Mechanochemical block copolymerization in heterogeneous systems of the solid poly(vinyl chloride) with styrene by ultrasonic irradiation

Summary The effect of several forms of suspension polymerized poly(vinyl chloride) particles on mechanochemical block copolymerization in the solid poly(vinyl chloride)-styrene-sodium dodecyl sulfate solutions has been studied by ultrasonic irradiation at 60 °C. The block copolymerization of styrene was initiated by free radicals produced from the poly(vinyl chloride) particles by ultrasonic waves. The rates of copolymerization increased with increasing the additional amount of the solid poly(vinyl chloride), the porosity, and the average diameter of the grain particles. In particular, the influence of the average diameter was much larger than that of the porosity. When the porosity and the average diameter were increased, the rates of decrease in the viscosity-average degree of polymerization of the degraded poly(vinyl chloride) were much increased. In addition, the changes in the composition of the block copolymer and homopolymers in the reaction products were obtained.     

Mechanochemical copolymerization of poly(vinyl chloride) with methyl methylacrylate in an open mill machine

Mechanical degradation of poly(vinyl chloride) (PVC) and mechanochemical copolymerization in poly(vinyl chloride)/methyl methylacrylate (PVC/MMA) systems were studied in an open mill machine. The effects of the mastication temperature, mastication time, and additives (oxygen, THF, or hydroquinone) on the mechanical degradation of PVC were investigated. The molecular weight of PVC decreased with increasing mastication time, and the efficiency of the mechanodegradation of PVC was lowered with increasing mastication temperature. The effects of the ratio of PVC to MMA, thin‐passage time, and initiator on mechanochemical copolymerization also were studied. The experimental results indicated that the degree of copolymerization increased with increasing thin‐passage times up to 45 times and then remained constant. There was a maximum degree of copolymerization at a ratio of 0.22 g/mL (PVC/MMA), and the efficiency of copolymerization always decreased with increasing time. The maximum degree and efficiency of copolymerization were 5.8 and 89%, respectively. The poly(vinyl chloride‐co‐methyl methylacrylate) copolymer can further improve the interfacial adhesion of PVC and PMMA. Thus it improves the mechanical properties of the PVC/CPE blend more effectively than pure PMMA. J. VINYL. ADDIT. TECHNOL. 12:42–48, 2006. © 2006 Society of Plastics Engineers.     

Mechanochemical synthesis and characterization of poly(vinyl chloride)-block-poly(ethylene-co-propylene) copolymers by ultrasonic irradiation

Mechanical degradation and mechanochemical reaction in heterogeneous and homogeneous systems of poly(vinyl chloride) and poly(ethylene-co-propylene) polymer have been studied by ultrasonic irradiation at 30 °C. The rates of decrease in the number-average molecular weights of the degraded poly(vinyl chloride) and poly(ethylene-co-propylene) polymer were much faster in order of the solid poly(vinyl chloride)—poly(ethylene-co-propylene) polymer solution, the swelled poly(vinyl chloride)—poly(ethylene-co-propylene) polymer solution, and the homogeneous solution systems. On the other hand, mechanochemical reaction occurred by free radicals produced from the chain scissions of both polymers by ultrasonic waves. The changes in the composition of the total block copolymer, the unreacted poly(vinyl chloride), and the unreacted poly(ethylene-co-propylene) polymer in individual reaction systems were obtained. In addition, the microscopic observation of the surfaces of the polymers on before and after mechanochemical reaction is carried out. Received: 10 May 2000/Revised version: 1 August 2000/Accepted: 3 August 2000     

Mechanochemical synthesis and characterization of poly(vinyl chloride) -block- poly(acrylonitrile-co-butadiene) copolymers by ultrasonic irradiation

Summary Mechanical degradation and mechanochemical reaction in heterogeneous and homogeneous systems of poly(vinyl chloride) and poly(acrylonitrile-co-butadiene) polymer have been studied by ultrasonic irradiation at 30 °C. The rates of decrease in the number-average molecular weights of the degraded poly(vinyl chloride) and poly(acrylonitrile-co-butadiene) polymer in the swelled poly(vinyl chloride) — poly(acrylonitrile-co-butadiene) polymer solution were much faster than the homogeneous solution system and the final average chain lengths led to the smaller values than those in the latter system. On the other hand, mechanochemical reaction occurred by polymer radicals produced from the chain scissions of both polymers by ultrasonic irradiation. The changes in the composition of the total block copolymer, the unreacted poly(vinyl chloride), and the unreacted poly(acrylonitrile-co-butadiene) polymer in both reaction systems were obtained. Received: 4 September 2001/Accepted: 22 October 2001     

Mechanochemical synthesis and characterization of poly(vinyl chloride)-block-poly(vinyl alcohol) copolymers by ultrasonic irradiation

Mechanical degradation and mechanochemical reaction in heterogeneous systems of the solid poly(vinyl chloride)-poly(vinyl alcohol) aqueous solutions have been studied by ultrasonic irradiation at 30 °C. The rate of decrease in the viscosity-average degree of polymerization of the degraded poly(vinyl chloride) was much faster than that of the degraded poly(vinyl alcohol). Mechanochemical reaction occurred by free radicals produced from the chain scissions of both polymers by ultrasonic waves. The copolymer was obtained and the molar ratio of the vinyl chloride and the vinyl alcohol units in its copolymer can be determined. In addition, the changes in the composition of the total block copolymer, the unreacted poly(vinyl chloride), and the unreacted poly(vinyl alcohol) were obtained. Received: 1 October 1998/Revised version: 9 January 1999/Accepted: 13 January 1999     

Mechanochemical block copolymerization in heterogeneous systems of the solid poly(vinyl chloride) with styrene by ultrasonic irradiation

Summary Mechanochemical block copolymerization in heterogeneous systems of the solid poly(vinyl chloride)-styrene-sodium dodecyl sulfate aqueous solutions has been studied by ultrasonic irradiation at 65 °C. The block copolymerization of styrene was initiated by free radicals produced from the poly(vinyl chloride) particles by ultrasonic waves. The initial rate of the block copolymerization Rp was given by Rp α [Styrene] [Sodium dodecyl sulfate]^1/2. Both copolymer and homopolymer were obtained. For example, when 2.506 g of the poly(vinyl chloride) particles, 24.23 g of styrene, and 54.00 g of sodium dodecyl sulfate aqueous solution (0.500 wt%) were added in the reaction system, the weight proportions of the block copolymer and polystyrene after 60 min were approximately 50 and 20%.     

Head to head polymers

Pure head to head (H–H) addition polymers, such as H–H polyolefins, H–H acrylates and H–H poly(vinyl halides), have been of interest for the understanding of the structure/properties relationship of addition polymers. These polymer structures have provided challenges of synthesis, characterization and of the measurements of their mechanical and rheological properties. H–H polymers have never been prepared by direct synthesis and indirect polymerization techniques have to be used. Some of the H–H polymers, the polyolefins, were made by polymerization of properly substituted dienes followed by hydrogenation. The H–H polyacrylates were synthesized by copolymerization followed by polymer reactions and the poly(vinyl halides), by halogenation of poly(1,4-butadiene). Improved halogenation techniques for poly(1,4-butadiene) have made H–H poly(vinyl chloride) and H–H poly(vinyl bromide) accessible in larger quantities and have allowed an extensive characterization of these polymers.

Blends of H–H with H–T polymers as well as H–H polymers with other polymers were studied. H–H Poly(vinyl chloride) or poly(vinyl bromide) blends with polycaprolactone and poly(methyl methacrylate) were also investigated. The thermal behavior and the thermal degradation behavior of these blends were investigated. The most striking result of these investigations was that H–H and H–T poly(vinyl chloride) are immiscible as is H–H and H–T polyisobutylene over almost the entire range of compositions.     

Free‐radical attachment of nadic anhydride onto poly(alkylene terephthalate)s

There has been little research on poly(alkylene terephthalate) modification by graft copolymerization with vinyl monomers. There is no reported information on graft polymerization in the molten state. In this study, nadic anhydride was grafted onto poly(butylene terephthalate) and poly(trimethylene terephthalate) with a free‐radical initiator in an internal mixer. The influence of the monomer and initiator concentrations on the degree of grafting was investigated. The degradation of these polymers was investigated and characterized with their complex melt viscosity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1839–1845, 2003     

A DSC investigation on the stabilizer distribution in PVC blends

The distribution of a liquid organotin stabilizer between the phases of heterogeneous poly(vinyl chloride) (PVC) blends has been studied by differential scanning calorimetry (DSC). This method can be used even at low stabilizer concentrations. At concentrations > 1 wt.-% the stabilizer can be detected in both phases of a PVC/SAN (poly(vinyl chloride)/poly(styrene-co-acrylonitrile)) blend. At lower concentrations no stabilizer could be found in the SAN phase. Determination of the induction period of thermal degradation at 180°C under nitrogen atmosphere showed no loss of thermal stability for blends containing the stabilizer partly in the SAN phase. Kinetic measurements with the DSC indicate a migration of the stabilizer out of the SAN phase, PVC/PMA (poly(vinyl chloride)/poly(methyl acrylate)) blends showed no solubility of the stabilizer in the soft PMA phase.     

Thermal degradation of poly(vinyl chloride) blends

Poly(vinyl chloride) was mixed with various poly(methacrylate)s and polycarbonates by combined precipitation from common solutions. The thermal stability of the samples was measured at 180°C under nitrogen, the HCl evolved was detected by conductometry. UV-Vis-spectra of degraded samples were measured to investigate the influence of the poly(methacrylate)s on the lengths of polyenes formed during the degradation of poly(vinyl chloride). The experiments show that the nature of the ester group is the dominating factor for the thermal stability of poly(vinyl chloride) in these blends. Poly(n-butylmethacrylate) exhibits the best stabilization for poly(vinyl chloride) in this series. Polycarbonates with a higher glass transition temperature than the temperature of degradation destabilize poly(vinyl chloride). Stabilization experiments with dibutyltin-bis(isooctylthioglycolate) show a costabilizing effect of the poly(methacrylate)s and polycarbonates.     

Preparation and thermal characterization of block copolymers by macroazonitriles having glycidyl azide and epichlorohydrin moieties

Poly(glycidyl azide) (PGA) an energetic polymer and polyepichlorohydrin (PECH) were condensed with 4,4′ azobis(4-cyanopentanoyl chloride) (ACPC) to prepare macro-azo-initiators. Block copolymers containing each of these polyethers as a block segment combined with polystyrene (PS) or poly(vinyl acetate) (PVAc) have been drived by the polymerization of monomers initiated with this macro-azo-initiators. Thermal properties of block copolymers were investigated with differential scanning calorimetry (DSC) and thermogravimetry. DSC traces showed single glass transition temperatures in between the related segments of copolymers. Dynamic thermogravimetric analysis revealed the individual degradation behaviors of block segments © 1996 John Wiley & Sons, Inc.     

Study of Vinyl Acetate Partitioning in Emulsion Copolymerization of Vinyl Chloride-Vinyl Acetate by FTIR and HNMR Spectroscopy

Emulsion copolymerization of vinyl chloride with vinyl acetate comonomer was performed. Potassium persulfate, a mixture of stearyl alcohol and sodium lauryl sulfate, was used and reactions were performed at 55 °C in a pressurized reactor. By sampling during the reaction in different intervals copolymer composition was investigated using FTIR and NMR spectroscopy. The results showed that the partitioning of vinyl acetate in the copolymerization in general follows the Mayo-Lewis copolymerization equation with some discrepancy. This was attributed to the gaseous nature of vinyl chloride monomer and the differences between polymerization in heterogeneous and homogeneous systems. Both FTIR and NMR spectroscopy showed two peaks in vinyl acetate content of copolymer beyond 65% conversion which was attributed to the elimination of vinyl chloride droplets in the media and replacing them with vinyl acetate monomer. The first increase is related to the consumption of vinyl chloride droplets and the second is related to the consumption of gaseous vinyl chloride; in both instances vinyl acetate governs the polymerization.     

N,N-dicyclohexylcarbodiimide assisted synthesis and characterization of poly(vinyl alcohol-co-vinyl levulinate)

Poly(vinyl alcohol-co-vinyl levulinate) was synthesized by N,N-dicyclohexylcarbodiimide assisted esterification of poly(vinyl alcohol) with free levulinic acid using 4-pyrrolidino pyridine as a catalyst in N,N-dimethyl acetamide/lithium chloride solvent system in order to optimize the reaction condition. The vinyl levulinate content in the copolymer was attained up to 0.95. The ¹³C NMR dyad compositional analysis indicated the block character of the copolymer was 0.92, suggesting almost random poly(vinyl alcohol-co-vinyl levulinate) was formed. Glass transition temperature dependence on vinyl levulinate content of the copolymers fitted better into Gordon-Taylor equation as compared with Fox equation and the glass transition temperature of poly(vinyl levulinate) was given as 2.3 °C by the least regression method.     

有机聚硅氧烷接枝聚醋酸乙烯酯的研究

本工作合成了聚二甲基硅氧烷—8—聚醋酸乙烯酯,通过红外光谱、核磁共振光潜、电子显微镜照相等技术表征了接枝共聚物结构。研究了接枝率与反应时间、分子量大小、引发剂用量的关系。     

聚丙烯固相接枝N—羟甲基丙烯酰胺（HMA）：2.PP—g—N—HMA／PVC合金的研究

本文采用固相接枝方法制备聚丙烯接枝Ｎ－羟甲基丙烯酰胺共聚物，并与ＰＶＣ进行共混，详细考察了合金的力学性能，加热稳定性及微观形态结构的变化。     

Poly(vinyl chloride)‐b‐poly(hydroxypropyl acrylate)‐b‐Poly(vinyl chloride): Understanding the synthesis of an amphiphilic PVC block copolymer on a pilot scale

The aim of this work was to develop an understanding of the major difficulties associated with the scale‐up of the technology for the synthesis of poly(vinyl chloride) (PVC) block copolymers that contain hydrophilic segments, thus providing important directions to be followed in order to produce such new materials on the industrial scale. The synthesis was carried out in a two‐step process. First, the macroinitiator α,ω‐di(iodo)poly(hydroxypropyl acrylate) was synthesized in an aqueous medium by (single electron transfer)/(degenerative chain transfer) living radical polymerization (SET‐DTRP) catalyzed by Na₂S₂O₄. The block copolymer was then prepared by SET‐DTRP of vinyl chloride (VC) from the iodine‐terminal active chain ends of the macroinitiator, thereby leading to the formation of the block copolymer poly(vinyl chloride)‐b‐poly(hydroxypropyl acrylate)‐b‐poly(vinyl chloride). This report covers important aspects related to the characterization of the block copolymer produced and to the identification of the major limitations that must be overcome in order to produce this new material on the industrial scale. The results clearly show the differences between the theoretical predictions and the block copolymer compositions obtained by using a suspension polymerization method, which is the most‐used polymerization process in the PVC industry. J. VINYL ADDIT. TECHNOL., 19:94–104, 2013. © 2013 Society of Plastics Engineers     

Oxidative thermal decomposition of poly(vinyl chloride) compositions

“Pure” poly(vinyl chloride) resin and four compositions containing poly(vinyl chloride) were subjected to oxidative thermal degradation in air at &400°C both in a quiescent and a flow system. The volatiles formed were identified and quantitatively determined on a gram-per-gram basis. Hydrogen chloride was the main product found. The nature and relative concentration of the produced organic chlorinated species appeared to be dependent not only on the poly(vinyl chloride) constituent but also on the other ingredients. All the compositions contained phthalate ester plasticizers. In the dynamic system, these distilled largely unchanged, whereas under static conditions transformation into phthalic anhydride occurred.     

Kinetics of crosslinking of poly(vinyl chloride) in the presence of tetramethylthiuram disulfide and zinc oxide

Continuous measurements in a Vuremo curemeter at temperatures from 160°C to 195°C were used to estimate the extent of crosslinking of poly(vinyl chloride) which was plotted against cure time. The linearized forms of the cure curves clearly show that at obvious tetramethylthiuram disulfide–zinc oxide concentrations, the course of crosslinking differs significantly from the first-order rate law. These digressions caused by the degradation crosslinking of poly(vinyl chloride) were diminished by increasing tetramethylthiuram disulfide concentration, which simultaneously increases the ultimate extent of controlled crosslinking. On the basis of the above results, a method of the kinetic analysis of the cure curves is discussed.     

Mechanochemical block copolymerization in heterogeneous systems of the solid polyethylene with acrylamide aqueous solutions by ultrasonic irradiation

Summary Mechanochemical block copolymerization in heterogeneous systems of the solid polyethylene-acrylamide-sodium dodecyl sulfate aqueous solutions has been studied by ultrasonic irradiation at 30 °C. An additional effect of the solid polyethylene and the effects of acrylamide, and sodium dodecyl sulfate concentrations on mechanochemical block copolymerization were investigated. The block copolymerization of acrylamide was initiated by free radical produced from the polyethylene particles by ultrasonic waves. The rate of copolymerization R _p increased with increasing additional amount of polyethylene and that value was of the order of 10^-3 mol/l s. In addition, the R _p was given by R _p [Acrylamide] [Sodium dodecyl sulfate].     

Properties of Poly(vinyl chloride)/poly(ethylene oxide)/polyaniline Conductive Films: The Effect of Poly(ethylene glycol) Diglycidyl Ether

The effect of polyaniline and poly(ethylene glycol) diglycidyl ether on tensile properties, morphology, thermal degradation, and electrical conductivity of poly(vinyl chloride)/poly(ethylene oxide)/polyaniline conductive films was studied. The poly(vinyl chloride)/poly(ethylene oxide)/polyaniline conductive films were prepared using a solution casting technique at room temperature until a homogeneous solution was produced. Poly(vinyl chloride)/poly(ethylene oxide)/polyaniline/poly(ethylene glycol) diglycidyl ether conductive films exhibit higher electrical properties, tensile strength, modulus of elasticity but lower final decomposition temperature than poly(vinyl chloride)/poly(ethylene oxide)/polyaniline conductive films. Scanning electron microscopy morphology showed that the polyaniline more widely dispersed in the poly(vinyl chloride)/poly(ethylene oxide) blends with the addition of poly(ethylene glycol) diglycidyl ether as surface modifier.