Soiling of plasticized poly(vinyl chloride)

The effects of three plasticizers and two plasticizer concentrations on the topography and soiling of poly (vinyl chloride) (PVC) were studied. Palmitic acid and triolein were chosen to represent solid and liquid soils. The feasibility of using infrared spectroscopy to quantify the amount of soil on PVC was examined. The structure of the solid model soil on plasticized PVC was studied with optical microscopy and atomic force microscopy. Palmitic acid formed two different structures on the PVC surface. Both the type and concentration of the plasticizer influenced the structure of the oily soil on plasticized PVC. The wetting of plasticized PVC with the liquid oily soil was compared to wetting with water through the measurement of the contact angles. Plasticized PVC was hydrophobic and oleophilic. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Weathering of plasticized poly(vinyl chloride)

A series of flexible plasticized poly(vinyl chloride) (PVC) compositions containing different organotin compounds and ultraviolet absorbers has been exposed for 4.5 years at four outdoor sites in Australia with widely differing climatic conditions. Loss of plasticizer by evaporation during the exposure was measured and an empirical correlation was found with the average daily maximum temperature at each site. The relative effectiveness of the organotin compounds and ultraviolet absorbers in preventing deterioration of the PVC was estimated by measuring the viscosity of the polymer after exposure. This method of assessment is compared with the results of mechanical tests on the specimens.     

A hysteresis in plasticized poly(vinyl chloride)

Plasticized poly(vinyl chloride) formulations were prepared in solid and foam form, and mechanical hysteresis was measured by low-speed tension and compression on an Instron tester and by high-speed rebound on a resiliometer. Hysteresis was greatest in copolymers with vinyl acetate, at low plasticizer concentration, with inefficient plasticizers, at high concentrations of reinforcing fillers, at high expansion to low density, and at high speed of testing. Conversely, resilience was greatest at high plasticizer concentration, with more efficient plasticizers, with non-reinforcing fillers, and at high density.     

Smoke suppressants for plasticized poly(vinyl chloride)

Addition of plasticizers to poly(vinyl chloride) generally increases its flammability and frequently increases smoke production during its burning. Flame retardants added to plasticized PVC can reduce flammability, but increase smoke production. This study shows that proper choice of combined use of other polymers, phosphate plasticizers, fillers and other flame retardants, produces measured synergistic improvements in flame retardance and smoke suppression which could benefit applications such as PVC wire and cable insulation.     

Blends of poly(vinyl chloride) with plasticized polyaniline

A series of poly(vinyl chloride) (PVC)/polyaniline (PANI) blends plasticized and protonated simulataneously by bis(2-ethylhexyl) hydrogen phosphate, bis(4-nitrophenyl) phosphate, diphenyl phosphate, or dibenzyl phosphate was prepared by a mass homogenization technique. Thermal analysis studies by means of thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealed that PVC/PANI blends with bis(2-ethylhexyl) hydrogen phosphate were characterized by the highest thermal stability values. Kinetic analysis of the decomposition process by the isoconversional Friedman method showed that the activation energy did not change substantially over the broad conversion range; further advanced kinetic analysis by a nonlinear regression method revealed that the kinetic function that was the best approximation for the experimental data was based on a reaction of nth order.     

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.     

Chlorinated poly(vinyl chloride) and plasticized chlorinated poly(vinyl chloride)—thermal decomposition studies

The thermal decomposition of chlorinated poly(vinyl chloride) and three plasticized chlorinated poly(vinyl chloride) systems has been investigated. The routes of decomposition of these systems have been elucidated by investigating char formation and by using a combination of thermogravimetric analysis (TGA) and prolysis/gas chromatography/mass spectroscopy methods (Py/GC/MS). The effects of the charforming/smoke‐suppressing iron(III) compound FeOOH in these polymer systems has also been investigated. The structure of both CPVC polymer and plasticzer determine the path of thermal decomposition and also the quantity and nature of the decomposition compunds formed. Changes in oxygen index and the formation of smoke during burning in these systems have been related to the char that is formed and also to the chemical nature of the decomposition products.     

On the dynamic state of plasticized poly(vinyl chloride)

The spin probe technique is suggested to be suitable for the study of polymer-plasticizer interactions. In this work it was found that the rotational relaxation time (τ) of probe radicals in plasticized poly(vinyl chloride) (PVC) diminishes strongly when the amount of plasticizer is increased. A linear correlation between τ and Young's modulus (G) was observed. This indicated that the microstate considerably influences the mechanical behaviour of the gel. The translational diffusion constant of plasticizer molecules at 25°C was calculated to change from 0.2 times; 10^-8 cm²/s (PVC weight fraction 0.83) to 4.6 times; 10^-8 cm²/s, (PVC weight fraction 0.20). These values indicate a high degree of freedom for lateral motion of plasticizer molecules in gels.     

Rheological and mechanical properties of plasticized poly(vinyl chloride)

The dependence of rheological properties of a plasticized, filled poly(vinyl chloride) compound on three different methods of thermomechanical treatments has been studied. These three different states of the compound are the dry blend mixed at a maximum temperature of 93°C, the two-roll milled sample prepared at 150°C from the dry blend and the molded sample pressed at 170°C from the previously milled material. At 150°C the viscosity and elasticity of the molded sample are considerably higher than those of the dry blend and the milled sample. At higher temperatures, although their flow curves more or less merge, extrudate swell, extrudate appearance and extrudate tensile properties of the three samples vary. The mechanical and Theological properties of the quenched and annealed molded samples and those of the same compound without filler have also been investigated.     

Irreversible deformation of plasticized and impact-modified poly(vinyl chloride)

Tensile mechanical properties of DOP-plasticized poly(vinyl chloride) (PVC) and methyl methacrylate-butyl acrylate copolymer (MMA-BA) or ethylene vinyl acetate-vinyl chloride copolymer (EVA-VC) modified PVC have been studied. The irreversible deformation processes have been investigated using optical microscopy. Thermal analysis and x-ray diffraction were used to investigate the structure of the PVC blends. The differences in behavior observed for the modified and plasticized PVC are discussed on the basis of their morphology.     

Flow instability in capillary extrusion of plasticized poly(vinyl chloride)

Flow instability in a capillary extrusion is studied for a high molecular weight, plasticized poly(vinyl chloride) (PVC). The onset of melt fracture correlates with the long time relaxation ascribed to the generation and/or growth of PVC crystallites. An increase in the residence time in the cylinder leads to this long time relaxation and results in the melt fracture, although the apparent shear stress remains constant, irrespective of the residence time. The extrudate temperature and the species of the plasticizer also have a significant influence on the apparatus of the extruded products. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1277–1283, 2001     

Blends of plasticized poly(vinyl chloride) and waste flexible poly(vinyl chloride) with waste nitrile rubber powder

Blends of poly(vinyl chloride) (PVC) with varying contents of plasticizer and finely ground powder of waste nitrile rubber rollers were prepared over a wide range of rubber contents through high‐temperature blending. The effects of rubber and plasticizer (dioctyl phthalate) content on the tensile strength, percentage elongation, impact properties, hardness, abrasion resistance, flexural crack resistance, limiting oxygen index (LOI), electrical properties, and breakdown voltage were studied. The percentage elongation, flexural crack resistance, and impact strength of blends increased considerably over those of PVC. The waste rubber had a plasticizing effect. Blends of waste plasticized PVC and waste nitrile rubber showed promising properties. The electrical properties and LOI decreased with increasing rubber and plasticizer content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1552–1558, 2004     

Diamide derivatives as photostabilizers for plasticized poly(vinyl chloride)

Some diamide derivatives have been prepared, characterized, and investigated as photostabilizers for plasticized poly(vinyl chloride) (PVC), containing dioctyl phthalate and dibutyl phthalate in a concentration of 30% by weight of the polymer. The stabilizing efficiency of the prepared diamides was evaluated by determining the weight loss percentage that resulted from HCl evolution during the photodegradation process. Moreover, the efficiency was evaluated by determining the amount of gel formed as well as the intrinsic viscosity of the soluble fractions of the photodegraded polymer. The extent of discoloration of the photodegraded stabilized and plasticized PVC was also investigated. The stabilization mechanism and the effect of plasticizers on the photostability of PVC are discussed. J. Vinyl Addit. Technol., 2008. © 2008 Society of Plastics Engineers     

Plasticizer migration from plasticized into unplasticized poly(vinyl chloride)

There exist important industrial applications, such as hoses or plastic windows, dealing with closely combining plasticized and rigid poly(vinyl chloride). Nevertheless, migration of plasticizer causes severe variation of the mechanical performance of the end-products. This work comprises an effort to investigate and understand these phenomena, also as an extension of previous work of ours in migration to liquid environments. The common system plasticized PVC/dioctylphthalate/unplasticized PVC was studied under two-sided diffusion conditions, i.e., from a thin sheet of plasticized sheet. The whole assembly was placed between two glass plates and then was held in an oven at 64°C to simulate accelerated test conditions. Some pressure was also applied to ensure perfect contact between the plastic sheets. Three different levels of initial plasticizer concentration (48, 66, and 100 phr) have been considered for a period of about five months, until equilibrium was reached. During this period the migration process was monitored by weight changes. Plots of M_t/M_∞ vs. t^½, where M_∞ the amount migrated at equilibrium and M_t the amount lost at time t, resulted in evident linear relationship. Therefore, it was proved that the Fick's law approximation for short times can be used to describe the migration kinetics for this solid/solid system. On the other hand, macroscopic observations revealed that no plasticizer was accumulated at the interface, i.e. all plasticizer leaving the plasticized sheet entered the rigid ones. Finally, it seems that the controlling stage is the diffusion inside plasticized PVC while possible annealing of the plasticized polymer structure cannot be excluded.     

Glass transition and physical ageing in plasticized poly(vinyl chloride)

Several samples of poly(vinyl chloride) both unplasticized and plasticized with dioctyl phthalate, have been examined by differential scanning calorimetry. It was observed that, while the glass transition temperature T_g decreased as expected with increasing plasticizer content, a small portion of the sample appeared to be resistant to the plasticizer. This was manifest in the appearance of a second T_g corresponding to the unplasticized sample which remained unaffected by addition of plasticizer. The ageing behaviour of the samples was also examined using enthalpy relaxation measurements and it was observed that the presence of plasticizer accelerates the ageing process, probably due to the fact that there is greater mobility of the chains in the plasticized samples.     

The solubility of vinyl chloride in poly(vinyl chloride)

The solubility of vinyl chloride monomer (VCM) in PVC powders has been studied by equilibrium vapor pressure and microbalance gravimetric techniques at temperatures from 30 to 110°C. At temperatures and VCM concentrations above the glass transition, the solubility closely follows the Flory-Huggins equation with χ = 0.98 and is independent of temperature and of the PVC type, molecular weight, or history. In the glassy state, the VCM solubility is higher than the Flory-Huggins value and shows pronounced dependence upon time and the PVC history. These results have been interpreted through the dual-mode sorption concept of Michaels, Vieth, and Barrie: Normal dissolution follows the Flory-Huggins relation, and the additional glassy-state solubility represents the contribution of a hole-filling process. Changes in solubility with time and sample history parallel well-known volume relaxation processes, indicating that vapor solubility measurements offer a direct and sensitive measure of the free-volume state of glassy polymers.     

Photostabilization of poly(vinyl chloride) by protective coatings

The light stability of poly(vinyl chloride) plates has been substantially increased by protecting their surface with a UV‐cured acrylic clearcoat containing both a UV absorber and a HALS radical scavenger. To ensure a long‐lasting adhesion, the coating was photochemically grafted onto the PVC substrate. The coated PVC sample remained transparent, non‐colored, and glossy upon accelerated QUV‐B weathering for up to 3000 hours. An additional advantage of this method of photostabilization is to improve some of the surface properties of the coated polymer, such as its resistance to solvents, abrasion, and scratching. The method was also successfully used to recover highly photodegraded PVC and make it even more weathering‐resistant than the original polymer.     

Diffusion of stabilizers in polymers. IV. 2,4-dihydroxybenzophenone in plasticized poly(vinyl chloride)

The diffusion of the radioactively labeled ultraviolet stabilizer 2,4-dihydroxybenzophenone in compression-molded sheets of plasticized poly(vinyl chloride) was studied over the temperature range of 30°C–75°C. No detectable diffusion occurred in the 0% and 10% plasticized poly(vinyl chloride) when the diffusion temperature was below the glass transition temperatures of the polymers. Diffusion coefficients have been measured for plasticizer concentrations of 20, 30, 40, and 50 wt%. In each case, the variation of the diffusion coefficient D with temperature T can be represented by an Arrhenius expression D = D₀ exp(?E/RT). The linear relation log D₀ = ?7.1 + 0.20E/T was obtained as an empirical expression of the results.     

Thermal analysis of the glass transition of plasticized poly(vinyl chloride)

Earlier studies by differential scanning calorimetry showed anomalous behavior of T_g with varying amounts of dioctyl phthalate, while by dynamic mechanical analysis 2 T_g's were found over a limited concentration range. In this study, two adjacent T_g's were found over the complete range of concentrations of dioctyl phthalate or dioctyl adipate, changing in relative contributions over the range. The results are shown to be consistent with the earlier work and to fit the Couchman model more closely than other models tested.     

Deformation behavior of plasticized poly(vinyl chloride) membranes with barium content

Barium complexes were embedded in plasticized poly(vinyl chloride) (PVC) membranes. Effects of these metallic complexes were followed as a function temperature and strain rate. It was found that both the elastic modulus and yield stress decrease with barium content. This behavior is attributed to a lack of uniform structure and the existence of irregularities and voids in the bulk membranes. Another factor which may reduce the tensile strength is te internal and interfacial residual stresses developed at the metal-matrix interface. These internal stresses and the structural nonuniformity influence the electrical conduction mechanism and performance of the PVC matrix ion-selective electrodes during aging. Also, it was observed that the yield stress of these membranes has a strain rate and temperature dependence.