Synthesis of thermoplastic poly(ester-olefin) elastomers

Abstract

A series of thermoplastic poly(ester-olefin) elastomers, based on poly(ethylene-stat-butylene), HO-PEB-OH, as the soft segment and poly (butylene terephthalate), PBT, as the hard segment, were synthesized by a catalyzed transesterification reaction in solution. The incorporation of soft hydrogenated poly(butadiene) segments into the copolyester backbone was accomplished by the polycondensation of α, ω-dihydroxyl telechelic HO-PEB-OH, (PEB Mn = 3092 g/mol) with 1,4-butanediol (BD) and dimethyl terephthalate (DMT) in the presence of a 50 wt-% high boiling solvent i.e., 1,2,4-trichlorobenzene. The molar ratio of the starting comonomers was selected to result in a constant hard to soft weight ratio of 60:40. The synthesis was optimized in terms of both the concentration of catalyst, tetra-n-butyl-titanate (Ti(OBu)4), and stabilizer, N,N'-diphenyl-p-phenylenediamine (DPPD), as well as the reaction time. It was found that the optimal catalyst concentration (Ti(OBu)4) for the synthesis of these thermoplastic elastomers was 1.0 mmol/mol ester and the optimal DPPD concentration was 1.0 wt-%. The extent of the reaction was followed by measuring the inherent viscosity of the reaction mixture. The effectiveness of the incorporation of the soft segments into the copolymer chains was proved by Soxhlet extraction with chloroform. The molecular structures, composition and the size of the synthesized poly(ester-butylene)s were verified by 1H NMR spectroscopy, viscometry of dilute solutions and the complex dynamic melt viscosity. The thermal properties of poly(ester-olefin)s were investigated by differential scanning calorimetry (DSC). The degree of crystallinity was also determined by DSC. The thermal and thermo-oxidative stability were investigated by thermogravimetric analysis (TGA). The rheological properties of poly(ester-olefin)s were investigated by dynamic mechanical spectroscopy in the melt and solid state.

U radu je prikazana sinteza i karakterizacija poli(estar-olefina) sa 40 mas. % mekih olefinskih, nepolarnih segmenata. Nepolarni olefinski pretpolimeri su ugrađivani u polimerne lance da bi se poboljšala hidrolitička i termička stabilnosti i ostvarilo bolje razdvajanje faza. Za sintezu poli(estar-olefina) korišćena je katalizovana transesterifikacija dimetiltereftalata, butandiola i a, w-dihidroski poli(etilen-stat-butilena) (HO-PEB-OH, Mn = 3092 g/mol) u rastvoru. Kao rastvarač korišćen je teško isparljiv 1,2,4-trihlorbenzen. Sinteza ovih termoplastičnih elastomera je optimizovana u pogledu koncentracije katalizatora, tetra-n-butil-titanata (Ti(OBu)4), stabilizatora, N,N'-difenil-p-fenilendiamina (DPPD), kao i vremena izvođenja druge faze reakcije polikondenzacije. Pokazano je da prisustvo rastvarača utiče na povećanje kompatibilnosti komponenti rastopa reakcione smeše, odnosno efikasnosti uvođenja fleksibilnih nepolarnih olefinskih segmenata u polimerne lance. Sintetisani blok-kopoliestri okarakterisani su u pogledu sastava i sadržaja tvrdih segmenata 1H NMR spektroskopijom, a u pogledu veličine makromolekula viskozimetrijom razblaženih rastvora (ηinh) i rastopa (η*) polimera. Termička svojstva i stepen kristaliničnosti sintetisanih poli(estar-olefina) su analizirani pomoću diferencijalne skenirajuće kalorimetrije (DSC), termooksidativna svojstva termogravimetrijskom analizom (TGA), a reološka svojstva dinamičko mehaničkom spektroskopijom kako u stanju rastopa tako i u čvrstom stanju.