改性微粒硅溶胶对草浆的助留助滤试验

本文研究了阳离子淀粉、硼改性硅溶胶用量和铝改性硅溶胶用量对改性硅溶胶与阳离子淀粉或CPAM组成不同助留助滤体系的助留助滤效果的影响。研究结果发现：阳离子淀粉／改性硅溶胶微粒体系有良好的助留助滤效果．优于一元助留助滤体系．其中硼改性硅溶胶微粒体系的助留助滤效果好于铝改性硅溶胶微粒体系。     

硼改性微粒硅溶胶的助留助滤试验

研究了剪切力和CPAM、阳离子淀粉、硼改性硅溶胶用量对硼改性硅溶胶与阳离子淀粉或CPAM组成不同助留助滤体系的助留助滤效果的影响;同时研究了硫酸铝用量、pH值及电解质用量对助留助滤效果的影响.研究结果发现:阳离子淀粉/硼改性硅溶胶微粒助留体系的抗剪切能力优于阳离子淀粉一元助留体系.阳离子聚合物/硼改性硅溶胶微粒助留助滤体系的助留助滤效果优于一元助留助滤体系,同时大大地改善了纸页的匀度.阳离子淀粉/硼改性硅溶胶微粒助留助滤体系在pH值4～8时,以及在松香施胶体系中硫酸铝用量≤3%时较为适用,该体系抗电解质干扰能力强.     

硼改性微粒硅溶胶的超滤浓缩及稳定性

选用超滤法浓缩硼改性微粒硅溶胶,在室温、操作压力3.5 kPa的条件下、选用截留相对分子质量为10000的醋酸纤维素超滤膜浓缩硼改性微粒硅溶胶,其截留率大于93%,可将硼改性微粒硅溶胶浓缩到15%~16%,并且硼改性微粒硅溶胶不易变性。实验采用阴离子及非离子表面活性剂来提高高浓度硅溶胶的稳定性,结果表明,用量0.01%的羧甲基纤维素分散效果最佳,对硼改性微粒硅溶胶的性能几乎没有影响,有利于实现商品化。     

硼改性微粒硅溶胶的研制及应用

用硼化物对硅溶胶进行表面改性，最佳的改性方案是将硼化物与硅酸钠混合形成尾料。再将未碱化、末熟化的酸性硅溶胶滴加入尾料中。n（B）：n（Si）=0．08-0．1，硼改性微粒硅溶胶体积分数约为5％。其助留助滤性能优良，与空白样相比可使浆料留着率提高2～3倍，留着率比进口的NP882提高约30％。硼改性制备的硅溶胶霞现性好，性能稳定。     

硼改性微粒硅溶胶助留助滤体系的絮聚机理

通过几种絮聚模型-DDJ动态滤水仪法、结合激光粒度仪研究絮团大小的变化以及纸张匀度的比较,发现硼改性微粒硅溶胶对浆料絮聚机理是先加入阳离子聚合物,使纤维与细小组分絮聚成较大的絮聚体,初始絮聚体受到高剪切力作用,被打散成小碎块,从而为带负电荷的硼改性微粒硅溶胶暴露出更多的链圈和链尾.硼改性微粒硅溶胶就在这些吸附于不同浆料粒子上的链圈和链尾之间,靠静电中和及与聚合物中非带电段的吸附作用,使近距离的细小碎块桥联而发生重新絮聚,形成较初始絮聚体更小、更均一、更致密的絮团网络.结果大幅度提高了细小纤维和填料的留着率,改善了浆料的滤水性.同时又获得了良好匀度的纸页.     

二氧化钛的无机改性

在一定的温度和压力条件下,采用单质硅溶解法制备用于改性的大粒径硅溶胶,利用表面包覆技术,在TiO2的表面形成致密的SiO2膜,以达到改性的目的。实验得出:在反应温度160℃,反应压力0.5 MPa,反应时间9h,硅粉用量15 g,催化剂用量0.4g的条件下制得分散良好的硅溶胶;通过硅酸钠对pH值的调节来对TiO2浆液进行预分散,并用自制硅溶胶对TiO2浆液进行无机改性,当SiO2/TiO2=3.5%,pH=8时,改性后TiO2浆液分散稳定性有极大改善。     

碱性硅溶胶改性及其对荧光黄耐光性能影响

以正硅酸乙酯(TEOS)为前驱体,氨水为催化剂制备碱性硅溶胶,采用偶联剂γ-缩水甘油醚氧丙基三甲氧基硅烷(GPTMS)对其进行改性,探讨了偶联剂用量对改性硅溶胶吸光度、粒径及其分布的影响;采用FT-IR红外光谱和热失重对改性前后硅溶胶进行分析;将改性硅溶胶整理到荧光黄染色棉织物上,对织物的耐光性能进行测试.结果表明,当n(TEOS)∶n(GPTMS)=7∶3时,改性硅溶胶的吸光度最小,粒径最小;FT-IR红外光谱和热失重分析证明了未改性硅溶胶表面有大量羟基存在,改性硅溶胶表面的羟基被GPTMS中的有机链取代;当n(TEOS)∶n(GPTMS)=7∶3时,水溶性荧光黄染棉织物经改性硅溶胶整理后耐光性提高了38%.     

铝盐改性膨润土超声波脱附研究

利用超声波对吸附硅酸盐后的铝盐改性膨润土(Si-AlMB)进行脱附,以便在生产过程中可以循环使用铝盐改性膨润土（AlMB）。通过对脱附工艺的探讨,得出最佳脱附工艺为：NaOH用量（对Si-AlMB）30 mL/g、温度60℃、超声波功率150 W的条件下处理 3 min,反应后硅的脱附率可达84.5%。通过扫描电镜、红外光谱和能谱分析对脱附物的成分进行表征发现,脱附物的主要成分为铝硅酸盐。超声波脱附时,超声波破坏了铝原子与膨润土的连接键以及铝原子与硅原子的连接键;在脱附过程中,硅元素与铝元素同时被脱附下来。     

硼酸铵掺杂硅溶胶整理真丝织物的阻燃性能

采用溶胶-凝胶法制备了纯硅溶胶和硼酸铵掺杂(硼/硅复合)硅溶胶,并将其应用于真丝织物的阻燃整理。讨论了复合溶胶体系中硼/硅摩尔比对阻燃整理后真丝织物的极限氧指数(LOI)的影响,并采用热重分析(TGA)、微型燃烧量热仪(MCC)和烟密度试验箱(NBS)等手段对整理前后真丝织物的热降解性能、热释放性能和抑烟性能进行了测试和表征。试验结果表明:当溶胶体系中的硼/硅摩尔比为12时,整理后真丝织物的极限氧指数(LOI)最高,达到了29.7%,表现出良好的阻燃性能;相比于纯硅溶胶,硼/硅复合溶胶体系能显著降低真丝织物在燃烧过程中的热释放速率、重量损失率以及烟气释放量。     

聚醚改性硅油高分子表面活性剂

近年来，有机硅材料领域的研究异常活跃。本文系统地介绍了一种有机硅材料-聚醚改性硅油高分子表面活性剂。聚醚改性硅油有五种结构类型，按照聚醚链段与硅原子的连接形式又可分为水解型和非水解型两种。它们一般是由亲水性的聚醚链段与疏水性的聚二甲基硅氧烷链段通过化学键连接而成。水解型聚醚改性硅油一般由缩合法制得，非水解型聚醚改性硅油主要通过硅氢加成、酯化反应和环氧基-聚醚反应制得。聚醚改性硅油以其优异的表面性能在皮革、纺织、造纸以及个人护理品等诸多方面具有广阔的应用前景。     

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.     

Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH₃CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH₂PO₄-20.6 mM Na₂B₄O₇ buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.