The thermal degradation of some polymeric di-alkyl esters of itaconic acid

One group of polymers that may help relieve the dependence on crude oil is based on itaconic acid, the biotechnological production of which has become feasible. Itaconic acid and its derivatives can easily be incorporated into polymers and may serve as a substitute for petrochemically derived acrylate or methacrylate monomers. The applications of polymers based on itaconic di-esters depend largely on their thermal stability. The thermal stability of poly(di-itaconates) is dependent, not only on the general structure of the monomer repeating unit, but also on the structure of the ester substituent. Depolymerization, initiated by b-scission or random main chain scission, is the dominant thermolysis mechanism in most cases. The depolymerization of poly-(di-itaconates) may be accompanied by de-esterification, elimination, cross-linking, random main or side chain scission and carbonization. Comparison of the thermal degradation mechanism of polymeric di-esters of itaconic acid to that of corresponding poly(methacrylates) confirms the viability of substituting poly(methacrylates) by poly(di-itaconates). [Projekat Ministarstva nauke Republike Srbije, br. 172062

Simplification of the synthesis of the reversible addition–fragmentation chain transfer agent 2-(2-cyanopropyl)-dithiobenzoate

The general literature procedure for the preparation of the reversible addition–fragmentation chain transfer (RAFT) agent 2-(2-cyanopropyl)-dithiobenzoate (CPDB) was modified by omitting the recrystallisation of the intermediate di(thiobenzoyl)disulphide. The yield of the CPDB in the simplified synthesis was increased four times compared to the standard one. The behaviour of the CPDB obtained by the modified procedure and by the standard one in the polymerisation of methyl methacrylate was investigated. The CPDB synthesized by the simplified procedure showed itself to be a good RAFT agent, giving excellent control over the polymerisation of methyl methacrylate and it behaved in the same manner as the CPDB prepared by the literature method. The obtained poly(methyl methacrylate) had a narrow molecular weight distibution (PD = 1.1)

The thermo-oxidative degradation of poly(2-chloroethyl methacrylate) in the presence of antioxidants

U radu je ispitana oksidativna termijska degradacija poli(2-hloretil metakrilata) (PCEMA) u prisustvu komercijalnih antioksidanata amino tipa CHIMASSORB 119 (CH 119) i CHIMASSORB 944 (CH 944) i smeše antioksidanata, IRGANOX 1010, fenolnog derivata, i IRGAPHOS 168, fosfita (maseni udeli 1:1). Ispitivanja su izvedena termogravimetrijskom (TG) metodom, a na osnovu karakterističnih temperatura 10% gubitka mase, oblika diferencijalnih TG (DTG) krivih i srednjih vrednosti energije aktivacije termijske degradacije, ispitivan je uticaj pojedinih antioksidanata.The oxidative thermal degradation of poly(2-chloroethyl methacrylate) (PCEMA) was studied in the presence of the following commercial antioxidants: CHIMASSORB 119 (CH 119) and CHIMASSORB 944 (CH 944), both based on amines, and a mixture of IRGANOX 1010, a phenol derivative, and IRGAPHOS 168, a phosphite (mass ratio 1:1), by the thermogravimetric (TG) method. On the basis of the obtained results, the characteristic temperatures of 10% mass loss, Tio%, the shape of the differential TG (DTG) curves and mean values of the thermal degradation activation energy, Ea, it was concluded that the commercial photostabilisers CH 119 and CH 944 could not successfully stabilize the thermal degradation of PCEMA, while in the case of the presence of the antioxidant mixture IRGANOX 1010 and IRGAPHOS 168 (1:1) slight stabilizing effects were observed

Improvement to the Flynn-Wall method of determining apparent activation energies of the thermal degradation of polymers

An improvement to the Flynn-Wall method of determining apparent activation energies of the thermal degradation of polymers is presented. The method involves the deconvolution of differential thermogravimetric (TG) curves and the reconstruction of the corresponding TG curves of the individual thermal degradation processes, to which the Flynn-Wall method is then applied separately. The method is illustrated using poly(diisobutyl itaconate) as an example

Termička razgradnja nekih polimernih dialkil estara itakonske kiseline

One group of polymers that may help relieve the dependence on crude oil is based on itaconic acid, the biotechnological production of which has become feasible. Itaconic acid and its derivatives can easily be incurporated into polymers and may serve as a substitute for petrochemically derived acrylate or methacrylate monomers. The applications of polymers based on itaconic di-esters depend largely on their thermal stability. The thermal stability of poly(di-itaconates) is dependent, not only on the general structure of the monomer repeating unit, but also on the structure of the ester substituent. Depolymerization, initiated by b-scission or random main chain scission, is the dominant thermolysis mechanism in most cases. The deploymerization of poly- (di-itaconates) may be accompanied by de-esterification, elimination, cross-linking, random main or side chain scission and carbonization. Comparison of the thermal degradation mechanism of polymeric di-esters of itaconic acid to that of corresponding poly(methacrylates) confirms the viability of substituting poly(methacrylates) by poly(di-itaconates). .Jednu grupu polimera, koji bi mogli da umanje zavisnost od sirove nafte, čine polimeri na bazi itakonske kiseline, čija biotehnološka proizvodnja postaje isplativa. Itakonska kiselina i njeni derivati mogu lako da se ugrade u polimere i mogu da služe kao zamena za petrohemijski dobijene akrilatne i metakrilatne monomere. Primena polimera na bazi di-estara itakonske kiseline zavisi u velikoj meri od njihove termičke stabilnosti. Termička stabilnost poli(di-itakonata) zavisi ne samo od opšte strukture monomerne ponavljajuće jedinice, već i od strukture estarskog supstituenta. Depolimerizacija, inicirana kidanjem ili nasumičnim raskidanjem veze u osnovnom lancu, je dominantan mehanizam termolize u većini slučajeva. Depolimerizacija poli(di-itakonata) može da bude praćena de-esterifikacijom, eliminacijom, umrežavanjem, nasumučnim raskidanjem veze u osnovnom i/ili bočnom lancu i karbonizacijom. Poređenje mehanizma termičke razgradnje polimernih di-estara itakonske kiseline i odgovarajućih polimetakrilata potvrđuje održivost zamene polimetakrilata poli(di-itakonatima).

Termička stabilnost poli(sec-butil metakrilata)

The thermal stability of a series of poly(sec-butyl methacrylate)(PsBMA) samples was investigated by non-isothermal thermogravimetry (TG). The PsBMA samples were synthesised by bulk radical polymerization in the presence of various amounts of n-dodecyl mercaptan, an efficient chain transfer agent. By deconvoluting the differential TG (DTG) curves, the individual stages of the thermolysis of PsBMA were analyzed in detail: depolymerization, initiated by end-chain and random main chain scission, and desertification. The thermolysis activation energies of individual reactions were determined by the Flynn-Wall method. .Ispitana je termička stabilnost serije uzoraka poli(sec-butil metakrilata) (PsBMA) neizotermnom termogravimetrijskom (TG) metodom. Uzorci PsBMA sintetizovani su radikalnom polimerizacijom u masi u prisustvu različitih količina n-dodecil merkaptana, efikasnog prenosioca aktivnosti lanca. Dekonvolucijom diferencijalnih TG (DTG) krivih uzoraka PsBMA detaljno su analizirane pojedine faze termolize PsBMA: depolimerizacija, inicirana β kidanjem i nasumičnim raskidanjem veze u osnovnom lancu, i deesterifikacija. Energije aktivacije reakcija termolize PsBMA određene su metodom Flynn-Wall-a.

The thermal degradation of some isomers of poly(di-butyl itaconates)

The non-oxidative and oxidative thermal degradation of poly(di-iso-butyl itaconate) (PDiBI), poly(di-n-butyl itaconate) (PDnBI), and poly(di-sec-butyl itaconate) (PDsBI) were studied by following changes in the polymer residue such as mass loss, limiting viscosity number (LVN) and the formation of carboxylic groups. Depolymerization is the dominant degradation mechanism of PDiBI, while PDnBI and PDsBI predominantly degrade by deesterification. The thermolysis mechanism is determined by the number of beta-hydrogen atoms in the ester substituent: five in PDsBI, two in PDnBI and one in PDiBi

Sinteza i karakterizacija 2-merkaptoetil metakrilata

The synthesis of 2-mercaptoethyl methacrylate from methacrylic acid and 2-mercaptoethanol by etherification using acetyl chloride as catalyst was optimized. The purity of the obtained product was controlled by gas chromatography and its identity confirmed by H-NMR and FTIR spectroscopy. 2-Mercapto-ethyl methacrylate could find application as a chain transfer agent in radical polymerizations.Sinteza 2-merkaptoetil metakrilata esterifikacijom metakrilne kiseline 2-merkaptoetanolom je optimizovana. Čistoća dobijenog proizvoda je kontrolisana gasnom hromatografijom i potvrđena 1H-NMR i FTIR spektroskopijom. 2-Merkaptoetil metakrilat može da se primeni kao sredstvo za prenošenje aktivnosti lanca u radikalnim polimerizacijama

The thermal degradation of poly(ditetrahydrofurfuryl itaconate)

The goal of this investigation was to study the thermal degradation of poly(ditetrahydro-furfuryl itaconate) (PDTHFI) by thermogravimetry (TG). The monomer was polymerized in bulk at 40 degreesC using AIBN as initiator. Non-oxidative degradation was studied under nitrogen, while oxidative degradation was studied under air, applying four heating rates (2.5, 10, 20 and 40 K/min), up to 600 degreesC. The apparent activation energy of thermal degradation, E-a, was calculated using the Flynn-Wall method. The obtained non-oxidative TG curves of PDTHFI are parallel and no heating rate effect was observed. A carbonaceous residue remained at 600 degreesC, regardless of the heating rate applied. The E-a of PDTHFI is constant in the whole mass loss range and its mean value is 124 kJ/mol. The non-oxidative differential TG (DTG) curves of PDTHFI consist of two peaks, the second being dominant. If it is assumed that depolymerization is the main degradation mechanism, analogous to other polyitaconates, these two peaks could be ascribed to two depolymerization initiation modes: end-chain beta -scission and random main chain scission. The oxidative TG curves are more complex than the non-oxidative ones and show a heating rate effect. The E-a steadily increases in the mass loss range of 5-50% from 120 to 200 kJ/mol. The oxidative DTG curves consist of a major peak with two shoulders and a second minor peak

The photopolymerisation of methacrylic acid by colloidal semiconductors

Methacrylic acid was photopolymerised using CdS and composite, CdS/HgS and CdS/TiO2, colloidal semiconductor particles as initiators. The previously proposed photoinitiation mechanism involving the photogenerated positive hole in the valence band of the CdS colloid was confirmed by the electron scavenging action of TiO2. The effect of pH on the course of the polymerisation was investigated and is discussed