Investigation of lanthanum trioxypurine with zinc stearate and pentaerythritol as complex thermal stabilizers for poly(vinyl chloride)

Lanthanum trioxypurine (LaTr) was triumphantly synthesized by reacting trioxypurine and lanthanum nitrate at neutral condition and was characterized by elemental analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The thermal stability effect of LaTr with its assistant thermal stabilizers about zinc stearate (ZnSt₂) and pentaerythritol (Pe) on poly(vinyl chloride) (PVC) was investigated by Congo red test, discoloration test, UV–vis spectroscopy test, and thermal decomposition kinetics. The results showed that the addition of LaTr as thermal stabilizer could significantly enhance static stability time and long‐term stability of PVC. It could be mainly attributed to the anions in the structure of LaTr, could efficiently absorb the hydrogen chloride released by PVC, and have ability to replace unstable chlorine atoms on structure of PVC. Moreover, the mixing of LaTr, Pe, and ZnSt₂ could reveal an excellent synergistic effect and both promote the initial color and the long‐term thermal stability of PVC. The thermal stability of PVC reached the optimal state when the ratio of LaTr/Pe/ZnSt₂ was 1.8/0.6/0.6. In addition, compared with the reaction energy E_a and UV–vis spectroscopy test's result of PVC samples, the order of PVC's thermal stability was PVC/LaTr/Pe/ZnSt₂ > PVC/LaTr/Pe > PVC/LaTr. The result was further ascertained that LaTr/Pe/ZnSt₂ showed excellent synergistic effect and could be used as an excellent complex thermal stabilizer for PVC. J. VINYL ADDIT. TECHNOL., 25:347–358, 2019. © 2019 Society of Plastics Engineers     

Influence of acrylate processing aid‐based ionomer containing lanthanide (La(III)) ion on thermal stability,fusion, transparency and mechanical properties of rigid poly(vinyl chloride)

An acrylate processing aid (ACR)‐based ionomer containing lanthanide (La(III)) ion was synthesized and the influences of the ionomer on thermal stability, fusion time, transparency and tensile properties of rigid poly(vinyl chloride) (PVC) were investigated. Results revealed that the ionomer with a suitable La(III) content behaved as a good stabilizer as well as processing aid to the rigid PVC product. The ionomer could accelerate fusion of PVC much more quickly than ACR because of the strong interaction between La(III) carboxylate and PVC. Moreover, it exhibited a stabilizing efficiency comparable to lanthanum and calcium stearates (LaSt₃ and CaSt₂). The composite stabilizer of ionomer/zinc stearate (ZnSt₂) exhibited an ability to improve initial discoloration better than LaSt₃/ZnSt₂ and CaSt₂/ZnSt₂ because the ionomer could form a complex with ZnSt₂ much more slowly than LaSt₃ and CaSt₂. The compounds stabilized using ionomer/ZnSt₂ exhibited a transparency comparable to those stabilized using organotin or liquid barium/zinc stabilizers, which was much better than those stabilized using LaSt₃/ZnSt₂ and CaSt₂/ZnSt₂. Copyright © 2011 Society of Chemical Industry     

Effect of lanthanide (La(III))‐containing ionomer on thermal stabilization of poly(vinyl chloride)

A type of lanthanide (La(III))‐containing ionomer based on acrylate processing aid (ACR) for poly (vinyl chloride) (PVC) was synthesized, and influence of the ionomer on thermal stabilization of PVC was investigated with visual color comparison and Congo red methods. Results revealed that the ionomer with a suitable La(III) content behaved as a good costabilizer to PVC. It was able to extend static stabilization time of PVC and postpone “zinc burning.” The stabilizing efficiency of the ionomer to PVC depended on ion content, which was discussed in terms of Eisenberg–Hird–Moore model. Moreover, Fourier transform infrared test verified that this ionomer can react with zinc stearate (ZnSt₂) to form some new structures, which is responsible for postponing “zinc burning.” The ionomer and epoxidized soybean oil exhibited a synergistic effect on the stabilizing efficiency of calcium stearate (CaSt₂)/ZnSt₂ stabilizer to PVC compounds. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Zinc glycerolate with lanthanum stearate to inhibit the thermal degradation of poly(vinyl chloride)

Zinc glycerolate (ZnGly) was prepared and used as a poly(vinyl chloride) (PVC) thermal stabilizer in this work. ZnGly was characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), thermogravimetry (TGA), and transmission electron microscopy (TEM). Visual color evolution and thermal stability time at 180°C were used to examine the stabilizing efficiency of the samples. The thermal stability of PVC was significantly enhanced through adding ZnGly or ZnGly with lanthanum stearate (LaSt₃). Compared with zinc stearate (ZnSt₂), it was demonstrated the initial color stability was markedly improved and the thermal stability time was obviously extended by adding ZnGly. The thermal stability time of ZnGly was threefold than ZnSt₂. In comparison with CaSt₂/ZnSt₂, the extent of coloration of PVC samples was significantly inhibited though adding LaSt₃/ZnGly. It was verified that the appropriate percents of ZnGly in the mixture were between 25 and 50%. A possible mechanism for the stabilizing efficiency of ZnGly was also proposed. The stabilizing efficiency was attributed to the stabilizer's ability to absorb hydrogen chloride and replace the labile chlorine atoms on PVC chains. Moreover, the dynamic thermogravimetric analysis was used to confirm that combination of LaSt₃ with ZnGly presented an obvious improvement of stability on thermal degradation of PVC. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Chlorinated poly(vinyl chloride) stabilization by pentaerythritol/calcium‐zinc stearate mixtures: The fate of pentaerythritol

The stabilization effect of pentaerythritol (Pe) combined with calcium and zinc stearates (CaSt₂/ZnSt₂) on chlorinated poly(vinyl chloride) (CPVC) is investigated. Congo red and dynamic thermal stability data indicate that Pe alone has a mild stabilizing effect on the degradation of CPVC. Addition of mixed CaSt₂/ZnSt₂ to this system leads to a significant improvement in stability. Thermogravimetric studies indicate that premature weight loss, not observed with either Pe alone or with CaSt₂/ZnSt_2, is observed when the combined Pe/CaSt₂/ZnSt₂ systems are employed to stabilize CPVC. Fourier transform infrared (FTIR) spectroscopy and electrospray ionization mass spectrometry (ESIMS) both indicate that condensation (oligomerization) and chlorination of Pe occur when Pe and Pe/CaSt₂/ZnSt₂ systems are employed to stabilize CPVC. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Zinc maleate and calcium stearate as a complex thermal stabilizer for poly(vinyl chloride)

Zinc maleate (ZnMA) and calcium maleate (CaMA) were synthesized by reaction of maleic acid with the corresponding metal oxides and were characterized by X‐ray diffraction, thermal analysis, and Fourier‐transform infrared (FTIR) spectroscopy. The thermal stabilizing effects of ZnMA and CaMA on poly(vinyl chloride) (PVC) were investigated at 180°C in air by a static stability test. The stabilization mechanism of ZnMA and the synergism of ZnMA/CaSt₂ (St = stearate) were also studied by UV‐visible and FTIR spectroscopies, as well as a thermal stability test. The PVC with the ZnMA stabilizer exhibited good thermal and color stability caused by the ability of ZnMA to replace the labile chlorine atoms in PVC chains, absorb hydrogen chloride, and react with the polyene intermediates via a Diels–Alder mechanism. The gel content of the PVC/ZnMA samples reached 31% after 2 min of heating and 44% after 10 min, thereby indicating that crosslinking could easily occur with ZnMA, probably owing to catalysis by Zn species. The static and dynamic stability results showed that the synergistic effect of the ZnMA/CaSt₂ stabilizer was greater than that of ZnSt₂/CaSt₂. J. VINYL ADDIT. TECHNOL., 20:1–9, 2014. © 2014 Society of Plastics Engineers     

Synergistic effect of acetonedicarboxylic acid diethyl ester and calcium/zinc stearates on poly(vinyl chloride) thermal stability

Acetonedicarboxylic acid diethyl ester (AADE) is obtained by the interaction of ethanol with acetonedicarboxylic acid that is prepared from anhydrous citric acid. The thermal stabilizing effect of calcium and zinc stearates (CaSt₂/ZnSt₂) combined with AADE on poly (vinyl chloride) (PVC) is evaluated by the Congo red test, conductivity test, thermal aging test, and thermogravimetric analysis. The results of thermal stability tests show that the addition of AADE can improve not only the thermal stability but also the color stability of PVC. The improvement in stabilizing effectiveness is ascribed to the synergistic effect between CaSt₂/ZnSt₂ and AADE. The thermal stability mechanism of AADE is also under discussion with the help of quantum chemical calculations. The results of quantum chemical calculations indicate that, besides having the ability to form complexes with zinc ion, AADE has an evident tendency to replace the allyl chloride of the PVC. The results of the thermal aging test and quantum chemical calculations show that the thermal stabilizing effectiveness of AADE is higher than that of stearoyl benzoyl methane (β‐Diketones). J. VINYL ADDIT. TECHNOL., 21:228–234, 2015. © 2014 Society of Plastics Engineers     

Effect of zinc stearate and/or epoxidized soybean oil on gelation and thermal stability of PVC‐DOP plastigels

The effects of zinc stearate (ZnSt₂) and/or epoxidized soybean oil (ESO) on mechanical properties and on thermal stability of plastigels obtained from polyvinylchloride (PVC) and dioctylphthalate (DOP) plastisols were studied using calorimetric, spectroscopic, and tensile‐testing techniques. Plastigels having 2.5 or 5.0 part ZnSt₂ and/or 5 part ESO and 60 part DOP per 100 part PVC (phr) were gelled by heating at 140°C. The tensile strength of plastigels with no additive and having 5 phr ZnSt₂, ESO, and both ZnSt₂ and ESO were 0.79, 0.46, 0.98, and 0.58 kN/cm², respectively. The decrease of tensile strength of plastigels with ZnSt₂ could be explained by the existence of ZnSt₂ in the solid phase in plastigels, as shown by differential scanning calorimetry (DSC). ESO helped better fusion of the plastisols without any additive and with ZnSt₂. Higher tensile strengths of ESO containing plates indicated more complete gelation of the plastisols. The thermal stability of plastigels in terms of color and their yellowness index (YI) were higher for ZnSt₂ containing plastigels. Conjugated polyene concentrations were calculated from UV spectra of the films heated at 140°C. The reaction rate constant of the dehydrochlorination of PVC changed with the additives. Faster dehydrochlorination than control gels occurred in gels having ZnSt₂ at long heating times due to the autoaccelerating effect of ZnCl₂ formed by reaction of eliminated hydrogen chloride and ZnSt₂. Organic acid formation reaction between ZnSt₂ and HCl formed by dehydrochlorination is investigated from the IR band at 1540 cm⁻¹ and 3400 cm⁻¹ during heating of the plastigel films. A synergistic effect of ESO and ZnSt₂ was observed when the mechanical strength and heat stability were considered together. Although ESO increased tensile strength, ZnSt₂ increased thermal stability of the plastigels at early times when they were present simultaneously in plastisols. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2488–2498, 1999     

Improvement of the processability and thermal stability of poly(vinyl chloride) with 5,6-diamino-1,3-dimethyluracil

Uracil derivatives are potential nontoxic thermal stabilizers of poly(vinyl chloride) (PVC) and have a better stabilization effect. 5,6-diamino-1,3-dimethyluracil (DDU) was investigated as a thermal stabilizer for PVC. The stabilization effect of DDU was measured by thermogravimetric analysis, thermal aging test, and recording the time of the color change of the Congo red paper (Congo red test). Meanwhile, the processability of PVC stabilized by DDU was investigated through dynamic performance test. The results showed a better stabilizing effect compared with calcium stearate (CaSt₂) and zinc stearate (ZnSt₂). To explain the stabilization of DDU, the probable mechanism was suggested that DDU absorbed and chemically bonded with hydrogen chloride. Therefore, DDU could be used as a thermal stabilizer of PVC.     

Synergistic effect of adipic acid pentaerythritol ester with calcium and zinc stearates on poly(vinyl chloride) thermal stability

Adipic acid pentaerythritol ester (AAPE) was synthesized in this study and confirmed by Fourier transform infrared spectroscopy (FTIR). The synergistic effect of AAPE with calcium and zinc stearates (CaSt₂/ZnSt₂) on poly(vinyl chloride) (PVC) thermal stability was evaluated by the conductivity test, thermal aging test, and thermogravimetric analysis (TGA). The results showed that the addition of CaSt₂/ZnSt₂ combined with AAPE could improve color stability and long‐term thermal stability of PVC. The results of UV‐visible spectroscopy showed that CaSt₂/ZnSt₂/AAPE could prevent the generation of conjugated double bonds. The possible mechanism is that AAPE can chelate ZnCl₂ to prevent the thermal degradation via dehydrochlorination. The contrast tests showed that the synergistic effect of AAPE and CaSt₂/ZnSt₂ is more obvious than that of polyethylene (PE) and CaSt₂/ZnSt₂, which may be attributed to the lower melting point of AAPE and the better compatibility with PVC. J. VINYL ADDIT. TECHNOL., 22:293–299, 2016. © 2014 Society of Plastics Engineers     

Phosphate ester groups‐containing ricinoleic acid‐based Ca/Zn: Preparation and application as novel thermal stabilizer for PVC

Phosphate ester groups containing ricinoleic acid‐based Ca/Zn (LPPRA‐Ca and LPPRA‐Zn) stabilizer was successfully synthesized from ricinoleic acid (RA) and used as thermal stabilizers for poly(vinyl chloride) (PVC). These thermal stabilizers were characterized by Fourier transform infrared spectrometry, ¹H nuclear magnetic resonance, and inductively‐coupled plasma atomic emission spectroscopy. The effects of LPPRA‐Ca/LPPRA‐Zn, CaSt₂/ZnSt₂, and other stabilizers on the thermal stability of PVC were studied through Congo Red test, discoloration tests, thermogravimetric analysis (TGA), TGA–infrared, and TGA–mass spectrometry. The thermal stability tests show that LPPRA‐Ca/LPPRA‐Zn displays the best initial color stability and long‐term thermal stability for PVC. The superior performance is attributed to the synergistic effect of LPPRA‐Ca and LPPRA‐Zn. Moreover, a lower Zinc content of LPPRA‐Zn in PVC helps to decrease the “zipper dehydrochlorination” of the product, which contributes to a better initial thermal stability. Except for the better stabilization performance, LPPRA‐Ca/LPPRA‐Zn also displays better plasticization performance for PVC compared with other stabilizers. A possible stabilizing mechanism of PVC/LPPRA‐Ca/LPPRA‐Zn system was presented. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45940.     

Design of nitrogen-containing organic thermal stabilizer with resistance to “zinc burning” and its application

Using maleic anhydride and 6-amino-1,3-dimethyluracil as raw materials, by adding zinc oxide and introducing metal ions, the aminouracil zinc maleate (AM-Zn) was synthesized. The structure of the product was analyzed by Fourier transform infrared spectroscopy and ¹H NMR spectroscopy. The molecule contains ester group, carbon–carbon double bond, carboxylate and diazo group, which can be used as the main thermal stabilizer for poly(vinyl chloride) (PVC). The thermal stability and excellent resistance to zinc burning of AM-Zn were characterized by Congo red method, thermal aging method, thermal weight loss method, electrical conductivity, and other detection methods. In addition, the compound use of AM-Zn and CaSt₂ could further improve the thermal stability performance, which was excellent compared with the commercially available CaSt₂/ZnSt₂. The thermal stabilization effect was the best when CaSt₂/AM-Zn = 2:1, the initial whiteness could reach 50 min, and it was not completely blackened and aged within 80 min. The static stabilization time was 65 min, and the thermal stabilization time is increased by 40 min compared with CaSt₂/ZnSt₂. The thermal stabilization mechanism was analyzed, and the designed and synthesized AM-Zn, a multifunctional molecular structure, had a strong potential as a thermal stabilizer for PVC.     

Effect of lanthanum cyanurate as novel organic thermal stabilizers for polyvinyl chloride

Lanthanum cyanurate was synthesized by reacting cyanuric acid and lanthanum nitrate at basic condition and was characterized by elemental analysis and Fourier transform infrared spectroscopy. Its application as thermal stabilizer for poly(vinyl chloride) (PVC) was investigated by Congo red test and discoloration test. In comparison with other heat stabilizers, including lanthanum stearate, calcium stearate, and zinc stearate, lanthanum cyanurate exhibits high stabilizing effect with excellent initial color of PVC. The stability time reaches the maximum (80 min) when the percentage of lanthanum cyanurate in PVC is 2.5%. The combination stabilizers (LaC₃N₃O₃/Zn(St)₂ obviously increase the complete discoloration time of PVC in comparison with the stabilizer of Zn(St)₂. The stability time of PVC increases from 14 min (stabilized by zinc stearate) to 26 min (stabilized by LaC₃N₃O₃/Zn(St)₂). LaC₃N₃O₃ also shows a slightly stronger effect on tensile strength of PVC than La(St)₃. Therefore, the LaC₃N₃O₃ can be used to replace La(St)₃ and serve as a costabilizer to improve stabilization efficiency of calcium/zinc stabilizers for PVC. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

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     

N′‐acryloyl benzhydrazide as a thermal stabilizer for rigid poly(vinyl chloride)

N′‐Acryloyl benzhydrazide (ABH) was examined as a thermal stabilizer and costabilizer for rigid poly(vinyl chloride) (PVC) in air at 180°C. Its high stabilizing efficiency was shown by its high thermal stability value (T_s) when compared with those of two common reference stabilizers used industrially, dibasic lead carbonate (DBLC) and a calcium–zinc soap. Blending this organic stabilizer with the reference stabilizers in different ratios had synergistic effects on both the thermal stability and the extent of discoloration of the PVC. The Ni²⁺ complex of ABH gave better thermal stability and lesser discoloration than the parent organic stabilizer. Also, blending that complex with DBLC in different ratios gave better stability and lower discoloration. Thermogravimetric analysis confirmed the improved stability of PVC in the presence of the ABH stabilizer. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers.     

A zinc Schiff base complex as high-efficiency stabilizer for flexible poly(vinyl chloride) against thermal degradation

A high-efficiency zinc chelate stabilizer, Zn-(2-hydroxybenzylidene) aspartic acid (Zn-HBAPA), has been synthesized. From dehydrochlorination and discoloration tests conducted at 180°C, Zn-HBAPA has shown to be an excellent thermal stabilizer for flexible poly(vinyl chloride) (PVC) when compared with industrially used cadmium-zinc soap stabilizer. Blending CaSt₂ derivatives and costabilizer THAM (tris[hydroxymethyl]aminomethane) with synthesized Zn-HBAPA stabilizer in different ratios substantially improved the thermal stability of PVC while maintaining the initial color of the PVC. The thermal stability time and the induction time were 55.5 and 52 min, respectively. The initial color of PVC samples held for more than 70 min, and the time to turn the PVC samples completely black took 160 min. Results also showed that not only did the Zn-HBAPA stabilizer show a good synergistic effect when combined with CaSt₂ and THAM, but it also exhibited good compatibility with PVC.     

Influence of nano‐CeO2 as Co‐stabilizer on the thermal stabilization efficiency of novel calcium/Zinc soap stabilizers for poly(vinyl chloride)

The novel organic calcium (Ca)/zinc (Zn) stabilizer of poly(vinyl chloride) (PVC) was synthesized from poly (zinc methylacrylate) and Ca adipate. The influences of Zn/Ca soap weight ratios and nano‐CeO₂ as co‐stabilizer on the thermal stability of PVC were investigated. Congo red testing, thermogravimetric analysis, dynamic rheology, and dynamic mechanical analysis of the mixtures were performed. The results show that the novel stabilizer has good stabilization efficiency on PVC. When 5 phr (parts by weight per hundred parts of resin) of novel stabilizer (weight ratio of Zn/Ca soap is 6/4) in 100 phr of PVC is used as stabilizer, the Congo red time can reach 192 min, which is 131 min longer than 5 phr of the mixture of 3 phr of Zn stearate and 2 phr of Ca stearate as stabilizer. If 3 phr of mixture of Zn methylacrylate with Ca adipate (weight ratio of Zn/Ca soap is 4/6) and 2 phr of nano‐CeO₂ are used as co‐stabilizers, the Congo red time is 205 min. The combination of nano‐CeO₂ with Ca/Zn soap stabilizer shows an obvious improvement for the thermal stability of the PVC. J. VINYL ADDIT. TECHNOL., 20:243–249, 2014. © 2014 Society of Plastics Engineers     

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.     

Thermooxidative degradation of PVC in solution in the presence of metal stearate stabilizers

Detailed research has been carried out to determine the effect of metal stearates (PbSt₂, CdSt₂, BaSt₂, CaSt₂, and ZnSt₂) on the thermooxidative degradation of PVC in inert dilute solution. The induction periods of free HCl evolution increase in the presence of PbSt₂, CdSt₂, CdSt₂, BaSt₂, and CaSt₂, while ZnSt₂, due to ZnCl₂ formation, leads to fast HCl loss without induction period. The induction periods are much shorter than those obtained during thermal degradation, but the relative order of effectiveness of these stabilizers is the same as in inert atmosphere: PbSt₂ > CdSt₂ > BaSt₂ > CaSt₂ > ZnSt₂. After the induction period, the initial rates of free HCl evolution decrease as metal stearate concentrations increase. Surprisingly, this dependence is independent of the kind of metal. At higher stabilizer concentrations, the initial rates of free HCl loss during the thermooxidative degradation approach the initial dehydrochlorination rate of thermally degraded PVC. As UV and visible spectra indicate, there is a sharp change in the normalized integral absorption versus time plots at the end of the induction periods in the presence of PbSt₂, CdSt₂, and BaSt₂. Based on these experimental results, it has been concluded that effective metal stearates have manifold roles in the course of PVC stabilization under thermooxidative conditions. The main role of these compounds is not the replacement of labile structures and HCl-scavenging, but the blocking of the rapid zip-elimination is the most important event of the stabilization process. However, this blocking is reversible, which becomes effective mainly right after the consumption of the metal soaps (reversible blocking mechanism). Another important effect of these stabilizers is that they destroy peroxides and/or peroxy radicals (antioxidant effect).     

Synthesis of Bismuth(III)Neodecanoate and Its Application to Poly(Vinyl Chloride) as a Thermal Stabilizer

The bismuth(III)neodecanoate (Bi(Ne)₃) was synthesized via the method of co-reaction of bismuth oxide, neodecanoic acid, and acetic anhydride and then characterized by Fourier transform infrared spectroscopy (FTIR) and elemental analysis (EA). The effect of Bi(Ne)₃ as a thermal stabilizer on poly(vinyl chloride) (PVC) was assessed by thermal aging test, Congo red test, conductivity measurement, and thermogravimetric analysis, respectively. The results showed that Bi(Ne)₃ significantly provided PVC with a good initial color and long-term stability. Bi(Ne)₃ played a role in improving the stabilizing efficiency of PVC through absorbing hydrogen chloride (HCl) and displacing labile chlorine atoms in PVC molecular chains.