Stability Of PVC Research Articles

The effects of thermally reversible agents on PVC stability properties

One kind of thermally reversible cross-linking agents for improving PVC thermally stability was synthesized. The chemical structure and thermally reversible characteristics of cross-linking agents were investigated by FTIR and DSC analysis, respectively. FTIR results confirmed that the cyclopentadienyl barium mercaptides ((CPD-C2H4S)2Ba) were successfully synthesized. DSC results showed it has thermally reversible characteristics and the depolymerization temperature was between 170 °C and 205 °C. The effects of cross-linking reaction time on gel content of Poly(vinyl chloride) compounds was evaluated. The gel content value arrived at 42% after being cross-linked for 25 min at 180 C. The static thermally stability measurement proved that the thermally stability of PVC compounds was improved.

Recycling the Cork Powder in a PVC-Based Composite Material: Combined Effect on Physico-Mechanical and Thermal Properties

Abstract A large amount of cork powder (CP) produced by cork industry ended up in landfills, they are the result of the crushing of natural floor (bark) cork oak, hence the need to recycle these wastes to prevent environmental problems. To this end, the work is to combine the powdered cork recovered with a thermoplastic material to provide a cork based composite (CPC) having physico-mechanical characteristics and thermal very interesting. Several formulations of composite materials based on PVC (as matrix), cork powder (as a charge) and a PVC-g-MA coupling agent, have been the subject of experimental study to evaluate the physical-mechanical and thermal properties. To investigate the combined effect of cork powder and PVC-g-MA on composite properties, the samples were manufactured by varying the content of PC (30 %, 40 % and 50 %) with two PVC-g-MA concentrations. Improving the stability of PVC which is accentuated in the presence of the coupling agent. In addition, it was found that the incorporation of the coupling agent has enabled the elimination of the adverse effect of cork powder, improving the tensile strength. The composite obtained in this study yielded some promising properties, even if building strategies to achieve greater strength and rigidity could beings needed for specific applications.

Effect of dual functional ionic liquids on the thermal degradation of poly(vinyl chloride)

The short-term thermal stability of PVC on addition of functional ionic liquids (ILs) based on phosphonium and pyridinium cations, and a docusate anion, was studied using FTIR, TGA-MS and TGA-FTIR. The thermal stability of PVC plasticized with these ILs is reduced and the activation energy for thermal degradation for the first step of PVC degradation lowered, relative to neat PVC. This feature is not dependent on the thermal stability of the IL itself, as their addition to neat PVC did not result in increased thermal stability of the resin. Analysis of the gases evolved during thermal degradation showed that there is no variation in the mechanism of PVC degradation in the presence of ILs, the only difference observed is that HCl is evolved at lower temperatures for PVC-ILs samples. The ILs had no effect on the second step of the thermal degradation of PVC. The decrease in the thermal stability of PVC-ILs is associated with two different effects: firstly, the anion weakens the CH bond while the cation forms complexes and weakens the CCl bond; second, the IL interaction with the polymer chains partly substitutes the interaction between the polymer chain and heat stabilizers (e.g. stearates) added to the PVC compound. In this way, the latter tends to be expelled from the bulk polymer, thus not being available for PVC stabilization at high temperature. Heat stabilizer migration is related to the solvating power of the ILs: the higher the solvating power, the higher the migration of heat stabilizer, the lower the thermal stability of the polymer.

Thermogravimetric analysis in the evaluation of the inhibition of degradation of rigid poly(vinyl chloride) using biologically active phthalimido aromatic hydrazide derivatives

Four novel antimicrobial phthalimido aromatic hydrazide derivatives were synthesized from N-(4-chlorocarbonylphenyl) phthalimide with benzhydrazide, salicylhydrazide, p-aminobenzohydrazide or p-aminosalicylhydrazide. They were characterized by FTIR, 1H NMR, mass spectra, elemental analyses and antimicrobial activities. These derivatives were investigated as thermal stabilizers for rigid PVC using thermogravimetric analysis technique, in nitrogen. The results revealed the greater stabilizing efficiency of the investigated derivatives as shown by their higher initial decomposition temperature and higher residual weight percent in relation to dibasic lead carbonate (DBLC), cadmium-barium-zinc (Cd–Ba–Zn) stearate and n-octyltin mercaptide (n-OTM) industrial stabilizers. The stabilizing efficiency increased with the introduction of electron donating substituent groups in the aromatic ring of the phthalimido aromatic hydrazide derivatives.

Thermal stability and thermal aging of poly(vinyl chloride)/MgAl layered double hydroxides composites

MgAl-LDH (layered double hydroxides) were prepared with CO(NH2)2, NH4Cl and NH3·H2O by the coprecipitation method, respectively. Corresponding composite membranes were prepared by the coating method. LDHs were characterized by WAXS, CO2-TPD and SEM. The morphology of the PVC/LDHs composite membranes were characterized by means of SEM. The thermal stability of the membranes was analyzed by air aging box and TGA-FTIR. The SEM results show that nano-particles can be compatible with poly(vinyl chloride) (PVC) matrix homogeneously by the stirring-ultrasound blend method with two steps. Furthermore, the air aging box results proved that MgAl-CO(NH2)2-LDH has the best effect on thermal stability of PVC. TGA-FTIR results show that MgAl-CO(NH2)2-LDH could adsorb more HCl that resulted from the degradation of PVC and improve the pyrolysis temperature of the first degradation stage by 15 K compared with PVC.

Study on preparation and performance of zinc cyanurate thermal stabilizer for PVC

Study on preparation and performance of zinc cyanurate thermal stabilizer for PVC

Synergistic effects of zinc-mannitol alkoxide with calcium/zinc stearates and with β-diketone on thermal stability of rigid poly(vinyl chloride)

Zinc-ethanol metal alkoxide was primarily synthesized as an intermediate material toward zinc-mannitol alkoxide (Zn-Man), which was further prepared through the alcohol exchange reaction with the zinc-ethanol alkoxide by mannitol. The synergistic effects of Zn-Man with several commonly used thermal additives such as calcium stearate (CaSt2), zinc stearate (ZnSt2), CaSt2/ZnSt2 and stearoyl benzoyl methane (β-diketone) on poly(vinyl chloride) (PVC) thermal stability were investigated from conductivity measurement, thermal aging testing and Ultraviolet–visible (UV–vis) spectroscopy. The thermal stability tests showed that Zn-Man distinctly prolonged the long-term thermal stability of rigid PVC. If used with CaSt2/ZnSt2 or β-diketone, the thermal stability time (Ts) increased to 165.2 and 164.7 min, respectively, from the initial 101.5 min of PVC stabilized with pure Zn-Man, but excess dosage of CaSt2/ZnSt2 or β-diketone deteriorated the long-term thermal stability. The initial coloring was excellently improved when Zn-Man combined with ZnSt2, CaSt2/ZnSt2 or β-diketone; while the synergistic effect between Zn-Man and CaSt2 was not significant. Moreover, testing results demonstrated that the optimal mass ratio of 3/1 showed better synergistic effects. The thermal stabilizing mechanism was also investigated through the combination of theoretical analysis and experimental testing.

Effect of base‐deposited graphene oxide on the thermal stabilization of poly(vinyl chloride)

AbstractGraphene oxide was deposited in a base solution to form base‐deposited graphene oxide (bd‐GO) particles. The structure and properties of the bd‐GO particles were evaluated using transmission electron microscopy, powder X‐ray diffraction and X‐ray photoelectron, Fourier transform infrared, UV‐visible and fluorescence spectroscopies. The effect of the bd‐GO particles on the thermal stabilization of poly(vinyl chloride) (PVC) was investigated using the Congo red test and thermogravimetric analysis. The results showed that the thermal stability of PVC was greatly improved by the bd‐GO particles. Furthermore, this stabilization mechanism was investigated using UV‐visible spectroscopy and nitrogen adsorption–desorption isotherm analysis. It was found that the improvement of thermal stability was mainly related to the deactivation of thermally labile structural defects in the PVC chains by the carboxylate and alkoxide moieties of the basic groups in the bd‐GO particles, and the highly efficient adsorption of the bd‐GO particles with hydrogen chloride produced during PVC degradation. © 2015 Society of Chemical Industry

Organic Based Heat Stabilizers for PVC: A Safer and more Environmentally Friendly Alternatives

Organic based stabilizers have been considered as a new technology providing environmentally friendly heat stabilizer for PVC pipe production to substitute conventional lead stabilizer as well as calcium zinc stabilizer. In this research, PVC samples stabilized with 5 types of heat stabilizers i.e. 1) commercial lead stabilizer, 2) commercial calcium zinc stabilizer, 3) commercial organic based stabilizer (OBS), 4) 1,3-dimetyl-6-aminouracil (DAU) and 5) eugenol, were investigated. From dynamic mechanical analysis, storage modulus at room temperature of PVC stabilized with DAU was found to provide the highest value among those stabilizers. Glass transition temperature of the PVC stabilized with all types of heat stabilizers was determined to be approximately 99°C except the value of about 89°C in eugenol stabilized PVC. Furthermore, PVC stabilized with commercial lead, calcium zinc stabilizer and commercial OBS could be reprocessed up to at least 5 cycles. Whereas, PVC stabilized with DAU was found to be able to withstand the processing cycle up to 4 cycles. Additionally, PVC stabilized with DAU showed the most outstanding short term thermal stability and can maintain its original color for at least up to 4 processing cycles. Finally, repeated processing of PVC stabilized with each type of heat stabilizers showed negligible effect on mechanical properties for at least up to 3 processing cycles. From the above results, it is evident that DAU showed high potential use as a safe and effective organic based heat stabilizer for PVC to substitute traditional lead or calcium zinc compounds.

Investigation of the effects of nonisothermal suspension polymerization of vinyl chloride on the fusion and degradation behavior of poly(vinyl chloride)

Thermal stability of poly(vinyl chloride) (PVC) samples polymerized under a temperature trajectory was studied from the point of view of morphological and microstructural characteristics. The results are compared with those of the PVC samples obtained by polymerization at constant temperature having the same K value. The Brabender® plastograph data indicated that the final PVC synthesized with the temperature trajectory showed lower fusion time and higher thermal stability time. The nonisothermal condition also increased the degree of fusion of the final PVC resin, reflecting lower temperature/time required to process it. It was found that the thermal stability of nonisothermally produced PVC as characterized by dehydrochlorination rate decreased (improved) with the increasing monomer conversion until a minimum value was reached that corresponded to the conversion at the pressure drop. However, the dehydrochlorination rate remains almost constant with conversion for an isothermal grade PVC resin. Although the evolution of the number of internal double bonds as well as extent of discoloration of PVC with conversion shows a decreasing trend, the labile chlorine concentration exhibits a maximum at early conversion. The reason for the former can be explained by the temperature dependence of reactions forming defect structures, which are kinetically controlled and thus favored at higher temperatures. The latter, however, can be explained because of the increasing importance of transfer reactions to polymer with increasing polymer concentration. Finally, the results from differential thermogravimetry verify an improvement in thermal stability of the final PVC prepared by using a temperature trajectory during vinyl chloride monomer suspension polymerization. J. VINYL ADDIT. TECHNOL., 23:259–266, 2017. © 2015 Society of Plastics Engineers

Synergistic effect of maleimido phenyl urea derivatives mixed with some commercial stabilizers on the efficiency of thermal stabilization of PVC

Four novel antimicrobial maleimido phenyl urea stabilizers 1–4 were synthesized from N-[4-(chlorocarbonyl) phenyl] maleimide with phenyl urea and its derivatives (p-methyl, o-chloro and p-carboxy). The effect of mixing maleimido phenyl urea stabilizer 2 with each of the reference stabilizers, dibasic lead carbonate (DBLC), cadmium-barium-zinc stearate (Cd-Ba-Zn stearate) or n-octyltin mercaptide (n-OTM), on the stabilization efficiency in thermal degradation of rigid PVC at 180 °C in air, has been investigated. Mixing was effected in the range of 0–100 wt% of stabilizer 2 relative to each of the reference stabilizers. The stabilizing efficiency was evaluated by measuring the length of the thermal stability period (Ts), the period during which no detectable amount of hydrogen chloride gas could be observed, and also from the rate of dehydrochlorination as measured by continuous potentiometric determination, and by the extent of discoloration of the degraded polymer samples. The results show a true synergistic effect from the combination of stabilizer 2 with any of the reference stabilizers. Mixing of the stabilizers improves the Ts values, decreases the rate of dehydrochlorination and lowers the extent of discoloration of the polymer. The maximum synergism was attained when stabilizer 2 is mixed with either of the three reference stabilizers in equivalent weight ratio (50%/50%). The observed synergism may be attributed to the different mechanisms by which the investigated and the reference stabilizers work.

Thermal aging and accelerated weathering of PVC/MMT nanocomposites: Structural and morphological studies

ABSTRACTThis work focuses on the influence of weathering factors—UV radiation, humidity, and temperature on the structure and morphology of poly(vinyl chloride)/montmorillonite (PVC/MMT) nanocomposites obtained by melt blending. It has been observed that organically modified MMT (OMMT) deteriorates the weathering resistance, the thermal behavior, as well as the long‐term stability of PVC. Decomposition of the organic modifier of MMT causes substantial color changes in the PVC nanocomposites as it facilitates the dehydrochlorination process of the polymer. However, the nonmodified MMT provides some stabilization during PVC weathering. The nanocomposites after annealing are characterized by higher glass transition temperature. The increase in heat capacity step (Δcp) during glass transition suggests that in the PVC composites with nonmodified MMT stronger molecular interactions between the polymer and clay platelets occur than in PVC/OMMT nanocomposites. The scanning electron microscopy images on the surface and the cross section show that thermal aging and weathering proceed by different mechanisms. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42090.

Effect of Orotic Acid on the Stabilization Efficiency of Ca-Zn Thermal Stabilizers for Poly(vinyl chloride)

The effect of orotic acid (OA) and its mixtures with calcium stearate (CaSt2) and zinc stearate (ZnSt2) in various ratios on the thermal stability of PVC has been investigated by Congo red and discoloration tests. The results shows that OA acts as a long-term thermal stabilizer for PVC like CaSt2, and the combination of OA and ZnSt2 exhibited a synergistic stabilization effect at a certain ratio. This is due to the ability of OA to absorb HCl released during the degradation of PVC to diminish its catalytic effects, and react with ZnCl2 to stop its catalytic effect for PVC. CaSt2-ZnSt2/OA stabilizers exhibit good synergistic effects with both acceptable initial color and long-term stability for PVC

Synergistic effects of lanthanum-pentaerythritol alkoxide with zinc stearates and with β-diketone on the thermal stability of poly(vinyl chloride)

Lanthanum-pentaerythritol alkoxide (La-PE) was obtained by the traditional preparation method which was a reaction between La2O3 and pentaerythritol. The synergistic effects of La-PE with zinc stearates (ZnSt2) and with stearoyl benzoyl methane (β-diketone) on the thermal stability of poly(vinyl chloride) (PVC) were evaluated by the conductivity test, thermal aging test, and Ultraviolet–visible (UV-VIS) spectroscopy test. The results showed an improvement on the color stability and the long-term thermal stability of PVC, indicating that there was an obvious synergistic effect between La-PE and ZnSt2. In order to explore the mechanism, the capacity of La-PE to react with HCl was tested. The results showed that La-PE had lower capacity to neutralize HCl (80.30 mg HCl/1 g) than ZnSt2 (92.71 mg HCl/1 g). Furthermore, the thermal stability test of PVC stabilized with La-PE/ZnCl2 showed that the thermal stability of PVC with La-PE/ZnCl2 was similar to that of PVC with La-PE/ZnSt2 but better than PVC with pure La-PE. Thus, a possible synergistic mechanism of La-PE and ZnSt2 could be described where zinc species could catalyze the reaction of La-PE and the labile chlorine atoms in PVC chains. Moreover, the hydroxyl group on La-PE could chelate ZnCl2 to inhibit the “zinc burning” phenomenon. However, there was no synergistic effect observed between La-PE and β-diketone. Discoloration in PVC samples that stabilized with La-PE and β-diketone was noticed as early as in the milling process by the open twin-roller at 180 °C, even though it took 110 min for the reaction to change the color to completely black. The results of UV-VIS spectroscopy showed that a strong peak appeared at 360 nm representing the enol form of β-diketone when the dosage of β-diketone exceeded 1 phr. This indicated that the enol form of β-diketone did the work in the thermal stabilizing process and the dosage of β-diketone needed in the PVC stabilizers was very low.

폴리염화비닐(PVC)의 열안정성에 제올라이트가 미치는 영향

The effects of zeolite on the thermal stability of poly(vinyl chloride) (PVC) were investigated by the static thermal stability test, pyrolysis experiment and ultraviolet spectrum. The results showed that the porous zeolite could absorb hydrogen chloride (HCl), which suppressed the catalysis of HCl on thermal degradation of PVC, thus improved the thermal stability of PVC. The oxidizing acid which was loaded on zeolite had oxidated on the double bond that formed during the dehydrochlorination of PVC. This process could prohibit the growth of the conjugated polyene and improved the color of PVC. Hence, zeolite might be possible to come up with a high performance thermal stabilizer.

Tannin-Ca Complex as Green Thermal Stabilizer Additive for PVC: Viscoelastic Properties

This study investigated the viscoelastic and rheometeric properties of PVC stabilized with tannin-Ca complex as totally bio-based thermal stabilizer. Dynamic mechanical thermal analysis (DMTA) used to characterize the viscoelastic properties of PVC samples obtained by thermal mixing of PVC with three composition percentages (1.0, 2.0, and 3.0) part per hundred ratios (phr) of tannin-Ca complex with this polymer. The torque rheometery test used to monitor the effect of tannins derivative on the thermal stability and mixing properties of PVC formulations during samples processing. For that purpose, PVC sample with 2 phr commercial thermal stabilizer (Reapak B-NT/ 7060) was used for comparison and considered as reference samples. Before the glass transition temperature of PVC at 30°C - 60°C, the DMTA curves show that the values of storage modulus and tan delta of PVC samples stabilized with tannin derivative were very similar with those of PVC sample stabilized with commercial thermal stabilizer. The glass transition temperature (Tg) of PVC stabilized with commercial thermal stabilizer and with tannin-Ca complex occurred at about 76°C. In a sequence, after the glass transition region of PVC samples, the DMTA scans confirmed that the PVC samples with 2 phr tannin-Ca complex have relatively longer flowing stage which occurs at lower temperatures by 18°C per that of PVC sample stabilized with commercial stabilizer. Global results of the torque rheometery which have suitable plateau stages and the DMTA show that the processing thermal stability and thermal flexibility of PVC are clearly increased with the incorporation of tannin-Ca complex. All the PVC formulations with tannins-Ca complex show excellent viscoelastic properties which were found to be slightly best or much closed to those obtained for PVC stabilized with commercial thermal stabilization.

Epoxidized linolenic acid salts as multifunctional additives for the thermal stability of plasticized PVC

ABSTRACTCalcium and zinc salts of epoxidized linolenic acid were synthesized and used as multifunctional additives, to minimize or prevent the reaction of epoxidized soybean oil (ESO) with liberated hydrochloric acid (HCl) during the thermal degradation of poly(vinyl chloride) (PVC) in particular. These metal epoxy salts were incorporated as thermal stabilizers for both diisodecyl phthalate and ESO–plasticized PVC blends that underwent thermal degradation studies at 170°C. The overall performance of these metal epoxy salts was examined by thermal gravimetric analysis and visual color retention of the PVC blends. The weight loss profiles of the metal salt stabilized PVC were comparable to those of blends containing metal stearates. There were, however, vast improvements in color retention of the plasticized PVC using these novel additives. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41736.

Synthesis of lanthanum ricinoleate and its effect on thermal stability and mechanical properties in PVC

The lanthanum ricinoleate (abbreviated as Lari3) of rare earth heat stabilizer was synthesized by the reaction of ricinoleic acid, lanthanumnitrate and sodium hydroxide. The IR and fluorescence spectra methods confirmed the structure of the product. The thermal stability of PVC in the presence of Lari3 was studied by the Congo method and using TG analysis. The results showed that Lari3 could be used as a thermal stabilizer for PVC. When the ratio of Lari3/pentaerythritol was 3:1, the complex exhibited better synergistic effect. Incorporation of Lari3 to PVC resulted in a marked increase of maximum and onset degradation temperature as well as elongation and impact strength of PVC. Lari3 might replace the labile chlorine atoms to interrupt the formation of conjugated double bonds in PVC chains and act as HCl scavenger to restrain the self-catalyticdehydrochlorination.

The research of dibutyltin polymer on the thermal stability of PVC

A novel series of polymeric thermal stabilizers were synthesized by radical solution polymerization using dibutyltin maleate (DBTM), styrene (St) as main comonomers, methyl acrylate (MA), N-phenylmaleimide (NPMI), N-p-chlorophenylmaleimide (NCPMI), N-(4-nitrophenyl)maleimide (NNOPMI) as modified monomers, respectively, and AIBN as the initiator, namely P(DBTM/St), P(DBTM/St/MA), P(DBTM/St/NPMI), P(DBTM/St/NCPMI), and P(DBTM/St/NNOPMI). The structures were characterized by FTIR and 1H NMR spectra. The molecular weight and its distribution were measured with GPC. The dynamic stability was studied by the measure of hydrogen chloride from PVC, which were added into quantitive thermal stabilizers before processing. The depressant effects of thermal stabilizers were researched on discoloration due to degradation with thermal aging method. The parameters of thermal degradation dynamics were calculated by the Kissinger method. The effect order of the five stabilizers on thermal stability was P(DBTM/St/MA) > P(DBTM/St) > P(DBTM/St/NPMI) > P(DBTM/St/NCPMI)> (DBTM/St/NNOPMI).

Synthesis of Dibutyl tin (IV) Dilurate and its Application as a Safe Thermal Stabilizer in Polyvinyl Chloride

In this work a modified procedure was done to prepare dibutyl tin (IV) dilurate without impurity of substituated tributyl tin which has health effect. Purity of the final product was tested by using chromatography techniques. The product was used as a thermal stabilizer in soft PVC. Properties of the stabilized and unstabilized PVC films were investigated with different techniques such as IR spectroscopy, thermal gravimetric analysis and mechanical tests. The results show that dibutyl tin dilurate can be used as a thermal stabilizer for PVC with high efficiency.