Miscible blends from plasticized poly(vinyl chloride) and epoxidized natural rubber

Miscible blends from plasticized poly(vinyl chloride), and epoxidized natural rubber having 50 mol% epoxidation level were prepared in a Brabender Plasticorder by the melt-mixing technique. Changes in Brabender torque and temperature, density, dynamic mechanical properties, and differential scanning calorimetry of the samples were examined as a function of blend composition. The plasticized poly(vinyl chloride)/epoxidized natural rubber blends behaved as a compatible system at all composition ranges as evident from their single glass-rubber transition temperature (T_g) obtained from dynamic mechanical analysis as well as from differential scanning calorimetry. Profound changes in the nature of the glass-rubber transition were noted with respect to blend composition. The T_g-width values of blends lie between those of plasticized poly(vinyl chloride) and epoxidized natural rubber.     

Miscible blends of poly(butyl methacrylate) densely grafted on fumed silica with poly(vinyl chloride)

Poly(butyl methacrylate) (PBMA) densely grafted on a fumed silica particle consisting of primary particles with an average diameter of 14 nm, has been synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP). In these syntheses, a newly designed initiator, p-(bromomethyl)benzyl 2-bromoisobutylate was used for the immobilization of the initiator moiety on the silica particle to give the densely grafted PBMA. Thus synthesized nanocomposites have exhibited unusual miscibility with poly(vinyl chloride) (PVC) through differential scanning calorimetry (DSC). The derivative DSC peaks for the composite/PVC blends were significantly different from those for the conventional PBMA/PVC blends. This interesting finding is due to a wide gradient of the PVC concentration on a microscopic scale, resulting from the densely grafted PBMA chains; the PBMA component is enriched near the surface of the fumed silica, while the PVC component is enriched far from the surface. This gradient miscible state is strongly supported by dynamic mechanical analysis. Furthermore, a synergistic effect on storage modulus was seen in the nanocomposite/PVC blends.     

Miscibility in poly(vinyl chloride)/chlorinated poly(vinyl chloride) blends,and blends of different chlorinated poly(vinyl chlorides)

Blends of poly(vinyl chloride) with chlorinated poly(vinyl chloride) (PVC), and blends of different chlorinated poly(vinyl chlorides) (CPVC) provide an opportunity to examine systematically the effect that small changes in chemical structure have on polymer-polymer miscibility. Phase diagrams of PVC/CPVC blends have been determined for CPVC's containing 62 to 38 percent chlorine. The characteristics of binary blends of CPVC's of different chlorine contents have also been examined using differential calorimetry (DSC) and transmission electron microscopy. Their mutual solubility has been found to be very sensitive to their differences in mole percent CCl₂ groups and degree of chlorination. In metastable binary blends of CPVC's possessing single glass transition temperatures (T_g) the rate of phase separation, as followed by DSC, was found to be relatively slow at temperatures 45 to 65° above the T_g of the blend.     

Rheology of poly(vinyl chloride) blends

PVC/EVA blends were studied with an extrusion plastometer in order to examine the effect of EVA on the processability of PVC. The melt flow of PVC/EVA blends containing from 4 to 30 weight percent EVA follows a simple power law between 160 and 180°C. EVA reduced the melt viscosity and enhanced processability. Blends of PVC and EVA were morphologically incompatible. The molecular weight of extruded PVC in the blends was unchanged.     

Miscible blends containing bacterial poly(3‐hydroxyvalerate) and poly(p‐vinyl phenol)

The miscibility of poly(3‐hydroxyvalerate) (PHV)/poly(p‐vinyl phenol) (PVPh) blends has been studied by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The blends are miscible as shown by the existence of a single glass transition temperature (T_g) and a depression of the equilibrium melting temperature of PHV in each blend. The interaction parameter was found to be −1.2 based on the analysis of melting point depression data using the Nishi–Wang equation. Hydrogen‐bonding interactions exist between the carbonyl groups of PHV and the hydroxyl groups of PVPh as evidenced by FTIR spectra. The crystallization of PHV is significantly hindered by the addition of PVPh. The addition of 50 wt % PVPh can totally prevent PHV from cold crystallization. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 383–388, 1999     

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.     

Miscible blends of poly(vinyl phenyl ketone hydrogenated) and poly(styrene-co-4-vinylpyridine)

Miscibility behavior over a wide composition range was detected for polymer blends of poly(vinyl phenyl ketone hydrogenated) (PVPhKH) with poly(styrene-co-4-vinylpyridine) (PS-co-4VPy). Differential scanning calorimetry (DSC) and thermo mechanical analysis (TMA) reveal that each composition has only one glass transition temperature. The variation of the glass transition temperature with composition for PVPhKH/PS-co-4VPy miscible blends follows the Gordon-Taylor equation. FTIR analysis of this binary system indicates the existence of hydrogen bonding between pyridine ring of PS-co-4VPy and hydroxyl groups insert into PVPhKH. This specific interaction has a decisive influence in the phase behavior of PVPhKH/PS-co-4VPy blends.     

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.     

Compatibility of poly(vinyl chloride) and polyurethane blends

The compatibility and the mechanical properties of the blends of polyurethane (PU) elastomer and poly(vinyl chloride) (PVC) were studied. The results showed partial compatibility between PU and PVC. When the portion of PVC in blends exceeded 75%, the compatibility decreased. On the other hand, increasing the molecular weight of the glycol in PU improved the compatibility. The elongation decreased and the Young's modulus increased as the proportion of the weight of PVC in blends was increased. The tensile strength reached a minimum when PU/PVC was 50/50.     

Miscible blends of poly(4‐vinyl phenol)/poly (trimethylene terephthalate)

A new miscible blend of all compositions comprising poly(4‐vinyl phenol) (PVPh) and poly(trimethylene terephthalate) (PTT) was discovered and reported. The blends exhibit a single composition‐dependent glass transition and homogeneous phase morphology, with no lower critical solution temperature (LCST) behavior upon heating to high temperatures. Interactions and spherulite growth kinetics in the blends were also investigated. The Flory–Huggins interaction parameter (χ₁₂) and interaction energy density (B) obtained from analysis of melting point depression are negative (χ₁₂ = ?0.74 and B = ?32.49 J cm^?3), proving that the PVPh/PTT blends are miscible over a wide temperature range from ambient up to high temperatures in the melt state. FTIR studies showed evidence of hydrogen‐bonding interactions between the two polymers. The miscibility of PVPh with PTT also resulted in a reduction in spherulite growth rate of PTT in the miscible blend. The Lauritzen–Hoffman model was used to analyze the spherulite growth kinetics, which showed a lower fold‐surface free energy (σ_e) of the blends than that of the neat PTT. The decrease in the fold‐surface free energy has been attributed to disruption of the PTT lamellae exerted by PVPh in an intimately interacted miscible state. Copyright © 2004 Society of Chemical Industry     

Behavior of flexible poly(vinyl chloride)/poly(hydroxybutyrate valerate) blends

Blends of flexible poly(vinyl chloride) (PVC) and a poly(hydroxybutyrate valerate) (PHBV) copolymer were prepared and characterized with different techniques. The tensile strength of PVC did not show a marked reduction at PHBV concentrations up to 50 phr, despite a lack of miscibility between the two polymers. The crystallization of the PHBV copolymer was markedly hindered by the presence of PVC, as calorimetric results revealed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Translucent blends of chlorinated polyethylene with poly(vinyl chloride)

Some experimental chlorinated polyethylene (CPE) resins that produced translucent blends with PVC were used to study the effects of CPE chlorine content and chlorine distribution on the morphology, optical clarity, and toughness of blends with PVC. The CPE resins were characterized in terms of the glass transition temperature, residual crystallinity, density, and refractive index. Increasing residual crystallinity and increasing chlorine content both increased the refractive index closer to that of PVC. A linear relationship was observed between the fourth power of the refractive index and the CPE glass transition temperature. With a phase-separated blend morphology in all cases, improved transparency was achieved in this system by reducing the refractive index difference between CPE and PVC. Both haze and transparency showed the predicted linear dependence on the square of the refractive index difference. To a first approximation, modifications of the experimental CPE resins that improved optical transparency of the blends also tended to reduce the toughness enhancement.     

Studies of polyester/chlorinated poly(vinyl chloride) blends

Chlorinated poly(vinyl chloride) (CPVC) was solution blended with poly(caprolactone) (PCL), poly(hexamethylene sebacate) (PHMS), poly(α-methyl-α-n-propyl-β-propiolactone) (PMPPL), poly(valerolactone) (PVL), poly(ethylene adipate), poly(ethylene succinate) and poly(β-propiolactone). From calorimetric glass transition temperature (T_g) measurements, it is concluded that CPVC is miscible with polyesters having a CH₂/COO ratio larger than three (PCL, PHMS, PMPPL and PVL). The Gordon-Taylor k parameter was also calculated and found equal to 1.0 and 0.56 for PCL/CPVC and PHMS/CPVC blends, respectively. From these values, it is concluded that CPVC gives a stronger interaction with polyesters than poly(vinyl chloride) due to its larger chlorine content.     

Annealed segmented polyether ester—poly (vinyl chloride) blends

Hytrel, PVC and blends of these polymers containing, respectively, 75% and 45% by wt of Hytrel were annealed and the dynamic mechanical and sonic velocity behaviour of these annealed samples were compared with the unannealed materials. The annealed Hytrel showed evidence of enhanced segregation of the hard and soft segments, while for PVC there was a shift of the glass transition to a higher temperature. Annealing of the 75% by wt Hytrel blend resulted in increased phase separation of the constituent materials and a very broad tan δ—temperature dispersion. It was also concluded that the 45% by wt Hytrel blend again showed phase separation on annealing, but to a lesser extent.     

Miscibility of segmented polyurethane/poly(vinyl chloride) blends

Miscibilities of segmented polyurethanes (SPUs) and poly(vinyl chloride) (PVC) or functionalized poly(vinyl chloride) (FPVC) were studied with dynamic mechanical analysis, differential scanning calorimetry, and X‐ray diffraction. Mechanical properties of the blends were also studied with tensile measurements. The miscibility of the blends depended greatly on the hard‐segment content of SPU and the existence of the functional groups. The combination of SPU with a low hard‐segment content and PVC with functional groups made the blend system miscible. Moreover, controlling the blend composition of SPU/FPVC allowed us to modify the mechanical properties of SPU, where the elongation at break was multiplied without a significant change in its tensile strength. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3022–3029, 2001     

Free volume microprobe studies on poly(methyl methacrylate)/poly(vinyl chloride) and poly(vinyl chloride)/polystyrene blends

Blends of Poly(methyl methacrylate) (PMMA)/Poly(vinyl chloride) (PVC) and Poly(vinyl chloride) (PVC)/Polystyrene (PS) of different compositions were prepared by solution casting technique. The blends were characterized using Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), and Positron Lifetime Spectroscopy. DSC data were found to be inadequate to describe whether PMMA/PVC blends are miscible or not, possibly because of the small gap in their glass transition temperatures. On the other hand, PVC/PS blends were clearly found to be immiscible by DSC. FTIR results for PMMA/PVC indicate the possible interactions between the carbonyl group of PMMA and α‐hydrogen of PVC. Free volume data derived from Positron lifetime measurements showed that the PMMA/PVC blends to be miscible in low PVC concentration domain. For the first time, the authors have evaluated the hydrodynamic interaction parameter α, advocated by Wolf and Schnell, Polymer, 42, 8599 (2001), to take into account the friction between the component molecules using the free volume data. This parameter (α) has a high value (?57) at 10 wt% of PVC, which could be taken to read miscibility for PMMA/PVC blends to be high. In the case of PVC/PS blends, the positron results fully support the DSC data to conclude the blends to be immiscible throughout the range of concentration. As expected, the hydrodynamic interaction parameter α does not show any change throughout the concentration in PVC/PS blends, further supporting the idea that α is another suitable parameter in the miscibility study of polymer blends. POLYM. ENG. SCI., 46:1231–1241, 2006. © 2006 Society of Plastics Engineers     

A study of poly vinyl chloride / poly(butylene adipate-co-terephthalate) blends

Polymer blends were prepared by melt blending technique using poly vinyl chloride (PVC) and poly(butylene adipate-co-terephthalate) (PBAT). Different ratios of the blends were studied to investigate their mechanical, thermal and morphological properties. The FTIR spectrum indicated a slight increase of frequencies at C = O peak from 1714 to 1718 cm^-1 indicating a chemical interaction between C = O of PBAT and α-hydrogen of PVC. The tensile properties of PVC/PBAT blends highest at weight ratio of 50/50. The dynamic mechanical analysis (DMA) result proves that PVC and PBAT formed a miscible system with one glass transition temperature (T_g). The incorporation of PBAT results in a gradual decrease of the viscosity (loss modulus) and an increase of elasticity (storage modulus). The thermal properties of blend show the decomposition temperature of PVC in the blend decrease with the addition of PBAT. Scanning electron micrograph shows good interfacial adhesion on the tensile fractured surface of PVC/PBAT blend, which played important roles in enhancing the mechanical properties (strength and modulus).     

Plastification of poly(vinyl chloride) by polymer blending

Blends of poly(vinyl chloride) (PVC) with different copolymers have been studied to obtain a plasticized PVC with improved properties and the absence of plasticizer migration. The copolymers used as plasticizers in the blends were acrylonitrile butadiene rubber, ethylene vinyl acetate (EVA), and ethylene-acrylic copolymer (E-Acry). Blends were studied with regard to their processing, miscibility, and mechanical properties, as a function of blend and copolymer composition. The results obtained were compared with those of equivalent compositions in the PVC/dioctyl phthalate (DOP) system. Better results than PVC/DOP were obtained for PVC/acrylonitrile butadiene rubber blends. The plasticizing effect on PVC of EVA and E-Acry copolymers was similar to that of DOP. It is shown that crosslinking PVC/E-Acry blends or increasing the vinyl acetate content in PVC/EVA blends, are alternatives that can increase the compatibility and mechanical properties of these blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1303–1312, 2000     

Environmental degradation of some polymer blends. Blends of polystyrene with acrylonitrile butadiene styrene,poly(vinyl chloride), and polybutadiene and blends of polybutadiene with poly(vinyl chloride)

One class of polymer/additive which has become increasingly important is polymer blends. In this study the ultimate tensile strength, elongation at break, and the modulus of acrylonitrile–butadiene–styrene, poly(vinyl chloride), polybutadiene and polystyrene and their blends have been studied over an entire binary composition range. We have correlated these mechanical properties to their degradation behavior under natural and accelerated weathering by measurement of various indices during thermal and natural weathering. It was found that during natural weathering the presence of polystyrene in acrylonitrile–butadiene–styrene (ABS) improved the weatherability of ABS; the converse was true when the blends were heated in an air oven at 100°C. It was also found that the weatherability of PB was improved in the presence of polystyrene and large improvement in the rigidity was observed. Similarly, from a measurement of carbonyl index, it was found that PVC has a stabilizing effect on PB. In many cases, the 50:50 composition of the polymers gave the best compromise of good mechanical properties, heat stability, and outdoor weathering. The mechanisms of possible interactions between the degrading polymers are discussed.