Stabilization of poly(vinyl chloride). VIII. Synergisms between epoxy compounds and metal soaps

Effects of bisphenol A type epoxy compounds involving various average molecular weights on the zinc stearate/calcium stearate and the cadmium stearate/barium stearate synergetic soaps induced thermal stabilization of poly(vinyl chloride) (PVC) were investigated by colorimetry. The remarkable stabilization effects of epoxides could not be observed on the PVC films without synergetic soaps, while the stabilization of PVC was markedly enhanced by combined use of epoxides and synergetic soaps. The appearance of excessive coloration of cool color producing metal chloride–polyene complexes which were an origin of abrupt discoloration of stabilized PVC was retarded by using epoxides together with synergetic soaps. Moreover, as for PVC with or without synergetic soaps, the epoxy compounds did not inhibit the formation of longer polyene chains which were a chromophore for yellow orange of aged PVC. Further colorimetries and IR or X-ray photoelectron spectroscopies on the various PVC containing epoxy compounds and zinc chloride indicated that the epoxy groups caught the zinc chloride. The synergetic effect between epoxy compounds and synergetic metal soaps is ascribed to the action that the epoxides serve as an acceptor for the excessive cool color producing metal chloride produced from zinc stearate and cadmium stearate to retard the abrupt discoloration of stabilized PVC.     

Stabilization of poly(vinyl chloride). VI. Synergetic effects of aminopolycarboxylates or nitrogen-containing agents with zinc stearate/calcium stearate soap

Discoloration such as zinc burning was observed in aged poly(vinyl chloride) (PVC) compounded with synergetic soaps. This discoloration was caused by excessive formation of cool color-producing π complexes formed between double bonds in polyene chain and zinc chloride or cadmium chloride produced from the corresponding metal soap. The appearance of excessive color of the π complexes was reduced by adding some masking agents into PVC admixed with synergetic soaps. In the present study differences in masking effects results by adding solid or an aqueous solution of aminopoly-carboxylates such as glycine, ethylenediaminetetraacetates, and nitrilotriacetates to PVC stabilized with zinc stearate/calcium stearate synergetic soap. The mechanism of synergetic effect between nitrogen-containing agents and synergetic soaps upon the stabilization of PVC is also investigated by colorimetry. The aqueous solution of aminopolycarboxylates exhibits a greater masking effect than the solid. The masking effect of aminopolycarboxylates depends on the ease with which they are fnely dispersed into PVC. Colorimetry indicated that the masking effect of aminopolycarboxylates and other nitrogen-containing agents depends on forming the colorless complex compound with the excessive cool color-producing metal chlorides.     

Stabilization of poly(vinyl chloride). V. Synergism between metal soaps and polyols upon stabilization of poly(vinyl chloride)

The marked discolorations observed on aged poly(vinyl chloride) (PVC) containing synergetic metal soaps, in the early heating stage, were due to the excessive coloration of π complex of metal chloride and double bonds in the polyene chain. These excessive colorations were inhibited by masking the excessive metal chloride with some masking agents, thereby slowing down the abrupt discoloration of PVC. In this paper, the masking effect of various alcohols such as 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, hexylene glycol, glycerol, 1,2,4-butanetriol, trimethylolethane, trimethylolpropane, meso-erythritol, pentaerythritol, sorbitol, and dipentaerythritol is investigated. The polyhydric alcohols, except dihydric alcohols, showed superior masking effect and markedly improved the thermal stabilization effects of synergetic metal soaps. The mechanism for the synergetic effects between polyols and metal soaps should be based on the masking effect of polyols, owing to the formation of the colorless complex of polyols with excess metal chlorides obtained from the metal soap.     

Stabilization of poly(vinyl chloride). III. Synergism between metal soaps and masking agents on the stabilization of poly(vinyl chloride)

The stabilization mechanism by synergetic metal soaps containing complementary colors was previously reported. With increased heating times, the color of heated poly(vinyl chloride) (PVC) films containing Cd/Ba and Zn/Ca synergetic soaps markedly deviated from the polyene color. These color deviations usually decreased the thermal stability of PVC. Discoloration from polyene color to blue appeared especially on PVC films containing Zn/Ca synergetic soap and was concomitant with a marked decrease in thermal stability. The stabilization of PVC containing synergetic metal soaps can be improved by masking or removing the excessive color. In this work, the addition of various masking agents, such as ethylenediaminetetraacetic acid, o-phenanthroline, triethanolamine, urea, N,N′ -dimethylolurea, melamine, stearylamide, and lactams, to PVC containing synergetic metal soaps was investigated. It was shown that these masking agents do markedly slow down the discoloration of PVC.     

Synergetic effect of dimerized pentaerythritol esters with synergetic metal soap on the stabilization of poly(vinyl chloride)

The synergetic effect of dimerized pentaerythritol esters, as novel costabilizer, with metal soap, the mixture of zinc and calcium stearates, as stabilizer, on the undesirable discoloration of poly(vinyl chloride) (PVC) by heating was investigated. The dimerized pentaerythritol esters were prepared by the esterification of pentaerythritol using stearic acid and the dimerization of the obtained pentaerythritol ester using unsaturated dicarboxylic acid. This dimer was used to improve its poor compatibility with PVC. The degree of esterification for pentaerythritol was varied from half to the full amount of hydroxyl groups. Both stabilizer and costabilizer were compounded into poly(vinyl chloride) through roll mixing. As a result, the dimerized pentaerythritol esters showed good dispersibility in poly(vinyl chloride). The effect of suppressing the discoloration was obtained in the systems used, not only the half‐esterified type but also the full‐esterified type, although it had no hydroxyl group. The abrupt discoloration was caused by the formation of a π complex between cool color producing metal chloride, i.e., zinc chloride from the metal soap and double bonds from the dehydrochlorination in poly(vinyl chloride) chain. Usually, the hydroxyl group containing compounds are said to be useful for suppressing the discoloration because the hydroxyl group captures the metal chloride. In the costabilizing effect of the full esterified type, it was clarified from the X‐ray photoelectron spectroscopic analysis and infrared spectrum observations for the model mixtures, that the decomposition of the ester group could occur, and the excess zinc chloride was captured as colorless zinc carboxylate. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2029–2037, 2001     

Synergistic effect of metal soaps and natural zeolite on poly(vinyl chloride) thermal stability

The synergistic effect of metal soaps (zinc stearate and calcium stearate) and/or natural zeolite (clinoptilolite) on PVC thermal stability was investigated. For this purpose, PVC plastisol was prepared by mixing poly(vinyl chloride) (PVC) and dioctyl phthalate (DOP) and stabilized with different amounts of metal soaps and zeolite. Kinetic studies of dehydrochlorination at 140 and 160°C were done for unstabilized and stabilized PVC plastigels using 763 PVC Thermomat equipment. The stabilizing effect of zeolite on the increase in the induction period of the sample was considered to result from the absorption of HCl, a property that was thought to reduce the autocatalytic effect of HCl evolved at the initial stages of dehydrochlorination. Since the induction time of the sample having 0.53% of zinc stearate and 0.53% of zeolite was higher than those of the PVC plastigels having only zinc stearate or zeolite, the synergistic effect on thermal stability was observed at low levels of these additives. J. VINYL. ADDIT. TECHNOL., 11:47–56, 2005. © 2005 Society of Plastics Engineers     

Stabilization of poly(vinyl chloride). II. Stabilization mechanism through metal soaps by complementary color action

In a previous paper, it was pointed out that the stabilization mechanism through metal soaps might be affected by an effect of complementary color. In this work, the colors of heated poly(vinyl chloride) (PVC) films mixed with various metal soaps were investigated by using a differential colorimeter and a spectrophotometer. Monochromatic coloration was observed with PVC, PVC–Ca stearate, and PVC–Ba stearate systems. On the other hand, the phenomenon of color mixing was observed with PVC–Zn stearate, PVC–Cd stearate, PVC–Zn/Ca stearate, and PVC–Cd/Ba stearate systems. In particular, achromatic color remained with PVC–Zn/Ca stearate and Cd/Ba stearate systems for longer heating periods. This means that the stabilization mechanism for PVC compounded with metal soaps should be effected finally by subtractive complementary colors situated between polyene color and the color effected with the metal complex, in addition to being subject to the usual chemical stabilization mechanisms.     

Stabilization of poly(vinyl chloride). I. Change in color of poly(vinyl chloride) compounded with some metal soaps

Poly(vinyl chloride) (PVC) with one or more metal salts added was colored by the action of heat to investigate the stabilization mechanism. The coloration and the color difference of heated PVC compound films varied according to the metal salt added. The decoloration of the colored compound films was advanced markedly in THF, DMF, acetone, and ammonia. On the other hand, the heated achromatic PVC film containing Cd/Ba soaps underwent an opposite change, from colorless to yellow orange, in the above materials. This means that the coloration of heated compound films may result from the formation of some complex (for example, π complex of the polyene with the metal chloride). Furthermore, the colored film with cadmium stearate was decolored by roll mixing with the colored film containing barium stearate. These results indicate that the stabilization with metal soaps may be founded on a physical phenomenon such aa an effect of complementary color.     

Studies in the thermal degradation of poly(vinyl chloride)

Thermal degradation of poly(vinyl chloride) (PVC) was studied in nitrogen atmosphere in the presence of rubber seed oil and epoxidized rubber seed oil, barium and lead soaps of rubber seed oil, and epoxidized seed oil at various temperatures. The rate of dehydrochlorination at 1% degradation and the time required to attain 1% degradation were used to assess the effect of the thermal susceptibility of PVC to dehydrochlorination. It was found that epoxidized rubber seed oil, the metal soaps of rubber seed oil, and epoxidized rubber seed oil markedly enhance the thermal stability of PVC. The order of increasing stabilizing influence was metal soaps of epoxidized rubber seed oil > metal soaps of rubber seed oil > epoxidized rubber seed oil > rubber seed oil. © 1993 John Wiley & Sons, Inc.     

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     

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.     

Radiation yield of hydrogen chloride in the poly(vinyl chloride) foils irradiated by accelerated electrons

The G_HCl values of PVC foils, containing 18% of dioctylphthalate, irradiated with accelerated electrons were studied after addition of various amounts of the stabilizers: (I) ethylene glycol bis-β-aminocrotonate, (II) calcium/zinc laurate + epoxy compounds, (III) calcium/zinc stearate, (IV) dioctyltin bis(octylthioglycolate). The effect of stabilization turned out to be very good, especially when stabilizer I was used. In the case of soft PVC foils in contact with water, elution of hydrogen chloride occurs. This creates difficulties in preparing PVC foils sterilized radiatively for medical purposes, especially if the foils are expected to be in contact with water.     

取代二苯基脲对PVC的热稳定作用——性能递变规律与机理

用烘箱变色法研究了几种取代二苯基脲对聚氯乙烯(PVC)的热稳定性能。结果表明,取代二苯基脲均具有类似于硬脂酸锌的热稳定特性,属于初效型主热稳定剂,与硬脂酸钙(CaStz)和环氧大豆油并用存在着明显的协同效应;取代二苯基脲的热稳定性能随其分子中与尿母核相连基团的吸电子性的增强而提高;根据其热稳定性能递变规律可以推测出取代二苯基脲是通过其拨基C原子作为亲电原子与PVC发生亲电反应而发挥热稳定作用的,传统的Frye和Horst理论不适用于取代二苯基脲。     

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     

Thermal dehydrochlorination of poly(vinyl chloride) in the presence of Jatropha seed oil

Thermal degradation of poly(vinyl chloride) was studied in a nitrogen atmosphere in the presence of Jatropha seed oil, epoxidized Jatropha seed oil, and soaps (barium and cadmium) of Jatropha seed oil at various temperatures. The rate of dehydrochlorination measurement at 1% degradation, R_DH, and the time required for dehydrochlorination to attain 1% conversion were used to assess the effect of the additives on the susceptibility of the polymer to dehydrochlorination. It was found from the kinetic studies and the results from viscosity measurements on degraded polymer samples that the Jatropha seed oil derivatives suppressed the initial loss of HCl from the polymer and the extent of polymer chain scission accompanying the dehydrochlorination process. Thermal degradation studies of poly(vinyl chloride) in the presence of mixtures of barium and cadmium soaps of Jatropha seed oil were also carried out. It was found that soap mixtures containing less than 80 wt% cadmium soap exerted a deleterious (antagonistic) effect on the degradation of poly(vinyl chloride) while in the presence of soaps containing more than 80 wt% cadmium soap, considerably lower values of R_DH and higher values of t_DH were observed. The soap mixture containing 90 wt% cadmium soap was found to exhibit a remarkedly improved stabilizing effect on the dehydrochlorination of poly(vinyl chloride). © 1995 John Wiley & Sons, Inc.     

Diamide derivatives as photostabilizers for plasticized poly(vinyl chloride)

Some diamide derivatives have been prepared, characterized, and investigated as photostabilizers for plasticized poly(vinyl chloride) (PVC), containing dioctyl phthalate and dibutyl phthalate in a concentration of 30% by weight of the polymer. The stabilizing efficiency of the prepared diamides was evaluated by determining the weight loss percentage that resulted from HCl evolution during the photodegradation process. Moreover, the efficiency was evaluated by determining the amount of gel formed as well as the intrinsic viscosity of the soluble fractions of the photodegraded polymer. The extent of discoloration of the photodegraded stabilized and plasticized PVC was also investigated. The stabilization mechanism and the effect of plasticizers on the photostability of PVC are discussed. J. Vinyl Addit. Technol., 2008. © 2008 Society of Plastics Engineers     

无毒金属皂间协同热稳定效果的研究

通过静态刚果红法、热烘法来研究锌皂与各种不同金属皂间的协同热稳定效果。研究结果表明：初期型锌皂与其它长期型金属皂复合能显著改善初期热烘变色,表现良好协同稳定作用;新型锌的热稳定时间是硬脂酸锌的两倍,采用新型锌的复合皂的热稳定性能均比采用硬脂酯锌的复合皂明显提高,其中新型锌与硬脂酸钙的复合皂热稳定性能最好。     

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     

Thermal stabilization of poly(vinyl chloride) treated with organoaluminium compounds: 2. Effect of solvents

Poly(vinyl chloride) was treated with organoaluminium compounds in various solvents. The strong Lewis acids, alkyl-aluminium chlorides, predominantly cause the decomposition of PVC rather than the alkylation of the polymer regardless of solvents. In non-polar hydrocarbons, the treatment of PVC with trialkylaluminiums leads to increased heat sensitivity. In 1,2-dichloroethane solution and in benzene slurry, the trialkylaluminium-treated PVC exhibits significant improvement in thermal stability over unmodified PVC due to the exchange of the labile chlorines inherent in the polymer for relatively more stable alkyl groups. The apparent activation energy of the reaction of PVC with triethylaluminium in benzene slurry is the same as that in 1,2-dichloroethane solution, but the initial rate of alkylation of the polymer in benzene is about 10 times faster than that of the polymer in 1,2-dichloroethane. The aluminium concentration in the PVC particles is about twice that calculated from the swelling ratio of the PVC particles in benzene, suggesting that triethylaluminium not only penetrates into the swollen particles but is also adsorbed on the surface of the PVC particles to cause the increase in the aluminium concentration around the labile chlorines in the polymer chain. The alkylated PVC, compounded with only small amounts of zinc soap including an epoxidized oil and a chelating compound, shows excellent initial stabilization and long-term stability superior to the starting polymer even when this is compounded with 3 parts organotin stabilizers.     

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.