Study of dynamic mechanical properties of poly(vinyl chloride)–ethylene vinyl acetate copolymer and poly(vinyl chloride)–chlorinated ethylene vinyl acetate copolymer mixtures

The compatibility of the mixtures poly(vinyl chloride)—ethylene vinyl acetate copolymer and poly(vinyl chloride)—chlorinated ethylene vinyl acetate copolymer was studied by the method of dynamic mechanical testing. The character of G′ and G″ was confronted with the Takayanagi model. In all cases a limited compatibility of the components was observed.     

Dielectric and mechanical properties of poly(vinyl chloride)–dioctylphthalate systems

The mechanical properties, tensile strength, and elongation were investigated for poly(vinyl chloride) (PVC) samples mixed with dioctylphthalate (DOP) at concentrations from 0 to 100 parts per hundred parts PVC at 23°C. It was found that the tensile strength decreased with the increase of concentration, and the elongation was increased until a concentration of 30 DOP content, and then decreased. This leads to the suggestion that intermolecular plasticization is dominant until 30 DOP content, while interstructural plasticization is prevailing for higher concentrations. The permittivity ε′ and the dielectric loss factor ε″ of the same samples have been measured in the frequency range 10²–10⁵ Hz at temperatures from 3 to 96°C. Results show that as the DOP content increases in PVC, the dielectric absorption becomes broader, and the glass transition temperature T_g is lowered. The magnitude of the loss peak decreases with an increase of DOP content to a minimum at concentrations from 40 to 60 DOP content. At higher concentrations the loss peak is increased and T_g is unaltered. Another absorption was observed at 100 Hz and at high temperatures, which was attributed to Maxwell–Wagner effect or direct current conductivity or both of them. It was found that the sample containing 40 parts DOP in 100 parts PVC possesses the best mechanical and electrical properties.     

Dynamic mechanical properties of photopolymerizable poly(vinyl alcohol)–acrylate monomer blends

Dynamic mechanical properties of photopolymerizable poly(vinyl alcohol) (PVA)–monoacrylate blends were investigated by measuring dynamic shear modulus G′ and loss tangent, tan δ. The dynamic mechanical properties of the blends before being exposed to UV irradiation were governed by the weight percent of the monomers which act as plasticizers. On the other hand, the UV-irradiated blends seemed to be typical two-phase materials since they revealed two tan δ maxima whose positions were independent of the monomer content. Those two maxima were assigned to PVA and photopolymerized acrylates with reference to the dynamic mechanical data of PVA and a PVA-polyacrylamide polyblend. Those dynamic mechanical data suggested that insolubilization of the blend type photopolymers should be caused by a decrease in solubility due to graft polymerization of acrylate monomers onto PVA.     

Mechanical properties of oriented poly(vinyl chloride)–poly(caprolactone) blends

Blends of poly(vinyl chloride) (PVC) with polycaprolactone (PCL) of different compositions were prepared from solutions in tetrahydrofuran (THF). The dried blends were stretched at different temperatures above the glass transition, and the birefringence and mechanical properties were studied. It is shown that the birefringence of PVC and the 75/25 PVC/PCL blend follows an affine deformation scheme with a decreasing number of segments with deformation. The 50/50 PVC/PCL blend shows a complex orientation behavior because of the presence of crystallinity in the PCL phase. The mechanical properties of the blends are shown to increase with orientation, and the aggregate model is acceptably followed by the amorphous oriented blends.     

Dynamic mechanical properties and morphology of styrene–divinylbenzene copolymer/poly(vinyl chloride) systems

The morphology and dynamic mechanical properties of the composite materials [P(St–DVB)/PVC systems], prepared by copolymerization of styrene and divinylbenzene in the presence of fine PVC powder, were studied by electron microscopy and the dynamic mechanical test. The composite material (PSt/PVC composite), prepared by the polymerization of styrene in the presence of fine PVC powder, contains grafting polystyrene (PSt) onto PVC, which improves the compatibility of PSt and PVC. This result also suggests the formation of the graft copolymer of styrene–divinylbenzene onto PVC in the P(St-DVB)/PVC systems. Electron microscopy and the dynamic mechanical test indicate that P(St-DVB)/PVC systems have the two-phase nature with a styrene–divinylbenzene copolymer as the continuous phase [P(St-DVB) phase] and a PSt/PVC composite as the dispersed phase (PSt-PVC phase), in which PSt penetrates into the PVC domain. The domain size of the dispersed phase is 0.5–2μ. The crosslinking density of the P(St-DVB) continuous phase is larger than that estimated from the recipe. One of the reasons for this is ascribed to the difference of the diffusion constants of styrene and divinylbenzene into the PVC particles on the paste formation and polymerization process.     

Morphology and properties of poly(vinyl chloride)–polyurethane blends

The objective of this research was to study the morphology and properties of PVC–polyurethane blends. Studies on blends of a segmented polyether polyurethane with PVC were carried out utilizing differential scanning calorimetry, Rheovibron, stress–strain, infrared peak position studies, and infrared dichroism experiments. This thermodynamically incompatible system was made kinetically compatible by precipitation from tetrahydrofuran (THF) solutions. THF–dioxane solution casting and melt processing produced an incompatible system. The compatible polyurethane–PVC system contains a well-mixed PVC–polyether matrix phase as evidenced by T_g shifts, orientation characteristics, and infrared peak position changes. The aromatic urethane segments which exhibit microphase separation in the pure polyurethane are not solubilized by blending with PVC by any of sample preparation methods used in this study.     

Dynamic mechanical properties of poly(vinyl chloride) and polyurethane carboxylate blends

The miscibility of thermoplastic polyurethane elastomers (TPUs) with poly(vinyl chloride) (PVC) was studied. PVC blends with TPUs, prepared from 4,4-diphenylmethane diisocyanate as diisocyanate, hydroxy-terminated poly(butylene adipate) (PBA) as the soft segment, and dimethylolpropionic acid as the chain extender carrying a latent anionic site for neutralization by triethylamine, showed a single glass transition temperature (T_g), irrespective of neutralization of latent anionic sites of TPU. But in neutralized TPU/PVC blends, limited intimate segmental mixing was perceived from the mechanical properties observed. When hydroxy-terminated poly(propylene glycol) was used as the soft segment instead of hydroxy-terminated PBA, PVC/TPU blends showed two separate T_g's of PVC and TPU, irrespective of neutralization. © 1994 John Wiley & Sons, Inc.     

Rheological and mechanical properties of poly(vinyl chloride)/chlorinated poly(vinyl chloride) miscible blends

The properties of poly(vinyl chlorlde)/ehlorinated poly(vinyl chloride) (61.6 percent C1) blends, prepared by melt and solution blending, were measured by various tests. Based on the chlorinated poly(vinyl chloride) (CPVC) composition, percent chlorine, and mole percent CC1₂ groups, these blends were expected to show intermediate properties between miscible and immiscible systems. Indicative of miscible behavior were the single glass transition temperatures over the entire composition range for both melt and solution blended mixtures. A single phase was also indicated by transmission electron microscopy. However, the yield stress showed a minimum value less than either of the pure components in the 50 to 75 percent CPVC range, which is characteristic of two-phased systems. Specific volume, glass transition temperature, and heat distortion temperature were linear with binary composition. The storage modulus showed a small maximum, suggesting a weak interaction between the two miscible polymers. Heats of melting for the residual PVC crystallinity were also less than expected from linear additivity. At 160°C and 210°C, the logarithm of the complex viscosity was essentially linear with volume fraction of CPVC, except for a very slight decrease in the 50 to 75 percent CPVC range, which may have been a result of lower crystallinity. At 140°C, the complex viscosity of the CPVC was less than that of PVC owing to the higher crystallinity of the latter. The viscosities were similar at 160°C, but at 210°C, where most of the crystallites had melted, the complex viscosity of the CPVC was higher because of its higher glass transition temperature.     

Permeation characteristics of poly(vinyl alcohol)–poly(vinyl acetate) composite porous membranes

Poly(vinyl alcohol) (PVAc) composite porous membrane has been prepared from PVAc latex film by extraction with acetone. The PVAc latex was prepared by emulsion polymerization of vinyl acetate in the presence of PVA, employing the hydrogen peroxide–tartaric acid systemm as an initiator. The extraction degree of PVAc could be controlled in a wide range by changing the addition method of the initiator, and, acoordingly, PVA–PVAc omposite porous membranes which had variosu void volumes were obtained. The maximum void volume attained was ca. 90%. Permation characteristics of organic solvents wre investigated on the membranes whose extraction degrees were 95.6% and 80.7%. Thge feeds were benzene, n-hexane, cyclohexane, and their mixtures. neither swelling nor shrinkage in tje appearance size of the while benzene hardly permeated even at 20 kg/cm². The grafted PVAc in the mebrane was removed or converted into grafted PVA by treatment with sodium methylate, and then the depression of benzene permeation was lost. The grafted PVAc was suggested to be localizd on the cell wall and was found to function as a valve which closes with nenzene or a good solvent for PVAc and opens with n-haxane or a poor solvent for PVAc.     

Correlation between some solution and mechanical properties of poly(vinyl chloride) and chlorinated poly(vinyl chloride)

Correlations have been found between solubility parameters and some mechanical properties of a series of vinyl polymers containing 56.6–69.9% chlorine when tested below their glass transition temperature. It is shown that stress at yield increases similarly with chlorine content and with the volume occupied by a monomer unit in the polymer. Using the Reiner-Weissenberg theory of the dynamic strength of materials as a criterion and a rheological model based on a pair of Maxwell bodies in parallel with a Hooke spring, the amount of dissipated and conserved work to yield point was calculated. A parameter, defined as the ratio of work to cohesive energy density, describes the efficiency of the system. The overall efficiency of the system, based on work to break, and proportional efficiency, based on work to yield point, are affected by chlorine content and strain rate. In addition, a potential energy parameter is defined which describes the cohesive energy per volume occupied by monomer unit of the polymer. This parameter is proportional to the total work to break as well as to the ratio of the residual work after yield to total work at all strain rates tested. The major portion of work is conserved up to yield; only a small portion is dissipated. From the yield point to break, after the onset of viscous flow, the major part of this work is dissipated.     

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.     

Preparation and structure of poly(vinyl alcohol)–poly(vinyl acetate) composite porous membrane

The preparation of poly(vinyl alcohol) (PVA)–poly(vinyl acetate) (PVAc) composite porous membrane was investigated by extracting PVAc with solvent from films of PVAc lattices which were obtained by the emulsion polymerization of vinyl acetate (VAc) in the presence of PVA. The formation of the porous membrane depended upon whether or not PVAc in the latex film was easily extracted with solvent. In the case of using hydrogen peroxide (HPO)–tartaric acid (TA) as an initiator, in the film of the latex which was produced from the batch method in which all ingredients of the batch were put into the reaction vessel before starting polymerization, PVAc could be extracted over 90% of total PVAc with common organic solvents. In the film of the latex which was produced from the dropwise addition method of VAc and initiator, the PVAc extraction was about 20-30%. On the other hand, in the case of using ammonium persulfate as an initiator, the desired porous membrane was not obtained. The structure of the porous membrane obtained from the latex of the batch method by using HPO—TA consisted of spherical cells which were made up of PVA and grafted PVAc or insoluble PVAc like microgels, which were not extracted with organic solvent and were connected by small pores. The PVA—PVAc composite porous membrane is permeated by n-hexane with 5.58 × 10² mL/cm²·s at 0.5 kg/cm², by benzene with only 1.33 × 10^?3mL/cm²·s even at 60 kg/cm².     

Dynamic mechanical analysis of poly(vinyl chloride) compounds and blends

PVC is one of the most versatile and cost effective commercial polymers. A main limitation of PVC is optimizing its fabrication characteristics and end use properties with minimum adverse effect on either. PVC compounding technology is supersensitive due to effect of subtle variations in formulations causing “inspec” products during one production run and “out-of-spec” products in another. Large variations in properties are frequently due to improper mixing. Dynamic mechanical analyses provides a method of monitoring variations in mixing and their affect on morphological structure deviations which can lead to poor processing and end use properties.     

Dynamic mechanical studies of thermal aging in poly(vinyl chloride)

The effects of thermal aging on the dynamic mechanical properties of rigid poly(vinyl chloride) (PVC) and chlorinated poly(vinyl chloride) (CPVC) are examined in the glass transition (T_g) and β transition (T_β) regions. PVC, when quenched through T_g and then annealed at 40°C, exhibits a sub-T_g peak in the loss modulus function. The position of the peak moves to higher temperatures with increasing annealing time. The effect is analogous to sub-T_g endothermic peaks previously observed by differential scanning calorimetry (DSC). A sub-T_β peak in the tan δ or the loss modulus functions can be produced by quenching through T_β. The effect of heating rate on the sub-T_β peak is explored.     

Dynamic mechanical properties of titanium dioxide-filled poly(vinyl acetate) at 0–40°C.

The dynamic mechanical properties of titanium dioxide-filled poly(vinyl acetate) have been studied at filler concentrations of 0, 10, 20, 30, and 40 wt.-% TiO₂ by using a torsional pendulum. The damping factor was found to increase with higher temperatures. At 40°C., the damping factors for the different TiO₂ concentrations were estimated to be the same. Damping factors above 40°C. were difficult to obtain due to the rubbery nature of the TiO₂–poly(vinyl acetate) systems. From 24 to 35°C., 10 wt.-% TiO₂-poly(vinyl acetate) was closer in damping factor increase to unfilled poly(vinyl acetate) than to the higher TiO₂-content polymers. At all temperatures, damping factors decreased with higher TiO₂ concentration. As the temperature decreased to 0°C., damping factors for the filled systems approached a common value. Potential energy of filled systems as indicated by shear modulus values is increased by higher TiO₂ concentrations and lower temperature. Kinetic energy for the filled systems, as shown by the out-of-phase modulus, is actually increased by larger filler concentration and higher temperature. A model is proposed where introduction of TiO₂ filler acts to increase general long-range polymer chain stiffening and at the same time enables short-range chain mobility to rise, possibly through greater side-chain motion.     

Stabilization of poly(vinyl chloride). IV. Color changes on heating poly(vinyl chloride)–dye systems

The stabilization of poly(vinyl chloride) (PVC) involving complementary colors has been previously reported. Obliterating polyene color with various dyes containing complementary colors with the polyene color is studied on the basis of colorimetry. The changes in the color of heated PVC containing Thren Blue IRN, Ceres Blue GN, Oplas Violet 730, Macro-Lex Violet 3R, Macro-Lex Green 5B, or Macro-Lex Red 5B were investigated using a differential colorimeter. When the PVCs containing various dyes were heated, the discoloration from the color of each dye to the color mixture of each dye and polyene color was observed with increased heating times for all systems. In particular, an achromatic color has been observed, during the heat treatments, in PVC containing blue dyes such as Thren Blue IRN or Ceres Blue GN, which set up complementary color relationship with the polyene color. Thus the color of polyenes, which appears with advancing dehydrochlorination of PVC, is masked by the blue dyes. It is also apparent that the obliteration of polyene color does not depend on the chemical influences of the dyes added, but by color mixing of polyenes and the dyes. Cool-color dyes markedly slow down the appearance of polyene colors.     

The supermolecular structure of poly(vinyl chloride)–poly(methyl methacrylate) blends

Investigations of the supermolecular structure of PVC/PMMA blends, covering a wide range of composition, are presented. It was found that a transition layer exists between PVC and PMMA phases. The thickness of the transition layer is independent of blend composition. The scattering intensity distribution function for blends is characteristic of isotropic, amorphous systems with a completely random distribution of phases. It was shown that scattering intensity distribution function may be used for calculation of a distribution, which corresponds a two-phase system with sharp phase boundaries. Values of correlation lengths, inhomogeneity lengths, and specific surfaces were then calculated. A model of the supermolecular structure of PVC/PMMA blend was finally proposed.     

Contributions to characterization of poly(vinyl chloride)–lignin blends

The present study evaluates the impact of blending organosolv and kraft lignins, which are natural polymer by‐products in the pulp and paper industry, with plasticized poly(vinyl chloride) (PVC) in flooring formulations. Also examined is the impact of replacing dioctyl phthalate, a PVC industry general‐purpose plasticizer, with diethylene glycol dibenzoate (Benzoflex 2‐45), tricresyl phosphate (Lindol), or alkyl sulfonic phenyl ester (Mesamoll) in these formulations. The influence of the different types of lignins and plasticizers on the processibility, thermal, and mechanical properties of the blends is discussed. These properties demonstrate that partial replacement of PVC (20 parts) with different lignins is feasible for some formulations that can be successfully used as matrices for a high level of calcium carbonate filler in flooring products. In addition, the data demonstrate that the presence of certain plasticizers, which interfere with the intramolecular interactions existing in lignins, may allow the lignin molecules to have more molecular mobility. The morphology and the properties of PVC plasticized lignin blends are strongly influenced by the degree and mode of the lignin plasticization and its dispersion within the PVC matrix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2732–2748, 2006     

Preparation of poly(p-phenylene terephthalamide)/poly(vinyl chloride) molecular composite and its thermal and mechanical properties

Poly(p-phenylene terephthalamide) (PPTA) was blended with poly(vinyl chloride) (PVC) by solution-blending method. PPTA was metalated for dissolving in dimethyl sulfoxide. Dimethyl sulfoxide was used as a common solvent. In PPTA/PVC composite, PPTA accelerated the thermal degradation of PVC. PPTA molecules are aggregated as microfibrillar form in PVC matrix. Such microfibrils are dispersed homogeneously in PVC matrix, according to polarizing microscopic observation. The average diameter of the microfibrils becomes smaller in the composite with lower content of PPTA. In the surface region of PPTA microfibrils the intermolecular hydrogen bonds between C? Cl of PVC and N? H of PPTA are formed. Young's modulus and the yield stress at room temperature were higher in the composites than those in PVC. The modulus of the composites was higher, especially at the high temperatures above their glass transition temperatures, than that in PVC. The temperature dependence of modulus can be calculated by using the mechanical model equivalent to the quasi-3-dimensional microfibrillar model which will be approximately applied to the composite structure. It becomes apparent that the modulus of the PPTA microfibrils evaluated by using the mechanical model is higher in the higher molecular weight PPTA.