Mechanical properties of composites based on unsaturated polyester resins obtained by chemical recycling of poly(ethylene terephthalate)

Abstract

Composites based on unsaturated polyester (UPe) resins and fumed silica AEROSIL® RY 50, NY 50, RX 50 and NAX 50, as well as graphite, TiO2 or organically modified clay CLOISITE 30B were prepared in order to investigate the influence of reinforcing agents on the mechanical properties of composites. Unsaturated polyester resins were synthesized from maleic anhydride and products of glycolysis, obtained by depolymerization of poly(ethylene terephthalate) with dipropylene glycol (UPe1 resin) and triethylene glycol (UPe2 resin) in the presence of tetrabutyl titanate catalyst. The obtained unsaturated polyesters were characterized by FTIR spectroscopy, acid and hydroxyl values, and their mechanical properties were also examined. Significant increase of the tensile modulus, tensile strength and decrease of the elongation at break was observed for composites prepared after addition of 10 wt.% of graphite or 10 wt.% of TiO2 to the UPe resins, indicating strong interaction between matrix and filler particles. On the other hand, nanocomposites prepared using UPe2 and hydrophobically modified silica nanoparticles showed lower tensile strength and tensile modulus than polymer matrix. The presence of CLOISITE 30B had no significant influence on the mechanical properties of UPe1, while tensile strength and tensile modulus of UPe2 increased after adding 10 wt.% of clay.

U ovom radu sintetisani su kompoziti na bazi nezasićenih poliestarskih (UPe) smola i SiO2 (AEROSIL®:RY 50, NY 50, RX 50 i NAX 50), grafita, TiO2 ili organski modifikovane gline CLOISITE 30B u cilju ispitivanja uticaja punioca na mehanička svojstva kompozita. Nezasićene poliestarske smole su sintetisane polazeći od anhidrida maleinske kiseline i proizvoda glikolize dobijenih depolimerizacijom poli(etilen-tereftalata) sa dipropilen glikolom (UPe1 smola) ili trietilen glikolom (UPe2 smola) u prisustvu katalizatora tetrabutil titanata. Sintetisane nezasićene poliestarske smole su ispitane primenom FTIR spektroskopije, određen im je kiselinski i hidroksilni broj i ispitana su njihova mehanička svojstva. Molarna masa srednja po brojnoj vrednosti sintetisanih nezasićenih poliestarskih smola je između 1620-1630 g mol-1. Moduli istezanja i zatezna čvrstoća kompozita pripremljenih dodavanjem 10 mas.% grafita ili TiO2 nezasićenim poliestarskim smolama su značajno porasli u odnosu na čiste poliestre, dok se izduženje pri kidanju smanjilo, što ukazuje na postojanje jakih interakcija između matrice i čestica punioca. Sa druge strane, nanokompoziti sintetisani korišćenjem UPe2 i modifikovanih nanočestica SiO2 su imali manju zateznu čvrstoću i module istezanja nego čista nezasićena poliestarska smola. Pokazano je da prisustvo gline CLOISITE 30B nema značajan uticaj na mehanička svojstva smole UPe1, dok su vrednosti modula istezanja i zatezne čvrstoće UPe2 porasle nakon dodavanja 10 mas.% gline.