Suspension stabilizers for PVC production I: Interfacial tension measurements

The effect of commonly used suspension stabilizers on the interfacial tension of the vinyl chloride (VCM)/water interface was studied at 50°C, using the drop volume method. The measurements covered drop times from a few seconds to about 1000 s. The interfacial tension between VCM and pure water was found to be 32 mN/m. In the presence of additives, the interfacial tension varied with drop time. An equilibrium situation was probably not reached in any of these experiments. The surface activity of the poly(vinyl alcohol) increased with increasing acetate content. The interfacial tension decreased much more slowly with time in the presence of the poly(vinyl alcohol)s than with the cellulose ether tested. However, this polymer, Methocel F50, on adsorption at the interface formed a solid, mechanically strong surface film. The formation of such films was delayed by addition of ammonium laurate and/or Span 20.     

Suspension stabilizers for PVC production III: Control of resin porosity

Suspension PVC resins were prepared using dispersant systems based on a cellulose derivative, Methocel F50, and two poly(vinyl alcohol)s; Gohsenol GH20 and Rhodoviol 5/270. Ammonium laurate and Span 20 were tested as secondary dispersants. The resins were characterized by mercury porosimetry. The results showed that the porosity of the resins increased in the series Gohsenol < Methocel < Rhodoviol. This order seems to follow the order of increasing surface activity. A closer analysis of the data clearly showed, however, that porosity control in S-PVC manufacture is not due to a pure interfacial tension mechanism, not even in those cases where the dispersant systems do not contain any monomer-soluble components. Other possible mechanisms by which suspension stabilizers may affect resin porosity are briefly commented upon.     

Non-cadmium stabilizers for flexible PVC

Organo-metallic complexes containing cadmium are highly efficient heat and light stabilizers for flexible PVC. Recent toxicity studies and, more importantly, governmental reaction to these studies, places continued use of cadmium in vinyl heat and light stabilizers in possible jeopardy. The purpose of this paper is to study ways of replacing cadmium in liquid stabilizers for flexible PVC. The paper describes a practical study of stabilization using performance criteria such as static and dynamic heat stability and accelerated weathering resistance. It defines the performance of current typical-type stabilizers that contain cadmium. These will be performance-compared with non-cadmium-containing versions of the same stabilizers. Based on these results, a theory for cadmium stabilization will be developed and used in the design of a new set of noncadmium-containing stabilizers that show performance characterisitics nearly equal with the cadmium- containing stabilizers.     

Drop size distribution for spray by full cone nozzle

Experiments were carried out to measure the drop size distribution in the spray produced by a full cone nozzle. At the center of the spray the distribution has one peak that can be expressed as a logarithmic normal distribution function. However, the distribution at other part of the spray has two peaks. Here it can be expressed as the sum of two distribution functions. At the vertical distance of 50 cm from the nozzle and the radial distance of 20 cm from the center of the spray, the geometric mean diameters of the first and the second peak are 61 and 235 μm, respectively, for an injection pressure of 294 KPa. For the same condition, the logarithmic standard deviations of the first and the second peak are 2.08 and 2.40, respectively. At the same position in the spray the geometric mean diameter varies in proportion to —0.2 power of injection pressure and the logarithmic standard deviation does not depend on injection pressure.     

Drop size distribution in a graesser contactor

An investigation was conducted of drop size distribution in a Graesser contactor, employing five liquid – liquid systems, viz., kerosene/water, benzene/water, xylene/water, hexane/water and n–butyl acetate/water. A 100 mm (4 inch) diameter Graesser contactor was used for this purpose It was found that the drop size distribution in a Graesser contactor obeys the upper – limit distribution expressed as: where A correlation was developed relating the Sauter mean diameter (d₃₂) to other effective groups      

中国PVC热稳定剂生产现状及发展趋势

总结了中国PVC热稳定剂的生产现状。与世界先进水平相比,中国PVC热稳定剂还存在较大差距,主要表现在品种少、生产结构不合理、生产规模小、产业集中度低等方面;提出中国PVC稳定剂应向低毒、无污染、复合、高效等方向发展。     

聚氯乙烯生产现场的配电设计

阐述了聚氯乙烯生产现场配电设计情况,结合经验对聚氯乙烯生产现场的电气设计及安装提出了设计思路。     

Drop size distribution and mean drop size in a pulsed packed extraction column

Drop size distribution and mean drop size are used for calculation of interfacial area available for mass transfer. In this study, the drop size distribution and Sauter mean drop diameter (d₃₂) have been investigated using three different liquid systems in the absence of mass transfer in a pilot plant pulsed packed column. The drop size was measured at four different points along the active column height. Three operating variables have been studied including the pulse intensity (af) and flow rates of both liquid phases. The effect of liquid properties and height of the active column were also investigated. A combination of the pulse intensity and interfacial tension had the largest effect on the drop size distribution while none of the flow rates were of significance. The height of the column played an important role at the bottom of the active column, but the associated effect was reduced with increase of the height. Finally, a normal probability function of number density was proposed for prediction of the drop size distribution with an Average Absolute Relative Error (AARE) of 8.8% for their optimized constant. Furthermore, two correlations were presented involving height or flow rates of the two phases along with operating variables and physical properties of the liquids. These correlations had AARE values of about 8.5 and 7.8%, respectively.     

喷淋塔液滴粒径分布及比表面积的实验研究

以水和空气为实验介质,通过拍照法获得喷淋塔内液滴粒径分布,考察了不同喷淋量及空塔气速对塔内不同高度处液滴Sauter平均直径(SMD)的影响,并对液滴粒径分布进行了理论分析.结果表明,喷淋塔顶部液滴分布密集,底部稀疏,液滴群在下落过程中,平均粒径减小且趋于均匀化;塔顶处液滴SMD随喷淋量的增加而增大,处在塔中下部的液滴SMD则随喷淋量增大而减小,提高空塔气速,可减小平均粒径;理论分析认为,液滴粒径减小主要是由于发生了碰撞破碎的缘故,而塔内液滴大小不一是碰撞的主要原因;通过量纲1化拟合得到喷淋塔内液滴SMD经验关联式,其计算结果与实验值吻合较好;考虑液滴破碎的喷淋塔比表面积比不考虑破碎的比表面积大70%左右.     

Zinc maleate and zinc anthranilate as thermal stabilizers for PVC

The results of the evaluation of zinc maleate and zinc anthranilate as thermal stabilizers for poly(vinyl chloride) (PVC) are reported in this article. Calcium stearate, diphenyl isodecyl phosphite, and epoxidized soya oil were used as costabilizers. Both zinc compounds showed good stabilizing performance in static and dynamic tests, particularly at low concentrations. The best results were obtained with zinc anthranilate. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2603–2605, 2000     

PVC热稳定剂的发展趋势与锌基无毒热稳定剂技术进展

阐述了PVC热稳定剂的发展趋势与锌基无毒热稳定剂技术进展,目前实际使用的热稳定剂按主效稳定剂的不同可分为铅基、镉基、有机锡基、锑基、锌基和有机化合物基热稳定剂6类,根据现有热稳定剂体系的性能特点和目前的有关环保法规和标准,锌基和有机化合物基无毒热稳定剂是主要的发展方向,但锌基无毒热稳定剂具有更现实的推广应用价值和更大的市场空间。     

Mixed Ca/Zn thermal stabilizers for weatherable rigid PVC

Rigid PVC profiles for window frames are required to follow quality standards (usage properties and aging resistance). Our concern is to describe the role of additives and mainly thermal stabilizers on the required properties. Until recently, PVC stabilization was based on heavy metal soaps in the European PVC building industry. Though their resulting efficiency was not questioned, problems of toxicity were raised. Regarding the ecological pressure increase, numerous investigations on co-stabilizers have been carried out in order to improve the performances of mixed Ca/Zn systems. Our results show the properties of rigid profiles stabilized with Ca/Zn systems. First, the extruded profiles properties such as optical (color) and mechanical properties (impact resistance…) are shown. The aging resistance of toxic heavy metal free vinyl formulations is also studied in comparison with typical Pb/Ba/Cd. The performances achieved indicate that an opportunity to move from toxic heavy metallic stabilizers to mixed Ca/Zn systems, resulting, perhaps, in wider development of Ca/Zn stabilizing systems for food packaging and medical plastics.     

悬浮聚氯乙烯工程技术进展

简述了世界悬浮聚氯乙烯工程技术的进展情况。