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Thermal Stabilizers (thermal + stabilizer)
Selected AbstractsThermal degradation behavior of poly(vinyl chloride) in the presence of poly(glycidyl methacrylate)JOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008Magdy W. Sabaa Abstract The thermal degradation behavior of poly(vinyl chloride) (PVC) in presence of poly(glycidyl methacrylate) (PGMA) has been studied using continuous potentiometric determination of the evolved HCl gas from the degradation process from one hand and by evaluating the extent of discoloration of the degraded samples from the other. The efficiency of blending PGMA with dibasic lead carbonate (DBLC) conventional thermal stabilizer has also been investigated. A probable radical mechanism for the effect of PGMA on the thermal stabilization of PVC has been suggested based on data reported by FTIR and elemental analyses. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Studying and increasing light stability of rotomolding grade of polyethyleneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008E. Feyz Abstract This article covers the state-of-the-art light stabilizer for rotational molding and the influence of synergistic effects between light and thermal stabilizers, which improve physical and mechanical properties. Different formulations of polyethylene (PE) with light stabilizer, thermal stabilizer, and acid scavenger have been produced in twin-screw extruder. To study the light stability, sheets that produced by injection-molding machine have been put in weather-ometer instrument for 1000 h. After and before that, physical and mechanical properties have been evaluated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Effect of the combination of a benzophenone-type ultraviolet absorber with thermal stabilizers on the photodegradation of poly(vinyl chloride)JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 1 2010Xiuqin Xiang The effect of the combination of a UV absorber (Chimassorb 81) with different types of thermal stabilizers, including an organic calcium complex and an organotin mercaptide, on the photodegradation of poly(vinyl chloride) (PVC) was investigated by color difference measurements, UV,Vis spectroscopy, Fourier-transform infrared spectroscopy, thermogravimetric (TG) analysis, and viscosity-average molecular weight determination. Films of PVC containing 0.5 phr of Chimassorb 81, with and without 2 phr of a thermal stabilizer, were prepared by solution casting. Then the accelerated UV weathering of the films was carried out under xenon light with an irradiance of 0.51 W/(m2 · nm) at 65°C. The results showed that both Chimassorb 81 and the mixture of Chimassorb 81 with the organic calcium complex showed good behavior in inhibiting the photodehydrochlorination and photooxidation of PVC. In contrast, the combination of Chimassorb 81 and methyltin mercaptide significantly accelerated initial color development during the final 200 h of exposure because of the UV sensitivity of the organotin. Moreover, when Chimassorb 81 and the methyltin mercaptide were used together to stabilize PVC films, the expected antioxidant effect of the mixture was not observed, in contrast to the behavior found with other stabilized systems, perhaps because the Chimassorb 81 had been depleted by the methyltin mercaptide during the UV irradiation. The TG analysis revealed that ultraviolet irradiation had caused severe destruction of the PVC chains. However, addition of Chimassorb 81 or the combination of Chimassorb 81 with the organic calcium complex effectively prevented the destruction, as was demonstrated by changes in the activation energies for thermal degradation. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers [source] Studying and increasing light stability of rotomolding grade of polyethyleneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008E. Feyz Abstract This article covers the state-of-the-art light stabilizer for rotational molding and the influence of synergistic effects between light and thermal stabilizers, which improve physical and mechanical properties. Different formulations of polyethylene (PE) with light stabilizer, thermal stabilizer, and acid scavenger have been produced in twin-screw extruder. To study the light stability, sheets that produced by injection-molding machine have been put in weather-ometer instrument for 1000 h. After and before that, physical and mechanical properties have been evaluated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Effect of cyanoguanidine-metal and urea-metal complexes on the thermal degradation of poly(vinyl chloride)JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 1 2010Abir S. Abdel-Naby Tin, nickel, cobalt, zinc, and copper complexes of cyanoguanidine and urea were synthesized and investigated as thermal stabilizers for rigid poly(vinyl chloride) at 180°C in air. Their stabilizing efficiencies were evaluated by measuring the induction period (the period during which no evolved hydrogen chloride could be detected) and the rate of dehydrochlorination as determined by continuous potentiometric measurements, in addition to the extent of discoloration. The results clearly revealed the greater efficiency of all of the investigated metal complexes as compared to those of well-recognized reference stabilizers. The tin complex always exhibited the highest efficiency irrespective of the type of ligand used. The nickel and cobalt complexes also possessed high stabilizing efficiencies. The order of the stabilizing potency of the various metal complexes was Sn , Co, Ni , Zn, Cu. Combining the ligand itself with dimethyltin- s,s,-bis (isooctyl thioglycolate), as a reference stabilizer containing a tin atom, led to a true synergism. This synergistic effect might be attributed to the formation in situ of a complex between the ligand and the tin atom. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers [source] Effect of the combination of a benzophenone-type ultraviolet absorber with thermal stabilizers on the photodegradation of poly(vinyl chloride)JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 1 2010Xiuqin Xiang The effect of the combination of a UV absorber (Chimassorb 81) with different types of thermal stabilizers, including an organic calcium complex and an organotin mercaptide, on the photodegradation of poly(vinyl chloride) (PVC) was investigated by color difference measurements, UV,Vis spectroscopy, Fourier-transform infrared spectroscopy, thermogravimetric (TG) analysis, and viscosity-average molecular weight determination. Films of PVC containing 0.5 phr of Chimassorb 81, with and without 2 phr of a thermal stabilizer, were prepared by solution casting. Then the accelerated UV weathering of the films was carried out under xenon light with an irradiance of 0.51 W/(m2 · nm) at 65°C. The results showed that both Chimassorb 81 and the mixture of Chimassorb 81 with the organic calcium complex showed good behavior in inhibiting the photodehydrochlorination and photooxidation of PVC. In contrast, the combination of Chimassorb 81 and methyltin mercaptide significantly accelerated initial color development during the final 200 h of exposure because of the UV sensitivity of the organotin. Moreover, when Chimassorb 81 and the methyltin mercaptide were used together to stabilize PVC films, the expected antioxidant effect of the mixture was not observed, in contrast to the behavior found with other stabilized systems, perhaps because the Chimassorb 81 had been depleted by the methyltin mercaptide during the UV irradiation. The TG analysis revealed that ultraviolet irradiation had caused severe destruction of the PVC chains. However, addition of Chimassorb 81 or the combination of Chimassorb 81 with the organic calcium complex effectively prevented the destruction, as was demonstrated by changes in the activation energies for thermal degradation. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers [source] Photostabilizing effect of some thermal stabilizers for poly(vinyl chloride) in the presence of fillerJOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 4 2009D. Braun The commercial stabilizers Ca-Zn stearate and dibutyltin- S,S,-di(isooctyl thioglycolate) have been investigated as photostabilizers for rigid poly(vinyl chloride) (PVC) in the presence of two types of CaCO3 as filler (natural and modified). The results reveal the costabilizing efficiency of CaCO3, especially the natural type, when it is used in concentrations of 1,30% by weight. The stabilizing efficiency of CaCO3 is indicated by the longer induction period and the lower rate of dehydrochlorination. The stabilizing effect of CaCO3 may be attributed because of its opacity and action as a screening agent by reflecting ultraviolet light, thereby hindering the penetration of the light into the polymer matrix. In addition, CaCO3 has the ability to absorb the HCl evolved during processing. The slight difference in the stabilizing effect of natural CaCO3 compared to that of the modified one can be attributed to the modification process, that may decrease the number of active sites on the surface of CaCO3, that in turn are responsible for the absorption of the evolved HCl. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers [source] Mechanism of action and effectiveness of ester thiols as thermal stabilizers for poly(vinyl chloride),JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 4 2007Xianlong Ge Organic thiols containing at least one carboxylate ester group (ester thiols) are excellent thermal stabilizers for both rigid and plasticized poly(vinyl chloride) (PVC). Their mechanism of action is shown to involve the deactivation of unstable structural defects by nucleophilic chloride displacement, the retardation and removal of coloration through thiol additions to polyene double bonds, and the prevention of autoacceleration during thermal dehydrochlorination through polyene shortening reactions and the scavenging of free radicals formed from polyenes and HCl. An unusually facile displacement of labile chloride that is favored by thiol acidity can account, at least in part, for the relatively high effectiveness of dipentaerythritol hexakis(mercaptoacetate) as a stabilizer. J. VINYL ADDIT. TECHNOL., 13:170,175, 2007. © 2007 Society of Plastics Engineers [source] | ||||||||||