Photochemical stability and photostabilizing efficiency of poly(methyl methacrylate) based on 2-thioacetic acid-5-phenyl-1,3,4-oxadiazole complexes (original) (raw)
Related papers
The photostabilization of polystyrene (PS) films by 2,3-dihydro-(5-mercapto-1,3,4-oxadiazol-2-yl)-phenyl-2-(substituted)-1,3,4-oxazepine-4,7-dione compounds was investigated. PS films containing concentration of complexes 0.5% by weight were produced by the casting method from chloroform as a solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl and hydroxyl indices with irradiation time. The changes in viscosity average molecular weight of PS with irradiation time were also tracked (using benzene as a solvent). The quantum yield of the chain scission (Φ cs ) of these complexes in PS films was evaluated and found to range between 3.31 × 10 -6 and 7.89 × 10 -6 . Results obtained showed that the rate of photostabilization of PS in the presence of the additive follows the trend (I > II > III > IV). According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive like UV absorption, peroxide decomposer and radical scavenger.
The photostabilization of poly(vinyl chloride) (PVC) films by 2N-salicylidene-5-(substituted)-1,3,4thiadiazole compounds was investigated. The PVC films containing concentration of complexes 0.5% by weight were produced by the casting method from tetrahydrofuran (THF) solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl, polyene, and hydroxyl indices with irradiation time. The changes in viscosity average molecular weight of PVC with irradiation time were also tracked (using THF as a solvent). The quantum yield of the chain scission (U cs ) of these complexes in PVC films was evaluated and found to range between 4.72 Â 10 À8 and 8.99 Â 10 À8 . Results obtained showed that the rate of photostabiliza-tion of PVC in the presence of the additive followed the trend: SN > SC > SB > SI > SP According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among them, UV absorption, peroxide decomposer, and radical scavenger for photostabilizer mechanisms were suggested.
The Trend of Additives for Poly(vinyl chloride) as Photostabilizers: Article Review
Al-Nahrain Journal of Science, 2019
Conservation of poly(vinyl chloride) from the ultraviolet light that causes degradation, have very attention in recent decades. PVC formularizations have a large number of additives playing fundamental functions during their conversion and adjusting the behavior properties of final products. In this review, various types of additives are briefly discussed to show their important properties and reasons for addition to their essential mechanisms that cause retardation of photodegradation. The additives including organotin(IV), UV screeners, organic UV absorber and freeradical scavengers.
Molecules (Basel, Switzerland), 2018
Five Schiff bases containing a thiadiazole moiety have been used as poly(vinyl chloride) photostabilizers at low concentrations. The efficiency of Schiff bases as photostabilizers was investigated using various techniques, for example, the changes in poly(vinyl chloride) infrared spectra, molecular weight, chain scission quantum yield, and surface morphology were monitored upon irradiation with an ultraviolet light. Evidently, all the additives used inhibited poly(vinyl chloride) photodegradation at a significant level. The most efficient Schiff base exhibited a high level of aromaticity and contained a hydroxyl group. It seems possible that such photostabilization could be due to the direct absorption of ultraviolet radiation by the additives. In addition, Schiff bases could act as radical scavengers and proton transfer facilitators to stabilize the polymeric materials.
Photostabilising action of Zn and Ni salts of 3,5-DI-t.-butyl-4-hydroxybenzoic acid in polypropylene
European Polymer Journal, 1984
Abstrae~The photostabilising action of two metal chelates of the commercial antioxidant Shell acid (3,5-di-t.-butyl-4-hydroxybenzoic acid) viz. its zinc and nickel salts, is examined, using i.r. and derivative u.v.-visible spectroscopy and hydroperoxide analysis. The polymeric matrix was commercial polypropylene. The results show that both salts operate by inhibiting hydroperoxide formation during melt processing and thermo-oxidative conditions. The latter effect is attributed to a chain breaking donor mechanism which terminates, not alkylperoxyl, but macroalkyl radicals. Both salts are relatively efficient photostabilisers when compared with the parent antioxidant, probably because of their good photostability to both polychromatic and monochromatic radiation. The latter also shows that the nickel salt may also operate by scavenging alkoxyl and hydroxyl radicals during photo-oxidation. The addition of calcium stearate in conjunction with the salts produces some interesting effects which are explained in terms of metal exchange. 1031 EPJ.
The photostabilization of poly(methyl methacrylate) (PMMA) films having 2-(6-methoxynaphthalen-2-yl)propanoate and Sn(II), Ni(II), Zn(II) and Cu(II) complexes was investigated. The production of PMMA films containing such complexes (0.5% by weight) was carried out by the casting method using chloroform. The photostabilization activities of the compounds were determined by monitoring the hydroxyl index with irradiation time. The quantum yield of the chain scission (Φcs) for the complexes in PMMA films and the changes in the viscosity average molecular weight of PMMA with irradiation time were evaluated. The rate of photostabilization for PMMA in the presence of the additives was found to follow the order NiL2 > CuL2 > ZnL2 > SnL2 (L, ligand). Depending on the structure of the additive, such as a peroxide decomposer, UV absorption or a radical scavenger for the photostabilizer, several mechanisms are suggested.
International Journal of Chemistry, 2010
The influence of introducing benzothiazole and benzimidazole as a pending groups into the repeating unit of PVC has been studied on the bases of photostability measurements. The photostability of modified polymers were studied by monitoring the carbonyl Index (I CO), polyene index (I po) and hydroxyl index (I OH), all results obtained indicated that PAA, PSS, PNN, PSA and PNA gave lower growth rate of I CO , I PO and I OH with irradiation time with respect to unmodified PVC film (control). The following trends of photostability are obtained PAA>PSS>PNN>PSA>PNA According to the experimental results several reaction mechanisms were proposed depending on the presence of benzothiazole and benzimidazole moieties in the polymer chain. The mode of chain scission was also investigated by measuring the variation of average viscosity molecular weight with irradiation time for modified PVC. The degree of deterioration (α) and the average number of chain scission (S) values were also calculated.
PHOTO STABILIZERS FOR POLYMERS - NEW TRENDS (Review)
2015
This paper is a review presenting some new trends for photostabilization of polymers by application of polymerizable stabilizers, so that chemically or “self-stabilized” polymers can be obtained. The derivatives of 2-(2-hydroxyphenyl)-2Hbenzotriazole (HBT) and 2,2,6,6-tetramethylpiperidine (HALS) are among the most effective stabilizers used, so their polymerizable derivatives have been the objects of many investigations. The combination of different types and chemical structures of stabilizers, acting according to different mechanisms, is a very promising method to obtain a new type of stabilizer. The influence of these compounds on the photostability of copolymers with some vinyl monomers was demonstrated. New approaches for “one-step” coloration and stabilization of polymers by a combination “in-one molecule” of a chromophore and a stabilizer were described. Two of the possibilities are presented - when the stabilizer and the chromophore are combined in-one molecule through an s-...
Tin-Naphthalene Sulfonic Acid Complexes as Photostabilizers for Poly(vinyl chloride)
Molecules, 2021
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...
Polymer Degradation and Stability, 1984
The interactions of three metal chelates (nickel (II) 2,2'-thiobis (4-tertoctyl-phenolato), n-butylamine (Cyasorb UV 1084) and the nickel and calcium derivatives of bis(ethyl-3,5-di-tert-butyl-4-hydroxybenzyl) phosphonate (lrgastab 2002 and Irganox 1425)) with other commercial additives, in the stabilisation of polypropylene.film, are examined using normal and second-order derivative ultraviolet and infra-red spectroscopic techniques. It is shown that the observed behaviour is dependent on the particular additive, the processing history of the polymer and the metal chelate concerned, and is therefore highly complex. All three chelates show antagonism with a hindered piperidine, bis(2,2,6,6tetramethyl-4-piperMinyl) sebacate (Tinuvin 770), in unprocessed polymer, whereas one of the chelates behaves synergistically with this additive in processed samples. The chelates also show antagonism with a primary antioxidant, tris((3-(3',5'-di-tert-butyl-4-hydroxybenzyl)-2"aceto-ethyl)) isocyanurate (Goodrite 3125), whereas, with a secondary antioxidant, distearyl pent-aerithrityl diphosphite (Weston 618), their behaviour is synergistic in both unprocessed and processed polymer. Two of the chelates show synergism with 2-hydro.vy-4-n-octoxybenzophenone (Cyasorb UV531), the remaining chelate showing antagonism. Mixtures containing a three-additive system show a more complex behaviour. The results are explained in terms of hydroperoxide decomposition, inhibition, stabiliser dispersion, ultraviolet stability and additive compatibility.