Reaction of aluminium chloride with poly(divinyl benzene) particles--a reaction kinetic study using infrared spectroscopy

Porous poly(para-divinylbenzene) and poly(meta-divinylbenzene) particles were synthesised from para-divinylbenzene and meta-divinylbenzene monomers with toluene and 2-ethylhexanoic acid as porogens. The residual vinyl groups in the particles were thereafter reacted using aluminium chloride with dichlorobenzene as a catalyst. The conversion of vinyl groups was followed by analysing polymer particles taken from the reaction mixture at different time intervals. Infrared spectroscopy both in the mid and near infrared region was used as the analytical technique. The intensity changes in the overtone absorption at 1628 nm due to the vinyl bonds were used as the basis for the quantification of the vinyl group consumption. Infrared spectra of the particles in the mid IR were also measured to understand changes taking place in the polymer matrix during the reaction. The results indicated that residual vinyl groups in these polymer particles were consumed during the reaction with aluminium chloride. The reaction of aluminium chloride with the polymer matrix was explained by proposing mechanisms for the formation of different products during the reaction. The complex formed between aluminium chloride and the residual vinyl groups seemed to induce addition of HCl to the vinyl group or leads to crosslinking and/or cyclisation in the case poly(para-DVB) particles. The reaction of aluminium chloride with poly(meta-DVB) takes place to a lesser extent.     

Porous product with reduced apparent density keeps good mechanical properties. Extruded composites of poly(vinyl chloride) blown under microwave irradiation

New foaming method, enhanced by microwave irradiation, was elaborated and applied to obtain porous poly(vinyl chloride) and its composites with fine cell structure. The so called “thermal runaway” effect was observed during the heating of poly(vinyl chloride) under microwave irradiation. The temperature of this effect decreases as a result of additives incorporation into polymer matrix. Microwave irradiation allowed effective heating of extruded poly(vinyl chloride) and its composites with carbon black (CB) filler, behind the extruder head and decomposing azodicarbonamide (ADC) to obtain porous products. The use of CB additive to poly(vinyl chloride) significantly increased its ability to be heated under microwave irradiation as well as improved the cell structure and decreased the apparent density of final products.Among additionally used fillers (1 wt%) the montmorillonite caused the apparent density decrease of foamed materials ca. 10%, however beneficially influenced on the quality of cells structure, giving the products with isotropic cells and the highest cell density as well as keeping the tensile strength on similar level as in the case of the materials with CB and ADC only.     

Reaction of poly(vinyl chloride) with magnesium and grignard reagents

Reaction of poly(vinyl chloride) with magnesium under various conditions was attempted, but poly(vinyl chloride) did not react with magnesium. The reactions of poly(vinyl chloride) with benzylmagnesium chloride and allylmagnesium chloride as Grignard reagents were carried out in tetrahydrofuran at reflux temperature. It was found that the chlorine atoms in the poly(vinyl chloride) were replaced by benzyl and allyl groups by the coupling reaction, and a small amount of Grignard reagent of poly(vinyl chloride) was formed by the magnesium–halogen exchange reaction. The extent of the substitution increased with increasing reaction time and concentration of the Grignard reagent.     

New polyacrylate-based lead(II) ion-selective electrodes

A novel polyacrylate-based matrix for potentiometric ion-selective electrodes has been developed. Isododecyl acrylate, acrylonitrile and hexanedioldiacrylate co-monomers along with the thermo-initiator 2,2-dimethoxy-2-phenylacetophenone were used as polymeric matrix components. A lead(II)-selective electrode (Pb-ISE) was constructed using the above matrix. The electrode showed comparable analytical performance in the micromolar range to Pb-ISEs with conventional poly(vinyl chloride)-based membranes containing neutral ionophore and with solid-state membranes containing a mixture of lead sulphide and silver sulphide. Electrochemical impedance spectroscopy studies revealed much lower ion mobility in the polyacrylate membrane than in plasticized poly(vinyl chloride) membranes. This result additionally indicates the possibility of obtaining a lower detection limit for ISEs using the new acrylate matrix.     

Poly(vinyl chloride) Nanocomposites

Poly(vinyl chloride) is one of the major thermoplastics beside other commodities polymers like polyethylene and polystyrene. However, some of its main characteristics such as plasticity, thermal and photo stability are inferior to other commodity polymers. Adding nano scale inorganic fillers to poly(vinyl chloride) or other polymers in view to obtain polymer nanocomposites with superior properties has drawn the attention of many researchers in the last decades. Poly(vinyl chloride) nanocomposites are obtained mainly by in situ polymerization, solution based or mixing techniques. The resulting products show improvement of most important properties of poly(vinyl chloride) such as thermal, mechanical, rheological, flammability, antibacterial, etc. This paper presents preparation ways of poly(vinyl chloride) nanocomposites using different nano fillers and the improved properties compared with those of virgin poly(vinyl chloride).     

Preparation and characterization of wet poly(vinyl chloride)-polypyrolle composite film

Wet poly(vinyl chloride) (wPVC) coated glassy carbon (GC) electrode was prepared by casting a DMF solution of poly(vinyl chloride) on glassy carbon and immersing it in methanol, and then in water. The wPVC coated GC (wPVC/GC) electrode showed electrochemical activity in aqueous solution; therefore, it was possible to obtain a wPVC/polypyrolle (PPy) composite by electropolymerization from aqueous solution of pyrolle (Py) into the wPVC matrix on the electrode. PPy segregated in wPVC matrix and the mechanical properties of PPy was improved by forming a composite without changing the electrochemical properties of PPy. The PPy/wPVC ratio can be controlled by controlling the concentration of PVC in DMF solution.     

Thermal and radiation-induced dehydrochlorination of poly(vinyl chloride). II. Head-to-head structures

The mechanism of dehydrochlorination of 2,3-dichlorobutane and chlorinated polybutadiene which are model compounds of head-to-head poly(vinyl chloride) has been investigated by pyrolysis, thermal, and ultraviolet-induced decomposition. The activation energy of dehydrochlorination for head-to-head poly(vinyl chloride) in nitrogen was 23 kcal/mole at temperatures of 150–190°C, which is slightly smaller than that (29 kcal/mole) for head-to-tail poly(vinyl chloride). The conjugated double bonds were formed by thermal and radiation decomposition of head-to-head poly(vinyl chloride), similar to head-to-tail poly(vinyl chloride). The probability of polyene formation by radiation-induced dehydrochlorination is larger than that by thermal decomposition and is affected by the conformation and the molecular motion of the main chain. This may be due to the alternative mechanism of dehydrochlorination in the thermal and radiation decomposition. The amount of head-to-head linkage of poly(vinyl chloride) samples prepared with various catalysts is dependent on polymerization temperature rather than the kinds of catalyst. Commercial poly(vinyl chloride) has 6–7 head-to-head linkages per 1000 monomeric units.     

Properties of ethylene–propylene–vinyl chloride graft copolymers. II. Viscoelasticity and composition of graft copolymer and composite

The viscoelasticity and volume expansion of the raw polymerizate of ethylene–propylene copolymer with vinyl chloride grafts, and of the individual components has been studied. The raw polymerizate (composite) and the pure ethylene–propylene–vinyl chloride graft copolymer were found to consist of two phases. The pure graft copolymer has an ethylene–propylene matrix containing some fraction of poly(vinyl chloride) (PVC) grafts and a microphase with the remainder of the PVC grafts. The raw polymerizate consists of a PVC matrix plasticized with ethylene–propylene chains and a microphase of the ethylene–propylene copolymer. An attempt has been made to calculate the participation of components in microphases and the minimum dimension of the PVC microphase aggregates.     

Retardation of discoloration of poly(vinyl chloride) and decolorization of discolored poly(vinyl chloride) with diimide

Retardation of discoloration of poly(vinyl chloride) with diimide was studied in dimethylformamide at 130°C. with the use of p-toluenesulfonylhydrazide (PSH) as a source of diimide. A process was proposed that involved prolonging the induction periods of discoloration by inhibiting the development of conjugated polyene structure. The optimum proportion of PSH was one fourth of the poly(vinyl chloride), the best results. Furthermore, poly(vinyl chloride) discolored by thermal degradation in o-dichlorobenzene or gamma-ray irradiation under vacuum was decolorized in solution at 130°C. by addition of PSH. The decolorized poly(vinyl chloride) thus obtained was thermally stable compared with that obtained by oxidative methods.     

Structure Analysis of PVC Nanocomposites

In this paper poly(vinyl chloride)/clay nanocomposites were prepared by melt intercalation using a single screw extruder. Problems with thermal stability of these nanocomposites during compounding were largely eliminated by pre-treatment of the organoclay with plasticizer (dioctyl phthalate), which created a barrier between polymer and quaternary amine. These nanocomposite materials were analyzed with respect to their morphology. The intercalation, exfoliation, nano-phase dispersion and orientation were investigated using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and X-ray diffraction (XRD). Moreover, different types of sample preparation for these techniques were tested as well. It was found that partially intercalated and disordered structure arose in poly (vinyl chloride) composites containing sodium type of montmorillonite, while a fine dispersion of partial to nearly full exfoliation of individual montmorillonite layers in poly (vinyl chloride) matrix was observed when this clay was organically modified. Finally, the influence of different mixing time (in extruder) on nano-phase morphology was surveyed.     

THE COMPATIBILITY OF BLENDS OF POLY(VINYL CHLORIDE) OR CHLORINATED POLY(VINYL CHLORIDE) WITH POLY(METHYL METHACRYLATE)

IR spectral shifts of carbonyl vibrational absorption for ethyl acetate, which acts analogically as the structural unit of poly(methyl methacrylate), in cyclohexane, chloroform, chlorinated paraffins, poly(vinyl chloride) and chlorinated poly(vinyl chloride) were measured. The results suggest that there are specific interactions between the carbonyl groups and the chlorinated hydrocarbons which could be responsible for the apparent compatibility of poly(vinyl chloride)—poly(methyl methacrylate) and chlorinated poly(vinyl chloride)—poly(methyl methacrylate) blends. Additionally, the effects of the preparation mode of blend films on phase separation and observed compatibility are discussed.     

Block copolymerization with trapped radicals

Acrylonitrile–styrene, vinyl chloride–styrene and vinyl chloride–methyl methacrylate block copolymers were obtained by employing trapped radicals in polyacrylonitrile or poly(vinyl chloride) formed in a heterogeneous system by tri-n-butylboron in air as initiator. The trapped polymer radicals were activated on addition of dimethylformamide as solvent. Confirmation of block copolymers was carried out with solvent extractions, elementary analysis, and turbidimetry. In block copolymerization, the polyacrylonitrile trapped radical was more active than the poly(vinyl chloride) radical. Results of kinetic studies were used to consider the mechanism of polymerization.     

Compatibility of binary systems of poly(methyl methacrylate), poly(vinyl chloride) and poly(vinyl acetate)

The influence of the thermal treatment on the stability in time of the dispersion degree of films containing binary polymer mixtures, poly(vinyl chloride)/poly(methyl methacrylate), poly(vinyl chloride)/poly(vinyl acetate) and poly(vinyl acetate)/poly(methyl methacrylate), was studied by thermogravimetry and optical microscopy with phase contrast. The dispersion degree depends particularly on the composition of the polymer mixture and can be improved by thermal treatment at temperatures above the glass temperatures of both homopolymers. It seems that this thermal treatment yields exclusively metastable structures with a general tendency to phase separation in a short time after thermal treatment, the heterogeneity mixtures (as film) being more pronounced.     

Pyrolysis–gas chromatographic analysis of poly(vinyl chloride). II. In situ absorption of HCl during pyrolysis and combustion of PVC

A pyrolysis–gas chromatographic technique for measuring the amount of hydrogen chloride released during the high temperature pyrolysis of poly(vinyl chloride) resins, plastisols, copolymers and compounds containing inert fillers has been developed. The technique, which is also applicable to the analysis of chlorinated polyethylene and chlorinated poly(vinyl chloride), is based on the use of a standard precursor of HCl, poly(vinyl chloride) homopolymer. The analysis has been successfully used to measure the degree of in situ absorption of HCl during pyrolysis by certain basic fillers [K₂CO₃, CaCO₃, CaO, MgO, Al(OH)₃, Na₂CO₃, Al₂O₃ and LiOH] dispersed in a poly(vinyl chloride)–o-dioctyl phthalate matrix. Combustion of a number of combustion residues (chloride determination) revealed that the amount of HCl absorbed by the basic filler was independent of the method of degradation (pyrolysis or combustion). Flammability measurements of those matrices having the same composition indicate that in situ absorption of HCl during combustion has little effect on the overall flammability of these materials.     

Plasticized PVC reinforced with cellulose whiskers. I. Linear viscoelastic behavior analyzed through the quasi‐point defect theory

In a previous article, the processing of nanocomposite materials of plasticized poly(vinyl chloride) (pPVC) reinforced by cellulose crystalline whiskers was presented as well as preliminary dynamic mechanical measurements. The purpose of the present work is to evaluate the possible change of molecular dynamic of poly(vinyl chloride (PVC) at the interface with cellulose whiskers. The analysis, based on the quasi‐point defect (qpd) theory for the anelastic deformation of amorphous polymer, confirms that PVC is heterogeneous. Thus, the matrix is described as a parallel assembly of phases with different plasticizer concentration (i.e., different glass transition temperature). It is shown that the whiskers do not lead to supplementary relaxation in the matrix, at least in the time–temperature window of the study, but, the satisfying modeling of the composite supports the assumption of a thin layer of immobilized phase around the whiskers. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2151–2164, 1999     

Head to Head Polymers. 42. Head to Head Poly(Vinyl Halide) Blends: Thermal and Degradation Behavior

Abstract

Improved halogenation techniques for poly(1, 4-butadiene) have made well-defined head to head poly(vinyl chloride) and head to head poly(vinyl bromide) accessible in larger quantities. This allowed the preparation and study of blends of poly(vinyl chloride) or poly(vinyl bromide) with polycaprolactone and poly(methyl methacrylate); blends were also prepared between the poly(vinyl halides). The thermal behavior and the thermal degradation behavior of these blends were investigated. It was confirmed that head to head and head to tail poly(vinyl chloride) are immiscible over almost the entire range of compositions.     

Poly(vinyl chloride)–poly(ethylene oxide) block copolymers: Synthesis and characterization

Poly(vinyl chloride)-poly(ethylene oxide) block copolymers have been synthesized in solution and emulsion. The polymers were made by first synthesizing macroazonitriles through the reaction of 4,4′-azobis-4-cyanovleryl chloride with hydroxy-terminated poly(ethylene oxide) of varying molecular weights. These macroazonitriles had molecular weights in the range of 3000–88,000 and degrees of polymerization from 5 to 24. Thermal decomposition of the azolinkages in the presence of vinyl chloride monomer yielded block copolymers containing form 2 to 20 wt % poly(ethylene oxide). The structures of the block copolymers were characterized by spectrometric, elemental and molecular weight analyses. The possibility of some graft polymerization occurring via free-radical extraction of a methylene hydrogen from the poly(ethylene oxide) was considered. Polymerization of vinyl chloride with an azonitrile initiator in the presence of a poly(ethylene oxide) yielded predominately homopolymer with some grafted poly(vinyl chloride).     

Effect of interfacial adhesion on the mechanical properties of poly(vinyl chloride) modified with cross-linked poly(methyl methacrylate) particles prepared by seeded emulsion polymerization

The effect of interfacial adhesion on the mechanical properties of an incompatible polymer blend was investigated. For this purpose, the preparation of non-cross-linked and cross-linked poly(methyl methacrylate) particles having mean sizes of about 0.8 μm was completed by seeded emulsion polymerization, and the number and the distribution of cross-linked points in the particles were varied. The emulsion particles obtained were powdered by a freeze–dry method and dispersed into a poly(vinyl chloride) matrix by melt blending. The non-cross-linked particles were completely dissolved in the matrix because poly(methyl methacrylate) has good compatibility with poly(vinyl chloride). On the other hand, in the case of the cross-linked particles, the mutual diffusion of the polymer molecules was restricted within the particle/matrix interfacial regions owing to the cross-linked points. Additionally, interfacial structures with different concentration slope dependent upon the number and the distribution of inner cross-linked points were developed with the same domain size. Mechanical and fracture properties were measured. As a result, both yield stress and fracture toughness decreased with a decrease in the interfacial adhesion, and the decrease was found to occur as a result of interfacial debonding. When the interfacial adhesion was sufficient it was never observed that the level was lower than that of the components. Received: 6 April 2000 Accepted: 29 September 2000     

Vinyl chloride polymers and their use in polymer blends

A short introduction to polymer-polymer miscibility and to the prediction of the miscibility of polymers is given. The four main types of polymer-modified poly(vinyl chloride) (plastification, impact modification, processing aids and heat deflection temperature modification) are explained by examples. The thermal stability of poly(vinyl chloride) in such blends is discussed; the effectivity of tin-stabilizers may be higher in such blends than in pure poly(vinyl chloride).     

Microscopic FT-IR analysis of blends from functionalized polyolefins and poly(vinyl chloride) or polystyrene

Binary mixtures consisting of ethylene-propylene copolymer functionalized with diethyl maleate (FEP) and poly(vinyl chloride) or polystyrene have been studied by means of the microscope-FT-IR system. Parallel DSC measurements have been carried out on the functionalized ethylene-propylene copolymer/poly(vinyl chloride) mixtures. Intermolecular interactions involving the carbonyl of the ester groups of the copolymer and the methin hydrogen of poly(vinyl chloride), through hydrogen bonding, have been evidenced in the various microareas of the samples. Intensity of these effects depends on composition in different domains of the blends. An increase of the gauche sequences with respect to the long and short trans sequences of poly-(vinyl chloride) chains has been detected with increasing the content of FEP. The partial compatibility of FEP/poly (vinyl chloride) blends has been confirmed by DSC measurements.