Graft copolymerzation of poly(vinyl chloride) with styrene. I. Synthesis and characterization

Graft copolymerization of poly(vinyl chloride) (PVC) partially dehydrochlorinated by heating in nitrobenzene was investigated using styrene as monomer and anhydrous AlCl₃ as cationic initiator in the temperature range of 0–35°C. Effect of monomer, catalyst, and PVC concentration on % graft-on was also evaluated. Introduction of labile sites in PVC by partial dehydrochlorination in nitrobenzene resulted in an increase in % graft-on. Intrinsic viscosity of PVC–g–polystyrene in THF initially increased with an increase in % graft-on. At higher % graft-on a decrease in [η] was observed.     

Graft copolymerization of styrene onto poly(vinyl p-nitrobenzoate) by chain transfer reaction

To obtain highly branched graft copolymers, styrene (St) was grafted onto poly(vinyl p-nitrobenzoate) (PVNB) as a trunk polymer through the chain transfer reaction of growing polystyrene (PSt) radicals to the pendent aromatic nitro groups on the trunk polymer. The number of PSt branches increased with St concentration at constant concentrations of PVNB and azobisisobutyronitrile (AIBN) as an initiator, and decreased with AIBN concentration at constant PVNB and St concentrations. The maximum number of branches attained was 43 (P_n of PVNB was 970), which corresponds to 23 monomer units of PVNB per PSt branch. It is confirmed from the results of infrared spectroscopy that the addition of the growing polystyrene radicals occurs not at the benzene rings but at the nitro groups on the benzene rings. Polymerization of St was also carried out in the presence of isopropyl p-nitrobenzoate (IPNB) as a model compound of PVNB. IPNB was found to retard the polymerization of styrene more strongly than PVNB. The chain transfer constant of the polystyrene radicals to IPNB was more than twice as large as that to PVNB.     

Graft copolymerization of N‐isopropylacrylamide onto poly(vinyl chloride)

Poly(vinyl chloride) (PVC) was dehydrochlorinated in alkali solution and then grafted with N‐isopropylacrylamide (NIPAM) using benzoyl peroxide as an initiator under a nitrogen atmosphere. The results show that grafting of NIPAM onto dehydrochlorinated PVC (DHPVC) by means of chemical initiation is easily performed. The influence of various reaction conditions such as NIPAM concentration, reaction time, initiator concentration, and PVC content on the grafting copolymerization was investigated. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1234–1241, 1999     

Rheological behavior of poly(vinyl chloride) mixture. II. Elastic behavior

This study was undertaken in order to understand the effect of low molecular weight additives on the visco-elastic properties of polymers and, in particular, Diamond Shamrock Corporation's PVC-40 resin. The viscous response has been reported in Part I of this series (11). This report describes the elastic properties of these mixtures. A new theoretical analysis of elastic response has been formulated. The direct calculation of stored elastic energy from capillary rheometer measurements is now possible. The conclusion drawn from both the viscous and elastic response study is that a change in viscosity is not a necessary nor sufficient condition for improved processability. Increased flow is obtained by lowering the viscous losses, but the melt fracture phenomena may be unchanged. In order to completely characterize the compound, both viscous and elastic response must be measured.     

Preparation and application of low molecular weight poly(vinyl chloride). II. Thermal stability of blended poly(vinyl chloride)

The blending effect of poly(vinyl chloride) (PVC) with relatively higher molecular weight (HMW-PVC) and relatively lower molecular weight (LMW-PVC) has been investigated by measuring various thermal stability and fusion times. The thermal stability of the blended PVC is improved when the small amount of LMW-PVC obtained using mercapto compounds as a chain-transfer agent is blended into PVC with HMW-PVC. At the LMW-PVC content from about 5–30 wt %, the thermal stability of the blended PVC is much more improved. Furthermore, the blended PVC with LMW-PVC, obtained using mercapto compounds, exhibits significant improvement in the discoloration time. The fusion time of the blended PVC is related to the weight-average polymerization degree of LMW-PVC and the LMW-PVC content. © 1994 John Wiley & Sons, Inc.     

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%.     

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.     

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.     

Thermal analysis of irradiated poly(vinyl chloride)

The thermal decomposition and resultant disposal of waste poly(vinyl chloride) (PVC) is facilitated by preliminary exposure to ionizing radiation, such as energetic electrons, in an oxygen atmosphere. The results of isothermal and temperature-programmed thermogravimetry, differential thermal analysis, and effluent gas analysis in nitrogen and in oxygen indicate that the major effect of irradiation is to render PVC increasingly susceptible to oxidation. The presence of oxygen during heating enhances the decomposition. Crystalline order in PVC is destroyed by irradiation.     

Thermal analysis of compounded poly(vinyl chloride)

Differential thermal analysis of mixtures of poly(vinyl chloride) and dioctyl phthalate shows a compound endothermic peak due to decomposition of both polymer and plasticizer. The thermal behavior of other plasticizers is similarly affected in the presence of poly(vinyl chloride). The addition of zinc oxide or ferric oxide decreases the thermal stability of the mixture and, under isothermal conditions, a resultant induction period allows the estimation of an activation energy for the dehydrochlorination of poly-(vinyl chloride) and of the relative effectiveness of thermal stabilizer systems.     

Thermal analysis of poly (vinyl chloride) fractions

The thermal stability of commercial poly(vinyl Chloride) and its four fractions having different intrinsic viscosities (1.152–0.397 dl/g) has been investigated thermogravimetrically in the presence of atmospheric oxygen, up to a temperature of 400°C, by using the nonisothermal technique. The results indicate that the thermal stability of the polymer is inversely proportional to its intrinsic viscosity. The kinetic parameters have been evaluated for the early stages of decomposition (2% to 20%). The results have been explained on the basis of different structures of the polymer chain in fractions of high and low intrinsic viscosity.     

Thermal degradation behavior of poly(vinyl chloride) in the presence of poly(glycidyl methacrylate)

The thermal degradation behavior of poly(vinyl chloride) (PVC) in presence of poly(glycidyl methacrylate) (PGMA) has been studied using continuous potentiometric determination of the evolved HCl gas from the degradation process from one hand and by evaluating the extent of discoloration of the degraded samples from the other. The efficiency of blending PGMA with dibasic lead carbonate (DBLC) conventional thermal stabilizer has also been investigated. A probable radical mechanism for the effect of PGMA on the thermal stabilization of PVC has been suggested based on data reported by FTIR and elemental analyses. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Rheological behavior of poly(vinyl chloride) mixtures. I. Viscous behavior

An investigation of the viscous flow properties of mixtures of low molecular weight materials, such as lubricants and plasticizer, with PVC has been carried out. In all examples studied the PVC exhibited a discontinuity in flow with increasing temperature. This was interpreted as a phase change in the melt. A diffusion fractionation of the low molecular weight species was used to rationalize the shear rate dependent viscous behavior of these melts.     

Irradiation of poly(vinyl chloride) with H2 plasma. II

Poly(vinyl chloride) films blended with plasticizers, stabilizers, and fillers are irradiated with a beam of H₂ plasma. The polymer partially loses its solubility in cyclohexanone. The viscosity of the soluble part decreases in the initial stages and then increases on further irradiation. Crosslinking was followed by dehydrochlorination and discoloration of the polymer. The electrical conductivity was measured as a function of the irradiation dose and time. The plasticizers enhanced the action of plasma while the stabilizers and fillers reduced it.     

Graft copolymerization of styrene onto poly(p-nitrophenyl acrylate) by chain transfer reaction

Styrene (St) was polymerized in the presence of poly(p-nitrophenyl acrylate) (PNPA) with azobisisobutyronitrile as an initiator to prepare graft copolymers through the chain transfer reaction of growing polystyrene (PSt) radicals to the aromatic nitro groups on PNPA. The maximum number of branches attained was 16.4 (P _n of PNPA was 1780), which corresponds to 108 monomer units per PSt branch. This is far less than the value of 43, previously obtained for poly(vinyl p-nitrobenzoate) as a trunk polymer. Therefore, several model compounds for trunk polymers were prepared, and the chain transfer constants of PSt radicals to these model compounds were determined. As a result of the Hammett plot, it is concluded that higher electron attracting property of the substituents increases the reactivity of nitro groups to the growing PSt radicals, resulting in more highly branched graft copolymers.     

Modification of poly(vinyl chloride). XIX. Electroplating of poly(vinyl chloride)

As a preliminary treatment in the PVC-electroplating procedure, treatment with dimethylformamide followed by sensitization leads to a finely roughened and a highly hydrophilic surface with reducing power. This is caused by the formation of an ionic complex compound between dimethylformamide and tin(II) chloride absorbed in the PVC surface. A much more finely and deeply etched surface which exhibits higher adhesion through the mechanical interlocking effect is obtained with the PVC blends containing the plasticizer with a low value of interaction parameter and with a solubility parameter approximate to that of PVC. Adhesion of the metal layer to the PVC surface thus obtained is improved about 1.5 times by thermal aging at 120°C for 20 min.     

Thermal decomposition of chlorinated poly(vinyl chloride) (CPVC)

Chlorinated poly(vinyl chloride) (CPVC) shows reductions in flammability and smoke production over PVC. The thermal decomposition of pure CPVC (without stabilizer or lubricant) was studied by dynamic thermogravimetric analysis (TGA) at heating rates from 5 to 100°C/min in atmospheres of nitrogen, air, and oxygen. In each case, a two‐step decomposition was observed similar to that for PVC where dehydrochlorination is followed by pyrolysis/oxidation of the carbonaceous residue. The rate of dehydrochlorination was dependent on atmosphere, occurring slightly slower in nitrogen than in air, and slightly more quickly in oxygen than in air. The decomposition of the residual char was clearly dependent on the conditions in which it was formed. Under dynamic conditions, chars formed at high heating rates appeared more resilient to oxidative degradation than those formed more slowly. However, when chars were formed by heating at different rates and then held at 500°C, the char formed at the slowest heating rate was the slowest to be oxidized. The uptake of oxygen by the char appears to be rate‐limiting. At low heating rates char oxidation is similar in both air and oxygen. As the heating rate is raised, the rate of mass loss of char in air becomes progressively closer to that in nitrogen until at 100°C/min they are almost identical. This work is important to the understanding of the decomposition and flammability of CPVC and flame‐retarded CPVC, where the char formation is one of the flame‐retardant mechanisms.     

Anomalous dynamic mechanical behavior of poly(vinyl chloride)

In this paper, we present a study of the dynamic mechanicall behavior of a quenched poly(vinyl chloride). A new relaxation between the glass transition and the β transition is reported. We have related this new relaxation to an absence of physical aging.     

Nonlinear viscoelastic behavior of plasticized poly(vinyl chloride)

This paper shows how an empirical nonlinear creep relation suggested by Leaderman might be justified on the basis of an approximate nonlinear viscoelastic constitutive equation. In addition, experimental evidence is presented which tends to support the proposed theory.