Miscibility,phase behavior,and mechanical properties of ternary blends of poly(vinyl chloride)/polystyrene/chlorinated polyethylene-graft-polystyrene

The effectiveness of chlorinated polyethylene-graft-polystyrene (CPE-g-PS) as a polymeric compatibilizer for immiscible poly(vinyl chloride)/polystyrene (PVC/PS) blends was investigated. The miscibility, phase behavior, and mechanical properties were studied using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), Izod impact tests, tensile tests, and scanning electron microscopy (SEM). DSC and DMA studies showed that PVC is immiscible with chlorinated polyethylene (CPE) in CPE-g-PS, whereas the PS homopolymer is miscible with PS in CPE-g-PS. The PVC/PS/CPE-g-PS ternary blends exhibit a three-phase structure: PVC phase, CPE phase, and PS phase that consisted of a PS homopolymer and PS in CPE-g-PS. The mechanical properties showed that CPE-g-PS interacts well with both PVC and PS and can be used as a polymeric compatibilizer for PVC/PS blends. CPE-g-PS can also be used as an impact modifier for both PVC and PS. SEM observations confirmed, after the addition of CPE-g-PS, improvement of the interfacial adhesion between the phases of the PVC/PS blends. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 995–1003, 1998     

Functionalization of lignin: Synthesis of lignophenol‐graft‐poly(2‐ethyl‐2‐oxazoline) and its application to polymer blends with commodity polymers

Lignophenol (LP)‐graft‐poly(2‐ethyl‐2‐oxazoline) (POZO) was prepared to reuse lignin, an industrial waste material, and to produce novel LP‐based polymer blends with poly(vinyl chloride) (PVC), poly(bisphenol A carbonate) (PC), polyvinylpyrrolidone (PVP), and polystyrene (PSt) as commodity polymers. The resulting graft polymer was soluble in various types of organic solvents such as chloroform, THF, acetone, and methanol, unlike LP. The miscibility of LP‐graft‐POZO with commodity polymers was measured by differential scanning calorimetry (DSC) to determine the glass transition temperatures (T_g). In the cases of the blends of LP‐graft‐POZO with PVC, PC, and PVP, the T_g values decreased during the second scan. Moreover, in the cases of the blends with PVC and PVP, the T_g values were not detected during the third scan. Therefore, it was inferred that LP‐graft‐POZO was miscible with PVC, PC, and PVP while forming single phases; in particular, the blends of LP‐graft‐POZO with PVC and PVP exhibited a secondary miscibility because the T_g values were not detected. Furthermore, the blend of LP‐graft‐POZO with PC exhibited better thermostability than LP and LP‐graft‐POZO. These results indicated that LP blended with POZO could be used as a polymer additive and as an adhesive to combine different polymers, organic–inorganic polymers, etc. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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     

Biodegradable polymer blends of poly(3-hydroxybutyrate) and poly(DL-lactide)-co-poly(ethylene glycol)

The melting and crystallization behavior and phase morphology of poly(3-hydroxybutyrate) (PHB) and poly(DL-lactide)-co-poly(ethylene glycol) (PELA) blends were studied by DSC, SEM, and polarizing optical microscopy. The melting temperatures of PHB in the blends showed a slight shift, and the melting enthalpy of the blends decreased linearly with the increase of PELA content. The glass transition temperatures of PHB/PELA (60/40), (40/60), and (20/80) blends were found at about 30°C, close to that of the pure PELA component, during DSC heating runs for the original samples and samples after cooling from the melt at a rate of 20°C/min. After a DSC cooling run at a rate of 100°C/min, the blends showed glass transitions in the range of 10–30°C. Uniform distribution of two phases in the blends was observed by SEM. The crystallization of PHB in the blends from both the melt and the glassy state was affected by the PELA component. When crystallized from the melt during the DSC nonisothermal crystallization run at a rate of 20°C/min, the temperatures of crystallization decreased with the increase of PELA content. Compared with pure PHB, the cold crystallization peaks of PHB in the blends shifted to higher temperatures. Well-defined spherulites of PHB were found in both pure PHB and the blends with PHB content of 80 or 60%. The growth of spherulites of PHB in the blends was affected significantly by 60% PELA content. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1849–1856, 1997     

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.     

Miscibility enhancement on the poly(vinylchloride)/poly(methylmethacrylate) blend and characterization by inverse gas chromatography: The corrected polymer–polymer interaction parameters from the probes dependency

The miscibility of poly(vinyl chloride)/poly(methylmethacrylate) (PVC/PMMA) system was improved by introducing some pyrrolidone units into the main chains of PMMA. For that purpose, we have synthesized two copolymers of poly(methylmethacrylate‐co‐vinylpyrrolidone) (MMVP) through a radical polymerization and carried out a comparative study of PVC/MMVP blends by inverse gas chromatography (IGC) and differential scanning calorimetry (DSC) methods. The adequacy of seven n‐alkane probes has been tested to determine the thermodynamic parameters. The miscibility of the two systems has been proved by a single T_g for each blend. This observation was also confirmed by DSC analysis. To highlight the presence of interaction and its intensity between PVC and MMVP in the blends, the polymer–polymer interaction parameters have been evaluated by IGC trough which the influence of the solute has been resolved. The Schneider approach confirmed the miscibility of these systems as the K deviates positively from unity. The miscibility has been appeared highlighted from the positive difference in surface energy between the pure polymers and their blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Gas permeation of polymer blends. I. PVC/ethylene–vinyl acetate copolymer (EVA)

The transport behavior of O₂ and N₂ were studied for series of physical blends of PVC with EVA having different vinyl acetate (VAc) contents in the EVA (45 and 65 wt-%) and using different milling temperatures (160° and 185°C). The polymer blends were further characterized by dynamic mechanical measurements, density measurements, and x-ray diffraction. At higher VAc content in EVA and with higher milling temperature, the rate of permeation (P) and the rate of diffusion (D) decrease, and the activation energy of D (from Arrhenius plots) increases. Furthermore, the experimental density values of PVC/EVA-45 blends agree well with calculated values, assuming volume additivity of the two components, while those of PVC/EVA-65 blends are higher than the calculated densities. These results are interpreted as due to denser packing of polymer molecules and increased PVC-EVA interaction at higher VAc content and with higher milling temperature, indicating better compatibility between the blend components. The x-ray diffraction data give no evidence of crystallinity. Sharp increases in P and D values at about 7.5% EVA (by weight) are found for PVC/EVA-45 blends (in agreement with our previous work) but not for PVC/EVA-65 blends. This is interpreted as due to a phase inversion at increasing EVA content in the former blends but not in the latter blends. The dynamic mechanical measurements show that the PVC/EVA-65 blends milled at 160°C behave largely as semicompatible systems with maximum interaction between the two polymers at compositions of about 50/50 by weight.     

Influence of impact load‐temperature conformity on toughening of poly(vinyl chloride) by core‐shell rubber particles

The work focused on the elucidation of several key parameters in toughening poly(vinyl chloride) (PVC) by the methyl methacrylate–butadiene–styrene (MBS) core‐shell particles. Accordingly, blends containing various weight percent of the MBS particles were prepared and characterized by dilute solution viscometry, dynamic light scattering, dynamic mechanical thermal analysis, transmission electron microscopy, and temperature variable impact test. The results showed PVC/MBS solution miscibility in almost all compositions with their maximum thermodynamic affinities at about 17 and 67 wt % of MBS in tetrahydrofurane (THF). In addition, MBS weight percent increase in its blend with the PVC above 10 led to severe impact energy raise with eventual leveling at about 17 wt %. Furthermore, blend toughness and its components miscibility in solution increased in parallel up to 20 wt % of MBS particles. On the other hand, blend toughness declined with test temperature decrease toward impact modifier core T_g at about ?30°C even for the sample with 20 wt % of the MBS particles. Finally, the brittle‐ductile transition of the blend containing 20 wt % of the MBS particles comparison with its matrix tan δ‐temperature correlation implied 2500 J/m impact energy equivalence with 90°C sample temperature rise in secondary relaxation activation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of poly(vinyl chloride)/chlorinated polyethylene blend composition on thermal stability

Blends of poly(vinyl chloride) (PVC) with different ratios of chlorinated polyethylene (CPE) were degradated by the thermogravimetric method under dynamic conditions (50–600°C) in an inert atmosphere. The effect of the miscibility and composition of the PVC/CPE blends on the thermal stability were investigated. DSC curves of the blends show neither a shift of the PVC glass transition temperature nor a shift of the CPE melting temperature, which means that these blends are heterogeneous. The characteristics of the TG curves were determined, some of which (T_1%,T_5%, Δm₁) can be used as indicators of the thermal stability of the blend. The apparent activation energy of PVC dehydrochlorination in the blends was also calculated. Comparison of the experimental TG curves and TG curves predicted by the additivity rule indicates the existence of the components' interaction in the PVC/CPE blends. The addition of CPE improves the thermal stability of PVC for all the investigated blends in the temperature range where α_calc is greater than α_exp. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 166–172, 2000     

Miscibility and transesterification in ternary blends of poly(ethylene naphthalate)/poly(pentamethylene terephthalate)/poly(ether imide)

Miscibility and morphology of poly(ethylene 2,6‐naphthalate)/poly(pentamethylene terephthalate)/poly(ether imide) (PEN/PPT/PEI) blends were studied by differential scanning calorimetry (DSC), optical microscopy (OM), proton nuclear magnetic resonance imaging (¹H‐NMR), and wide‐angle X‐ray diffraction (WAXD). OM and DSC results from ternary blends revealed the immiscibility of PEN/PPT/PEI blends, but ternary blends of all compositions were phase‐homogeneous following heat treatment at 300°C for over 60 min. Annealing samples at 300°C yielded an amorphous blend with a clear and single T_g at the final state. Experimental data from ¹H‐NMR revealed that PEN/PPT copolymers (ENPT) were formed by the so‐called transesterification. The effect of transesterification on glass transition and crystallization was discussed in detail. The sequence structures of the copolyester were identified by triad analysis, which showed that the mean sequence lengths became shorter and the randomness increased with heating time. The results reveal that a random copolymer improved the miscibility of the ternary blends, in which, the length of the homo segments in the polymer chain decreased and the crystal formation was disturbed because of the irregularity of the structure, as the exchange reaction proceeded. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3840–3849, 2006     

Characterization of interfaces in Poly (styrene-co-acrylonitrile) (SAN) based ternary polymer blends: A new approach from positron lifetime spectroscopy

Positron lifetime spectroscopy is used to develop a new approach to characterize the individual interfaces in ternary polymer blends and hence determine composition dependent miscibility level. This approach has its genesis in KSR and KRZ models for the evaluation of hydrodynamic interaction parameters (α_ij). The method successfully applied for binary blends (single interface) earlier is theoretically modified for ternary blends and experimentally verified by measuring free volume content in blends and their constituents. We have tested the efficacy of this method in two ternary blends namely SAN/PVC/PMMA and SAN/EVA/PVC at different compositions. The effective hydrodynamic parameter α_eff evaluated using individual α values turns out to be handy in predicting the overall miscibility level of a ternary blend. Results show that SAN/PVC/PMMA exhibits maximum α_eff of ?9.67 at composition 75/5/20 and SAN/EVA/PVC shows ?3.18 at 50/35/15 indicating that miscibility level is high at these compositions for these two blends. DSC and SEM studies have also been used to supplement positron results.     

Effect of dehydrochlorination of PVC on miscibility and phase separation of binary and ternary blends of poly(vinyl chloride), poly(ethylene-co-vinyl acetate) and poly(styrene-co-acrylonitrile)

The enhancement of miscibility at the lower critical solution temperature (LCST) of the blends poly(vinyl chloride)/poly(ethylene-co-vinyl acetate) (PVC/EVA), poly(vinyl chloride)/poly(styrene-co-acrylonitrile) (PVC/SAN) and poly(vinyl chloride)/poly(ethylene-co-vinyl acetate)/poly(styrene-co-acrylonitrile) (PVC/EVA/SAN) was observed at the micron level. Such miscibility is attributed to the dehydrochlorination and formation of hydrogen bonds between blend components. However, macrolevel immiscibility of these blends heated to the LCST was observed. Such microdomain compatibility of these blends gives a synergistic character. Brittle-type failure observed for LCST samples testifies to the synergism in treated blends. ©1997 SCI     

Phase separation of impact‐modified PVC/PMMA blends under melt‐blending conditions

Poly (vinyl chlride)/Poly (methyl methacrylate) (PVC/PMMA) blends were prepared by melt blending at 160°C and 190°C over an entire composition range. The miscibility of the blends was characterized by dynamic mechanical thermal analysis, transmission electron microscopy, and light transmittance testing. The blends prepared at 160°C were homogeneous on our observed scale, while the blends prepared at 190°C clearly showed phase separation. The stress‐strain behaviors of the blends prepared at 160°C were investigated. The results showed that the toughness of the blends could be improved by an increase of PVC content, resulting effectively in a removal of intrinsic strain softening, a decrease in yield stress, and an increase in strain hardening. Furthermore, a core‐shell structured modifier was introduced into the PVC/PMMA blends, and the impact property of the blends was studied. The results showed that the addition of rubber particles could improve the toughness of the two series of blends. However, the blends prepared at 190°C had higher impact strengths than those prepared at 160°C, a result which may be attributed to phase separation. J. VINYL ADDIT. TECHNOL., 19:11–17, 2013. © 2013 Society of Plastics Engineers     

Reactively formed ENPT copolymers as compatibilizers in ternary blends of poly(ethylene naphthalate)/poly(pentamethylene terephthalate)/poly(ether imide)

The compatibility of ternary blends of poly(ethylene naphthalate)/poly(pentamethylene terephthalate)/poly(ether imide) (PEN/PPT/PEI) was studied by examining the transesterification of PEN and PPT. ENPT copolymers were formed in situ as compatibilizers between PPT and PEI components in ternary blends. Differential scanning calorimetric (DSC) results for ternary blends showed the immiscibility of PEN/PPT/PEI, but ternary blends of all compositions were phase‐homogeneous after heat treatment at 300°C for more than 60 min. Annealing samples at 300°C yielded amorphous blends with a clear, single glass transition temperature (T_g), as the final state. Additionally, ENPT copolymer improved the compatibility of ENPT/PPT/PEI blends, yielding a homogeneous phase in the ENPT‐rich compositions. The morphology of the ENPT/PPT/PEI blends was altered from heterogeneous to homogeneous by controlling the concentration of PPT in the ENPT copolymers as well as the concentration of the ENPT copolymers. Moreover, a homogeneous phase with a clear T_g was observed when the concentration of PPT in the ENPT copolymer fell to 70 wt% in the ENPT/PEI = 50/50 blends. Experimental results indicate how the concentration of PPT in the ENPT copolymer affects miscibility in the ENPT/PEI blends. POLYM. ENG. SCI. 46:337–343, 2006. © 2006 Society of Plastics Engineers     

Preparation and characterization of poly(methyl methacrylate) beads

The phase behavior of Poly(ethylene terephthalate)/Poly(ethylene‐2,6‐naphthalate)/Poly(ethylene terephthalate‐co‐ethylene‐2,6‐naphthalate) (PET/PEN/P(ET‐co‐EN)) ternary blends in molten state was evaluated from differential scanning calorimetry (DSC) and NMR results as well as optical microscopic observations. Copolymer of ethylene terephthalate and ethylene‐2,6‐naphthalate was prepared by a condensation polymerization, which was a random copolymer with an intrinsic viscosity (IV) of 0.3 dL/g. The phase diagram of the ternary blends revealed that the miscibility of ternary blends in molten state was dependent on the fraction of P(ET‐co‐EN) in the blends and holding time of the blends at high temperatures above 280°C. With increase in the holding time, the fraction of copolymer in the blends necessary to induce the immiscible to miscible transition decreased. For the blends with longer holding time at 280°C, the phase diagram in molten state was irreversible against the temperature, although a reversibility was found for the blends with short holding time of 1 min at 280°C. The irreversibility of phase behavior was not explained simply by the increase of copolymer content produced during heat treatment. Complex irreversible physical and chemical interactions between components and change of phase structure of the blend in the molten state might influence on the irreversibility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Quantitative study of the annealing of poly(vinyl chloride) near the glass transition

Poly(vinyl chloride) displays a normal DSC of DTA curve for the glass transition when quenched from above its T_g. However if cooled slowly or annealed near the glass transition temperature, a peak appears on the DSC or DTA curve at the T_g. In this paper quantitative studies of the time and temperature effects on the production of this endothermal peak during the annealing of PVC homopolymer and an acetate copolymer are presented. The phenomenon conforms to the Williams, Landell, and Ferry equation for the relaxation of polymer chains, the rate of the peak formation becoming negligible at more than 50°C below T_g. The energy difference between the quenched and annealed forms is small. For a PVC homopolymer annealed 2 hr at 68°C, which is T_g ?10°C, the difference is 0.25 cal/g. For a 13% acetate copolymer of PVC similarly annealed, the difference is 0.36 cal/g. The measured rates of the process give a calculated activation energy of 13–14 kcal/mole for PVC homopolymer and copolymer. This appearance of a peak on the T_g curve for a polymer when annealed near the glass temperature appears to be a general phenomenon.     

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.     

Viscoelastic and engineering properties of poly(vinyl chloride) plasticized with polycaprolactone-based polyurethanes

The plasticization of poly(vinyl chloride) (PVC) by polyurethanes made from polycaprolactone (PCL) diol and p.p′-diphenylmethane diisocyanate (MDI) was investigated. By varying the PCL chain length and substituting with polyether chains such as poly(tetramethylene ether) (PTME) or poly(ethylene oxide) (PEO), also of various chain lengths, the efficiency of plasticization was changed. High urethane content, such as obtained with PCL-530/MDI, decreased the miscibility of the polyurethane and PVC. Plasticizing efficiency of the polyurethanes, as indicated by transparency, flexibility, and engineering properties of the blend, increased on increasing the initial PCL chain length. However, polyurethanes containing very high-molecular-weight PCL (e.g., PCL-3000) slowly crystallized from a 50:50 blend with PVC. PVC/polyurethane ratio also had a significant effect on crystallization, as indicated by the rapid crystallization of PCL-2000/MDI polyurethane when it exceeded 50 wt % in the blend. The transparency and flexiblity of 50:50 blends were lowered by systematically replacing PVC-miscible PCL-2000 segments in the polyurethane with PTME-2000, PEO-200, and PEO-1500 segments. The polyurethanes became highly immiscible in PVC beyond the limiting mole fraction replacements of 0.6 for PTME-2000, 0.8 for PEO-200, and 0.4 for PEO-1500. Such chemical modification gave controlled and temperature-dependent miscibility in PVC and consequently blends with broadened glass transitions and high damping properties over a wide temperature range. Decreased miscibility in the blend gradually decreased elongation at break and tensile strength, but increased the modulus. A general correlation of the viscoelastic and tensile properties of the 50:50 blends with the weight fraction, rather than mole fraction, of the PCL content in the polyurethane composition was found; replacement of PCL beyond a limiting weight fraction by polyethers and MDI produced PVC-immiscible polyurethane. These limiting weight fractions are 0.6, 0.5, and 0.4 with PTME-2000, PEO-200, and PEO-1500, respectively, which denotes the order of decreasing miscibility of these polyurethanes in PVC. Viscoelastic and engineering properties of the blend with a particular polyurethane could also be controlled by varying the PVC/polyurethane ratio. Many of these semimiscible blends showed evidence by lower critical solution temperature (LCST) behavior at about ?30°C, but complete cloud and point curves were not constructed.     

Fourier transform infrared studies of poly(vinyl chloride) blends with ethylene Co- and terpolymers

The miscibility of poly(vinyl chloride) (PVC) with various ethylene copolymers and terpolymers were investigated using FT-IR spectroscopy. All blends reported were 50/50 by weight. In blends of PVC with ethylene/dimethyl acrylamide copolymer (E/DMA), frequency shifts were observed in the amide carbonyl (proton acceptor) and the α-hydrogen of PVC (proton donor) characteristic bands. In blends of PVC with ethylene/ethyl acrylate/carbon monoxide terpolymer (E/EA/CO), both the ester carbonyl and the ketone carbonyl characteristic frequencies showed mutual shifts and appeared as if they merged together. Small frequency shifts were also observed in the α-hydrogen of PVC characteristic bands. In blends of PVC with ethylene/vinyl acetate/carbon monoxide terpolymer (E/VA/CO), the ester carbonyl frequency showed a shift while that of the ketone carbonyl was essentially unchanged. On the other hand, in PVC blends with ethylene/vinyl acetate copolymer (E/VA), the ester CO frequency did not show any shift, which is consistent with their observed immiscibility. Thus, it is clear that incorporating a ketone ? C?O in ethylene/ester copolymers to form the corresponding terpolymers enhances their miscibility with PVC as earlier proposed on the basis of dynamic mechanical studies. Similar results were shown for blends of PVC with ethylene/2 ethyl hexyl acrylate/carbon monoxide terpolymer (E/2EHA/CO). Frequency shifts imply specific interactions which suggest polymer-polyer miscibility on a molecular scale.     

Thermal,Spectroscopic, and Mechanical Properties of Blend Films of Poly(N-Vinyl-2-Pyrrolidone) and Sodium Alginate

Blends of poly(N-vinyl-2-pyrrolidone) (PVP) and sodium alginate (NaAlg) were prepared by casting from aqueous solutions. These blends were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and tensile strength test. The miscibility in the blends of PVP and NaAlg was established on the basis of the thermal analysis results. DSC showed that the blends possessed single, composition-dependent glass transition temperatures (T _g s), indicating that the blends are miscible in amorphous state. FT-IR studies indicate that there are the intermolecular hydrogen bonding interactions, i.e., –OH·····O=C in PVP/NaAlg blends. This blend films also exhibited the higher thermal stability and improved the elongation at break in dry states.