不饱和PAE树脂的合成及性能研究

采用马来酸酐替代部分己二酸合成高固含量的不饱和聚酰胺多胺环氧氯丙烷(PAE)树脂,通过化学分析、红外光谱等手段初步研究不饱和PAE树脂的结构,并探讨马来酸酐的用量、添加方式、反应温度和保温时间等因素对不饱和PAE树脂性能的影响.结果表明,在氮气保护,n(马来酸酐和己二酸)∶n(二乙烯三胺)=1∶1.05,马来酸酐用量为二元酸的20％,对甲基苯磺酸用量为反应单体总量的0.7％,反应温度为160℃,反应时间为5h的条件下,得到黏度适宜的预聚体聚酰胺多胺(PPC);在n(环氧氯丙烷)∶n(二乙烯三胺)=1.5∶1,PPC与前期水的质量比为1∶1,反应温度为65℃,反应时间为3h的条件下,合成的不饱和PAE树脂稳定性增强.用合成的不饱和PAE树脂作为湿强剂对纸张进行增强,在不饱和PAE树脂用量为1.5％时,纸张湿强度为24.4％.     

改性PAE-St纸张湿强剂的合成与应用

研究了接入疏水侧链聚酰胺(PAE)与环氧氯丙烷反应合成的改性PAE与苯乙烯乳液聚合制得一种纸张增强剂改性PAE-St,探讨了各步反应的物料配比、反应时间、反应温度等影响因素,确定了改性PAE-St的最佳合成条件改性PAE与St的摩尔比为12,反应温度为60℃,反应时间为6h,引发剂用量为所有单体总质量的0.3%.比较了改性PAE-St和传统PAE对纸张的增强效果,结果表明,与传统PAE增强剂相比,改性PAE-St增强纸张的干湿强度都有所提高.     

PAE湿强剂在彩色纱管（贴面）纸中的应用

该文介绍了湿强剂聚酰胺多胺环氧氯丙烷树脂（PAE树脂）在纺织用彩色纱管（贴面）纸中的应用,研究了PAE湿强剂对不施胶纸、施胶纸、不同酸值的施胶纸和染色施胶纸的湿增强作用,同时研究了PAE湿强剂与其他助剂的共用效果,研究了PAE湿强剂用量对湿增强效果的影响.结果表明,PAE湿强剂对经过施胶具有抗水性的纸张,其湿增强效果明显.     

柔软型湿强剂的合成及应用

叙述了二乙醇胺改性聚酰胺多胺环氧氯丙烷(PAE)湿强树脂的合成,分别讨论了中间体合成的影响因素和第二步反应的影响因素,并确定了湿强剂较佳的合成条件及应用条件,明显降低了产品有机氯的含量.研究表明,二乙醇胺改性PAE树脂湿强剂较佳的合成条件:n(DEA)/{n(DEA) n(DETA)}=0.2,第二步反应温度为60℃,第二步反应时间60min,n(EPI)/n(Intermediate)为0.75;湿强剂浆料中最佳添加量为1.5%,此时纸张湿强度达35%,柔软度达0.687mN.     

改性三聚氰胺甲醛树脂提高纸张湿强度的研究

制备了一种稳定性大于6个月的醚化改性三聚氰胺甲醛树脂(MF),并研究了其对纸张强度的影响;通过红外光谱、差示扫描量热、扫描电子显微镜等对聚合物及纸张的检测结果表明,制备的改性MF湿强剂对纸张物理性能有显著增强作用,纸张湿强度保留率为24%,将其与聚酰胺聚胺环氧氯丙烷(PAE)复配应用于抄片中,不但显著提高了纸张的湿强度、干抗张强度、施胶度等性能,而且拓宽了改性MF的pH值使用范围,减少了酸用量,有利于在中性条件下抄纸.     

新型聚酰胺树脂的合成及其在造纸中的应用

PAE为活性高分子树脂,固含量越高稳定性越难控制。本文探讨一种固含量为35%PAE的制备工艺条件及与市售增强剂进行比较。实验证明选择胺酸摩尔比为1.05:1,聚酰胺预聚体催化剂的最佳用量为1.0%(对总量的摩尔比),反应温度为170℃左右,环氧氯丙烷与聚酰胺预聚体摩尔比为1.1:1,反应温度为60℃。环氧化反应后得到黏度为200～240mPa·s(涂-4杯50～60s)的聚酰胺树脂,干抗张强度优于市售PAE,湿抗张强度略低,PAE/CMC或PAE/CMS二元增强系统比单独使用PAE效果较优。     

固体碱催化亚麻籽油乙酯化反应工艺研究

制备环境友好型固体碱催化剂NaOH/膨润土,用于催化亚麻籽油乙酯化反应,得α–亚麻酸乙酯(ALA)。分别考察醇油摩尔比、催化剂用量、反应温度及反应时间等因素对酯交换反应影响,经正交实验确定制备α–亚麻酸乙酯最佳工艺条件;研究表明,当醇油摩尔比为9∶1、催化剂用量为5%、反应温度为80℃、反应时间为1.5 h时,亚麻籽油转化率最高,可达91.56%。     

聚丙烯酰胺-乙二醛聚合物用作造纸湿强剂的研究与应用

研究了聚丙烯酰胺-乙二醛聚合物(PAMG)湿强剂的合成制备条件;制备的产物在中性偏弱碱性(pH7～8)的体系中使用,表现出最佳的湿强效果;尤其适合在麦草浆等短纤维较多的浆料体系中使用;使用该湿强剂抄造的纸张在水中浸泡表现出暂时性的湿强效果;在PAE(聚胺聚酰胺环氧氯丙烷)中添加10%左右的PAMG,可以有效的提高PAE的湿强效果。     

PAE与海藻胶增强体系在纸张中的应用研究

通过利用不同黏度的海藻胶（SA）与PAE共同作用来提高纸张的干湿抗张强度,得出了与PAE共同作用的SA的最佳黏度在350mPa.s附近,并通过SA与PAE的不同用量配比得出黏度为350mPa.s的SA与PAE的较优配比为PAE：SA=3：2（PAE用量0.75%,SA用量0.5%）,此时纸张的湿抗张指数达到了43.3N.m/g,较空白纸页和单独加入0.75%的PAE所抄造纸页分别提高了43.3倍和2.5倍。然后对PAE/SA的最佳配比和最佳用量进行探讨,并通过扫描电子显微镜（SEM）对空白纸页、单独加入PAE纸页和加入PAE/SA二元体系纸页的微观结构进行了观察,结果表明加入PAE/SA二元体系可在纸页纤维表面形成明显的膜结构,从而提高纸页的湿抗张强度。最后对加填碳酸钙和滑石粉对PAE/SA二元体系的影响进行了探讨。     

高取代度羧甲基玉米淀粉制备工艺的研究

以玉米淀粉为原料,乙醇为溶剂,氯乙酸为醚化剂,研究高取代度羧甲基淀粉的制备工艺。还比较了不同淀粉、醚化剂的种类以及Na OH状态对取代度的影响。结果表明,最佳工艺为:二次加碱法,95%(质量分数)的乙醇作溶剂,淀粉乳浓度为25%,氯乙酸用量为115 g,Na OH用量为2.25(摩尔比,碱∶酸),碱化温度为40℃,碱化时间为10 h,碱化Na OH用量为1(摩尔比,碱∶酸),醚化温度为40℃,醚化时间为10 h,醚化阶段用14 g Na_2CO_3代替部分Na OH。一步法制备了取代度(DS)=1.21,反应效率(RE)=61.38%的羧甲基淀粉(CMS),非晶颗粒态淀粉的取代度比原淀粉略高,四种淀粉制备CMS取代度从高到低依次为马铃薯淀粉、木薯淀粉、蜡质玉米淀粉、玉米淀粉,氯乙酸作醚化剂时取代度远高于氯乙酸钠,固体碱制备CMS的取代度比液体碱高。     

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.