Reducing the migration of additives from plasticised poly(vinyl chloride)

This paper reports work studying the partial substitution of the commonly used plasticiser di-octyl phtalate (DOP) by the permanent plasticisers ethylene-vinyl-acetate (EVA) and acrylonitrile-butadiene-styrene (ABS) in order to reduce migration of additives initially present in poly(vinyl chloride) (PVC) stabilised with epoxidised sunflower oil (ESO). Various formulations with and without the two different permanent plasticisers were prepared. Their tensile properties were compared. Migration tests with agitation at 40°C in two food simulants (olive oil and 15% aqueous ethanol) were carried out. The mass variation of the PVC samples with time was investigated. Migration phenomena were studied by using various analytical methods such as Fourier transform infrared spectroscopy (FTIR), atomic absorption spectrometry (AAS) and scanning electron microscopy (SEM). The results showed that additives migration can be considerably reduced by partial substitution of DOP with both permanent plasticisers used. The best results were obtained with the binary system of plasticisers based on DOP:ABS (30:10).     

Some further studies on factors affecting the leaching of lead from unplasticized poly (vinyl chloride) pipes

Several extractants were used to further study the leaching rate of lead from unplasticized poly (vinyl chloride) pipes under different temperatures. The effects of the concentration of extractant and extraction time on the leaching of lead were also investigated. The results show that the complexing agent (EDTA) extracts much more lead from the pipes than other extractants. The study also shows that the extrusion temperature of the pipe affects the leaching rate of lead by tap water, nitrate, sulphate, carbonate, phosphate and EDTA. The lower rate of lead extraction is obtained from the pipe when extruded at 190°C as compared to those extruded at 170 to 180°C.     

Novel poly (vinyl chloride) matrix membrane electrodes for the determination of phenolic pollutants in waste water

The construction and electrochemical response characteristics of poly (vinyl chloride) matrix membrane sensors for seven phenolic compounds (phenol, o-cresol, p-cresol, p-chlorophenol, o-nitrophenol, alpha-naphthol and beta-naphthol) are described.The membranes incorporate ion association complexes of these seven phenolic anions with phenanthroline-iron(II) as electroactive materials.These sensors show linear response for phenol, o-cresol, p-cresol, p-chlorophenol, o-nitrophenol, alpha-naphthol, and beta-naphthol over wide concentration ranges, with an average anionic slope 54.3 mV per concentration decade.The suggested sensors exhibit fast response time (1 min), low determination limits (1 x 10(-5)M), good stability (2-3 weeks), reasonable selectivity to phenolic compounds in the presence of other water pollutants. The average percentage recovery was 99.78+/-0.088 for individual phenolates and 99.61+/-0.198 for phenolates in mixtures.The investigated sensors were successfully used for direct potentiometric determination of traces of these phenolic compounds in wastewater samples. Results with mean accuracy of 99.74+/-0.29%, 99.82+/-0.36%, 99.65+/-0.47%, 99.73+/-0.37%, 99.77+/-0.30%, 99.86+/-0.31% and 99.91+/-0.22% was obtained for the seven sensors, respectively.These results were compared with data obtained using the British pharamacopial method (The British Pharmacopoeia, Her Majesty's Stationary Office, London, 1993) and others (Clarke's Isolation and Identification of Drugs in Pharmaceuticals Body Fluids and Post-mortem Materials, 2nd Edition, The Pharmaceutical Press, London, 1998).     

聚醋酸乙烯/聚乙烯醇体系的吸水自膨胀性研究

聚醋酸乙烯(PVAc)在碱性条件下可部分或全部水解为聚乙烯醇(PVA)，利用PVA的吸水性，控制水解条件，可制得适用于各种变形缝、伸缩缝、管道接头防水密封的PVAc／PVA吸水自膨胀材料：PVAc／PVA吸水后体积膨胀率达10％～100％，讨论水解条件对其吸水体积膨胀率的影响。     

色谱法测定氯乙烯单体的探讨

随着人们生活质量的提高，高档的室内装饰装修越来越多的采用新型材料，聚氯乙烯卷材地板（又称聚氯乙烯地板革）常用于室内装饰。为保护人体健康，限制有害物质含量，改善相应的室内环境，我们根据GB１８５８６－２００１《室内装饰装修材料聚氯乙烯卷材地板中有害物质限量》对以聚氯乙烯树脂为主要原料并加入适当助剂的聚氯乙烯地板聚氯乙烯复合铺炕革，聚氯乙烯车用地板中的氯乙烯单体进行分析。一、实验部分１．试剂与材料（１）氯乙烯：纯度大于９９．５％．（２）N，N－二甲基乙酰胺（DMAC）：在测试条件下不含氯乙烯的色谱保留时…     

Comparative study of the uses of poly(4-vinylpyridine) and poly(diallyldimethylammonium) chloride for the removal of perchlorate from aqueous solution by polyelectrolyte-enhanced ultrafiltration

An application of polyelectrolyte-enhanced ultrafiltration utilizes cationic polyelectrolytes to electrostatically bind anionic species. The colloid and target anion are then concentrated using an ultrafilter, producing a filtrate with a lower concentration of the target. This study compared the performances of poly(4-vinylpyridine) (P4VP) and poly(diallyldimethylammonium) chloride (PDADMAC) for the removal of perchlorate. Potentiometric titration data revealed that the ionization properties of P4VP in aqueous solution vary as functions of titrant utilized, degree of protonation, and counterion concentration. The greater affinity of perchlorate over chloride for the protonated pyridine residues of P4VP provided up to 95.8% retention of perchlorate under the solution conditions investigated. Through ultrafiltration experiments, the effects solution pH, counterion concentration, and polymer concentration were examined for both P4VP and PDADMAC. In addition, the effectiveness of P4VP recovery and reuse was also assessed.     

Studies on vinyl chloride migrating into drinking water from polyvinyl chloride pipe and reaction between vinyl chloride and chlorine

To determine the conditions for the migration of vinyl chloride monomer (VCM) into water from polyvinyl chloride (PVC) pipes and to examine the reaction between VCM and the chlorine present in drinking water, we studied the migration of VCM into water. It was found that migration of VCM into water from PVC pipes (containing 29.5 ppm VCM) could only be detected by using an apparatus that prevented volatilization of VCM and increasing the surface area of the pipe wall in contact with the water. The amount of VCM which could undergo action of the chlorine in the water decreased markedly with the age of the pipes and when the pH was lowered. VCM occurred in the water was converted to chloroacetaldehyde, chloroacetic acid, etc., by its reaction with chlorine, while the amounts of these reactants varied with pH of the solution was changed.     

浅论火灾烟气流速的测试方法

通过对几种典型的流速测试方法进行比较 ,提出采取双向式流速测试探头测试是目前较为理想的火灾烟气流速的测试方法 ,并对其测试原理、修正方法、误差分析等作了具体介绍。     

Modification of poly(vinylidene fluoride) ultrafiltration membranes with poly(vinyl alcohol) for fouling control in drinking water treatment

A commercial poly(vinylidene fluoride) flat sheet membrane was modified by surface coating with a dilute poly(vinyl alcohol) (PVA) aqueous solution followed by solid-vapor interfacial crosslinking. The resulting PVA layer increased membrane smoothness and hydrophilicity and resulted in comparable pure water permeation between the modified and unmodified membranes. Fouling tests using a 5 mg/L protein solution showed that a short period of coating and crosslinking improved the anti-fouling performance. After 18 h ultrafiltration of a surface water with a TOC of approximately 7 mg C/L, the flux of the modified membrane was twice as high as that of the unmodified membrane. The improved fouling resistance of the modified membrane was related to the membrane physiochemical properties, which were confirmed by pure water permeation, X-ray photoelectron spectroscopy, and contact angle, zeta potential and roughness measurements.     

Flame Retardance and Smoke Suppression of Poly(vinyl chloride) Using Multicomponent Systems

Metal-based organic complexes (MBO) are a class of FRSS additives that comprise a transition metal and an organic ligand that cleaves at an elevated temperature thereby releasing the metal in a reactive state. They help in the formation of char and thus act as an effective smoke suppressant. Use of MBO complexes as flame retardant smoke suppressants, phosphate ester as a flame retardant and active filler as endothermic material is reported here as multicomponent FRSS systems. MBOs used in the present study are the chelates of pentanediono. They were used alone as well as in combination with aluminum trihydrate (ATH) as filler were used to impart flame retardancy and smoke suppression to poly vinylchloride. Their performance was measured in terms of flammability, smoke generation, char formation and evolution of combustion gases. MBOs of molybdenum and chromium were found to be very efficient flame retardant smoke suppressants.     

Equilibrium dialysis and ultrafiltration investigations of perchlorate removal from aqueous solution using poly(diallyldimethylammonium) chloride

Use of perchlorate salts in military activities and the aerospace industry is widespread. These salts are highly water-soluble and are, to a large extent, kinetically inert as aqueous species. As a groundwater contaminant, perchlorate is now being detected in an increasing number of locations and is believed to interfere with the uptake of iodide by the thyroid, which can result in decreased hormone production. The United States Environmental Protection Agency (US EPA) has established a reference dose for perchlorate of 0.0007 mg/kg/day, which translates to a drinking water equivalent level of 24.5 ppb. This study investigated the application of polyelectrolyte-enhanced ultrafiltration (PEUF) for the selective removal of perchlorate from aqueous solution through equilibrium dialysis and ultrafiltration experiments. Using poly(diallyldimethylammonium) chloride, the effectiveness and efficiency of PEUF in the removal of perchlorate from other aqueous solution components was investigated by testing parameters such as polyelectrolyte concentration, pH, and ionic strength. Removal of perchlorate from synthetic groundwater initially containing 10.3 ppm perchlorate and also containing chloride, sulfate, and carbonate was also examined. Perchlorate separations of greater than 95% were achieved, even in the presence of 10-fold excesses of competing ions.     

Correlation of gravimetric smoke measurement by the arapahoe chamber with optical smoke measurement by the NBS chamber for flaming combustion

The relationship between the optical density and the particulate mass concentration of fire smoke is further developed. A correlation is obtained for relating gravimetric determinations made with the Arapahoe Smoke Chamber to light transmission measurements made with the NBS chamber. The correlation is particularly good for plastics, but less satisfactory for wood. Possible explanations for the latter deficiency are proposed.     

A combination of damage locating vector method (DLV) and differential evolution algorithm (DE) for structural damage assessment

In this study, a two-stage method is presented for identifying multiple damage scenarios. In the first stage, the damage locating vector (DLV) method using normalized cumulative energy (nce) is employed for damage localization in structures. In the second stage, the differential evolution algorithm (DE) is used for damage severity of the structures. In addition, in the second stage, a modification of an available objective function is made for handing the issue of symmetric structures. To verify the effectiveness of the present technique, numerical examples of a 72-bar space truss and a one-span steel portal frame are considered. In addition, the effect of noise on the performance of the identification results is also investigated. The numerical results show that the proposed combination gives good assessment of damage location and extent for multiple structural damage cases.     

火灾烟气生成量的实验测量及其工程计算方法

介绍了火灾烟气生成量的四种实验测量方法——直接测量法、燃烧产物取样分析法、速度温度的点式测量法以及速度矢量的LDV/PIV全场测量法,并给出了几种常用的火灾烟气生成量的工程计算方法及其所基于的羽流模型。讨论了受限火羽流(墙边羽流和墙角羽流)质量流量与非受限轴对称火羽流质量流量之间的关系。指出了其中有待进一步研究的问题。     

现场检测烟雾计量技术研究

概述了点型感烟火灾探测器灵敏度现场检测的必要性,经过大量的实验和测试工作,解决了现场检测用标准烟源和小尺寸光学密度计量两项关键技术,为开发点型感烟火灾探测器灵敏度现场检测设备提供技术支持。     

海藻酸-羧甲基壳聚糖/聚乙烯醇水凝胶的制备及对蛋白药物释放的探讨

以牛血清白蛋白(BSA)为模型药物,制备了海藻酸-羧甲基壳聚糖(CMCS)/聚乙烯醇(PVA)复合水凝胶,考察了海藻酸水凝胶微球的粒径和微球在水凝胶基质中的分散性,分析了复合水凝胶基质的结构、溶解分数以及水凝胶在不同pH值下的溶胀率和药物释放。结果表明,药物的累积释放率(CR)随pH值的升高而升高,当pH值为1.2时CR为32%,当pH值为6.8时CR为53%,当pH值为8.0时CR达到70%,表明该复合水凝胶的释药性能受pH值的影响较大。     

A method of extracting smoke from buildings using a water-air jet pump

The authors present a theory that predicts the performance of a water-air jet pump having a high air to water volume flow ratio and describe an experiment using such a system. They also discuss the application of such a system to the removal of smoke and gases from buildings.     

Synergistic effects of inorganic tin compounds and Sb2O3 on thermal properties and flame retardancy of flexible poly(vinyl chloride)

The effects of inorganic tin compounds such as zinc hydroxystannate (ZHS), tin dioxide (SnO₂), and tin monoxide (SnO), Sb₂O₃, and their mixtures on the flame retardant and smoke suppressant properties of flexible poly(vinyl chloride) (PVC), and their flame retardant and smoke suppressant actions, were studied using the limiting oxygen index (LOI) test, the smoke density rating (SDR) test, thermogravimetric analysis/differential thermogravimetry/differential thermal analysis (TGA/DTG/DTA), scanning electron microscopy (SEM), and quantitative analysis. The results showed that the incorporation of small amounts of inorganic tin compounds and their mixtures with Sb₂O₃ can increase the LOI of PVC and decrease the SDR during combustion. Partial replacement of Sb₂O₃ in flexible PVC by ZHS resulted in a significant synergistic improvement in flame retardant behavior. TGA/DTG/DTA, SEM, and quantitative analysis showed that ZHS acts as a flame retardant in the solid phase, Zn²⁺ can catalyze dehydrochlorination of PVC and promote early cross-linking, leading to rapid charring, and Sn⁴⁺ can react with the char, thereby increasing the char stability. These actions, combined with the vapor-phase role of Sb₂O₃, can significantly enhance the flame retardancy of PVC.     

Smoke reduction from polyvinyl chloride (PVC)

Understanding the problem implicit in the title of this paper requires knowledge of the pyrolysis and combustion of the polymer itself, and also of its side compounds in the material and chiefly the plasticizers. These processes are now partly known and reasonably well understood, and the main points of our knowledge are stressed here. Although a very large number of additives have been proposed as smoke suppressors, little is known about their precise action. They probably react with HCl and air, and then they may be only precursors of active species. It is suggested that these active species may be either catalysts of intermolecular reactions during pyrolysis, which change the composition of the fuel to be burnt outside the material and reduce it to produce more char, or oxidation catalysts which cause the combustion of the char directly to CO and CO₂. Dynamic experiments lead to a more scietific approach to the phenomena and, further, give results that can be compared in favourable cases with those of semi-natural scale tests.     

对射式光束感烟探测器6424（A）的调试及改进

介绍了使用绿色激光笔这一简单的辅助工具对对射式光束感烟探测器6424(A)进行调试的方法,以及对对射式光束感烟探测器使用过程中的故障防御及设备保护上提出了改进的方法.