Tailoring the desired optical and mechanical performance of polyester‐plasticized PVC films: the role of different light stabilizers on the photo‐degradation

Effect of hindered amine light stabilizer (HALS: C944) and ultraviolet absorbers (UVAs: UV326, UV531) on the photo‐stabilities of polyester‐plasticized poly(vinyl chloride) (PVC) and polyester‐plasticized PVC/pigment yellow (PY) films were studied systematically. Both ultraviolet absorbers (UVAs) and hindered amine light stabilizer (HALS) could slow down the discoloration of polyester‐plasticized PVC and polyester‐plasticized PVC/PY films. However, the addition of UVAs protected polyester‐plasticized PVC films from being discolored and its efficiency is higher than HALS. The specific order of stabilizing effect on the photo‐oxidation is UV326 > UV531 > C944. For the optical performance, both UVAs and HALS could help to maintain the transmittance of visible light after photo‐degradation. The former could effectively adsorb ultraviolet (UV) light and resulted in lower transmittance of UV light. For the polyester‐plasticized PVC/PY systems, even though HALS and UVAs cannot help to maintain the shielding ability in high‐energy visible region after UV irradiation, they can help prevent the loss in transmittance of visible light. The surface morphology exhibited small holes on the surface of the films that contain UV531 or UV326; while large and deep holes were observed on the surface of PVC films without additives, C944‐doped and C944/PY‐doped films, indicating the higher UV‐stabilizing effect of UVAs. With regard to mechanical properties, UVAs and HALS can help to prevent the loss. Our present study systematically revealed the role of different stabilizers on the polyester‐plasticized PVC and polyester‐plasticized PVC/PY systems and paved the way to offer PVC materials with functional optical performance and desired long‐term performance using different light stabilizers. Copyright © 2017 John Wiley & Sons, Ltd.     

Effects of Epoxidation Content of ENR on Morphology and Mechanical Properties of Natural Rubber Blended PVC

This research work has concerned a study on toughness of PVC/natural rubber (NR) blends compatibilized with epoxidized natural rubber (ENR). The aim of this work was to investigate the effect of degree of epoxidation on morphology and mechanical properties of the blends. Epoxidized natural rubber with a variety of epoxidation contents were prepared by reacting the NR latex with formic acid and hydrogen peroxide at various chemical contents. Chemical structure and epoxidation content of epoxidized natural rubber were evaluated by FTIR and ¹H-NMR techniques. After that, three grades of ENR with epoxidation contents of 15, 25 and 42 % (by mole) were further used for blending with PVC and NR in an internal mixer at 60 rpm and at 170 °C. From tensile and impact tests, it was found that tensile elongation and impact strength of the materials remarkably increased with degree of epoxidation. On the other hand, tensile strength and modulus of the materials rarely changed with the epoxidation content. An increase in toughness of the blends with epoxidation content was related to a better molecular interaction between PVC and ENR as suggested by torque-time curves of the materials.     

Migration of Additives from Poly(vinyl chloride) (PVC) Tubes into Aqueous Media

The stability and migration product of medical PVC tubes plasticized with polyadipates were investigated by ageing in phosphate buffer at pH 1.679 and water at different temperatures. Changes in the PVC tubes were studied by water absorption, weight loss, Fourier infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The low molecular weight migration product that was released was extracted and silylanized before gas chromatography/mass spectroscopy (GC/MS) identification and quantification. After 70 days, the weight loss was less than 0.5% and only a small amount of adipic acid migrated when a tube was aged at 37°C in water and phosphate buffer (pH 1.679), and at 70°C in water after 56 days. However, when aged at 70 and 110°C, gradual deactivation of heat stabilizer after 21 days of ageing in buffer solution and separation of plasticizer from PVC matrix occurred. When the tube was aged at 110°C, significant degradation of both polyadipates and PVC were observed. Adipic acid and 1,4-butanediol monomers and oligomers of polyadipate were the major migration products from polyadipates in the water ageing solution, while only a relatively high amount of adipic acid was identified as the main product in the buffer ageing solution.     

N-(Substituted phenyl) itaconimides as organic stabilizers for plasticized poly(vinyl chloride) against photo-degradation

Several N-(substituted phenyl)itaconimide derivatives, N-(RPh)II (R: -NO₂, -COOH, -H, -OH, -OMe, -Me, -Cl, or -Br), have been investigated as organic photo-stabilizers for poly(vinyl chloride) (PVC) plasticized with dioctyl phthalate (DOP). Their stabilizing efficiencies are evaluated by measuring the length of the induction period (Ts), the period during which no detectable amounts of hydrogen chloride gas could be observed, and also from the rate of dehydrochlorination as measured by continuous potentiometric determination, and the extent of discolouration of the degraded polymer. The efficiencies are also evaluated by determining the amount of gel formation as well as the intrinsic viscosity of the insoluble and the soluble fractions of the degraded polymer, respectively. The results have proved the greater stabilizing efficiency of the N-(RPh)II derivatives relative to that of the phenyl salicylate UV absorber which is a commonly used industrial stabilizer. A radical mechanism is proposed to account for the stabilizing action of the investigated products.     

软质聚氯乙烯分子网络及其Gaussian模量

采用应力松弛实验及Haward模型, 研究了增塑剂含量、填料[CaCO3、炭黑(CB)]和丁腈橡胶(NBR)对软质聚氯乙烯(PPVC)的分子链缠结网络结构、分子链滑移及Gaussian模量的影响. 结果表明, 在PPVC主网络达到极限伸长之前, PPVC材料的粘弹行为能很好地符合Haward模型. 增塑剂、CaCO3和CB虽然不改变主网络的缠结结构, 并且主网络的极限伸长不变, 但增塑剂可以降低主网络的网链密度, 而CaCO3和CB可以提高主网络的网链密度; 同时增塑剂可减弱次级网络, 增大PVC分子链滑移, 使材料的Gaussian模量下降; CaCO3和CB可增强次级网络, 减小PVC分子链滑移, 使材料的Gaussian模量增加. NBR的加入可以改变主网络的缠结结构, 增加主网络的极限伸长; 既可降低PPVC主网络的缠结密度, 又可减弱次级网络, 使Gaussian模量降低.     

Some connections between viscoelastic properties of PVC and plasticized PVC and molecular kinetics

A coupling model that has been shown in the past to be capable of relating macroscopically measured relaxation parameters to molecular ones has been presented. In this article the coupling model is applied to the analysis of stress relaxation data collected by Cama and Sternstein on PVC and plasticized PVC. The Kohlrausch-Williams-Watts form, exp — (t/τ*)^1?n, using n = 0.77 is found to be capable of describing the stress relaxation master curve at temperatures below the glass transition, T_g. From the temperature-independent apparent activation energy found by Cama and Sternstein, the primitive activation energy of the α-relaxation was calculated to be 7.5 kcal/mol, which is a reasonable value for the energy barrier to internal rotational isomerism in PVC. Support for this value is found from the data on two plasticized PVCs with different T_gs and apparent activation energies. By applying the coupling model in a similar manner, the primitive activation energies were found to be 8.5 kcal/mol for PVC plasticized with 6 pph dioctylphthalate and 7.7 kcal/mol for PVC plasticized with 6 pph tricresyl phosphate. Within experimental uncertainties, the three primitive activation energies can be considered to be the same. This finding is consistent with the physical basis for primitive activation energy and its identification with the internal rotation barrier, which should be independent of the type and amount of plasticizer in the system. Analysis of Cama and Sternstein's data on the effect of repeated stress aging on stress relaxation of quenched samples of PVC and plasticized PVC show that the coupling constant n increases systematically with each successive stress-aging cycle until it approaches the value for slow-cooled samples. These results are consistent with the notion that stress-aging changes the structural state of the glass in ways similar to physical aging.     

Structure of reactively extruded rigid PVC/PMMA blends

A novel route for producing polymer blends by reactive extrusion is described, starting from poly (vinyl chloride)/methyl methacrylate (PVC/MMA) dry blend and successive polymerization of MMA in an extruder. Small angle X‐ray scattering (SAXS) measurements were applied to study the monomer's mode of penetration into the PVC particles and to characterize the supermolecular structure of the reactive poly(vinyl chloride)/poly(methyl methacrylate) (PVC/PMMA) blends obtained, as compared to the corresponding physical blends of similar composition. These measurements indicate that the monomer molecules can easily penetrate into the PVC sub‐primary particles, separating the PVC chains. Moreover, the increased mobility of the PVC chains enables formation of an ordered lamellar structure, with an average d‐spacing of 4.1 nm. The same characteristic lamellar structure is further detected upon compression molding or extrusion of PVC and PVC/PMMA blends. In this case the mobility of the PVC chains is enabled through thermal energy. Dynamic mechanical thermal analysis (DMTA) and SAXS measurements of reactive and physical PVC/PMMA blends indicate that miscibility occurs between the PVC and PMMA chains. The studied reactive PVC/PMMA blends are found to be miscible, while the physical PVC/PMMA blends are only partially miscible. It can be suggested that the miscible PMMA chains weaken dipole–dipole interactions between the PVC chains, leading to high mobility and resulting in an increased PVC crystallinity degree and decreased PVC glass transition temperature (T_g). These phenomena are shown in the physical PVC/PMMA blends and further emphasized in the reactive PVC/PMMA blends. Copyright © 2005 John Wiley & Sons, Ltd.     

Transition from crazing to shear deformation in ABS/PVC blends

ABS/PVC blends were prepared over a range of compositions by mixing PVC, SAN, and PB‐g‐SAN. All samples were designed to have a constant rubber level of 12 wt % and the ratio of total‐SAN to PVC in the matrix of the blends varied from 70.5/17.5 to 18/80. Transmission electron microscope and scanning electron microscope have been used to study deformation mechanisms in the ABS/PVC blends. Several different types of microscopic deformation mechanisms, depending on the composition of blends, were observed for the ABS/PVC blends. When the blend is a SAN‐rich system, the main deformation mechanisms were crazing of the matrix. When the blend is a PVC‐rich system, crazing could no longer be detected, while shear yielding of the matrix and cavitation of the rubber particles were the main mechanisms of deformation. When the composition of blend is in the intermediate state, both crazing and shear yielding of matrix were observed. This suggests that there is a transition of deformation mechanism in ABS/PVC blends with the change in composition, which is from crazing to shear deformation. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 687–695, 2006     

稀土掺杂PVC的紫外及微波交联研究

聚氯乙烯 (ＰＶＣ)是我国目前产量最大 ,应用面最广的高分子原材料。但其耐热性、稳定性及抗老化性都较差。我们考虑到使用稀土掺杂以改进其相关性能 ,同时掺入了少量从水玻璃中提取出来的活性硅醇到ＰＶＣ中以增加其柔性 ,探索了紫外辐射交联和微波辐射交联对ＰＶＣ机械力学性能的影响。本文采用ＰＶＣ流延膜来进行辐射交联并测定样品的力学性能。结果发现 ,稀土掺杂的结果使得样品的扯断伸长率大幅度提高 ,拉伸强度上升显著。而添加活性硅醇后ＰＶＣ流延膜的扯断伸长率进一步提高 ,拉伸强度则下降 ,柔性得以提高。将氯化钕溶于 95 %的乙醇…     

Development and characterization of reactive extruded PVC/polyacrylate blends

This paper describes a method to obtain polymer blends by the absorption of a liquid solution of monomer, initiator, and a crosslinking agent in suspension type porous poly(vinyl chloride) (PVC) particles, forming a dry blend. These PVC/monomer dry blends are reactively polymerized in a twin‐screw extruder to obtain the in situ polymerization in a melt state of various blends: PVC/poly(methyl methacrylate) (PVC/PMMA), PVC/poly(vinyl acetate) (PVC/PVAc), PVC/poly(butyl acrylate) (PVC/PBA) and PVC/poly(ethylhexyl acrylate) (PVC/PEHA). Physical PVC/PMMA blends were produced, and the properties of those blends are compared to reactive blends of similar compositions. Owing to the high polymerization temperature (180°C), the polymers formed in this reactive polymerization process have low molecular weight. These short polymer chains plasticize the PVC phase reducing the melt viscosity, glass transition and the static modulus. Reactive blends of PVC/PMMA and PVC/PVAc are more compatible than the reactive PVC/PBA and PVC/PEHA blends. Reactive PVC/PMMA and PVC/PVAc blends are transparent, form single phase morphology, have single glass transition temperature (T_g), and show mechanical properties that are not inferior than that of neat PVC. Reactive PVC/PBA and PVC/PEHA blends are incompatible and two discrete phases are observed in each blend. However, those blends exhibit single glass transition owing to low content of the dispersed phase particles, which is probably too low to be detected by dynamic mechanical thermal analysis (DMTA) as a separate T_g value. The reactive PVC/PEHA show exceptional high elongation at break (～90%) owing to energy absorption optimized at this dispersed particle size (0.2–0.8 µm). Copyright © 2005 John Wiley & Sons, Ltd.     

Flow-injection potentiometric determination of triiodide by plasticized poly(vinyl chloride) membrane electrodes and its application to the determination of chlorine-containing disinfectants

Plasticized poly(vinyl chloride) (PVC) membranes of different compositions were tested for use in the construction of potentiometric flow detectors for triiodide. A membrane with a 2:1 (w/w) 2-nitrophenyl octyl ether to PVC ratio was selected. The influence of thiosulphate in the carrier solution composition and of the flow-injection variables on the determination of triiodide was studied. In the selected conditions, a linear relationship between peak height and log[I₃⁻] was obtained between 5 × 10⁻⁶ and 1 × 10⁻⁴ mol l⁻¹ triiodide. Peak height relative standard deviations for 2 × 10⁻⁵ and 1 × 10⁻⁴ mol l⁻¹ triiodide were ±0.4 and ±1.8%, respectively, and sampling frequency was 80 samples per hour. The method proposed was applied satisfactorily to the iodometric determination of different chlorine-containing disinfectants, among them trichloroisocyanuric acid and dichloroisocyanurate in several types of commercial sample.     

Physico-Mechanical Characteristics of Some EPDM/Plasticized PVC Blends

Summary: In this study were prepared blends based on ethylene propylene terpolymer rubber (EPDM) and plasticized poly (vinyl chloride) (PVC). These blends are immiscible and need to be compatibilized. The following compatibilization methods were used: (1) addition of a compatibilization agent; there were used: maleinized EPDM, maleinized polyethylene (PE), chlorinated polyethylene (CPE) and maleinized polypropylene (PP); chlorinated polyethylene has proved to be the most efficient; the amount of the added CPE giving the best physico-mechanical characteristics was of 7,5 parts to 100 polymer parts; (2) reactive compatibilization, using crosslinked copolymer formation strategy; three different crosslinking systems were used: (a) common method with sulphur and accelerators, (b) crosslinking with benzoyl peroxide and trimethylpropane trimethacrylate (TMPT DL 75), (c) vulcanization with phenol resin and tin chloride. The best physico-mechanical characteristics were obtained with the EPDM/plasticized PVC blends crosslinked with 8 phr phenol resin. Such types of polymer blends can be processed by methods specific for plastics, removing thus vulcanization operation required in case of elastomers. These blends can be used in the manufacture of hoses, gaskets, footwear constituents etc.     

Preparation and characterization of PVC/PANI conductive composite with extremely low percolation threshold

Aniline was polymerized in the presence of poly(vinyl chloride) (PVC) powders in hydrochloric acid to in situ prepare poly(vinyl chloride)/polyaniline (PVC/PANI) composite particles. UV‐vis spectra and FT‐IR spectra indicate PANI in PVC/PANI composite particles possessed a higher oxidation state with decreased aniline content in reactants. Both conductivity and impact strength of the dodecylbenzenesulfonic acid (DBSA) doped PANI composites (PVC/PANI‐DBSA), which were compression molded from the in situ prepared PVC/PANI particles, increase with the pressing temperature and decrease with the increase of DBSA doped PANI (PANI‐DBSA) loading. An excellent electric conductivity of 5.06 × 10^?2 S/cm and impact strength of 0.518 KJ/m² could be achieved for the in situ synthesized and subsequently compression molded composite. Copyright © 2004 John Wiley & Sons, Ltd.     

Thermal degradation of PVC synthesized with a titanocene catalyst II. Complementary isothermal results

The use of an isothermal degradation method on metallocene produced PVC and commercial PVC, under nitrogen and air atmospheres, reveals more details about degradation routes. Without regard to the polymer origin, the hydrochloric acid release occurs in two steps, which are reflected in molecular weight only under a nitrogen atmosphere; otherwise, the oxygen appears to be included in the scission/crosslinking process. On the one hand, Met PVC has unsaturations from its synthesis, producing a faster HCl release compared to Com PVC; consequently, its degradation resistance is lower. On the other hand, Com PVC has more oxidized species and has a natural tendency to include more of them. Surface area seems to have an important effect and is directly related to the rate of hydrochloric acid release. The latter is not supported by the chain oxidation mechanism, making the effect of the applied atmosphere more critical to the results obtained from the degradation experiments.     

Development of PVC/Silica Hybrids Using PVC Plastisols

A novel method for producing a plasticised PVC with increased porosity has been developed, by the use of an organic-inorganic hybrid. Silica was produced in situ from tetraethoxysilane via a hydrolytic sol-gel processing route. Tetrahydrofuran was used as co-solvent, and γ-glycidyloxypropyl-trimethoxysilane as coupling agent. The films produced were transparent, with moderate mechanical properties. A film containing 20% silica showed a 45% increase in water vapour permeability.     

Degradation behavior and application of recycled PVC sheet made of floor sheet for railway vehicle

A floor sheet made of plasticized poly(vinyl chloride) (PVC) is used as interior material for railway vehicle. Some of the floor sheets mainly used in Express and Shinkansen vehicles were layered by vulcanized surface to protect against the fire. Therefore, these floor sheets have been considered as inappropriate material for recycling. In this paper, some varieties of recycled sheets made of these floor sheets have been studied with respect to a long-term stability which is necessary for practical application. Through the weathering test, these recycled sheets indicated suitable mechanical properties for long-term outdoor use; however, at the beginning of weathering test, the elongation was reduced by the rapid flow out of plasticizer. The mechanical strength was closely related to the plasticizer concentration. Based on the plasticizer concentration, the tensile strength could be estimated without dependence of specimen preparations and the slope of the elongation was related to the content of the floor sheet. To prevent flowing out of plasticizer, virgin PVC was laminated to the surface of recycled sheet. The laminated sheet was set up at the outdoor to be used as an anti-weed sheet. For more than five years, the laminated sheet has kept on preventing overgrowth of weed and flow out speed of plasticizer has decreased by the effect of virgin PVC lamination. It is presumable that the laminated sheet was estimated to be used as the anti-weed sheet for more years.     

Overview of the recent literature on flame retardancy and smoke suppression in PVC

This paper presents an overview of the recent literature on flame retardancy of poly(vinyl chloride) (PVC). A short overview of mechanisms of thermal decomposition of PVC, especially those which lead to char formation, is also presented because this gives insight into the mechanisms of flame retardant action. New developments in the area are mostly focused on combinations of various flame retardants and smoke suppressants in the search for synergistic effects. Because different additives show different mechanisms of action, synergistic combinations are very probable. New developments in phosphate ester plasticizers are reported in the literature. Copyright © 2005 John Wiley & Sons, Ltd.     

Evaporative loss kinetics of di(2-ethylhexyl)phthalate (DEHP) from pristine DEHP and plasticized PVC

The migration of di(2-ethylhexyl)phthalate (DEHP) from poly(vinyl chloride) (PVC) to a surrounding gas phase at temperatures below 120 °C kinetically is controlled by evaporation. The effects on the DEHP loss rate of nitrogen flow rate, relative humidity and degradation of the plasticizer at 100 °C was assessed. The sample mass decreased linearly with time for both pristine DEHP and plasticized PVC at comparable rates, suggesting that a thin film of DEHP was present on the jacketing insulation during desorption. The latter hypothesis was supported by infrared spectroscopy and by the fact that DEHP is an amphiphilic molecule that will tend to aggregate at the surface with the hydrophobic 2-ethylhexyl units at the air interface. The effect on the migration rate of moisture present in the gas phase was negligible. The DEHP loss rate increased in a retarding non-linear fashion with increasing gas flow rate. In one of the experiments, DEHP was accidently degraded as revealed by discoloration, the presence of low molar mass degradation products (liquid chromatography) containing additional carbonyl groups (infrared spectroscopy) and an increase in the evaporation rate at temperatures between 100 and 130 °C.     

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     

苯乙烯/聚氯乙烯接枝膜的热稳定性研究

用自由基悬浮聚合法合成了苯乙烯 /聚氯乙烯接枝膜 ,并对产物热处理 ,然后进行紫外 -可见光谱 ,红外光谱 ,热失重分析。结果表明接枝苯乙烯后的聚氯乙烯膜热稳定性得到了提高。同时 ,讨论了热稳定性机理。