The Mathematical Models of the Initial Stage of the Thermal Degradation of Poly(Vinyl Chloride)

Abstract

The mathematical models of the initial stage of the thermal dehydrochlorination of PVC are proposed. It is shown that abnormal unstable fragments having constants of rates of degradation equal to 10^?3–10^?4sec^?1 have the greatest influence on the thermal degradation of PVC at 180–200°C. The groups having chlorine near tertiary carbon and chloroallylic groups may be such fragments.     

Polymeric Additives for Poly(Vinyl Chloride)

The melt and physical properties of PVC compounds and articles are strongly influenced by the morphology of the PVC. PVC powder exists as various agglomerates [l-41 wherein the primary particles are bound together as “grains” which in turn may be collected and enveloped in a “skin” in the case of the most common, suspension polymerized, PVC. We will discuss the influence on and interaction with these various PVC structures and the polymeric additives classified as processing aids, impact modifiers, and surfacealtering agents.     

Isothermal and Dynamic Thermogravimetric Degradation of Rigid and Plasticized Poly(Vinyl Chloride)/Poly(Methyl Methacrylate) Blends

The thermal degradation of rigid and plasticized poly(vinyl chloride) (PVC)/poly (methyl methacrylate) (PMMA) blends was investigated by means of isothermal and dynamic thermogravimetric analysis in a flowing atmosphere of air. For that purpose, blends of variable composition from 0 to 100 wt% were prepared in the presence (15, 30 and 50 wt%) and in the absence of di-(2-ethyl hexyl) phthalate (DEHP) as plasticizer. The thermal degradation of the blends was investigated by isothermal thermogravimetry at 180°C during 120 min. It was found that the main processes are the dehydrochlorination of PVC and depolymerization of PMMA. The dynamic thermogravimetric experiments were carried out in the temperature range of 30 ? 550°C. The results showed that the thermal degradation of rigid and plasticized PVC/PMMA blends in this broad range of temperatures is a three-step process and that PMMA exerted a stabilizing effect on the thermal degradation of PVC during the first step by reducing the dehydrochlorination.     

硬聚氯乙烯低发泡挤出成型研究

采用自由发泡挤出的方法研究了硬聚氯乙烯低发泡挤出成型的配方设计和工艺条件控制。讨论了稳定剂品种，改性剂品种和发泡剂用量对制品密度，泡孔结构以及外观表面的影响。还揭示了口模温度和螺杆转速与制品密度的关系。     

Study on the Thermal Stability and Stabilization Mechanism of a Novel Thermal Stabilizer for Rigid Poly (Vinyl Chloride)

A novel thermal stabilizer for rigid poly (vinyl chloride) has been examined. Its high stabilizing efficiency is detected by the extent of discoloration and the mass loss rate of the degraded samples when compared with some of reference stabilizers. A higher stabilizing efficiency is produced as the novel thermal stabilizer is mixed with different co-stabilizers. The study results for thermo oxidative stability of the degraded samples with novel thermal stabilizer have shown that the novel thermal stabilizer can prevent or delay the thermal oxidative degradation of PVC. A probable stabilization mechanism for the novel thermal stabilizer has been proposed.     

Effect of Processing Parameters and Vibrating Field on Poly(Vinyl Chloride) Microcellular Foam Morphology

The effects of processing parameters such as processing pressure, temperature, mixing time and rotor speed on polyvinyl chloride foams were investigated by using a novel microcellular foaming setup. The experimental results show that a proper temperature and a high pressure can promote CO₂ dissolving in polymer, which makes cell density increase and cell size decrease. Increasing mixing time and rotor speed also promote CO₂ dissolving in PVC and speed up forming single-phase polymer/CO₂ solution. The effects of oscillatory shear on polyvinyl chloride cell morphology were also studied. The combined shear improves the mixing, and thus shortens the time needed for homogeneous polymer/supercritical CO₂ solution formation. Foamed samples with the cell density of 1.0 × 10⁷–3.5 × 10⁸ cells/cm³, average cell size of 15–60 µm and bulk density of 0.6–0.87 g/cm³ had been produced.     

Synthesis of Bismuth(III)Neodecanoate and Its Application to Poly(Vinyl Chloride) as a Thermal Stabilizer

The bismuth(III)neodecanoate (Bi(Ne)₃) was synthesized via the method of co-reaction of bismuth oxide, neodecanoic acid, and acetic anhydride and then characterized by Fourier transform infrared spectroscopy (FTIR) and elemental analysis (EA). The effect of Bi(Ne)₃ as a thermal stabilizer on poly(vinyl chloride) (PVC) was assessed by thermal aging test, Congo red test, conductivity measurement, and thermogravimetric analysis, respectively. The results showed that Bi(Ne)₃ significantly provided PVC with a good initial color and long-term stability. Bi(Ne)₃ played a role in improving the stabilizing efficiency of PVC through absorbing hydrogen chloride (HCl) and displacing labile chlorine atoms in PVC molecular chains.     

The Effect of Adding Lignin to Poly(Dimethyl Siloxane)—Poly(Vinyl Chloride) Blends

A new adhesive sealant with improved mechanical properties has been prepared by blending a sealant based on poly(dimethyl siloxane)-(PDS) with poly(vinyl chloride)-(PVC) and Kraft lignin (L). During this study, California redwood was used as substrate. Two commercial primers were also used to examine their effects on the adhesion of joints. By adding a small amount of L, the modulus of the sealant based on PDS + 10% PVC is improved. The application of primers to the wood substrate has significantly improved the adhesion of PDS, PDS + 10% PVC and PDS + 10% PVC + L polyblends. Improvement in adhesion increased the stress-strain values of the joints. Statistical inference of the experimental results are also discussed.     

Peel Adhesion of Poly(Vinyl Chloride) to Nitrile Rubbers

In addition to molecular interaction and physical entanglement of the molecular chains across the interface in poly (vinyl chloride)-nitrile rubber joints, at high temperatures and long contact times interfacial chemical bonds may be formed which seem to couple the two adherends thereby resulting in cohesive failure of the rubber matrix on peeling. This is verified by performing the peel tests at high temperatures, low peel rates and under swollen conditions. Infrared spectroscopic studies of the PVC/NBR blend reveal the formation of chemical bonds at the contact temperatures studied. The peel fracture energy is found to depend on the acrylonitrile content and presence of carboxylic content in the NBR, and the presence of stabilizer and plasticizer in the PVC phase, in addition to the molding and testing conditions.     

氯醚树脂的制备及其在涂料中的应用研究进展

综述了氯醚树脂的结构和性能、合成工艺、改性方法及其在涂料中的应用研究进展,阐述了以悬浮聚合和乳液聚合制备氯醚树脂的一些方法,其中乳液聚合法既可以采用水溶性热引发剂体系也可采用氧化 -还原引发体系。目前,对溶剂型 /水性氯醚树脂的改性方法主要以丙烯酸树脂、环氧树脂及纳米二氧化硅和纳米二氧化钛等为主,改性后的氯醚树脂的性能显著提高,这拓宽了氯醚树脂的应用范围,目前主要的应用方向为防腐涂料、防污涂料、防火涂料乃至导电涂料等领域。     

抑烟剂对聚氯乙烯热分解特性的影响

采用热分析、实时傅立叶变换红外光谱等手段，研究了几种常用的抑烟剂(钼化合物和铁化合物)对聚氯乙烯(PVC)热分解特性和热氧化降解特性的影响。热失重的实验结果表明，添加抑烟剂的PVC分解后的残渣量与不含抑烟剂的PVC相比，都有所提高，尤其是含有钼酸铵、氧化钼或Fe2O3的PVC复合物。实时FTIR表明抑烟剂改变TPVC热氧化降解历程，并对C-H和C-Cl键的分解产生较大的影响。     

Modification of Poly(Vinyl Chloride) for Biocompatibility Improvement and Biomedical Application-Review

Poly(vinyl chloride) is widely used in biomedical devices. This review deals with various applications of PVC and modified PVC in the medical field. Blended, grafted, and plasma-treated modified PVCs are described for various medical applications. Plasma treatment of PVC devices is a versatile and useful method for changing the surface properties, as compared to blending and grafting.     

Thermal Behavior and Photovoltaic Performance of Fullerene Grafted Dehydrochlorinated Poly(Vinyl Chloride) in Bulk Heterojunction Solar Cells

This study describes the development of an alternative conducting polymer for organic photovoltaic cell application. Chemical structure of poly(vinyl chloride) (PVC) was modified by two reactions, dehydrochlorination followed by fullerenation. The aim of this work was to explore the feasibility of using this chemically modified PVC (C₆₀-g-DHPVC) as an electron acceptor phase in ITO/PEDOT:PSS/P3HT:acceptor/TiO_x/Al bulk heterojunction (BHJ) solar cell. From the result, it was found that the power conversion efficiency of the BHJ cell employing PCBM as an electron acceptor alone increased from 0.5% to the maximum value of 1.34%, after the addition of C₆₀-g-DHPVC.     

应变状态下徐冷玻璃态PVC老化现象研究

通过机械拉伸试验和差示扫描量热法(DSC)等手段对物理老化和应变老化的聚氯乙烯(PVC)试样进行研究。力学性能测试结果表明:应变状态下老化试样的屈服应力和弹性模量均大于物理老化试样的屈服应力和弹性模量,而断裂伸长率则相反。这说明PVC试样在应变状态下的老化导致材料脆性增加。DSC测试中,观察到应变状态下老化试样的吸热峰随着时间的增加表现在滞后于物理老化试样。这种现象可以解释为应变状态下老化试样形成了与物理老化试样不同的结构。     

ZB对无卤阻燃PVC体系性能的影响

研究氢氧化铝(ATH)对聚氯乙烯力学性能的影响,并在此基础上研究硼酸锌(ZB)对无卤阻燃聚氯乙烯体系的力学性能、阻燃性能以及电学性能的影响.结果表明:随着硼酸锌的加入,体系的力学性能先提高后降低,硼酸锌与ATH有协同阻燃抑烟作用,体积电阻率在整个过程中呈下降的趋势.     

Enhanced Thermal Stability and Flame Retardancy of Poly(Vinyl Chloride) Based Composites by Magnesium Borate Hydrate-Mechanically Activated Lignin

Journal of Inorganic and Organometallic Polymers and Materials - To improve the thermal stability and flame retardancy of poly(vinyl chloride) (PVC) based composites, magnesium borate...     

PVC/黏土纳米复合材料研究进展

文章简要概述了黏土的有机改性机理,聚氯乙烯/黏土纳米复合材料的特性及其制备方法、结构与表征方面的研究进展。对熔融插层共混法、溶液插层共混法、原位聚合法和插层聚合法进行了介绍和比较,对聚氯乙烯/黏土纳米复合材料的重点研究领域和发展趋势提出了具有前瞻性的预测。     

Alpha Relaxation Study of Poly(Vinyl Chloride Co-Vinylacetate-Co-2-Hydroxypropyl Acrylate)

By using thermally stimulated depolarization current (TSDC) technique, and coupling it with the thermal sampling (TS) method, the relaxation behavior of Poly(vinyl chloride-co-vinylacetate-co-2-hydroxypropyl acrylate) (PVVH) has been investigated in the vicinity of its glass transition temperature, T_g. The global TSDC spectra of amorphous PVVH with varying the poling field and poling temperature revealed the presence of two TSDC peaks. The first peak at about 347 K and is ascribed to the glass transition temperature and can be referred as α-relaxation. The second one is obtained in the temperature range 353–383 K and is attributed to the space charge relaxation and can be referred as ρ-relaxation. Fine structure of α-relaxation peak was obtained using the thermal sampling method. All the molecular parameters, such as activation energy (E_a) and preexponential factor (τ₀), have been estimated. In addition, the compensation law was found to be valid; and the compensation parameters such as compensation temperature (T_c) and compensation time (τ_c) have been determined.     

Thermal Degradation Studies of Poly (Amide-Ester)s

Abstract

The thermal behaviour of poly(amide-ester)s with the amide group in the side chain was studied. Polymers were sinthesized from the diphenol-amides N-(2,6-dichloro-4-nitrophenyl)-2, 2-bis(4-hydroxyphenyl)-propanamide, N-(2, 6-dichloro-4-nitrophenyl)-3,3-bis(4-hydroxyphenyl)-butanamide, and N-(2,6-dichloro-4-nitrophenyl)-4, 4-bis(4-hydroxyphenyl)-pentanamide and terephthaloyl chloride, isophthaloyl chloride and adipoyl chloride under phase-transfer conditions using several phase-transfer catalysts. The thermal decomposition temperature was influenced by both, the nature of the diacid and the length of the side chain, those derived from terephthaloyl chloride being more stable than those derived from isophthaloyl chloride and adipoyl chloride. All polymers degrade in a single-step process and the kinetics parameters were determined using the Arrhenius relationship and a computer program.     

Novel Strategy for Anhydride-Functionalization of Poly(Vinyl Chloride): Synthesis and Characterization

A new strategy for anhydride-functionalization of poly(vinyl chloride) is suggested. First, some chlorine groups of poly(vinyl chloride) were converted to phenylamine-oxy groups by a nucleophilic substitution reaction in the presence of a solvent composed of 4-aminophenol, K₂CO₃, and dry N,N-dimethylformamide at room temperature, to avoid cross-linking. The phenylamine-functionalized poly(vinyl chloride) was further reacted with maleic and 1,2,4-benzenetricarboxylic acid anhydrides. The chemical structures of all samples as representatives were characterized by Fourier transform infrared and nuclear magnetic resonance spectroscopies. The chemical compositions of the synthesized anhydride-functionalized poly(vinyl chloride) were investigated by elemental analysis, and their thermal behaviors were characterized by means of differential scanning calorimetry and thermogravimetric analyzer.