接触角增大,吸水率降低,拉伸强度先升后降,断裂伸长率降低。随着DMPA用量的增加,乳液粒径变小,分布变窄,稳定性变好,外观由乳白色变为半透明;胶膜的接触角降低,吸水率增大,拉伸强度增大,断裂伸长率降低。当蓖麻油用量为7%、DMPA用量为4%时,改性乳液稳定,胶膜耐水性和力学性能好,涂层织物耐静水压高。研究表明:适量CO改性有助于水性聚氨酯涂层织物耐静水压的提高。     

氮丙啶/聚氨酯复配乳液膜性能表征及其表面施胶性能

采用氮丙啶对阴离子水性聚氨酯交联改性,制备了氮丙啶改性水性聚氨酯乳液。研究表明:当n(NCO)/n(OH)=1.6,氮丙啶用量为2.5%时,此水性聚氨酯乳液具有优异的表面施胶性能,以质量分数为1%的氮丙啶/聚氨酯复配乳液进行表面施胶时,纸张的耐折度达到125次,湿强度为36.2%,施胶度为67s。通过红外、力学性能及原子力显微镜对聚合物结构及膜性能进行了表征,红外表明氮丙啶与聚脲氨酯链段参加反应生成酯;力学性能显示聚氨酯胶膜的拉伸性能得到提高,断裂伸长率变小;原子力显微镜显示氮丙啶/聚氨酯复配乳液膜表面粗糙度增加,提高了纸张表面的施胶度。     

高硅含量阳离子型硅丙乳液的合成及应用北大核心

以甲基丙烯酸甲酯、丙烯酸丁酯和丙烯酸为基础单体,γ-甲基丙烯酰氧丙基三(三甲基硅氧基)硅烷为改性单体,在阳/非离子复合乳化剂(3%)、引发剂(1%)和交联剂(1.5%)的作用下,采用种子乳液聚合半连续法,制备了高硅含量的有机硅改性丙烯酸酯乳液。通过外观观察、稳定性测试、粒度测量、红外光谱、热重分析、透射电镜、接触角及扫描电镜,分析研究了核壳粒子的形貌结构、热稳定性和吸水率,以及不同有机硅含量和不同乳液稀释浓度对织物拒水效果的影响。结果表明,有机硅单体参与了共聚反应,所得乳液外观均匀,色泽乳白泛蓝,稳定性好,平均粒径为170 nm左右,具有清晰的核壳结构。随着有机硅含量的增加,共聚物的耐热性提高,吸水率明显降低。乳液对织物进行整理后发现,当乳液稀释质量浓度相同时,随着有机硅含量的增加,织物表面对水接触角逐渐提高;当有机硅含量相同时,随着乳液的稀释质量浓度降低,织物表面对水接触角逐渐提高,拒水性能优良。     

高硅含量阳离子型硅丙乳液的合成及应用

以甲基丙烯酸甲酯、丙烯酸丁酯和丙烯酸为基础单体,γ-甲基丙烯酰氧丙基三(三甲基硅氧基)硅烷为改性单体,在阳/非离子复合乳化剂(3%)、引发剂(1%)和交联剂(1.5%)的作用下,采用种子乳液聚合半连续法,制备了高硅含量的有机硅改性丙烯酸酯乳液。通过外观观察、稳定性测试、粒度测量、红外光谱、热重分析、透射电镜、接触角及扫描电镜,分析研究了核壳粒子的形貌结构、热稳定性和吸水率,以及不同有机硅含量和不同乳液稀释浓度对织物拒水效果的影响。结果表明,有机硅单体参与了共聚反应,所得乳液外观均匀,色泽乳白泛蓝,稳定性好,平均粒径为170 nm左右,具有清晰的核壳结构。随着有机硅含量的增加,共聚物的耐热性提高,吸水率明显降低。乳液对织物进行整理后发现,当乳液稀释质量浓度相同时,随着有机硅含量的增加,织物表面对水接触角逐渐提高;当有机硅含量相同时,随着乳液的稀释质量浓度降低,织物表面对水接触角逐渐提高,拒水性能优良。     

羧基丁苯胶/封闭聚氨酯的制备及其对纸张的防水增强作用

以咪唑为端异氰酸酯基封闭剂制备封闭聚氨酯(BPU)预聚体,然后以羧基丁苯胶水溶液进行反相乳化,并加入交联剂制得水分散羧基丁苯胶/封闭聚氨酯(CSBL/BPU)纸张防水增强剂。CSBL/BPU的综合性能与BPU封闭率、羧基丁苯胶与封闭聚氨酯的比例、交联剂含量及复合乳液添加量有关,当封闭率BR10%、m(BPU):m(CSBL)=2:1、ω(交联剂)=2%、ω(乳液)=8%时,纸张具有良好的防水性能、黏合强度和机械性能。     

有机硅改性MDI水性聚氨酯的合成和应用

试验合成了有机硅改性MD I型水性聚氨酯(SWPU)乳液,测试分析了水性聚氨酯的力学性能、耐热性能和耐水性能,考察了有机硅含量对水性聚氨酯结构与性能的影响。结果表明,当有机硅含量为2%时,SWPU乳液稳定性好,胶膜接触角高达94°,吸水率降至5.8%,断裂伸长率达980%,而且拉伸强度有所增强,因此该SWPU具有较好的力学性能、表面性能和耐水性。采用SWPU涂层胶进行涂层整理,可赋予织物较好的耐水压与透湿性能。     

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.