低游离甲醛脲醛树脂胶粘剂的合成研究

对低游离甲醛脲醛树脂胶粘剂的合成条件进行了探索.通过降低甲醛与尿素的摩尔比、选取合适的三聚氰胺加入量和加入时间、优化尿素分批加入比例,合成了一种低游离甲醛含量的脲醛树脂胶粘剂.结果表明,控制甲醛/尿素摩尔比为1.1,三聚氰胺加入量占尿素质量2%并在中期加入,尿素分批加入比例为60:15:25时合成的脲醛树脂游离甲醛含量在0.1%以下.该胶粘剂生产成本低,合成时间短,树脂综合性能及其胶合板的胶合性能良好.     

超低甲醛硬挺整理剂的合成及应用

研究了低游离甲醛含量脲醛树脂的合成工艺条件,采用添加三聚氰胺、聚乙烯醇和醚化的方法,对脲醛树脂进行改性,以降低游离甲醛的含量,保持其稳定性和硬挺效果.探讨了甲醛/尿素摩尔比、反应温度、pH值等因素对脲醛树脂综合性能的影响.通过FTIR、Zeta电位和SEM测定,表征了脲醛树脂的结构和性能.结果表明,经三聚氰胺和聚乙烯醇改性并醚化后的脲醛树脂,游离甲醛含量低、综合性能好.     

胶原蛋白改性脲醛树脂胶黏剂的研究

以铬鞣革屑中提取的蛋白质对脲醛树脂进行改性,目的主要是为了提高,脲醛树脂的胶接强度、降低其生产成本及其游离甲醛含量。试验表明:当蛋白质提取液与脲醛树脂1∶1混合时,可以使其胶接强度达到最大值6.95MPa,而当蛋白质提取液的加入量为脲醛树脂的1.5倍时,游离甲醛含量为0.053%,远低于国家标准的要求(0.3%)和纯脲醛树脂中游离甲醛的含量(0.385%),而此时胶接强度也达到了国家标准的要求(1.9MPa)。     

胶乳在改性脲醛树脂胶粘剂中的应用

在人造板生产中,乳液胶粘剂主要应用于人造板贴面加工.本研究主要利用胶乳对脲醛树脂进行改性,同时在脲醛树脂合成过程中加入一定数量的氧化淀粉,进一步提高改性脲醛树脂的综合性能.生产的低摩尔比胶合板用改性脲醛树脂胶粘剂具有游离甲醛含量低,预压性能好,生产工艺简单等特点,制作的胶合板胶合强度和甲醛释放量均满足国家标准要求.     

制革废弃物提取蛋白制备低甲醛高性能脲醛树脂

通过探究四种甲醛捕捉剂对脲醛树脂游离甲醛含量和黏度的影响,结果表明将制革废弃物提取蛋白和亚硫酸钠复配且质量比为1∶2时,获得脲醛树脂的游离甲醛含量为0.160%,黏度为17.2 s。此胶粘剂制备刨花板的各项物理性能均符合国家标准。制革废弃物提取蛋白和亚硫酸钠的复配能有效抑制脲醛树脂中的游离甲醛并提高其黏度,扩大了制革废弃物提取蛋白的应用。     

纳米二氧化钛改性脲醛树脂胶黏剂研究

以锐钛型纳米二氧化钛为改性剂,对脲醛树脂胶黏剂进行改性研究,以期得到低毒脲醛树脂胶黏剂的制备工艺技术。首先使用无机复合修饰的合成路线,通过改变锐钛型纳米二氧化钛的添加量、纳米二氧化钛的添加时机和甲醛与尿素(F/U)的摩尔比进行实验,研究纳米二氧化钛对脲醛树脂胶黏剂产品性能的影响。结果表明:当甲醛与尿素(F/U)的摩尔比为1.3,纳米二氧化钛在树脂反应后期加入,且加入量为尿素质量的1%,合成出的脲醛树脂性能较好,湿状胶合强度达到0.8MPa,游离甲醛含量为0.49%。该胶黏剂符合国家标准GB14732-93中对水基缩甲醛类胶黏剂甲醛的限量规定小于0.5%的要求。     

脲醛树脂胶的几点刍议

讨论了甲醛中甲醇含量对脲醛树脂胶的影响,游离甲醛的影响因素,脲醛树脂胶反应终点的控制,固化剂对脲醛树脂胶的影响等问题。     

胶乳在改性脲醛树脂胶粘剂中的应用

在人造板生产中，乳液胶粘剂主要应用于人造板贴面加工。本研究主要利用胶乳对脲醛树脂进行改性，同时在脲醛树脂合成过程中加入一定数量的氧化淀粉，进一步提高改性脲醛树脂的综合性能：生产的低摩尔比胶合板用改性脲醛树脂胶粘剂具有游离甲醛含量低，预压性能好，生产工艺简单等特点，制作的胶合板胶合强度和甲醛释放量均满足国家标准要求。     

脲醛树脂胶的几点刍议

讨论了甲醛中甲醇含量对脲醛树脂胶的影响，游离甲醛的影响因素，脲醛树脂胶反应终点的控制，固化剂对脲醛树脂胶的影响等问题。     

低毒脲醛树脂胶贮存期的研究

脲醛树脂胶是人造板及一些建筑材料生产中最常用的一种胶粘剂，具有较高的胶接强度、耐冷水性能和适当的耐热水性能等优良性能。但是。树脂中存在有害于人体健康的游离甲醛。近些年来科研工作者在探索和研究有效的生产方法以降低脲醛树脂胶中游离甲醛含量。然而。有些方法在降低脲醛树脂胶游离甲醛含量的同时却带来了脲醛树脂胶的贮存期缩短的问题。给人造板生产带来不便。本文介绍了几种生产低毒长贮存期脲醛树脂的方法，供同行参考。     

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.     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the