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.     

Etude par résonance magnétique nucléaire des polychlorures de vinyle polymérisés par les systémes titanate de butyle–alcoyles-aluminium

NMR analysis of the chain ends of samples of poly(vinyl chloride) prepared using a Ti(OBu)₄–alkylaluminum system in CCl₄ reveals that the mechanism of the formation of free radicals depends on whether the alkylaluminum used is chlorinated or not. In the first case, some of the radicals are reactive in the initiation step of the polymerization, while in the latter case theses radicals first undergo transfer to CCl₄, then the CCl₃· formed initiates the polymerization of vinyl chloride. The poly(vinyl chloride) radicals are chiefly stopped by transfer to CCl₄ (chlorine abstraction) or to alkylaluminum (hydrogen abstraction). In transfer reactions between growing radicals and alkylaluminum, the radicals formed have to react with CCl₄ before reinitiating the polymerization of vinyl chloride.     

Miscibility in poly(vinyl chloride)/chlorinated poly(vinyl chloride) blends,and blends of different chlorinated poly(vinyl chlorides)

Blends of poly(vinyl chloride) with chlorinated poly(vinyl chloride) (PVC), and blends of different chlorinated poly(vinyl chlorides) (CPVC) provide an opportunity to examine systematically the effect that small changes in chemical structure have on polymer-polymer miscibility. Phase diagrams of PVC/CPVC blends have been determined for CPVC's containing 62 to 38 percent chlorine. The characteristics of binary blends of CPVC's of different chlorine contents have also been examined using differential calorimetry (DSC) and transmission electron microscopy. Their mutual solubility has been found to be very sensitive to their differences in mole percent CCl₂ groups and degree of chlorination. In metastable binary blends of CPVC's possessing single glass transition temperatures (T_g) the rate of phase separation, as followed by DSC, was found to be relatively slow at temperatures 45 to 65° above the T_g of the blend.     

Studies of polyester/chlorinated poly(vinyl chloride) blends

Chlorinated poly(vinyl chloride) (CPVC) was solution blended with poly(caprolactone) (PCL), poly(hexamethylene sebacate) (PHMS), poly(α-methyl-α-n-propyl-β-propiolactone) (PMPPL), poly(valerolactone) (PVL), poly(ethylene adipate), poly(ethylene succinate) and poly(β-propiolactone). From calorimetric glass transition temperature (T_g) measurements, it is concluded that CPVC is miscible with polyesters having a CH₂/COO ratio larger than three (PCL, PHMS, PMPPL and PVL). The Gordon-Taylor k parameter was also calculated and found equal to 1.0 and 0.56 for PCL/CPVC and PHMS/CPVC blends, respectively. From these values, it is concluded that CPVC gives a stronger interaction with polyesters than poly(vinyl chloride) due to its larger chlorine content.     

Chemical recycling of poly(vinyl chloride): Application of partially dehydrochlorinated poly(vinyl chloride) for producing a chemically modified polymer

Poly(vinyl chloride) (PVC) pipes were chemically modified to produce a sulfonated polymer with dehydrochlorinated PVC samples as intermediates. Two intermediates were formed: (1) partially dehydrochlorinated PVC with long sequences of conjugated double bonds and (2) the product of the partial dehydrochlorination of PVC and the nucleophilic substitution of chlorine by hydroxyl groups. The IR spectra showed that the dehydrochlorinated samples were heterogeneous materials, showing different proportions of elimination products, hydroxyl substitution, and partial oxidation. Samples dehydrochlorinated with poly(ethylene glycol) with a molecular weight of 400 g/mol for 24 h and 15 min showed the highest sulfonation yield, which was related to the sulfonation mechanism occurring predominantly because of the presence of hydroxyl groups in a mixture of vinyl alcohol and vinyl chloride units. The sulfonation was confirmed by the presence of a medium‐intensity band at 1180 cm^?1, assigned to sulfonic groups. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A kinetic study of acetoxylation of benzyl chloride—a model of activated allylic chlorides in PVC—using a crown ether complex

Benzyl chloride has been used in a kinetic study of chlorine replacement by acetoxy groups to model the behaviour of allylic chlorine during the acetoxylation of poly(vinyl chloride). Chlorine substitution was carried out in tetrahydrofuran at 30°C using a potassium acetate-crown ether complex with methanol to ensure homogeneous solution. The process followed an S_N2 mechanism. The orders of reaction with respect to benzyl chloride and potassium acetate were close to one, and the second order velocity constant was 4.2 x 10^?5 litre mol^?1 s^?1 when the molar ratio of crown ether to potassium acetate was approximately unity. Higher ratios caused a slight increase in rate constant. Substitution was followed by NMR spectroscopy which also revealed a proton exchange between methanol and acetate anion with an equilibrium constant 9.4 x 10^?2. This observation has suggested an explanation for the effect of some free-radical inhibitors on the rate of acetoxylation of poly(vinyl chloride) by potassium acetate in the presence of crown ether.     

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     

Blends of bitumen with polar polymers

Abstract

Blends of a Venezuelan 100 penetration grade bitumen have been made in a Z-blade masticator mixer with four common polar polymers –poly(vinyl chloride), poly(ethylene terephthalate), Nylon 11, and a thermoplastic polyurethane – at levels ranging from 10 to 40 pph (i.e. 9 to 29 wt-%). They were characterised by fluorescence optical microscopy, differential scanning calorimetry, and dynamic mechanical thermal analysis. All blends were stiffer than the bitumen by at least a factor of 50 at temperatures below the glass transition, which was lowered by the presence of the polymer. Loss processes were detected at about 40 to 60°C in the poly(ethylene terephthalate) and Nylon 11 blends, in the latter case being clear when the concentration rose to 40 pph, as if a polymer rich phase was then extensive. The blends at high temperatures were much more viscous than the bitumen, but all flowed readily at temperatures between 70 and 120°C.     

氯化铵应用研究进展

在中国,氯化铵主要用作氮肥,附加值很低,严重制约了联碱企业的经济效益,而且存在氯资源浪费、长期施用易造成土壤板结等问题。文章分析了中国在氯化铵应用中的不合理状况,介绍了国内外氯化铵应用工艺研究现状,对以氯化铵为原料制取氨气、氯化氢、氯气、氯代烃等其他化工产品的工艺进行了分析比较,表明以氯化铵为原料制备氨气、氯化氢或氯气的工艺虽然在特定领域有着一定的应用,但并不适合从整体上解决中国数量庞大的氯化铵出路问题。提出了氯化铵参与乙炔氢氯化和乙烯氧氯化合成氯乙烯的工艺路线,能够充分利用氯化铵中的氯资源并产出高附加值的氯乙烯产品,对解决中国氯化铵不合理利用现状具有重要的参考和指导意义。     

Miscibility,morphology and tensile properties of vinyl chloride polymer and poly(ε‐caprolactone) blends

The miscibility, morphology and tensile properties of three blend systems of poly(ε‐caprolactone) (PCL) with poly(vinyl chloride) (PVC) and with two chlorinated PVCs (CPVCs) with different chlorine contents (63 wt% and 67 wt% of Cl) have been studied. Based on the shifts of single glass transition temperature, the Gordon–Taylor K parameter is calculated as a measurement of interaction strength between PCL and (C)PVCs. Higher K values are found for blends of (C)PVCs with higher chlorine content, together with the interaction χ parameters estimated from the melting point depression results. The morphology observed with polarized light microscopy shows that spherulites exist in blends rich in PCL (≥50 wt%) only. Wide angle X‐ray diffraction studies indicate that the crystal structure of PCL is independent of the Cl content of (C)PVCs. The tensile properties of various blends exhibit a minimum as the PCL content increases. The elongation at break increases with increasing PCL content. © 2000 Society of Chemical Industry     

Morphology and mechanical behavior of poly(vinyl chloride)/poly(butadiene–co–acrylonitrile) latex interpenetrating polymer networks

A series of poly(vinyl chloride)/poly(butadiene–co–acrylonitrile) interpenetrating polymer networks (IPNs), all having 50/(25–25) weight compositions, was synthesized in latex form. The latex particles were studied after each step of the two-staged polymerization and after molding or casting. Transmission electron microscopy together with dynamic mechanical spectroscopy suggest a graded composition within the latexes, in which the poly(vinyl chloride) seed latex network I forms a core that is partially penetrated by the poly(butadiene–co–acrylonitrile) network II, yielding increased amounts of poly(butadiene–co–acrylonitrile) in the shell of the latex particles.     

Self-crosslinkable plastic-rubber blend system based on poly (vinyl chloride) and acrylonitrile-co-butadiene rubber

That the melt-mixed blend of poly (vinyl chloride) and acrylonitrile-co-butadiene rubber becomes crosslinked during high-temperature molding is evident from Monsanto rheometric, solvent swelling, and infrared spectroscopic studies. Dynamic mechanical analysis shows that such a self-crosslinkable plastic-rubber blend is miscible in different blend ratios. The degree of crosslinking depends on the blend ratios and the molding conditions. The cross-linking reaction involves the allylic chlorine sites in poly (vinyl chloride) and the ? C?N group in the nitrile rubber. © 1993 John Wiley & Sons, Inc.     

PVC — origin,growth, and future

Application of poly(vinyl chloride) (PVC) was first described in a patent in 1913, but only after 1930 did a sustained interest in PVC arise in a number of industrial laboratories. Nowadays PVC is the second thermoplastic resin behind polyolefins with a worldwide capacity of ca. 31 million tons. In its nearly 70 year history, PVC has contributed to much progress in polymer science and technology, e. g., to emulsion and suspension polymerization, detailed analysis of polymer structure, chemistry of stabilization, plasticization, chemical modification, and plastics processing. But PVC also plays an important role in many environmental discussions on polymers, e. g. chlorine chemistry, toxicity of vinyl chloride, or waste and recycling problems. Within the time frame of 70 years, some recent developments in controlled polymerization of vinyl chloride, stabilization, modification of bulk properties and chemical and material recycling of PVC are discussed.     

Modification of polyolefin films by photochlorination

Composite polyolefin membranes with graded chlorination gradient were obtained by photochlorination of polyethylene, polypropylene, and polystyrene films using ultraviolet and visible light. The maximum chlorine contents of these membranes were 12%, 8.5%, and 6.5%, respectively. As for polyethylene, the surface photochlorination reduced gas permeation of carbon dioxide and oxygen down to 1/30 and 1/21 of the original polyethylene; it also improved the wettability without changing substantially other favorable physical properties such as tensile strength, elongation, and water vapor permeation. The water contact angle of chlorinated polyethylene was comparable to that of poly(vinyl chloride). The infrared spectra suggest the presence of the chlorine of the ? CHCl? CHCl? type rather than of the ? CCl₂? type in the photochlorination of polyethylene. In an effort to obtain useful membranes with a photocrosslinking functional group as a side chain, surface-photochlorinated polyethylene was allowed to react with sodium N,N-dimethyldithiocarbamate or sodium N-methyl-N-carboxymethyldithiocarbamate in dimethylformamide at 50°C for 48 hr according to the procedure by which poly(vinyl chloride) was previously reacted. The polymer thus obtained has 4.1 mole-% ? SCS? NMe₂ and 3.4 mole-% ? SCS? N(CH₃)CH₂COONa groups.     

Long term behaviour of poly(vinyl chloride) products under soil buried and landfill conditions

Abstract

The long term performance of poly(vinyl chloride) (PVC) products has been investigated in laboratory scale landfill simulation assays. Leachate and gas were monitored and PVC samples were inspected. No degradation of the PVC polymer was observed. Plasticised PVC products showed a certain loss of additives. In addition, leachate samples from actual landfill sites were analysed for phthalates and organotin compounds. A preliminary assessment of the environmental impact indicates that there is no significant contribution of PVC waste to concentrations of heavy metals in landfills, and the presence of phthalates and organotin compounds in the leachate is not expected to constitute a risk to the aquatic environment.     

Synthesis of Silicon Carbide Nanocrystals Using Waste Poly(vinyl butyral) Sheet

SiC nanocrystals were prepared using waste poly(vinyl butyral) sheet as a carbon source. SiO₂/poly(vinyl butyral) mixtures are converted to SiO₂/pyrolytic carbon composites via pyrolysis at low temperatures (500°C) in an Ar atmosphere. Subsequently, low‐temperature magnesiothermic reduction and purification processes result in the formation of tiny SiC nanocrystals. The size of the synthesized SiC nanocrystals ranged from 3 to 12 nm, i.e., they are smaller than the SiO₂ precursor offering large specific surface area of 175.76 m²/g and are single phase as 3C–SiC. Hence, 3C–SiC nanocrystals were successfully synthesized using waste poly(vinyl butyral) through this simple, inexpensive, and scalable process, which will be a new application in the recycling industry.     

聚氯乙烯/丁腈胶粉共混型热塑性弹性体

将聚氯乙烯与废丁腈胶粉经高温机械共混，制备了动态交联的共混型热塑性弹性体。讨论了共混比，硫化体系及其用量，废胶粉品种（丁腈胶粉，轮胎胶粉）等因素对热塑性弹性体性能的影响，同时将聚氯乙烯／丁腈胶粉与聚氯乙烯／轮胎胶粉制备的共混型热塑性弹性体的性能进行了比较。结果表明，以聚氯乙烯100份（质量份，下同），邻苯二甲酸二辛酯50份，丁腈胶粉80份，丁腈橡胶20份，过氧化二异丙苯0．5份，氧化锌5份及适量其他助剂可制得综合性能较好的共混型热塑性弹性体。扫描电镜结果显示该共混型热塑性弹性体具有较好的相容性。     

Dielectric behavior of some polar high polymers at ultra-high frequencies (microwaves)

The dielectric behavior of different polar high polymers at ultra-high frequencies has been investigated by means of a dielectrometer, suitably modified to permit measurements at different temperatures. Experimental measurements were made at about 9 × 10⁹ cps over the temperature range of ?150 to 200°C. for polyoxymethylene, polythiomethylene, poly(3,3′-chloromethyl)oxetane (Penton), polycarbonate of 4,4′-dioxydiphenyl-2,2′-propane (Makrolon), poly(vinyl alcohol), poly(vinyl acetate), poly(vinyl chloride), vinyl chloride–vinyl acetate copolymer, and two ABS plastics, type B (blend) and type G (graft). On comparing the dielectric behavior of the examined materials at ultra-high frequencies with the corresponding ones determined at low or at radiofrequencies, it is observed that, in the microwave region, all relaxation peaks, either connected with cooperative motions in main chain (primary processes) or with local motions in the backbone or in side chains (secondary processes), usually observed at lower frequencies, tend to disappear; the corresponding relaxation effects, however, manifest themselves through a progressive increase of losses with increasing temperature, which is particularly marked above the glass transition temperature T_g. The latter transition, in spite of the very high frequency, is easily distinguished, in most cases, by the sudden change of slope in the tan δ versus temperature curve which accompanies its onset. This is explained on the basis of the very wide distribution times of molecular relaxation processes in polymers and the increase in strength of the secondary relaxation effects, which is verified at T_g, as a consequence of the increased kinetic energy of macromolecules and of the larger free volume for orientation of side chains. Each case is discussed separately and the experimental results interpreted on the basis of the molecular structure and chain mobility of the examined polymers.     

Improvements to C-ring fracture toughness test for poly(vinyl chloride) pipes

Abstract

Examination of the published procedure for performing calculations on data obtained from the C-ring fracture toughness test for unplasticised poly(vinyl chloride) reveals a major flaw. The dimensions of the specimens do not satisfy the ASTM criteria for plane strain conditions and correction factors are therefore introduced. However, there is an error in the calculation procedure, which results in variations in the severity of the test with pipe wall thickness. An improved approach is proposed and recommendations are made for changing the ISO/DIS 11673·2 test standard, to allow for variations in the yield strength of unplasticised poly(vinyl chloride) and to identify the calculated data as K _c rather than K _1c.     

Use of poly(vinyl chloride) as chlorinating agent in recycling of metals

Abstract

Poly(vinyl chloride) has the formula –(CH₂ CHCl)_n– and on combustion in excess air yields HCl, CO₂ , H₂O, and O₂ . Although these gases may not be suitable for the production of pure HCl, the gases are entirely suitable to treat many metallic scrap and oxide residues to yield products more suitable for recycling or as valuable chemicals.