Biodegradation of plasticized poly(vinyl chloride) containing cellulose

The plasticized poly(vinyl chloride) (PVC‐P) and its blend with cellulose (PVC‐P/cell) were prepared by means of extrusion. The samples were then biodegraded in forest soil as well as in soil enriched with cellulolytic microorganisms. Moreover, the samples were vaccinated with chosen species of fungi whose direct effect on polymer was then observed. The course of biodegradation was monitored in terms of, and by means of the following: weight loss, carbon dioxide evolved, attenuated total reflectance infrared (FTIR‐ATR) spectroscopy, gel permeation chromatography (GPC), as well as visual and microscopic observation (OM, SEM). The mechanical properties of samples were studied using the standard tensile tests. It was found that biodegradation in soil occurs in PVC‐P and this process is accelerated in the composition of PVC‐P with cellulose. The biodecomposition yield of PVC‐P/cellulose blends (calculated as relative percentage weight loss) is several dozen times higher than that of PVC‐P. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 903–919, 2007     

Dynamic mechanical properties of plasticized poly(vinyl chloride)

The complex compliance in extension of gels of poly(vinyl chloride) (PVC) in di(2-ethylhexyl) phthalate (DOP) and in tricresyl phosphate (TCP) was measured over the frequency range from 0.6 to 0.006 cps and the temperature range from ?66 to 65°C: the weight fractions of DOP and TCP in the gels were 0.32, 0.40, 0.49, and 0.59. Measurements were carried out in an apparatus using forced low-frequency longitudinal osillations. Data for the gels could not be combined by the method of reduced variables, since there were gradual changes with decreasing temperature, attributable to an increase in crystallinity. Application of the reduction method of Ninomiya and Ferry for solutions of crystalline polymers was found to be successful. The apparent melting temperatures (T′_m) were obtained from the temperature dependence of the vertical shift factors. An apparent heat of fusion of ca. 120 cal/mole of monomer unit was found. This melting range was in agreement with that of secondary crystallinity in plasticized PVC reported in calorimetric studies by Juijn. With decreasing temperature, two phenomena occurred in the temperature range from T_g + ca. 80°C to T_g: the vitrification of a concentrated amorphous solution and the slight crystallization of the polymeric component. The larger the difference between T_g and T′_m the broader the primary dispersion zone on the frequency scale. This broadening effect was explained as due to the difference in dependence of T_g and T′_m on plasticizer concentration, without any need to consider any specific interaction between plasticizer and PVC.     

Microcrystalline and three-dimensional network structure of plasticized poly(vinyl chloride)

Three-dimensional networks can be formed in plasticized poly(vinyl chloride) by chain entanglements and crystallites introduced in the system during the fusion and annealing processes. The fusion conditions influence the mechanical stability of the plasticized polymers, by establishing regions where one-phase systems are observed. During annealing at temperatures of between 170 and 190 °C, for up to 9 minutes, maximum degree of crystallinity of 0.079 was detected for samples plasticized with 20 wt% di-2-ethyl-hexyl-phthalate. Experimental analysis of mechanical properties and analysis of stress relaxation experiments showed that rubber elasticity theories could be applied with some approximation to plasticized PVC to analyze the structure of the three-dimensional networks formed.     

Fourier-transform infrared study of conformational changes in plasticized poly(vinyl chloride)

Fourier-transform infrared spectroscopy has been used for the detection of conformational changes induced by plasticization in atactic poly(vinyl chloride) (PVC). The amount of short trans syndiotactic sequences decrease upon plasticization. This change depends on the amount and kind of plasticizer. Difference spectra emphasize changes in the distribution of gauche defects in the chains as a function of temperature in plasticized PVC films.     

Fourier-transform infrared study of orientation in pure and plasticized poly(vinyl chloride)

Fourier-transform infrared spectroscopy has been used for the study of orientation of pure and plasticized PVC. The results show that orientation is independent of experimental conditions (temperature, strain rate, plasticizer) in the homogeneous deformation range. Such behavior is explained by the existence of a fringe micellar-type network with physical crosslinks. The network is partially destroyed during stretching. Furthermore, the orientation of the carbonyl group of the plasticizer is connected with PVC chain orientation.     

Influence of filler on migration from plasticized poly(vinyl chloride) composites

Influence of the filler (chalk) on migration of the plasticizer into air and water from poly(vinyl chloride) films plasticized with EDOS was studied by gravimetry, thermal analysis, and IR spectroscopy.     

Diffusivity of gases and main-chain cooperative motions in plasticized poly(vinyl chloride)

Permeability and time-lag measurements for H₂ and CO in poly(vinyl chloride) (PVC) plasticized with tricresyl phosphate show that the apparent diffusion coefficients at first decrease as the plas-ticizer concentration is increased. The diffusion coefficients then increase as the additive concentration is raised above 15 wt %. These changes in the apparent diffusion coefficients can be related to the behavior of a variety of mechanical properties and are attributed to antiplasticization and plasticization effects of low and high concentrations of tricresyl phosphate, respectively. The antiplasticization-plasticization effects reflect altered molecular motions of the polymer. Carbon-13 NMR rotating-frame relaxation rate measurements show directly that the cooperative main-chain molecular motions of PVC are reduced when the additive acts as an antiplasticizer and are increased when the polymer is plasticized. Both the apparent diffusion coefficient and the rotating-frame relaxation rate have a similar dependence on additive concentration. An application of the molecular theory of diffusion of Pace and Datyner accounts qualitatively for the way in which additives alter the average chain interaction energy, cooperative polymer main-chain motions, and the diffusion coefficients of gaseous penetrants.     

Leaching of organotin compounds from poly(vinyl chloride) (PVC) material

The release of mono-and di-butyltin species (MBT and DBT) in water after leaching of five different poly(vinyl chloride) (PVC) materials was investigated under mild conditions over a period of one month in batch reactor systems. Results showed that inorganic tin, MBT and DBT compound were released from the material tested under experimental static leaching conditions. The total amount of inorganic tin and organotin compounds observed upon leaching varied considerably from one PVC material to another.     

Degradation of poly(vinyl chloride) plasticized with non-phthalate plasticizers under sterilization conditions

Plasticized PVC formulations have traditionally been used in the production of medical devices, such as tubes and bags for plasma or blood because of their good performance in mechanical and thermal properties as well as their low cost. Clinical practice, in particular re-use after sterilization, can damage and promote degradation of these materials with the risk of release of polymer additives into physiological fluids and consequently risks to patient's health. Formulations with commercial plasticizers, alternative to traditional phthalates (citrate and carboxylate compounds) have been proposed in this work and their behaviour after repeated sterilization has been evaluated. Structural, mechanical, thermal and surface properties have been tested and no significant degradation was observed. No apparent risk of massive damage to plasticized PVC could be considered after repeated sterilization.     

Compatibility of iron-containing polymeric additives with a cable-grade plasticized poly(vinyl chloride)

Several linear polymeric ferrocene compounds with $\text{M}{}_{\mathrm{<mtext>n</mtext>}}$ in the range 1200–3000 have been compounded with a cable-grade, DIOP-plasticized PVC at concentrations of 1–5%; two non-polymeric ketoferrocenes and a heteroferrocene have been included for comparison. Moulded sheets, prepared from the compounded materials, have been evaluated for compatibility by visual inspection, from analyses prior to and after a heat aging treatment, and from stress-strain data. Best performance with respect to all three compatibility criteria has been observed for a poly(ferrocenylenemethylene) with $\text{M}{}_{\mathrm{<mtext>n</mtext><mtext>\; =\; 2400</mtext>}}$, which shows excellent compatibility up to a loading of 9%. Good performance has also been demonstrated for a number of related polymers substituted at the bridging carbon atom. These findings suggest promising applications for selected polymeric ferrocenes as multifunctional additives for PVC-based engineering and biomedical materials.     

Relaxation properties of plasticised poly(vinyl chloride) and PVC blends

The temperature-frequency dependence of dielectric parameters for several PVC-plasticizer systems and PVC blends was obtained. Kinetic and activation parameters and α-relaxation spectra were estimated. The increase of the polar group number and size in the plasticizer molecules results in the narrowing of the relaxation spectra and in the increase of inner mobility of PVC segments. It was found for PVC-ABS and PVC-Paraloid blends that all relaxation characteristics depend on the miscibility of components. The results were also confirmed by the cloud point data.     

Optical determination of ionophore diffusion coefficients in plasticized poly(vinyl chloride) sensing films

The knowledge of accurate diffusion coefficients of electrically neutral ionophores in solvent polymeric membranes is important in view of understanding and optimizing important sensor characteristics of ion-selective electrodes (ISEs) and their corresponding optical sensors. A spectroscopic imaging technique is introduced here to determine the diffusion coefficient of the chromoionophore (N,N-diethyl-5-(octadecanoylimino)-5H-benzo[a]phenoxazine-9-amine, ETH 5294) in solvent polymeric membranes with different types of plasticizers and varying polymer-plasticizer ratio. This method is based on following the changes in the absorbance profiles of the chromoionophore as a function of space and time. The desired membrane composition is solvent cast onto a glass slide and placed under a microscope objective. The membrane is then exposed to light from a mercury arc lamp which photobleaches the dye in a circular area, providing an interface from which the time rate of absorbance change is studied. Spectral images are acquired over fixed time intervals with a microscope equipped with a charge-coupled device (CCD) camera providing 0.41 μm nominal resolution. Two plasticizers, ortho-nitrophenyl octyl ether (o-NPOE) and bis(2-ethylhexyl) sebacate (DOS), are examined in poly(vinyl chloride) (PVC) by varying the ratio of polymer to plasticizer content and measuring the diffusion coefficient of the chromoionophore. Corresponding membrane compositions containing 10 wt.% of an inert lipophilic salt (ETH 500) are also examined. Near linear relationships between the logarithmic diffusion coefficients and the PVC content are observed that obey the following relationships: -0.0459 wt.% PVC (for PVC-DOS), -0.0468 wt.% PVC (for PVC-DOS-ETH 500), -0.0508 wt.% PVC (for PVC-NPOE), -0.0473 wt.% PVC (for PVC-NPOE-ETH 500).     

Dynamic mechanical properties of plasticized poly(vinyl chloride). Linear free energy relationship in the poly(vinyl chloride)–ester system

A considerable number of quantitative attempts have been made to predict the properties of solutions containing polar polymers and polar solvents. Thermodynamic approaches have generally failed to accurately describe these systems. This can be be ascribed to the difficulty in determining structural characteristics arising from the variety of secondary interactions present in these highly complex solutions. A linear free energy relationship has been used here to explore changes encountered in solutions of monofunctional esters in poly(vinyl chloride) undergoing mechanical deformation. This treatment appears valid only for the rubbery region of the viscoelastic spectrum of this polymer. The data indicate that the observed changes are a function of corresponding changes in polymer intramolecular interactions.     

Anomalies and error limits in electrical-conductivity measurements in plasticized transparent poly(vinyl chloride) films

The anomalous behavior of the electrical conductivity of transparent poly(vinyl chloride) films is experimentally studied at field voltages approaching the breakdown threshold, above the threshold, and far below the threshold. The effects of strong nonlinearity, relaxation drifts, and spontaneous reversible transitions between states with high and low electrical conductivities are revealed for the first time in “thick” (20–100 μm) plasticized transparent poly(vinyl chloride) films. When a certain threshold is exceeded, relaxation oscillations in the test sample are generated and their frequency is proportional to the applied voltage. During a “mild” breakdown, the polymer film passes into the high-conductivity state (the current increases by four or more orders of magnitude), which is identical to the states observed during low-voltage transitions. A simple qualitative model explaining the anomalous character of the electrical conductivity of plasticized poly(vinyl chloride) films is advanced.     

A stereochemical microstructure-based attempt to explain the dielectric behavior of poly(vinyl chloride) (PVC)

A poly(vinylchloride) (PVC) obtained by bulk polymerization at 70 °C was modified through substitution reaction with sodium benzenethiolate (NaBT) in cyclohexanone solution at 25 °C, at various conversions up to 15 mol %. According to earlier work, this allows to change, in a controlled way, the stereochemical microstructure in terms of mainly the content of mmr (meso, meso, racemic) tetrad termini of isotactic sequences of at least one heptad in length, and of its likely chain conformations. The samples were all studied by Dielectric Relaxation Spectroscopy, which allows to measure the real and the imaginary parts of the complex dielectrical constant in a frequency range between 1 and 10⁶ Hz, and a temperature range between 100 and 600 K. Most of the changes in the physical quantities that can be analyzed by this technique were found to parallel the changes in stereochemical microstructure with substitution extent. The temperature of the maximum of the dipolar losses, which relates to the temperature range where α relaxation occurs, appeared to increase somewhat up to 0.7% molar conversion. Then the tendency is towards stabilization. The relaxation time τ(T) as deduced from the Havriliak-Negami (NH) function, tends to decrease between 0 and 0.7 substitution percent, and to increase afterwards. The evolution of the Ngai's β parameter with substitution degree is also highly illustrative. It clearly decreases up to 0.7% and then it increases rapidly up to 7% and slowly afterwards. These changes are discussed by taking into account that 0.7 and 7% substitution extents agree with the removal of mmr under GTTG⁻TT conformation and of the same structure under GTGTTT conformation, respectively. From the results, some original correlations between stereochemical microstructure and molecular dynamic behaviors are proposed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2337–2347, 2004     

Diffusion of additives and plasticizers in poly(vinyl chloride)—II: The self-diffusion of the stabilizers dibutyltin dilaurate and dibutyltin bismonobutylmaleate in plasticized poly(vinyl chloride)

The self-diffusion coefficient, D, of dibutyltin dilaurate and dibutyltin bismonobutylmaleate have been obtained at 35, 45 and 55° in samples of poly(vinyl chloride) plasticized with 34, 60 and 100 phr of di(2-ethylhexyl)phthalate. D at 2 phr of the laurate is 3–5 times larger than for the smaller maleate molecule. In all cases, D increases with increasing plasticizer concentration, an effect interpreted in terms of the free volume theory of diffusion. D for the laurate increases by a factor of about 2.7 when the laurate diffusant concentration is increased from 0 to 4 phr. The activation energies for diffusion, E_D, lie between 50 and 90 kJ mol^?1. They increase with increasing plasticizer concentration but become constant at higher plasticizer concentrations (60–100 phr). It is impossible to correlate all the known data on diffusion in plasticized PVC with an equation of the form log D₀ = C₁ + C₂ E_D/RT     

Kinetic model of the evaporation process of benzylbutyl phthalate from plasticized poly(vinyl chloride)

The kinetic model of the physical process of evaporation of plasticizer from plasticized PVC foils was developed from the results of isothermal thermogravimetric investigation of evaporation of benzyl-butyl phthalate in the temperature range 120-150 °C under nitrogen flow. The kinetic parameters were estimated by integral method of analysis. Mathematical modeling of the kinetic of plasticizers evaporation was performed on the basis of function c=f(T,t) and kinetic equation of evaporation −dc/dt=f(T,c₀,c(t)). The developed mathematical model was described by the general kinetic equation . The differential quotients δ(−dc/dt)/δT=f(T,c₀,c(t))=f(T,c₀,t) and δ(−dc/dt)/δc₀=f(T,c(t))=f(T,c₀,t) were performed, and mathematical definition of the changes of the evaporation rate constant with the change of temperature and the change of the initial plasticized concentration were discussed.     

Photodynamic ion sensor systems with spiropyran: photoactivated acidity changes in plasticized poly(vinyl chloride)

We aim to introduce photoactivated optical ion sensors based on a triggered ion exchange process as novel dynamic tools. The quantification of the acidity change upon photoactivation of spiropyran within an organic membrane phase during photoexcitation is described here for the first time, suggesting a large pK(a) change of more than 6 orders of magnitude.     

Colorimetric analysis of thermal degradation of plasticized poly(vinyl chloride): Potentials and limitations

The kinetics of formation and consumption of polyenes is studied by measuring the change in color coordinates and color difference during the thermal aging of plasticized poly(vinyl chloride) at a temperature of 60–130°С under vented conditions and in a closed volume. It is shown that the initial rate of accumulation and the quasi-stationary concentration of polyenes at 100–130°С grow with temperature. The energy of activation of dehydrochlorination is 70 ± 3 kJ/mol. At a lower temperature (60–80°С), the intensity of color of the samples that are preliminarily aged at increased temperatures decreases. The reduction in the rate of this process with temperature in the range of 60–80°С and the presence of the quasi-stationary level at 100–130°С are related to competition of the processes of formation and oxidation of polyenes.