Chlorinated polyethylene modification of blends derived from waste plastics Part I: Mechanical behavior

Recycling of waste plastics as a blend of generic types is attractive since a difficult separations problem is avoided. However, blends of incompatible polymers are frequently very brittle and cannot be considered for many applications. Additives which modify the blend to give it ductility may provide a solution to this problem. Chlorinated polyethylene (CPE) made by a slurry process has been suggested for this application by Schramm and Blanchard. Further documentation of the effectiveness of this approach is given here. Addition of CPE to such a blend generally increases the elongation at break and the energy to break very dramatically with ordinarily some loss in strength and modulus. This approach works most effectively in blends of high polyethylene and poly(vinyl chloride) content. Three grades of CPE were studied here which revealed that the specific structure of the CPE molecule is a factor. The effectiveness of CPE for blend modification is believed to derive from the graded molecular structure acquired during chlorination.     

Study of poly(vinyl chloride) blends with solid‐state chlorinated polyethylene

The influence of solid‐state chlorinated polyethylene of various chlorine content and residual crystallinity on the mechanical properties of rigid poly(vinyl chloride) has been studied. The impact strength of poly(vinyl chloride) was found to increase significantly as 10–20 mass% chlorinated polyethylene, containing from 10.2 to 27.3% chlorine content (preferably 21.8% Cl) were added. This dependence corresponded to the higher elasticity and impact strength of the solid‐state chlorinated polyethylene with chlorine content below 30% as well as the microstructure of its chlorinated block fragments. Multicomponent system of high impact strength and good flowability, consisting of poly(vinyl chloride), chlorinated polyethylene, hydroxyl‐terminated polybutadiene, and ethylene–propylene–ethylidenenorbornene terpolymer was also obtained. Regardless of the incompatibility between the polymer components of this blend, the similarity in the chemical nature of poly(vinyl chloride) and chlorinated polyethylene blocks on one hand, and the methylene sequences in the chlorinated polyethylene and elastomers on the other, resulted in the formation of an efficient interfacial layer. The changes in the structure of the blends were established by both calorimetric and microscopic studies. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2602–2613, 2006     

利用规整接枝共聚物作为增容剂制备耐油热塑性弹性体

通过大单体技术合成了三种现整接校共聚物；主链为聚甲基丙烯酸及支链为甲基丙烯酸甲酯的接枝共聚物（ＰＭＡＡ－ｇ－ＰＭＭＡ）可用作氨醇橡胶与聚氯乙烯的熔融共混的增容剂，而主链为聚丙烯酰胺、支链为聚苯乙烯的接校共聚物（ＰＡＭ—ｇ－ＰＳ）及主链为聚甲基丙烯酸甲酯、支链为聚苯乙烯的接枝共聚物都能作为氯化聚乙烯与聚苯乙烯共混的增容剂。用量仅占２％即可制得耐油的热塑性共混物弹性体。     

The effect of plastic addition on coal caking properties during carbonization

The recycling process of waste plastics using coke ovens is now being studied. The effect of plastic addition on coal caking property was investigated. It was revealed that thermal decomposition products of plastics interacted with bituminous coal during carbonization in coke ovens. The effect of plastic addition on coal caking property varied with types of plastics. The addition of aliphatic polymers such as polyethylene (PE), polypropylene (PP) and poly(vinyl chloride) (PVC) had only a small effect on coal caking property and coke strength and in some cases PE addition increased coke strength. On the other hand, the addition of polystyrene (PS), poly(ethylene terephthalate) (PET) and terephtalic acid (TFA) inhibited coal expansion and fusion, decreased maximum fluidity and total dilatation, and deteriorated the coke strength. These differences were discussed from the viewpoint of the interaction between thermal decomposition products of plastics and hydrogen in coal. It was suggested that the radical formed as a result of PS or PET thermal decomposition abstracted hydrogen from coal, which resulted in the decrease in coal caking property.     

Thermoplastic composites from maleic anhydride modified post-consumer plastics

In attempts to identify potential applications for refined commingled postconsumer plastics, a feedstock containing about 80% polyethylene (PE) and lesser amounts of poly(ethylene terephthalate) (PET), polystyrene (PS), polypropylene (PP), and poly(vinyl chloride) (PVC) was modified through functionalization with maleic anhydride in a co-rotating intermeshing twin-screw extruder. The modified and unmodified blends were compounded with various fillers and reinforcements such as glass fibers, mica flakes, talc, and calcium carbonate. Injection molded composites based on the modified matrix had, in general, superior mechanical and thermal properties. These findings are discussed in view of the improved adhesion resulting from reactions and/or enhanced polar interactions at phase boundaries. Several compounds prepared in this work had overall property data comparable to, or approaching those, of equivalent commercial HDPE molding compounds that are commonly used in “durable” applications.     

Interphase effects in polymer-modified hydraulic cements

Earlier work has indicated the importance of interphase adhesion within these systems. The work here reported shows that, with reactive polymers, substantial chemical modification occurs at the surface of the polymer latex particle. With certain polymer types, such as polyethylene and polystyrene homopolymers, no evidence is found of such reactions; with others, such as poly(vinylidene chloride, vinyl chloride) and poly(ethyl acrylate, methyl methacrylate), substantial reaction occurs. Crosslinking and insolubilization frequently accompany these reactions, and the nature of the polymer is significantly altered.     

Catalytic degradation and dechlorination of PVC-containing mixed plastics via Al-Mg composite oxide catalysts

A alumina-magnesium composite oxide catalyst (Al-Mg) was synthesized for catalytic degradation of poly vinyl chloride (PVC) containing polymer mixtures, i.e. polypropylene (PP)/PVC, low-density polyethylene (LDPE)/PVC, polystyrene (PS)/PVC, and LDPE/PP/PS/PVC. In the catalytic degradations the Al-Mg composite oxide catalyst accelerated the rate of polymer degradation and lowered the carbon distribution of liquid products. In addition, it showed good effect on the fixation of evolved HCl and greatly decreased the chlorine content in the oil. These results suggested that the Al-Mg composite oxide catalyst can be effectively used for catalytic degradation and dechlorination of PVC-containing mixed plastics.     

Applications of polymer blends: Emphasis on recent advances

In the past decade, polymer blend technology has achieved an important position in the field of polymer science. With increased academic and industrial research interest, the application of polymer blend technology to commercial utility has grown significantly. This review on the applications of polymer blends will cover the major commercial blends in the categories of styrene-based polymer blends, poly(vinyl chloride) blends, polyacrylate blends, polyester and polycarbonate blends, polyolefin blends, elastomer blends, polyelectrolyte complexes, and interpenetrating polymer networks. New developments in polymer blend applications will be discussed in more detail. These systems include linear low-density polyethylene blends with either low- or high-density polyethylene, styrenemaleic anhydride terpolymer/ABS (acrylonitrile-butadiene-styrene) blends, polycarbonate/poly(butylene tetephthalate) blends, new PPO/polystyrene blends, and tetramethyl bisphenol A polycarbonate/impact polystyrene blends. Areas for future research to enhance the potential for polymer blend applications will be presented. The need for improved methods for predicting miscibility in polymer blends is discussed. Weldline strength is a major property deficiency of two-phase systems (even those with mechanical compatibility), and future research effort appears warranted to resolve this deficiency. The use of polymeric compatibilization additives to polymer blends has shown promise as a method to improve mechanical compatibility in phase-separated blends, and will be expected to be the subject of future research programs. Finally, the reuse of polymer scrap is discussed as a future application area for polymer blends. Unique applications recently proposed for polymer blends include immobilization of enzymes, permselective membranes, reverse osmosis membranes, selective ion-exchange systems, and medical applications using polyelectrolyte complexes.     

Peroxide modification of a multicomponent polymer blend with potential applications in recycling

A mixture of seven immiscible “virgin” plastics, namely low and high density polyethylene (LDPE and HDPE), polypropylene (PP), polyvinyl chloride (PVC), crystal and high impact polystyrene (PS and HIPS), and polyethylene terephthalate (PET), in proportions representative of those currently found in post-consumer plastics containers, was compounded in a corotating twin-screw extruder. The mechanical properties of the blend were improved through the addition of relatively high concentrations of a dialkyl peroxide which was also found to drastically affect the blend morphology. The results are interpreted in terms of improved dispersive mixing favored by the similarity in the rheological behavior of the modified blend components, improved physical properties of certain blend components upon peroxide modification, and, possibly, enhanced intefacial adhesion. © 1994 John Wiley & Sons, Inc.     

Reactive extrusion of poly(vinyl chloride) compounds with polyethylene and with ethylene-vinyl acetate copolymers

The mechanical properties of poly(vinyl chloride)/polyethylene blends can be improved by a reactive extrusion process in the presence of an organic peroxide and a coupling agent. With a judicious loading of dibenzoyl peroxide and triallyl isocyanurate coupling agent, such blends generally exhibit significantly greater ultimate tensile strengths and dynamic moduli. The nature of the sample posttreatment after compression molding is shown to have a major impact upon the relative magnitude of these differences. Evidence is also presented to suggest that such improvements result from a superior physical interlocking between blend components, rather than through the formation of co-crosslinked graft segments (which would, presumably, impart a compatibilization effect). Similar extrusion trials with a poly(vinyl chloride)/poly(ethylene-stat-vinyl acetate) mixture revealed a general worsening of material properties with increasing dibenzoyl peroxide levels. These observations can be rationalized by examination of the degradation reactions that likely occur in these reacting systems.     

The stability of blends of incompatible thermoplastics

Conventional thermodynamic reasoning would predict that it would be very difficult to melt blend incompatible polymers and that if such blends were made they would be highly unstable and would phase separate upon heating. A method has been developed to melt blend incompatible polymers (such as poly(methylmethacrylate) and polyethylene) to form two continuous interpenetrating phases and that upon prolonged heating the stability of the structure is increased rather than decreased.     

湿法磷酸生产中常用的非金属材料：Ⅰ．热塑性塑料

介绍部分热塑性塑料在湿法磷酸中的应用情况。重点介绍了以聚氯乙烯、聚乙烯、聚烯烃、聚丙烯、聚四氟乙烯为代表的热塑性塑料的性能;结合多年的使用经验,提出了在湿法磷酸各部位的热塑性塑料的选用意见。     

Rheology of solvent-cast polymer films

This paper describes and analyzes the results of an experiment where various thin polymeric films are continuously sheared between smooth glass substrates. The shear force per unit area has been measured as a function of mean uniaxial stress and temperature using representative “good” and “poor” casting solvents followed by a range of heat treatments. The polymers studied include high density polyethylene, polybisphenol-A–carbonate, poly(ethylene terephthalate), atactic polystyrene, isotactic polystyrene, atactic poly(methyl methacrylate), isotactic poly(methyl methacrylate), poly(vinyl acetate), poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(vinyl chloride), and polytetrafluoroethylene. The results indicate that the casting solvent has a very pronounced influence upon the rheology of the film. The casting solvents may apparently confer either ductile or brittle failure in the film and also influence the nature of the temperature and pressure dependence of the shear stress. The data have been analyzed using Eyring theory and also by reference to relevant published literature on the influence of solvent and thermal treatments on the morphology and deformation behavior of polymers. “Good” solvents generally tend to promote a brittle mode of failure with little temperature dependence. The same type of solvents also produced films which have higher shear strengths and show greater increases in shear strength with pressure. These data are adequately rationalized using free volume and entanglement notions.     

建筑塑料的增韧改性研究进展

综述了聚氯乙烯、聚丙烯、聚苯乙烯等常用建筑塑料的增韧改性研究进展，讨论了橡胶和热塑性弹性体共混增韧、刚性无机粒子增韧以及共聚、交联等化学增韧的方法和特点。     

聚合物共混物的红外光谱研究

采用傅立叶变换红外光谱（FTIR）技术，同时将谱图进行归一化处理，通过合谱共混谱研究了氯丁橡胶（CR）／聚氯乙烯（PVC）和CR／聚苯乙烯（PS）两个二元聚合物共混体系的相容性，结果表明，CR与PVC所组成的共混物中组分矣合物红外光谱特征吸收谱带发生较大位移，表现出较强的相互作用，CR与PS所组成的共混物的红外吸收特征峰发生了较小偏移，同时特征峰形略有变化，说明有较弱的相互作用。     

Compatibilization of commingled plastics with maleic anhydride modified polyethylenes and ultraviolet preirradiation

The improvement of the properties of commingled plastics was carried out with a prototype blend of Mexican municipal plastic waste with and without poly(vinyl chloride) (PVC). Compatibilizing agents such as high‐density, low‐density, and linear low‐density polyethylenes modified with maleic anhydride were used. The agents were prepared in the laboratory with peroxide, and their usefulness was compared with that of a commercially modified linear low‐density polyethylene. The blends with PVC were preirradiated with ultraviolet radiation for 12, 24, or 48 h to create oxidized groups to help in situ compatibilization during the blending step of the reactive extrusion process. Compatibilized materials showed a markedly more homogeneous morphology with improved mechanical properties: the elongation at break and impact strength increased with the compatibilization level. The presence of PVC in commingled plastics significantly reduced the beneficial effect of the maleic anhydride modified polyethylene as a compatibilizer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Generalized Flory–Huggins model for heat‐of‐mixing and phase‐behavior calculations of polymer–polymer mixtures

An extended and generalized Flory–Huggins model for calculating the heats of mixing and predicting the phase stability and spinodal diagrams of binary polymer–polymer mixtures is presented. In this model, the interaction parameter is considered to be a function of both temperature and composition. It is qualitatively shown that the proposed model can calculate the heats‐of‐mixing curves containing exothermic, endothermic, and S‐shaped or sigmoidal types and predict the spinodals, including the upper and lower critical solution temperatures, and closed‐loop miscibility regions. Using experimental results of analog calorimetry for four polymer mixtures of polystyrene/poly(vinyl chloride) (PS/PVC), polycarbonate (PC)/poly(ethylene adipate) (PEA), polystyrene/poly(vinyl acetate) (PS/PVAc), and ethylene vinyl acetate copolymer (EVA Co)/chlorinated polyethylene (CPE), the capabilities of the proposed functionality for the interaction parameter was studied. It is shown that this function can be used satisfactorily for the heat‐of‐mixing calculations and phase‐behavior predictions. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1328–1340, 2000     

Mass transfer study of chlorine dioxide gas through polymeric packaging materials

The mass transfer profile (permeability, diffusion, and solubility coefficients) of chlorine dioxide (ClO₂), a strong oxidizing agent that is used in food and pharmaceutical packaging, was determined through various common polymeric packaging materials. A continuous system for measuring permeation of ClO₂, using an electrochemical detector, was developed. It was observed that biaxially‐oriented poly(propylene), poly(ethylene terephthalate), poly(lactic acid), nylon, and a multilayer structure of ethylene vinyl acetate and ethylene vinyl alcohol were better barriers for gaseous ClO₂, as compared to polyethylene, poly(vinyl chloride), and polystyrene. The activation energies of permeation for ClO₂ through poly(ethylene terephthalate) and poly(lactic acid) were determined to be 51.05 ± 4.35 and 129.03 ± 2.82 kJ/mol, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, , 2009     

Compatibilizing agents in polymer blends: Interfacial tension,phase morphology,and mechanical properties

The interfacial tension, phase morphology, and phase growth was determined for four polymer blend systems: polyethylene/polystyrene, polyethylene/polyamide-6, polystyrene/polyamide-6, and polystyrene/poly(ethylene terephthalate). Generally, high interfacial tension correlates with coarse phase morphology and rapid phase coalescence. The addition of various potential compatibilizing agents to these binary blend systems results in lowered interfacial tension, finer and stabilized phase morphologies. The characteristics of different compatibilizing agents were compared for several of the blend systems. We also look at the influences of compatibilizing agents on mechanical properties of the blend systems. Some compatibilizing agents are able to produce substantial improvements in ultimate properties.     

纳米碳酸钙及其在塑料高性能化改性中的应用

介绍了不同晶形的纳米碳酸钙的特性、制备方法及其表面处理技术，简述了各种纳米碳酸钙改性塑料的制备方法，对纳米碳酸钙在聚氯乙烯、聚乙烯、聚丙烯等塑料的高性能化改性中的应用进行了综述，本文还指出纳米碳酸钙应用于塑料改性中存在的问题。