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.     

Binary blends of poly(vinyl chloride) stabilized by lithium acetate‐thermal studies

A series of blends of poly(vinyl chloride) (PVC) with (1) poly(methyl methacrylate) (PMMA) or (2) polyoxymethylene (POM), with lithium acetate as a stabilizing agent, was investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), either alone or coupled with Fourier transform infrared (FTIR) spectroscopy. It was found that lithium acetate has a significant effect on the thermal properties of blends under investigation. It causes the initial decomposition temperatures to increase by about 60–150°C for PVC–POM blends, a substantial suppression of the volatile products evolution for PVC/PMMA blends, and an improvement in the surface morphology for both polymer systems by lowering the degree of roughness. The origin of these effects was discussed by analysis of the intermolecular complexation between metal salt and PVC structural arrangements in the blends. Such interactions may lead to the formation of long‐range, directional‐specific structural regularities, which in turn thermally stabilize the whole system (strong interactions model). © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2576–2587, 1999     

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.     

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     

改性矿物填料增强橡胶/聚氯乙烯共混体系

研究了橡胶、增塑剂、矿物填料和表面处理剂对橡胶／聚氯乙烯(PVC)共混物力学性能的影响,用扫描电镜分析了有机胺类表面处理剂改性高岭土／丁腈橡胶(NBR)／PVC的界面结合状况。结果表明,当NBR用量为30份,邻苯二甲酸二辛酯用量为60份,有机胺类表面处理剂质量分数为3％,填充60份的超细碳酸钙或高岭土或牌号为SMF的蒙脱土时,可得到力学性能较佳的NBR／PVC共混物;不同矿物填料对NBR／PVC共混物的增强作用不同,经有机胺类表面处理剂改性后,以超细碳酸钙、高岭土和蒙脱土SMF的增强效果最为明显。     

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).     

Miscibility and melting behavior of poly(ethylene terephthalate)/poly(trimethylene terephthalate) blends

The miscibility and melting behavior of binary crystalline blends of poly(ethylene terephthalate) (PET)/poly(trimethylene terephthalate) (PTT) have been investigated with differential scanning calorimetry and scanning electron microscope. The blends exhibit a single composition‐dependent glass transition temperature (T_g) and the measured T_g fit well with the predicted T_g value by the Fox equation and Gordon‐Taylor equation. In addition to that, a single composition‐dependent cold crystallization temperature (T_cc) value can be observed and it decreases nearly linearly with the low T_g component, PTT, which can also be taken as a valid supportive evidence for miscibility. The SEM graphs showed complete homogeneity in the fractured surfaces of the quenched PET/PTT blends, which provided morphology evidence of a total miscibility of PET/PTT blend in amorphous state at all compositions. The polymer–polymer interaction parameter, χ₁₂, calculated from equilibrium melting temperature depression of the PET component was ?0.1634, revealing miscibility of PET/PTT blends in the melting state. The melting crystallization temperature (T_mc) of the blends decreased with an increase of the minor component and the 50/50 sample showed the lowest T_mc value, which is also related to its miscible nature in the melting state. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Miscibility and melting in poly(ethylene terephthalate)/ poly(bisphenol-A-carbonate) blends

Summary In the absence of significant tranesterification, blends of poly(ethylene terephthalate) and poly(bisphenol-A carbonate) were found to be almost completely immiscible over the range of compositions studied. Although the observed behavior was sometimes erratic, poly(bisphenol-A carbonate) appears to exert a significant influence on PET melting behavior and normalized heat of fusion.     

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.     

Melting point depression in poly(ɛ-caprolactone) / poly(styrene-co-acrylonitrile) blends

Summary The melting point depression of poly(-caprolactone)/poly(styrene-co-acrylonitrile) (PCL/SAN) blends with changes in acrylonitrile content of SAN and in blend ratio was investigated by differential scanning calorimetry. For the melting points at a constant blend ratio occur a minimum in dependence on the copolymer composition for blends containing about 20 wt% acrylonitrile in SAN. From melting point depression data a negative, binary interaction parameter was obtained for PCL/SAN blends containing a SAN with 19.2 wt% AN. By optical microscopy it can be shown that the shape of the spherulites changes with copolymer composition of SAN and blend ratio.     

Miscible polymer blends containing poly(vinyl chloride)

Polymer blends have received particular interest in the past several decades in both industrial and academic research. An initial survey of miscible polymer pairs (1) (1968) revealed 12 combinations. A later survey (2) (1979) noted approximately 180 miscible pairs. Today possibly over 500 miscible combinations have been noted in the open and patent literature (3). However, the vast majority of possible polymer blend combinations are not miscible (thus phase separated). A significant number of diverse polymer structures have been shown to exhibit miscibility with PVC. Several of these blends have been studied in detail and have shown specific interactions primarily involving the α-hydrogen and PVC (considered the proton donor in proton donor-proton acceptor hydrogen bonding type interactions). The blend of poly(?-caprolactone) with PVC illustrates this interaction and has been reported in many published papers. While polymer miscibility in PVC blends offers significant academic interest, industrial utility is also of considerable importance. The addition of low T_g, miscible polymers to PVC offers permanent plasticization. The addition of high T_g, miscible polymers to PVC yields the desired heat distortion temperature enhancement of rigid PVC. A specific example of permanent plasticization involves nitrile rubber blends which have been commercial since the early 1940's. This presentation will review the growing number of polymers noted to be miscible with PVC. The importance of specific interactions will be discussed.     

Crystallization and melting behaviour of poly(butylene terephthalate) in poly(butylene terephthalate)/polyarylate blends

Summary The crystallization and melting behaviour of poly(butylene terephthalate) has been studied in the pure state and in its blends with a polyarylate of bisphenol A and isophthalic/terephthalic acids. Differential scanning calorimetry has been used as experimental technique and the effects of different thermal treatments have been analyzed. Results show the hindrance for the crystallization of poly(butylene terephthalate) imposed by the presence of polyarylate, as well as the existence of multiple melting after isothermal crystallization. Explanations are given for the observed behaviours.     

The melting temperature (or not melting) of poly(vinyl chloride)

The best answer to what is the melting temperature of PVC is its previous processing temperature. That temperature is where secondary crystallites, created by gelation, melt and allow the primary particle flow units to flow again independently. In the case of powder compounds being processed for the first time, the question of melting is less relevant. The PVC, out of the polymerizer, contains crystallites that are not completely meltable. The issue is how easily the grains of PVC disperse to primary particle flow units. This property depends on polymerization conditions and the type of processing equipment. The temperature achieved affects the amount of fusion (gelation). J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers.     

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.     

Miscibility and crystallization of biodegradable poly(butylene succinate-co-butylene adipate)/poly(vinyl phenol) blends

Miscibility, crystallization kinetics, crystal structure, and microstructure of biodegradable poly(butylene succinate-co-butylene adipate) (PBSA)/poly(vinyl phenol) (PVPh) blends were studied by differential scanning calorimetry, optical microscopy, wide angle X-ray diffraction, and small angle X-ray scattering in detail in this work. PBSA and PVPh are miscible as evidenced by the single composition dependent glass transition temperature and the negative polymer-polymer interaction parameter. Isothermal crystallization kinetics of PBSA/PVPh blends was investigated and analyzed by the Avrami equation. The overall crystallization rates of PBSA decrease with increasing crystallization temperature and the PVPh content in the PBSA/PVPh blends; however, the crystallization mechanism of PBSA does not change in the blends. Furthermore, blending with PVPh does not modify the crystal structure of PBSA. The microstructural parameters, including the long period, thickness of crystalline phase and thickness of amorphous phase, all become larger with increasing the PVPh content, indicating that PVPh mainly resides in the interlamellar region of PBSA spherulites in the blends.     

Novel poly(butylene terephthalate)/poly(vinyl butyral) blends prepared by in situ polymerization of cyclic poly(butylene terephthalate) oligomers

Blends of in situ polymerized PBT from cyclic oligomers (c-PBT) and PVB were prepared with varying compositions and compared with mechanical blends of conventional PBT and PVB. The materials were characterized by a variety of techniques including DSC, DMTA, DETA, FTIR, NMR and GPC. It was found that the in situ prepared blend of c-PBT/PVB has one glass transition temperature and shows evidence of miscibility. In contrast, the conventional blend of PBT/PVB shows incompatibility after blending. The cause of miscibility in the in situ prepared PBT/PVB blends is thought to be the formation of a graft copolymer. These results show that there are unique possibilities for in situ processing by combining polymerization of cyclic polyester oligomers with blending.     

Accelerated weathering of pectin/poly(vinyl alcohol) blends studied by spectroscopic methods

The blends of pectin (PEC) and poly(vinyl alcohol) (PVA) at different components ratios were prepared by mixing in water. Thin polymeric films of PEC/PVA blends and pure polymers were obtained by casting method. All samples were then artificially aged using Suntest apparatus (Atlas) up to 780 h. The changes in chemical structure during sample ageing have been monitored by infrared and ultraviolet‐visible absorption spectroscopies. The first stage of weathering (up to ～ 300 h) was very slow and alteration of chemical structure was negligible in all samples. Prolonged ageing (>300 h) caused more significant degradation processes. FTIR spectra exhibited the highest changes in hydroxyl and carbonyl band ranges indicating the efficient photooxidation of macromolecules. The mechanisms of the observed processes have been discussed. It was found that PVA undergoes faster photoxidative degradation than pectin aged at the same conditions. The PEC/PVA blends exhibited the improved resistance to weathering comparing with both polymers aged individually. Mutual stabilization effect can be explained by intermolecular interactions between PEC and PVA confirmed by spectroscopic methods. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011