Crystallization of Poly(ε‐caprolactone)/Poly(vinyl chloride) Miscible Blends Under Strain: The Role of Molecular Weight

Summary: The effect of poly(ε‐caprolactone) (PCL) molecular weight on the orientation of crystalline PCL in miscible poly(ε‐caprolactone)/poly(vinyl chloride) (PCL/PVC) blends, melt crystallized under strain, has been studied by a combination of wide angle X‐ray diffraction (WAXD) and small angle X‐ray scattering (SAXS) studies. An unusual crystal orientation with the b‐axis parallel to the stretching direction was observed in miscible PCL/PVC blends with PCL of high molecular weight (>21 000). SAXS showed the presence of nanosize confined PCL in the PCL/PVC blends, which could be preserved at temperatures higher than the T_m of PCL but lower than the T_g of PVC. A mechanism based on the confinement of PCL crystal growth was proposed, which can explain the formation of b‐axis orientation in PCL/PVC blends crystallized under strain.

SAXS pattern of stretched PCL/PVC blend after annealing at 90 °C for 5 min.     

Segmental orientation in blends of poly(ϵ-caprolactone) with poly(vinyl chloride) and nitrocellulose

Binary blends of polycaprolactone (PCL) with poly(vinyl chloride) (PVC) and nitrocellulose (NC) have been shown to be compatible over a wide range of composition. In this study, segmental orientation was determined by dynamic, differential infrared dichroism for each component in the PVC and NC blends with PCL. In compatible amorphous blends, PCL orientation behavior was essentially the same as for the orientation of NC or the isotactic segments of PVC. Syndiotactic PVC segments showed higher orientations, reflecting the greater intrachain stiffness of the microcrystalline PVC phase. PCL segments in the blends where the PCL component was semicrystalline were found to exhibit orientation characteristics which were quite different from the orientation of the nitrocellulose and PVC components of the blends. By assuming that the NC orientation represented the response of the amorphous PCL, the orientation of the crystalline PCL was determined for a NC blend using a simple model of additive dichroism response. In PVC blends, a similar analysis using the amorphous-component response of PVC was made. In both cases the results from the dichroism model showed fair agreement with the PCL unit cell C-axis orientation from independent dichroism calculations.     

Investigation at the chain segmental level of the miscibility of poly(vinyl chloride)/atactic poly(methyl methacrylate) blends

We employed high‐resolution ¹³C cross‐polarization/magic‐angle‐spinning/dipolar‐decoupling NMR spectroscopy to investigate the miscibility and phase behavior of poly(vinyl chloride) (PVC)/poly(methyl methacrylate) (PMMA) blends. The spin–lattice relaxation times of protons in both the laboratory and rotating frames [T₁(H) and T_1ρ(H), respectively] were indirectly measured through ¹³C resonances. The T₁(H) results indicate that the blends are homogeneous, at least on a scale of 200–300 Å, confirming the miscibility of the system from a differential scanning calorimetry study in terms of the replacement of the glass‐transition‐temperature feature. The single decay and composition‐dependent T_1ρ(H) values for each blend further demonstrate that the spin diffusion among all protons in the blends averages out the whole relaxation process; therefore, the blends are homogeneous on a scale of 18–20 Å. The microcrystallinity of PVC disappears upon blending with PMMA, indicating intimate mixing of the two polymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2390–2396, 2001     

Segmental and secondary dynamics in hydrogen‐bonded poly(4‐vinylphenol)/poly(methyl methacrylate) blends

Broadband dielectric spectroscopy was used to study the segmental (α) and secondary (β) relaxations in hydrogen‐bonded poly(4‐vinylphenol)/poly(methyl methacrylate) (PVPh/PMMA) blends with PVPh concentrations of 20–80% and at temperatures from ?30 to approximately glass‐transition temperature (T_g) + 80 °C. Miscible blends were obtained by solution casting from methyl ethyl ketone solution, as confirmed by single differential scanning calorimetry T_g and single segmental relaxation process for each blend. The β relaxation of PMMA maintains similar characteristics in blends with PVPh, compared with neat PMMA. Its relaxation time and activation energy are nearly the same in all blends. Furthermore, the dielectric relaxation strength of PMMA β process in the blends is proportional to the concentration of PMMA, suggesting that blending and intermolecular hydrogen bonding do not modify the local intramolecular motion. The α process, however, represents the segmental motions of both components and becomes slower with increasing PVPh concentration because of the higher T_g. This leads to well‐defined α and β relaxations in the blends above the corresponding T_g, which cannot be reliably resolved in neat PMMA without ambiguous curve deconvolution. The PMMA β process still follows an Arrhenius temperature dependence above T_g, but with an activation energy larger than that observed below T_g because of increased relaxation amplitude. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3405–3415, 2004     

Influence of hyperbranched against linear architecture on crystallization behavior of poly(ε‐caprolactone)s in binary blends with poly(vinyl chloride)

Nonisothermal and isothermal crystallization behaviors of the hyperbranched poly(ε‐caprolactone) (HPCL)/poly(vinyl chloride) (PVC) and linear poly(ε‐caprolactone) (LPCL)/(PVC) blends were characterized with various blend composition such as 100/0, 95/5, 90/10, and 80/20, respectively. HPCL was synthesized through polycondensation of AB₂ macromonomer while LPCL and PVC were commercially purchased. The architectural characterization performed on ¹H NMR spectra revealed that HPCL consisted of about 3 AB₂ units and the linear segments consisted of 25 ε‐CL units. Through the nonisothermal crystallization analyses by modified Avrami approach with DSC crystallization exotherms, it was found that the crystallization rate was retarded by the increase in the noncrystallizable component (PVC) in the blends. This is in good agreement with the results of the isothermal crystallization analyses where time resolved small angle light scattering (SALS) and polarized optical microscopy (POM) were used. The effect of molecular architectural difference between HPCL and LPCL on the crystallization of their binary blends with PVC was elucidated by comparing the crystallization kinetic parameters. Both the nonisothermal and isothermal crystallization analyses showed that the crystallization rates of HPCL/PVC blends was faster than LPCL/PVC blends at given blend compositions. The faster crystallization of the HPCL/PVC blends is ascribed to the two specific architectural characteristics of HPCL; the branched structure and the incorporated long linear segments. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 577–589, 2007     

PDMS migration at poly(vinyl chloride)/poly(ɛ-caprolactone)/poly(ɛ-caprolactone)-b-poly(dimethylsiloxane) blends surfaces

Films composed of poly(vinyl chloride)/poly(?-caprolactone)/poly(?-caprolactone)-b-poly(dimethylsiloxane) [PVC/PCL/(PCL-b-PDMS)] blends were prepared by solvent casting from tetrahydrofuran. The PVC content was kept constant (60 wt %) while varying the PCL and PCL-b-PDMS contents, part of the PCL (0–20 wt %) in the PVC/PCL (60/40) blend being replaced with PCL-b-PDMS with different molecular weights of the PCL blocks. The prepared blends were investigated by infrared spectroscopy and contact angle measurements. FTIR analysis and contact angle measurements indicate that the PDMS blocks tend to migrate towards the surface and this migration is preferential to the side in contact with air.     

Synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl) methyl methacrylate‐co‐ethyl acrylate] by incorporation of carbon dioxide into epoxide polymer and the miscibility behavior of its blends with poly(methyl methacrylate) or poly(vinyl chloride)

This study was related to the investigation of the chemical fixation of carbon dioxide to a copolymer bearing epoxide and the application of the cyclic carbonate group containing copolymer‐to‐polymer blends. In the synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl) methyl methacrylate‐co‐ethyl acrylate] [poly(DOMA‐co‐EA)] from poly(glycidyl methacrylate‐co‐ethyl acrylate) [poly(GMA‐co‐EA)] and CO₂, quaternary ammonium salts showed good catalytic activity. The films of poly(DOMA‐co‐EA) with poly(methyl methacrylate) (PMMA) or poly(vinyl chloride) (PVC) blends were cast from N,N′‐dimethylformamide solution. The miscibility of the blends of poly(DOMA‐co‐EA) with PMMA or PVC have been investigated both by DSC and visual inspection of the blends. The optical clarity test and DSC analysis showed that poly(DOMA‐co‐EA) containing blends were miscible over the whole composition range. The miscibility behaviors were discussed in terms of Fourier transform infrared spectra and interaction parameters based on the binary interaction model. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1472–1480, 2001     

Phase behavior,crystallization, and morphology in thermosetting blends of a biodegradable poly(ethylene glycol)‐type epoxy resin and poly(ϵ‐caprolactone)

Thermosetting blends of a biodegradable poly(ethylene glycol)‐type epoxy resin (PEG‐ER) and poly(?‐caprolactone) (PCL) were prepared via an in situ curing reaction of poly(ethylene glycol) diglycidyl ether (PEGDGE) and maleic anhydride (MAH) in the presence of PCL. The miscibility, phase behavior, crystallization, and morphology of these blends were investigated. The uncured PCL/PEGDGE blends were miscible, mainly because of the entropic contribution, as the molecular weight of PEGDGE was very low. The crystallization and melting behavior of both PCL and the poly(ethylene glycol) (PEG) segment of PEGDGE were less affected in the uncured PCL/PEGDGE blends because of the very close glass‐transition temperatures of PCL and PEGDGE. However, the cured PCL/PEG‐ER blends were immiscible and exhibited two separate glass transitions, as revealed by differential scanning calorimetry and dynamic mechanical analysis. There existed two phases in the cured PCL/PEG‐ER blends, that is, a PCL‐rich phase and a PEG‐ER crosslinked phase composed of an MAH‐cured PEGDGE network. The crystallization of PCL was slightly enhanced in the cured blends because of the phase‐separated nature; meanwhile, the PEG segment was highly restricted in the crosslinked network and was noncrystallizable in the cured blends. The phase structure and morphology of the cured PCL/PEG‐ER blends were examined with scanning electron microscopy; a variety of phase morphologies were observed that depended on the blend composition. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2833–2843, 2004     

Mechanical properties of blends of PAMAM dendrimers with poly(vinyl chloride) and poly(vinyl acetate)

Hybrid blends of poly(amidoamine) PAMAM dendrimers with two linear high polymers, poly(vinyl chloride), PVC, and poly(vinyl acetate), PVAc, are reported. The interaction between the blend components was studied using dynamic mechanical analysis, xenon nuclear magnetic resonance (NMR) spectroscopy, and tensile property measurements. The data suggest a much higher degree of interaction between components of PVAc-containing blends compared to those containing PVC. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2111–2117, 1998     

Direct current conductivity and ion motions in poly(vinyl chloride)‐poly‐1,4‐cis butadiene blends by electrical relaxation method

Ionic conduction in poly(vinyl chloride) (PVC)‐poly‐1,4‐cis butadiene blends has been studied using the electrical relaxation method. Temperature dependence of direct current (dc) conductivity does not change at the glass transition of PVC but does change at higher temperatures. The shape of the frequency dispersion curve of the electric modulus in a frequency range from 0.01 to 100 Hz depends on temperature. At low temperatures, the shape of the dispersion curve is reproduced by calculation assuming the Debye decay function, whereas this is not reproduced at high temperatures. Two kinds of analysis of the dispersion curve are discussed for this complicated change in the shape of the dispersion. One is that the dispersion curve is regarded as a single process expressed by the Kohlrausch decay function, and the other is that the curve is regarded as two processes expressed by the Debye and the Kohlrausch decay functions. The observed dispersion of the electric modulus is not expressed by the single process but by the two processes. One of the two processes is characterized by the Debye decay function, and the other is characterized by the Kohlrausch decay function. The parameter of the Kohlrausch decay function for one of these processes has a value of 0.82, and this value does not depend on temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 226–235, 2002     

Epoxy resin/poly(ϵ‐caprolactone) blends cured with 2,2‐bis[4‐(4‐aminophenoxy)phenyl]propane. II. Studies by Fourier transform infrared and carbon‐13 cross‐polarization/magic‐angle spinning nuclear magnetic resonance spectroscopy

Crystalline thermosetting blends composed of 2,2′‐bis[4‐(4‐aminophenoxy)phenyl]propane‐crosslinked epoxy resin (ER) and poly(?‐caprolactone) (PCL) were investigated by means of Fourier transform infrared (FTIR) spectroscopy and high‐resolution solid‐state NMR spectroscopy. FTIR investigations indicated that there were specific intermolecular interactions between ER and PCL and that the intermolecular hydrogen‐bonding interactions were weaker than the self‐association in pure epoxy. The intermolecular hydrogen bonding was considered to be the driving force for the miscibility of the thermosetting blends. For the examination of the miscibility of the thermosetting blends at the molecular level, high‐resolution solid‐state ¹³C cross‐polarity/magic‐angle spinning (CP‐MAS) NMR spectroscopy was employed. The line width of ¹³C CP‐MAS spectra decreased with increasing PCL contents, and the chemical shift of the carbonyl carbon resonance of PCL shifted to a low field with an increasing epoxy content in the blends. The proton spin–lattice relaxation experiments in the laboratory frame showed that all the blends possessed identical, composition‐dependent relaxation times (i.e., the proton spin–lattice relaxation times in the laboratory frame), suggesting that the thermosetting blends were homogeneous on the scale of 20–30 nm in terms of the spin‐diffusion mechanism, and this was in a good agreement with the results of differential scanning calorimetry and dynamic mechanical analysis. For the examination of the miscibility of the blends at the molecular level, the behavior of the proton lattice relaxation in the rotating frame was investigated. The homogeneity of the thermosetting blends at the molecular level was quite dependent on the blend composition. The PCL‐lean ER/PCL blends (e.g., 70/30) displayed a single homogeneous amorphous phase, and the molecular chains were intimately mixed on the segmental scale. The PCL‐rich blends displayed biexponential decay in experiments concerning the proton spin–lattice relaxation times in the rotating frame, which was ascribed to amorphous and crystalline phases. In the amorphous region, the molecular chains of epoxy and PCL were intimately mixed at the molecular level. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1099–1111, 2003     

Fourier-transform infrared studies of polymer blends. II. Poly(ϵ-caprolactone)–poly(vinyl chloride) system

Fourier-transform infrared (FTIR) studies of the poly(?-caprolactone) (PCL)–poly(vinyl chloride) (PVC) blend system are presented. The results indicate that there are specific interactions between the PCL and PVC in both the molten and solid states which could be responsible for the apparent compatibility of the amorphous component of these blends. Additionally, FTIR difference spectra are presented to illustrate the potential of this technique for following the kinetics of crystallinity in polymer blend systems.     

Morphology and fracture behavior of toughening‐modified poly(vinyl chloride)/organophilic montmorillonite composites

Toughening‐modified poly(vinyl chloride) (PVC)/organophilic montmorillonite (OMMT) composites with an impact‐modifier resin (Blendex 338) were prepared by melt intercalation, and their microstructures were investigated with wide‐angle X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy. The mechanical properties of the PVC composites were examined in terms of the content of Blendex and OMMT, and the fracture toughness was analyzed with a modified essential work of fracture model. Intercalated structures were found in the PVC/OMMT composites with or without Blendex. Either Blendex or OMMT could improve the elongation at break and notched impact strength of PVC at proper contents. With the addition of 30 phr or more of Blendex, supertough behavior was observed for PVC/Blendex blends, and their notched impact strength was increased more than 3319% compared with that of pristine PVC. Furthermore, the addition of OMMT greatly improved both the toughness and strength of PVC/Blendex blends, and the toughening effect of OMMT on PVC/Blendex blends was much larger than that on pristine PVC. Blendex and OMMT synergistically improved the mechanical properties of PVC. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 286–295, 2004     

Biodegradation of plasticized poly(vinyl chloride) containing cellulose

The plasticized poly(vinyl chloride) (PVC‐P) and its blend with cellulose (PVC‐P/cell) were prepared by means of extrusion. The samples were then biodegraded in forest soil as well as in soil enriched with cellulolytic microorganisms. Moreover, the samples were vaccinated with chosen species of fungi whose direct effect on polymer was then observed. The course of biodegradation was monitored in terms of, and by means of the following: weight loss, carbon dioxide evolved, attenuated total reflectance infrared (FTIR‐ATR) spectroscopy, gel permeation chromatography (GPC), as well as visual and microscopic observation (OM, SEM). The mechanical properties of samples were studied using the standard tensile tests. It was found that biodegradation in soil occurs in PVC‐P and this process is accelerated in the composition of PVC‐P with cellulose. The biodecomposition yield of PVC‐P/cellulose blends (calculated as relative percentage weight loss) is several dozen times higher than that of PVC‐P. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 903–919, 2007     

聚ε-己内酯/聚氯乙烯球晶表面的XPS研究

聚合物薄膜在微电子领域中的应用日益增加.聚ε-己内酯/聚氯乙烯（PCL/PVC）是研究得最广泛的聚合物共混薄膜之一.PCL与PVC以一定比例混合时,可以形成环带球晶；同时,体系分为结晶PCL相及PCL/PVC非晶混溶相.用XPS和成象XPS分析技术,对PCL/PVC膜的表面化学组成和元素分布情况进行了研究.观察到PCL在薄膜表面富集.此外,成象XPS表明,PVC在球晶边界处富集,且球晶边界宽度约15 μm.     

Blends of polycarbonate and poly(ϵ‐caprolactone) and the determination of the polymer–polymer interaction parameter of the two polymers

The thermal properties of blends of polycarbonate (PC) and poly(ε‐caprolactone) (PCL) were investigated by differential scanning calorimetry (DSC). From the thermal analysis of PC‐PCL blends, a single glass‐transition temperature (T_g) was observed for all the blend compositions. These results indicate that there is miscibility between the two components. From the modified Lu and Weiss equation, the polymer–polymer interaction parameter (χ₁₂) of the PC‐PCL blends was calculated and found to range from −0.012 to −0.040 with the compositions. The χ₁₂ values calculated from the T_g method decreased with the increase of PC weight fraction. By taking PC‐PCL blend as a model system, the values of χ₁₂ were compared with two different methods, the T_g method and melting point depression method. The two methods are in reasonably good agreement for the χ₁₂ values of the PC‐PCL blends. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2072–2076, 2000     

Studies on poly(ε‐caprolactone)/thiodiphenol blends: The specific interaction and the thermal and dynamic mechanical properties

The effects of several low molecular weight compounds with hydroxyl groups on the physical properties of poly(ε‐caprolactone) (PCL) were investigated by Fourier transform infrared (FTIR) spectroscopy and high‐resolution solid‐state ¹³C NMR. PCL and 4,4′‐thiodiphenol (TDP) interact through strong intermolecular hydrogen bonds and form hydrogen‐bonded networks in the blends at an appropriate TDP content. The thermal and dynamic mechanical properties of PCL/TDP blends were investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis, respectively. The melting point of PCL decreased, whereas both the glass‐transition temperature and the loss tangent tan δ of the blend increased with an increase in TDP content. The addition of 40 wt % TDP changed PCL from a semicrystalline polymer in the pure state to a fully amorphous elastomer. The molecules of TDP lost their crystallizability in the blends with TDP contents not greater than 40 wt %. In addition to TDP, three other PCL blend systems with low molecular weight additives containing two hydroxyl groups, 1,4‐dihydroxybenzene, 1,4‐di‐(2‐hydroxyethoxy) benzene, and 1,6‐hexanediol, were also investigated with FTIR and DSC, and the effects of the chemical structure of the additives on the morphology and thermal properties are discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1848–1859, 2000     

Study of hydrogen‐bonding strength in poly(ϵ‐caprolactone) blends by DSC and FTIR

The hydrogen‐bonding strength of poly(?‐caprolactone) (PCL) blends with three different well‐known hydrogen‐bonding donor polymers [i.e., phenolic, poly(vinyl‐phenol) (PVPh), and phenoxy] was investigated with differential scanning calorimetry and Fourier transform infrared spectroscopy. All blends exhibited a single glass‐transition temperature with differential scanning calorimetry, which is characteristic of a miscible system. The strength of interassociation depended on the hydrogen‐bonding donor group in the order phenolic/PCL > PVPh/PCL > phenoxy/PCL, which corresponds to the q value of the Kwei equation. In addition, the interaction energy density parameter calculated from the melting depression of PCL with the Nishi–Wang equation resulted in a similar trend in terms of the hydrogen‐bonding strength. Quantitative analyses on the fraction of hydrogen‐bonded carbonyl groups in the molten state were made with Fourier transform infrared spectroscopy for all systems, and good correlations between thermal behaviors and infrared results were observed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1348–1359, 2001     

Thermal conductivity of poly(vinyl chloride)/polycaprolactone blends

Thermal diffusivity, heat capacity, and density of polyvinyl chloride/polycaprolactone (PVC/PCL) blends were measured by the laser flash method, DSC, and pycnometry, respectively. The thermal conductivity of the PVC/PCL blends was determined from the results. The miscibility of the blend and crystallinity of PCL were determined by DSC. The effect of blend structure on thermal conductivity is discussed. The phase compositions of the PVC/PCL blends are of three types depending on PCL content: i.e., up to 33%, from 33 to 70%, and above 70% PCL by weight. Thermal conductivity, thermal diffusivity, and heat capacity of the PVC/PCL blends are strongly affected by the phase composition of the blend, which changes in a complicated way with PCL content. © 1994 John Wiley & Sons, Inc.     

Effects of chain configuration on UCST behavior in blends of poly(L‐lactic acid) with tactic poly(methyl methacrylate)s

Chain configuration influences phase behavior of blends of poly(methyl methacrylate) (PMMA) of different tactic configurations (syndiotacticity, isotacticity, or atacticity) with poly(L ‐lactic acid) (PLLA). Blends system of sPMMA/PLLA is immiscible with an asymmetry‐shaped UCST at ～250 °C. The phase behavior of the sPMMA/PLLA blend is similar to the aPMMA/PLLA blend that has been already proven in the previous work to exhibit similar UCST temperatures (230–250 °C) and asymmetry shapes in the UCST diagrams. On the other hand, the iPMMA/PLLA blend remains immiscible up to thermal degradation without showing any transition to UCST upon heating. The blend system with UCST, that is, sPMMA/PLLA, can be frozen in a state of miscibility by quenching to rapidly solidify from the homogeneous liquid at UCST, where the T_g‐composition relationship for the sPMMA/PLLA blend fits well with the Gordon‐Taylor T_g model with k = 0.15 and the blend's T leads to χ₁₂ = ?0.26 for the UCST‐quenched sPMMA/PLLA blend. Both parameters (k and χ) as characterized for the frozen miscible blend suggest a relatively weak interaction between the two constituents (sPMMA and PLLA) in the blends. The interaction strength is likely not strong enough to maintain a thermodynamic miscibility when the blend is at ambient temperature or any lower temperatures below UCST. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2355–2369, 2008