核壳型氟化阳离子表面施胶剂的制备及应用

以苯乙烯、丙烯酸丁酯、甲基丙烯酸十二氟庚酯等为原料,不使用有机溶剂及乳化剂,采用自制阳离子聚合物为分散剂合成了核壳型氟化表面施胶剂(FAE).用IR、TEM、纸张物理性能检测等手段对聚合物结构、乳液粒子形态以及应用性能进行了表征.结果表明,以m(氧化淀粉):m(FAE)=85:15的施胶液进行表面施胶,当其施胶量为1.5 g/m2时,可使纸张的吸水性(cobb法)和表面强度分别达到29.9 g/m2和2.97 m/s,抗张指数和耐破指数分别达到58.8 N·m/g和2.76 kPa·m2/g.乳胶粒子呈球形,粒径分布均匀.     

丙烯酸酯聚合物表面施胶剂的合成与应用

采用种子半连续法乳液聚合工艺,以十六烷基三甲基氯化铵(CTAC)和壬酚基聚氧乙烯醚(OP-10)复配作为乳化剂,选用甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)和丙烯酸-β-异辛酯(2-EHA)为单体,经偶氮二异丁基脒盐酸盐(AIBA)引发上述单体的自由基乳液共聚反应,以制备一种阳离子型丙烯酸酯聚合物表面施胶剂。采用傅里叶红外光谱(FT-IR)和示差扫描量热分析仪(DSC)对聚合物进行表征;以马尔文粒度仪和透射电子显微镜(TEM)研究聚合反应中各种因素对乳液聚合的稳定性、聚合物乳胶粒子的粒径及其分布、乳胶粒子的形态结构的影响;通过扫描电子显微镜(SEM)、表面张力仪和Cobb值测定仪对采用该乳液表面施胶前后纸张的表面形貌、静态接触角以及抗水性进行观察和测试。研究结果表明,当AIBA用量为单体总量的1.6%、DMC用量为单体总量的5.0%以及2-EHA用量为单体总量的15.0%时,自制聚合物乳液的表面施胶效果最佳。     

含氟丙烯酸酯乳液表面施胶剂的制备与应用

以甲基丙烯酸六氟丁酯(FMA)、醋酸乙烯酯(VAc)、丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)为单体,采用种子乳液聚合法制备了一种能够明显提高纸张施胶效果的含氟聚丙烯酸酯乳液。分析了FMA用量对该乳液的性能影响,测定了乳胶膜的对水接触角和吸水率。试验结果表明,用含氟聚丙烯酸酯乳液与淀粉复配进行表面施胶,当其施胶量为1.5g/m2时,可使纸张表面强度增强的同时大大提高纸张的施胶度。     

无皂苯丙聚合物/AKD乳液表面施胶剂的制备与应用

以甲基丙烯酸(MAA)、苯乙烯(St)、丙烯酸丁酯(BA)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)为单体,通过无皂乳液共聚反应制备了一种两性聚合物乳液表面施胶剂(ASAP)。以其为分散稳定剂制备了ASAP/AKD乳液表面施胶剂。以质量分数为0.15%的ASAP/AKD、质量分数为5%氧化淀粉表面施胶液,施涂量为1.2g/m2,对草木混合浆抄造纸张进行表面施胶,施胶度达113s。在ASAP/AKD乳胶质量分数为0.20%时,能显著改善纸张表面强度,耐折度、环压指数分别提高71.4%和40.7%。     

SAE聚合物表面施胶剂的制备及应用

以苯乙烯、丙烯酸丁酯、丙烯酸甲酯、丙烯酸异辛酯、甲基丙烯酸羟乙酯、甲基丙烯酸羟丙酯等为主要原料．采用半连续滴加聚合技术制备了阴离子苯乙烯丙烯酸酯共聚物乳液。单独使用该乳液作为表面施胶剂对纸张进行表面施胶,探讨了表面施胶剂用量、施胶温度、干燥温度等条件对纸张的强度和抗水性能的影响．实验结果表明：用自制表面施胶剂对纸张施胶后可使纸张获得良好的抗水性能和物理强度,当表面施胶剂用量为5％、施胶温度为50℃、施胶后干燥温度在80℃以上时,表面施胶后纸张的各项性能指标达到最佳。     

含氟丙烯酸酯乳液的制备及其用作纸张防油剂的研究

以甲基丙烯酸十二氟庚酯(FM),丙烯酸丁酯(BA)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)、N-羟甲基丙烯酰胺(NMA)为原料.制备了自乳化阳离子含氟丙烯酸酯多元共聚物乳液.将w(DMC)=10%、软硬单体比例n(BA)/n(FM)=1.1、w(NMA)=5%时所合成的乳液以质量分数5%进行表面施胶,施胶量为1.2 g/m2时,抗油渗透时间为62 min,表面强度达4.3 m/s.并通过红外光谱(FT-IR)、差示扫描量热(DSC)和透射电镜(TEM)等埘乳液性能和共聚物结构进行了表征.结果表明,共聚物玻璃化转变温度为50%左右,乳液粒子呈规则球形,乳胶粒平均粒径为96～102 nm.     

苯乙烯-马来酸酐作分散剂的丙烯酸酯聚合物表面施胶剂的制备及应用

用溶液聚合法制备了苯乙烯-马来酸酐(SMA)共聚物,经氨水水解,得到水溶性高分子分散剂。以此作为高分子分散剂与苯乙烯(St)、丙烯酸(AA)、丙烯酸丁酯(BA)和丙烯酸羟乙酯(HEA)进行无皂乳液聚合制备出丙烯酸酯聚合物表面施胶剂。应用实验表明,单独使用进行表面施胶后的纸张有良好的抗水性能,施胶后的纸张施胶度可达120s,其抗张强度、耐破度、耐折度和环压强度分别可以提高21%、12.5%、26%和12.3%。     

纳米SiO2/苯乙烯-丙烯酸酯树脂纸张增强剂的制备及其应用

以含双键的纳米二氧化硅粉体与丙烯酸酯类单体通过原位无皂乳液聚合合成了表面施胶增强剂。材料的力学性能和耐水性均好,其中拉伸强度最高可达5.5 N.mm-2,断裂伸长率可达到102%;耐水性最低为12.5%。FT-IR分析表明,表面含双键的纳米SiO2(RNS-D)作为反应单体参与聚合反应,实现了聚合物-无机之间的化学键合,两者复合达到分子水平。应用结果表明,杂化材料用作纸张表面施胶增强剂不仅提高了纸张强度,还使纸张的施胶度得到了提高,在杂化材料用量为1%时抗张强度提高16.1%,拉毛强度提高30.4%,施胶度可达65 s。杂化材料与淀粉施胶剂复配有联合增效作用。     

麦草浆的含氟PUA中性胶湿部应用研究

用自制的阳离子含氟聚氨酯-丙烯酸酯复合乳液(PUA)作为中性施胶剂,研究了其在漂白麦草浆中的湿部应用,重点探讨了醋酸锆(ZA)、羧基丁苯胶乳(CSBL)、阳离子淀粉(CS)、硫酸铝(AS)、聚酰胺多胺环氧氯丙烷(PAE)和阳离子聚丙烯酰胺(CPAM)等6种助留剂对阳离子含氟PUA中性施胶剂施胶效果的影响。结果表明,在中性条件下,PAE和CS的助留效果最好:该施胶剂能够使纸张抗张指数提高24.08%、透气度降低18.07%;同时,还讨论了施胶顺序、pH和碳酸钙用量等湿部因素对施胶效果的影响。     

苯丙表面施胶剂的合成及应用

以马来酸酐、聚乙二醇1000、氯磺酸和氢氧化钠为原料制备了反应型乳化剂马来酸聚乙二醇酯硫酸钠(MP),然后以MP、苯乙烯、丙烯酸丁酯、丙烯酰胺和甲基丙烯酰氧乙基三甲基氯化铵为原料,以过硫酸铵为引发剂,制备了苯丙表面施胶剂。以FT-IR和TEM对合成的表面施胶剂进行了结构表征,FT-IR分析表明苯丙表面施胶剂具有预期的共聚物结构;TEM分析显示其乳液微粒呈球形,微粒直径约为145 nm。对比自制苯丙表面施胶剂和十二烷基苯磺酸钠(SDBS)/OP-10形成的乳胶膜的耐水性(自乳胶膜形成后15天测试2种乳胶膜的吸水率分别达到19.1%和44.2%)可知,自制苯丙表面施胶剂形成的乳胶膜具有很好的耐水性。与未施胶纸及采用市售产品和进口产品进行表面施胶的双胶纸相比,利用自制苯丙表面施胶剂和表面施胶淀粉复配对双胶纸进行表面施胶后的纸张的抗水性能和强度性能明显提高。     

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.     

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.     

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.     

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.     

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.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.     

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.