Tin-Naphthalene Sulfonic Acid Complexes as Photostabilizers for Poly(vinyl chloride)

Abstract

Poly(vinyl chloride) degrades when exposed to ultraviolet light for long durations; therefore, the photostability of polymeric materials should be enhanced through the application of additives. New organotin complexes containing 4-aminonaphthalene-1-sulfonic acid were synthesized and their role as poly(vinyl chloride) photostabilizers were evaluated. The reaction of 4-amino-3-hydroxynaphthalene-1-sulfonic acid and appropriate di- or trisubstituted tin chloride (triphenyltin chloride, tributyltin chloride, dibutyltin dichloride, and dimethyltin dichloride) in methanol under reflux gave the corresponding tin-naphthalene complexes with yields of 75%–95%. Elemental analyses and spectroscopic techniques including infrared and nuclear magnetic resonance (proton and tin) were used to confirm their structures. The tin complexes were added to poly(vinyl chloride) to produce thin films that irradiated with ultraviolet light. Various parameters were assessed, such as the weight loss, formation of specific functional groups, changes in the surface due to photoirradiation, and rate constant of photodegradation, to test the role played by the organotin complexes to reduce photodegradation in polymeric films. The results proved that organotin complexes acted as photostabilizers in these circumstances. The weight loss, formation of fragments containing specific functional groups, and undesirable changes in the surface of polymeric films were limited in the presence of organotin complexes. Organotin complexes containing three phenyl groups showed the most desirable stabilization effect. These act as efficient primary and secondary photostabilizers, and as decomposers for peroxides. In addition, such an additive inhibits the dehydrochlorination process, which is the main cause of poly(vinyl chloride) photodegradation.

Tin Complexes of 4-(Benzylideneamino)benzenesulfonamide: Synthesis, Structure Elucidation and Their Efficiency as PVC Photostabilizers

“…The optical images of the blank PVC surface before photoirradiation were smooth and regular with no cracks or discoloration. After irradiation, the surface showed cracks, white spots, darkened color, irregularity, and roughness [43,54]. The changes due to photoirradiation are mainly a result of dehydrochlorination and elimination of volatiles and breaking of bond [55].…”

“…roughness [43,54]. The changes due to photoirradiation are mainly a result of dehydrochlorination and elimination of volatiles and breaking of bond [55].…”

“…For example, the fold decrease in the Rq was 3.3-6.0 using Schiff bases [56][57][58], 5.2-16.6 using organotin complexes [59][60][61][62][63], and 16.8 using polyphosphates [64]. However, the use of tin complexes containing naphthalene sulfonic acid led to a remarkable decrease in the Rq of PVC up to 59.9-fold, possibly owing to the extended conjugation within the aromatic system of naphthalene [43]. one of the highest compared with those reported [56][57][58][59][60][61][62][63][64].…”

“…The efficiency of tin complexes is highly dependent on the organic moieties and substituents attached to the tin (Sn) atom [39]. Several tin complexes containing different aromatic moieties have been used to stabilize PVC against UV irradiation [40][41][42][43]. For example, tin complexes containing naphthalene sulfonic acid have been proven to be efficient in reducing the roughness factor (Rq) of PVC blends when irradiated with UV light for durations of up to 300 h [43].…”

FTIR, Weight, and Surface Morphology of Poly(vinyl chloride) Doped with Tin Complexes Containing Aromatic and Heterocyclic Moieties

“…Banned additives include flame retardants (e.g., chlorinated biphenyls), plasticizers (e.g., phthalates), stabilizers (e.g., phosphites), and those containing metals [ 20 , 21 , 22 , 23 ]. Various additives such as polyphosphates [ 24 ], polybenzimidazoles [ 25 ], metal oxides [ 26 , 27 , 28 ], pigments [ 29 ], Schiff bases [ 30 , 31 , 32 , 33 , 34 ], and substituted tin complexes containing aromatic moieties [ 35 , 36 , 37 , 38 ] have been used to improve photostability of PVC.…”