Improved mechanical properties of poly (vinyl alcohol) films with glycerol plasticizer by uniaxial drawing

In this work, the uniaxial stretching poly (vinyl alcohol) (PVA) films with glycerol as plasticizer were prepared to explore the influence of drawing temperature and drawing ratio. The structure and property were investigated with scanning electron microscope, wide‐angle X‐ray diffraction, X‐ray diffraction, differential scanning calorimetry, mechanical tests, etc. With the increase of stretching temperature, the melting and crystallization temperatures increased. The tensile strength and Young modulus of glycerol/PVA films increased first and then decreased; when the temperature was 80°C, the tensile strength and Young modulus reached to maximum values of 197.2 and 470 MPa, respectively. In addition, with the increase of draw ratio, the orientation degree of the PVA molecular chains increased, indicating the improved regularity of molecular chains. When the PVA films were stretched to 4 times, the tensile strength and Young modulus of the films reached 162 and 143 MPa, respectively, which were 4 and 1.3 times compared with those of unoriented films. These environmentally friendly PVA films with excellent mechanical properties would find wide applications in the industry such as packaging, coating, etc.     

Radiation effects on the thermal degradation of poly(vinyl chloride) and poly(vinyl alcohol)

Radiation effects on the formation of conjugated double bonds in the thermal degradation of poly(vinyl chloride) (PVC) and poly(vinyl alcohol) (PVA) were investigated. Thin films of PVC and PVA were either irradiated with γ-rays at ambient temperature (pre-irradiation) and then subjected to thermal treatment, or irradiated at elevated temperatures (in situ irradiation). An extensive enhancement of the thermal degradation was observed for the pre-irradiation of the PVC films, which was more effective than the effect of the in situ irradiation at the same absorption dose. For the PVA degradation, however, the effect of the in situ irradiation was larger than that of the pre-irradiation. The results were explained and related mechanisms were discussed based on radiation-induced chemical reactions and their individual contributions to the thermal degradation behaviors of the two polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3089–3095, 1998     

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     

Electrical conductivity of poly(vinyl chloride) obtained by photodehydrochlorination from laminated poly(vinyl chloride)/polypyrrole films

Poly(vinyl chloride) (PVC) has been converted to an electrically conductive structure by combined electrochemical and photochemical methods. PVC was cast on a polypyrrole (PPy) film electrode which had been electrochemically prepared. The PVC layer in the laminated PVC/PPy films was first dehydrochlorinated under the illumination of UV light, and the generated polyenes were subsequently doped with I₂ and FeCl₃. The maximum electrical conductivity achieved for such PVC film was 2.51 X 10^?2 and 8.63 10^?2 S cm^?1 after I₂ and FeCl₃ doping, respectively. The temperature dependence of the electrical conductivity showed different behavior in higher and lower temperature ranges. In the former (T > 243 K), the T^?1 law held, and the activation energy and bandgap were estimated as 0.25 and 0.49 eV, respectively. In the latter (T < 243 K), the conductivity mechanism followed the variable range hopping model (T^?1/4 law) in which the radius of the localized state wave function and the density of the localized states at the Fermi level were 1.25 × 10³ Å and 1.03 X 10¹⁵ eV^?1 cm^?3, respectively. © 1995 John Wiley & Sons, Inc.     

Diffusion of small molecules through modified poly(vinyl chloride) membranes

The transport properties of a set of four copolymers based on poly(vinyl chloride) (PVC) have been studied. The nucleophilic substitution of chlorine atoms with 4‐mercaptophenol sodium salt, 2‐thionaphthalene, 4‐(1‐adamantyl) thiophenol, and thiophenolate sodium salt as the nucleophiles has been performed, from low conversion levels (3%) to high levels (40%), and the permeability, solubility, and diffusivity of oxygen, nitrogen, carbon dioxide, and methane have been measured. The introduction of bulky groups to the PVC chain leads to chain separation and results in large increases in the free volume at conversions up to 10%. This brings about a 5‐fold increase in the diffusion coefficients that is almost independent of the bulkiness of the substituent. Solubility is little affected and instead tends to decrease as substitution progresses. The substitution of more than 10% of the chlorine atoms does not result in an improvement in the transport properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 964–971, 2002     

Formation of crystalline inclusion compounds of poly (vinyl chloride) of different stereoregularity with γ-cyclodextrin

This work reports the formation and detailed characterization of the γ-cyclodextrin (γ-CD) inclusion compounds (ICs) formed with two poly (vinyl chloride) samples with different isotactic content. The ICs were characterized by X-ray diffraction, solid state ¹³C-NMR, solution ¹H-NMR, FT-infrared, differential scanning calorimetry, and thermogravimetric analysis. Experimental evidence of the inclusion of the guest polymer chains into the narrow channels created by the γ-CD crystalline host lattice has been obtained. Examination of coalesced poly (vinyl chlorides) (PVCs) obtained after the host γ-CD is removed reveals different characteristics specifically for the coalesced PVC sample with higher isotactic content. An increase in T_g was observed by DSC for this PVC. To the contrary, the T_g of the coalesced PVC sample with lower isotactic content is almost the same as that of the as-synthesized sample. Thermogravimetric analysis indicated that coalesced PVC with higher isotactic content acquires a degree of stabilization after modification by threading into and being extracted from its γ-CD IC. The results suggest that an irreversible conformational change takes place when PVC forms ICs with a solid host lattice like γ-CD. The PVC molecules extend and reorganize into a more stable conformation in the IC, consequently improving the properties of the coalesced sample. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2503–2513, 2007     

Novel preparation of electrically conducting poly (vinyl chloride) by photo-dehydrochlorination from poly (vinyl chloride)/polypyrrole composite film

Polypyrrole (PPy) was deposited electrochemically on a platinum plate from a nitric acid solution of pyrrole. The PVC/PPy composite film was finally obtained by casting poly(vinyl chloride) (PVC) onto the PPy electrode from a tetrahydrofuran solution of PVC. The prepared composite film was irradiated at 90°C with a low-pressure mercury lamp in the stream of hydrogen gas saturated with steam, and the PVC film was dehydrochlorinated, leading to the formation of conjugated polyene. The electrical conductivity (σ) of the PVC film in the irradiated composite film was reveled: σ=2.51 × 10^?5S cm^?1. By iodine doping, σ was further enhanced up to 5.04 X 10^?3 S cm^?1. The tensile strength of the irradiated composite film became larger than that of the original PVC film; i.e., the stress at break was: 461 (composite film); 401 kg cm^?2 (PVC). These results were brought about by the doping of radical species to the conjugated polyene. The anion, NO^?₃, doped during the electrodeposition of PPy was photodecomposed to generate radical NO₂ and this species was doped to the polyene, resulting in the formation of electrically conductive PVC and mechanically improved composite film. © 1994 John Wiley & Sons, Inc.     

用DSC研究线形多嵌段聚氨酯与聚氯乙烯、氯化聚氯乙烯共混相容性

用示差扫描量热法（DSC）研究了线形多嵌段聚氨酯（PU）与聚氯乙烯（PVC）、氯化聚氯乙烯（CPVC）共混相容性，说明了PU／VC、PU／CPVC的相容是由于共混物中形成了新的氢键的缘故．聚酯型聚氨酯与PVC、CPVC的相容性要好子聚酸型聚氨酯，CPVC与PU的相容性又要好于PVC．聚氨酯中硬段的引入不利于PU／PVC、PU／CPVC的相容性．     

Dielectric investigation of the glass relaxation in poly(vinyl acetate) and poly(vinyl chloride) under high hydrostatic pressure

Measurements of the complex relative permittivity of poly(vinyl acetate) from 35 °C to 190 °C and poly(vinyl chloride) from 90 °C to 150 °C in the frequency range 10^–2 –10⁷ Hz and the pressure range 1–5000 bar are reported. Details of the pressure generating system and of the dielectric equipment are described.     

Preparation and properties of composites made from rice straw and poly(vinyl chloride) (PVC)

Rice straw was employed for the preparation of lignocellulosic‐poly(vinyl chloride) (PVC) composites. The effect of pretreatment of rice straw, concentration of PVC, pressure as well as pressing temperature on the mechanical properties and water absorption was studied. Also, the effect of lignin as coupling agent on the mechanical properties and water absorption of composite was studied. Composites of rice straw comprising both PVC and a coupling agent offer superior properties compared to those made from only rice straw and PVC. The extent of improvement in the mechanical properties and dimensional stability of composites depended not only on the pretreatment of rice straw, concentration of PVC and lignin but also on pressure and pressing temperature. Copyright © 2004 John Wiley & Sons, Ltd.     

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     

用FTIR研究线形多嵌段聚氨酯与聚氯乙烯、氯化聚氯乙烯共混相容性

用溶液法得到线形多嵌段聚氨酯（PU）与聚氯乙烯（PV）、氯化聚氯乙烯（CPVC）的共混物。用FTIR研究PU/PVC、PU／CPVC共混物的相容性，发现PVC、CPVC的加入破坏了PU中原来的氢键，并且PU中的炭基（C=0）与PVC、CPVC中的α－H形成了新的氢键，因而说明了PU／PVC、PU／CPVC共混物具有良好的相容性。     

Viscometric study of poly(vinyl chloride)/poly(vinyl acetate) blends in various solvents

The intermolecular interactions between poly(vinyl chloride) (PVC) and poly(vinyl acetate) (PVAc) in tetrahydrofuran (THF), methyl ethyl ketone (MEK) and N,N^′-dimethylformamide (DMF) were thoroughly investigated by the viscosity measurement. It has been found that the solvent selected has a great influence upon the polymer-polymer interactions in solution. If using PVAc and THF, or PVAc and DMF to form polymer solvent, the intrinsic viscosity of PVC in polymer solvent of (PVAc+THF) or (PVAc+DMF) is less than in corresponding pure solvent of THF or DMF. On the contrary, if using PVAc and MEK to form polymer solvent, the intrinsic viscosity of PVC in polymer solvent of (PVAc+MEK) is larger than in pure solvent of MEK. The influence of solvent upon the polymer-polymer interactions also comes from the interaction parameter term Δb, developed from modified Krigbaum and Wall theory. If PVC/PVAc blends with the weight ratio of 1/1 was dissolved in THF or DMF, Δb<0. On the contrary, if PVC/PVAc blends with the same weight ratio was dissolved in MEK, Δb>0. These experimental results show that the compatibility of PVC/PVAc blends is greatly associated with the solvent from which polymer mixtures were cast. The agreement of these results with differential scanning calorimetry measurements of PVC/PVAc blends casting from different solvents is good.     

Environmental stress cracking of poly(vinyl chloride) in alkaline solutions

The environmental stress cracking (ESC) effects on PVC of various high pH sodium hydroxide environments have been studied. The behaviour of PVC specimens in air and pH 12, 13, 13.5 and 14.39 sodium hydroxide solutions has been examined under three-point bend, tensile and creep conditions. Two parameters were used in three-point bend testing to determine the effect of an applied strain and high pH environment on the stability of PVC, namely time to craze initiation and width of crazing. It was found that, in general, crazing occurred sooner and to a greater degree with increasing strain and pH, although there was some evidence that craze growth was most rapid at pH 13.5. The results also indicated a critical strain value of 1.5–1.6%, below which crazing was not observed in any of these alkaline environments. Creep and tensile testing revealed that the time for which a PVC specimen was immersed in the environment was very important in determining the severity of the environmental effect. Creep tests at elevated temperatures showed that the time for the effects to be manifest decreased with increasing temperature. Creep rates were highest in pH 13.5 sodium hydroxide solution indicating that this was the most hostile of the environments considered.     

聚氯乙烯支载三氯化铁试剂催化醛与乙酸酐反应合成 乙酰缩醛

聚氯乙烯支载三氯化铁(PVC-FeCl3)试剂在室温条件下能方便快速催化各类醛与乙酸酐反应,以良好产率(75%～96%)生成相应乙酰缩醛。     

The influence of core-shell structured modifiers on the toughness of poly (vinyl chloride)

The core-shell structured grafted copolymer particles of polybutadiene grafted polymethyl methacrylate (PB-g-PMMA, MB) were prepared by emulsion polymerization. The MB particles were used to modify poly (vinyl chloride) (PVC) by melt blending. The mechanical properties of the PVC blends were investigated. The micro-morphology of the PVC blends was observed by scanning electron microscopy (SEM). The results indicated that the samples with the best impact strength could be obtained when the core-shell weight ratio of PB to PMMA is lower than 93:7, the mechanical properties correlated well with SEM morphologies, the addition of modifier with the ratio core to shell of 93:7 could reduce the domain size of the dispersed phase. Furthermore, the compatibility and properties of the blends were greatly enhanced and improved. The modifier particles could be well dispersed in the PVC matrix.     

Correlation between the tacticity and content of labile nondefect structures in poly(vinyl chloride)

The content of mm isotactic triads taking the GTTG^? conformation for samples of poly(vinyl chloride) (PVC) fractions of different tacticities was measured through a substitution reaction with sodium benzenethiolate. This quantity changed linearly with the ratio of rmmmrx to mmmmrx (x = m or r), as accurately determined by ¹³C NMR spectroscopy. In a comparison of this correlation and that obtained between the thermal degradation stability and overall isotactic content, as studied previously, some novel evidence for the GTTG^? conformation of a few mm triads, termini of isotactic sequences no shorter than one heptad as specific labile sites in PVC, was obtained. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3944–3949, 2002     

Terpyridine‐modified poly(vinyl chloride): Possibilities for supramolecular grafting and crosslinking

Commercially available poly(vinyl chloride) (PVC) was covalently modified with terpyridine supramolecular binding units in a two‐step reaction. First, PVC was modified with aromatic thiols to introduce OH functionalities into the polymer backbone, which were subsequently reacted with an isocyanate‐functionalized terpyridine binding unit. The resulting functionalized material contained metal‐ion binding sites, which could be used for grafting and crosslinking reactions. A grafting experiment was performed with a small organic terpyridine ligand. The complexation of the modified PVC with several transition‐metal ions was studied with ultraviolet–visible spectroscopy and gel permeation chromatography. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2964–2973, 2003     

PVB存在下PVC化学法脱氯化氢的研究

ＰＶＢ存在下ＰＶＣ化学法脱氯化氢的研究刘恒＊李大成陈朝珍（四川联合大学化工学院成都６１００６５）关键词聚氯乙烯，脱氯化氢，聚乙烯醇缩丁醛１９９６－０９－０８收稿，１９９７－０５－２６修回国家教育委员会留学归国人员资助费资助课题近年来在ＰＶＣ脱氯化氢制...