Degradation kinetics of PVC plasticized with different plasticizers under isothermal conditions

The aim of the present work is to elucidate the degradation kinetics of polyvinyl chloride (PVC) plasticized with some phthalate and nonphthalate plasticizers. A PVC thermomat instrument was utilized to maintain the isothermal degradation conditions at 140 and 160°C, and to suppress the oxidative degradation by means of nitrogen flow. The conductivity measurements were performed to follow hydrogen chloride (HCl) gas which is released upon PVC degradation and trapped in water. Dehydrochlorination of plasticized PVC films occurred with activation energies of about 23–160 and 26–117 kJ mol^?1 and the isokinetic temperatures, at which the dehydrochlorination rate constants of all p‐PVC films would have the same value, were found to be 171 and 128°C for initial and linear regions of dehydrochlorination curve, respectively. Plasticizer incorporation contributes to the stability of the films particularly after the consumption of stabilizer due to the dehydrochlorination. Influence of temperature rise by 20°C on the degradation rate constant is the lowest for DINCH having p‐PVC films as 0.36 and 0.42% increment at the initial region and linear region, respectively. On the other hand, DOTP reveals greater stability than the others do since the compensation ratio of the PVC film having DOTP is greater than the other films. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41579.     

Epoxidized dimeric acid methyl ester derived from rubber seed oil and its application as secondary plasticizer

A novel plasticizer epoxidized dimeric acid methyl ester (EDAMe) based on rubber seed oil was synthesized. Chemical structure of EDAMe was characterized by Fourier transform infrared (FTIR) and gel permeation chromatography (GPC). Effects of EDAMe as secondary plasticizer and its substitution of commercial plasticizer dioctyl terephthalate (DOTP) in soft poly(vinyl chloride) (PVC) films were studied. The thermal properties, mechanical properties and migration stabilities of PVC films were explored with DMA, TG, TG–FTIR, dynamic thermal stability analysis, tensile and migration tests. The results indicated that the epoxidized rubber seed oil based ester has significantly higher thermal stability than DOTP. When DOTP was substituted with 20% (m/m) EDAMe, the results of initial decomposition temperature (T_i), 10% and 50% mass loss temperatures (T₁₀ and T₅₀), and the first maximum weight‐loss temperature rate (T_P1) reached 267.2 °C, 263.5 °C, 307.3 °C and 298.9 °C, respectively. Furthermore, flexibility of the obtained PVC films enhanced significantly with the adding of EDAMe. The migration stabilities of EDAMe was also investigated and showed good migration resistance. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43668.     

Evaluating UV/H2O2 exposure as a DEHP degradation treatment for plasticized PVC

Millions of tons of plasticized poly(vinyl chloride) (PVC) materials are disposed every year. A biologically sustainable and green method for removal of toxic plasticizers from polymer systems after disposal is highly desired since plasticizers can leach out into the environment over decades. Here we compare the surface and bulk structural changes of DEHP‐plasticized PVC after two treatments intended to degrade bis‐2‐ethylhexyl phthalate (DEHP) in PVC plastic: short wave (254 nm) UV with and without the addition of 35 wt % H₂O_2. Sum frequency generation vibrational spectroscopy (SFG) reveals the addition of aqueous H₂O₂ decreases CH₃ signals on the surface of the films up to 8 h, due to increased molecular disorder and the removal of alkyl chains. Secondary ion mass spectrometry demonstrates that the degradation of DEHP after 8 h of reaction is similar with and without the use of H₂O₂. However, FTIR results reveal that the introduction of H₂O₂ reduces bulk DEHP degradation and leads to competing radical chain scission reactions with PVC. Therefore, simple short wave UV exposure may be an effective means to degrade DEHP within and on PVC plastic and the addition of H₂O₂ is only beneficial if additional degradation of PVC is needed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40649.     

Statistical thermal stability of PVC

Experimental design was used to optimize the processing parameters for the decomposition of poly(vinyl chloride). Factorial design and face centered composite design (FCC) were applied to determine the optimum conditions. A total of 10 g PVC powder was mixed with different amounts of zinc stearate (ZnSt₂) and natural zeolite and tested for thermal stability. Factorial fitted model was explained by first order pattern due to the significant main effect regression constants, and FCC model was described by second order model owing to higher order polynomial coefficients. FCC design was superior to factorial design as FCC considers not only its pure quadratic effects contribution but also its higher overall desirability for thermal stability of PVC. For factorial design the optimum conditions were determined as 163.06 mg for ZnSt₂, 399.99 mg for zeolite, and 140°C for temperature with desirability of 0.933. However, 400 mg for ZnSt₂, 333.24 mg for zeolite, and 140°C for temperature with desirability of 0.956 were obtained as the optimum conditions by FCC design. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Development of nanocomposites based on organically modified montmorillonite and plasticized PVC with improved barrier properties

Montmorillonite (MMT) was organically modified with tributyl citrate (TBC). Organoclays (OMMTs) were processed with diisononyl phthalate (DINP)‐plasticized polyvinyl chloride (PVC) to form polymer nanocomposites. The produced composite materials showed a contradictory change in properties to that expected of a layered silicate nanocomposite, with a decreased E‐modulus and increased gas permeability compared with a material without OMMT. It was experimentally shown that the TBC modifier was extracted from the OMMT and was dispersed in the PVC/DINP matrix, whereupon the OMMT collapsed and formed micrometer‐sized agglomerates. Further investigation revealed that TBC has a significant effect on the gas permeability and the E‐modulus, even at low additions to a DINP‐plasticized PVC. A PVC nanocomposite with the TBC acting as both the OM for MMT and as the primary plasticizer was produced. This material showed a significantly increased E‐modulus as well as a decrease in gas permeability, confirming that it is possible to develop a nanocomposite based on plasticized PVC, if both the organo‐modification of the MMT and the formulation of the matrix are carefully selected. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42876.     

Effect of zinc maleate/zinc oxide complex on thermal stability of poly(vinyl chloride)

In this study, zinc maleate (ZnMA) and zinc oxide (ZnO) complex (ZnMA/ZnO) was prepared by two methods, namely, by the reaction of maleic acid (MAH) with excess ZnO in aqueous solution and by direct mixing of ZnMA and ZnO at 180°C. The chemical structure of the complex was analyzed by X‐ray diffraction, thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy. The thermal stabilizing effect of the complex on poly(vinyl chloride) (PVC) was evaluated through static and dynamic stability methods. Compared to calcium and zinc soaps and ZnMA alone, the complex exhibited better thermal stabilizing effect on PVC. The stabilization mechanism was also investigated by ultraviolet–visible spectrometer, FTIR, TGA, and gel content analysis. The results indicated that the complex which involved the replacement of labile chlorine atoms hindered the formation of conjugated double bonds in PVC chains via Diels–Alder reaction, and ZnMA/ZnO complex also exhibited the ability to absorb hydrogen chloride. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41464.     

Lanthanum histidine with pentaerythritol and zinc stearate as thermal stabilizers for poly(vinyl chloride)

Lanthanum histidine [La(His)₂·(NO₃)·2H₂O or La(His)₂] was synthesized via the reaction of histidine and lanthanum nitrate, and it was investigated as a stabilizer for poly(vinyl chloride) (PVC). The results show that La(His)₂ exhibited a stabilizing effect on PVC as a long‐term stabilizer because it prolonged the stability time of PVC to 76 min, which was about 24 times longer than the stability time of the pure PVC. The stabilizing effect of La(His)₂ as a costabilizer with pentaerythritol (Pe) and zinc stearate (ZnSt₂) was also studied. The results show that the use of La(His)₂ with Pe or Pe/ZnSt₂ improved the stability time of PVC. La(His)₂/Pe/ZnSt₂ provided PVC with a good initial color and long‐term stability, and when it was prepared at mass ratios of 0.8:2.4:0.8 and 1.6:1.6:0.8, the stability times of PVC were improved to 86 and 88 min, respectively. As a nontoxic stabilizer, La(His)₂/Pe/ZnSt₂ has the potential to replace the toxic stabilizers widely used in PVC manufacturing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42878.     

Design of green zinc‐based thermal stabilizers derived from tung oil fatty acid and study of thermal stabilization for PVC

In this study, a new type of mixed calcium (Ca) and zinc (Zn) thermal stabilizers was prepared and evaluated for poly(vinyl chloride) (PVC) thermal stabilization. The mixed stabilizers were based on the Ca and Zn salts of polycarboxylic acid derived from eleostearic acid—the dominant fatty acid of tung oil fatty acids. Eleostearic acid was converted to a 21‐carbon diacid (C21DA) and a 22‐carbon triacid (C22TA), respectively, which were subsequently turned into calcium (Ca) and zinc (Zn) salts. Thermal stability of PVC compounds was examined by thermogravimetric analysis (TGA), discoloration test, Congo red test, and thermal decomposition kinetics. In comparison, commercial mixed Ca/Zn thermal stabilizers composed of stearate salts (CaSt₂/ZnSt₂), were employed as controls. Because the salts of C21DA, C22TA and stearate have different metal contents, thermal stabilization effects were compared on the basis of both equal salt weight and equal metal ion content. It was noted that under both cases the long‐term thermal stability of the PVC samples followed the order of C21DA‐Ca/C21DA‐Zn > C22TA‐Ca/C22TA‐Zn > CaSt₂/ZnSt₂. The results suggest that the mixed Ca/Zn salts based on tung oil‐derived polycarboxylic acids have higher metal ion contents and cycloaliphatic structures and can effectively improve the thermal stability of PVC. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44679.     

Preparation of intercalated Mg‐Al layered double hydroxides and its application in PVC thermal stability

The Mg‐Al oxide precursor prepared by the calcination of Mg‐Al‐carbonated layered double hydroxide (LDH) at 500 K for 4 h is used as the host material, 2‐hydroxy‐4‐methoxybenzophenone‐5‐sulfonic acid (BP) is used as the guest material, BP‐intercalated LDH (LDH‐BP) is prepared by ion‐exchange method. The structure of LDH‐BP is characterized by X‐ray diffraction (XRD), Fourier transform infrared (FTIR), and thermogravimetry and differential thermal analysis (TG‐DTA). The thermal stability of PVC/BP, PVC/LDH, PVC/LDH‐BP composites, as well as pure PVC is investigated by conventional Congo Red test and dynamic thermal stability analysis in both the open and closed processing environments. According to XRD and FTIR, BP anions have been intercalated into interlayer galleries of LDH. TG‐DTA results show that the layer‐anionic interaction results in the improvement of the thermal stability of BP. Congo Red tests indicate that the addition of BP catalyzes the thermal degradation of PVC. A little amount of LDH (such as 1 phr) makes PVC more stable, but excessive addition accelerates the thermal degradation of PVC. The addition of LDH‐BP markedly improves the static thermal stability of PVC. The results of dynamic thermal stability tests in both the open and closed processing environments are consistent with that of Congo Red tests. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Epoxidized castor oil-based diglycidyl-phthalate plasticizer: Synthesis and thermal stabilizing effects on poly(vinyl chloride)

Epoxidized castor oil-based diglycidyl-phthalate (ECODP) was synthesized and incorporated into poly(vinyl chloride) (PVC) for the first time. The chemical structure of the ECODP was confirmed. The plasticizing effects of ECODP as a replacement for commercial plasticizer dioctyl phthalate (DOP) were investigated. The thermal stability and mechanical properties of PVC films before and after aging were investigated using thermogravimetric analysis (TGA), TGA-FTIR analysis, dynamic mechanical analysis (DMA), and tensile tests. The results indicated that PVC films plasticized with ECODP significantly improved thermal stability, compatibility, and flexibility. When DOP was substituted with ECODP completely, the initial decomposition temperature, 5, 10, 50, and 70% mass loss temperatures (T_i, T₅, T₁₀, T₅₀, and T₇₀) increased by 24.7, 38.9, 32.0, 30.3, and 102.7 °C, respectively. The functional mechanism of the ECODP as a thermal stabilizing plasticizer and the plasticization mechanism of PVC composites were also investigated. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47142.     

Insights into the use of zinc–mannitol alkoxide as a novel thermal stabilizer for rigid poly(vinyl chloride)

Zinc–mannitol alkoxide (Zn–Man) was synthesized through alcohol exchange reaction, and investigated by means of Fourier transform infrared spectroscopy and elemental analysis. The thermal stability of Zn–Man for rigid poly(vinyl chloride) (PVC) was evaluated by Congo red testing, conductivity measurements, thermal aging testing, thermogravimetric analysis (TGA), and ultraviolet–visible (UV–vis) spectroscopy test. The experimental results demonstrate that the addition of Zn–Man not only apparently prolonged the static thermal stability time to approximately 96.5 min but also evidently improved the initial color of PVC. More importantly, the color of the PVC sheets stabilized with Zn–Man did not change to black within 180 min; this showed that no zinc‐burning phenomenon occurred. In addition, the results of TGA reveal that Zn–Man raised the initial degradation temperature of PVC to about 273.4°C. UV–vis testing indicated that the presence of Zn–Man decreased the content and shortened the length of the conjugated double bonds of PVC. The possible thermal stability mechanism is discussed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42038.     

Long‐term studies on PVC membranes used in tunnels

Building tunnels places very high demands on the durability of all materials used. However, up to now only very few real long‐term studies on waterproofing membranes used in tunnels have been carried out. Samples from soft poly(vinyl chloride) membranes with diverse ages of over 40 years were taken during refurbishment programs to ensure safety in various Swiss tunnels. The results of gel permeation chromatography as well as measurements of the plasticizer and gel content showed that all of the membranes have very low polymer degradation or, respectively, none detectable crosslinking of the polymer. The main change determined was the decrease in plasticizer content and the resulting increase in stiffness of the membranes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46689.     

The effect of additives on the thermal stability of poly(vinyl chloride)

The effect of a range of organic additives on the thermal stability of poly(vinyl chloride), both with and without a chloroparaffin extender, was studied using a number of experimental techniques. Of the additives used the best overall balance was provided by pentaerythritol, which increased stability when the extender was present and had no effect when it was absent. The congo red test emerged as the most suitable technique, being consistent and inexpensive and able to screen several additives simultaneously. Isothermal differential thermal analysis correlated with the congo red test but required more expensive equipment, was time-consuming and demanded good mixing of the poly(vinyl chloride) compound to give reproducible results. Thermogravimetry was not sufficiently sensitive and the heat stability test was the least useful of all.     

Effects of MgAlCe‐CO3 layered double hydroxides on the thermal stability of PVC resin

MgAlCe‐CO₃ layered double hydroxides (LDHs) with different Ce/Al molar ratios were prepared by the constant pH coprecipitation method. The synthesized materials were characterized by XRD and FTIR, and the results showed that the hydrotalcite‐like materials have a layered structure. Different LDHs as stabilizers were mixed with PVC resin. The tests of thermal aging and Congo red for the PVC composites were carried out at 180 ± 1°C, respectively. The results showed when MgAlCe‐CO₃‐LDHs were added into PVC as single thermal stabilizers, 3 phr (parts per hundred PVC resin) MgAlCe‐CO₃‐LDH with Ce/Al (molar ratio) = 0.075 has a better stabilizing effect on PVC than others. Compared with single thermal stabilizers (LDHs or Ca/Zn systems), the composite thermal stabilizers including 0.3 g calcium stearate (Cast₂), 1 g zinc stearate (Znst₂), and 3 g MgAlCe‐CO₃‐LDH have significantly enhanced the thermal stability of PVC sample, and the thermal stable time was over 190 min. The main reason could be concluded to the special structure of Ce element and the synergistic reaction among MgAlCe‐CO₃‐LDHs, Cast₂, and Znst₂. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Studies on the effect of laser radiation on the thermal stability of stabilized poly(vinyl chloride)

Nonisothermal studies were carried out using thermogravimetry (TG) and differential thermogravimetry (DTG) to obtain the activation energy of the decomposition for poly(vinyl chloride) (PVC), stabilized by ethyl, N‐phenylmaleimide, and 4‐carboxylate (ENPMC). Thermal gravitational analysis (TGA) indicated that the ENPMC–PVC samples decompose in two main breakdown stages. The effect of the addition of a stabilizer (ENPMC), with different concentrations, to PVC was studied. The results indicate that the addition of ENPMC with 0.01 g/1 g PVC enhances the thermal stability of pure PVC. Samples from 0.01 g ENPMC/1 g PVC were exposed to infrared laser radiation with energy fluency at levels between 0.95 and 8.53 J/cm². The results of the thermal experiments indicate that the onset temperature of decomposition T₀ and thermal activation energy of decomposition E_a are affected by the laser energy fluency owing to the simultaneous processes of degradation and crosslinking. The variation of transition temperatures with either the stabilizer concentration or the laser energy fluence was determined using differential thermal analysis (DTA). The results indicate that the irradiation with a laser to 7.11 J/cm² decreases the melting temperature of the pure PVC and this is most suitable for applications requiring the molding of this polymer at lower temperatures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2249–2255, 2003     

PVC薄膜中增塑剂在水环境中迁移规律研究

研究了PVC中的增塑剂在水中的迁移情况及时间、温度等因素对迁移的影响。同时研究了增塑剂迁移对薄膜力学性能的影响。     

Stabilization of epoxidized soybean oil‐plasticized poly(vinyl chloride) blends via thermal curing with genistein

In an effort to alleviate the well‐known toxicity effect of phthalate derivatives on human health, genistein (G) modified epoxidized soybean oil (ESBO) has been investigated as an alternative “green” plasticizer for poly(vinyl chloride) (PVC) with potential application in medical products. As evidenced by a single glass transition that shifts systematically with composition in conjunction with the melting point depression of G crystals, ESBO is not only a good plasticizer to PVC, but also miscible with G. Moreover, ESBO is an excellent compatibilizer to the immiscible PVC/G pair. Furthermore, PVC/ESBO/G ternary blends revealed complete miscibility in the amorphous state. Of particular interest is that ESBO‐plasticized PVC is thermally curable with G at elevated temperatures above 220 °C and affords relatively stable G modified ESBO‐plasticized PVC for blood contact medical applications such as blood bags and hemodialysis tubings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46472.     

DinCH and ESBO actual migration from PVC infusion tubings used in an oncopediatric unit

Plasticizer leaching from poly(vinyl chloride) (PVC) tubing is a well‐studied phenomenon and is a real issue in medical care today. The present study focuses on the release of two plasticizers 1,2‐cyclohexane dicarboxylic acid diisononyl ester (DINCH) (primary) and epoxidized soy bean oil (ESBO) (secondary) from PVC extension tubings used in an oncopediatric unit. The release of plasticizers is calculated by comparison to unused tubings with the same batch number. Both the DINCH and ESBO ratio diminishes in used versus new extension tubings. The loss of plasticizers has not been related to the presence of a specific drug. Our results confirm the leaching of classic plasticizers like the DINCH and of secondary plasticizers like the ESBO from tubings in real life. It confirms too the existence of a complex phenomenon in which exchanges between drugs, lipids, PVC matrices, and the administration sequences can change the global release of plasticizers. Considering all the variables involved in real‐life data, the in vitro testing appears to be the most efficient way to confirm these observations. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46649.     

Influence of crystallinity in the curing mechanism of PVC plastisols

The influence of the crystalline areas observed in poly(vinyl chloride) (PVC) the mechanical and thermal properties of PVC plastisols was studied. Several industrial‐degree PVC resins were used to obtain a broad range of molecular weights and processing conditions for PVC plastisols. The gelation process was fully studied at different temperatures and was related to the existence of crystalline areas at high temperatures, even near the glass transition. A simple explanation of the phenomena observed during the gelation of plasticized PVC is proposed, according to the variation in the mechanical and thermal properties at different temperatures. The final gelation was obtained at 140–150°C, which was a lower temperature than those at the beginning of the thermal degradation process. The thermodynamic aspects of the gelation of plasticized PVC were mainly controlled by the PVC resin properties, whereas the plasticizer only influenced the diffusion and stability of the material. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 538–544, 2004     

PVC／CaCO3热降解过程及多元醇对PVC的热稳定作用

利用热失重一红外光谱联机（TG-FTIR）分析技术研究了PVC／CaCO3共混物在氮气气氛下、30-900℃范围内的热降解行为。结果表明：PVC共混物的热降解过程可分为3个阶段,分别在170-380℃,380-570℃和570-758℃范围内。其中,第一阶段主要为PVC脱HCl反应阶段,热降解产物主要为HCl：第二阶段主要为共轭多烯结构的裂解和环化,产物为低烃类化合物、苯及其衍生物;第三阶段为碳酸钙的分解反应。产物为CO2。研究了几种多元醇化合物对PVC的热稳定作用,发现双季戊四醇与硬脂酸钙、硬脂酸锌之间的协同作用最好,其添加量愈多,共混物的稳定性愈好。