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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

N-(N′-Arylamino)maleimide derivatives N-(N′-RPh)AMI (R = H, 2-NO2, 4-NO2, 2,4-di-NO2) were investigated as organic thermal stabilizers and costabilizers for rigid poly(vinyl chloride) (PVC) at 180°C in air. Their stabilizing efficiencies were evaluated by measuring the induction period (Ts, the period during which no evolved hydrogen chloride could be detected) and the dehydrochlorination rate as measured by continuous potentiometric determination, as well as the extent of discoloration. The stabilizing efficiencies were compared with those of some industrially used stabilizers. The results clearly revealed the greater efficiency of all of the investigated derivatives except the unsubstituted N-(N′-Ph)AMI, which was found to possess efficiency comparable with those of the reference stabilizers. The dinitro aminomaleimide [2,4-di(NO2)AMI] exhibited the highest efficiency. The stabilizing efficiencies of the AMIs are attributed to the replacement of the labile chlorine atoms on the PVC chains by more thermally stable stabilizer moieties. An ionic mechanism is proposed that explains the stabilizing action. Mixing the investigated stabilizers with cyanoguanidine, which is known to act as an HCl absorber, led to a true synergistic effect. The effect of the degradation process of adding small amounts of K2CO3 to PVC stabilized with the materials under investigation also is discussed. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers

The reaction of poly(vinyl chloride) (PVC) with N-(N′-arylamino)maleimide derivatives was studied. The thermal stability of the modified polymer was improved markedly when compared with that of the unmodified polymer. The stability improvement was attributed to the replacement of the labile chlorine atoms by more stable organic groups. The modified polymer also showed a lower extent of discoloration when compared with that of unmodified PVC. In order to introduce a polymeric stabilizer into PVC, the dienophilic monomer was chemically grafted onto the polymeric chains. The mechanism of the chemical modification as well as that of the graft copolymerization are discussed. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers.

Three types of N[4-(N-substituted amino carbonyl)phenyl] maleimide (RPhMI:N-substituent (R) = phenyl, cyclohexyl, p-chlorophenyl) were grafted onto poly(vinyl chloride) (PVC) films by using gamma irradiation. The effects of different parameters on the graft yield were investigated. These parameters included radiation dose and monomer concentration. Thermal properties of the grafted polymer were investigated by the determination of dehydrochlorination rate, thermal gravimetric behavior, and UV stability.

The chemical 5,6,7,8-Tetrahydro-2-mercapto-4-(p-methoxyphenyl)-3-quinolinecarbonitrile (TMQC) has been investigated as a thermal stabilizer for rigid poly(vinyl chloride) (PVC) at 180°C in air. The results reveal the higher stabilizing efficiency of the investigated material, as shown by the longer induction period obtained in its presence relative to those produced by commonly used industrial stabilizers. Ultraviolet irradiation of the polymer stabilized by TMQC gives a lower extent of discoloration compared to that of unstabilized PVC. Reaction of TMQC with the polymer in solution also has been studied in order to investigate the mechanism of stabilization.