Dinamičko-mehanička i termička svojstva kompozita baziranih na nezasićenim poliestarskim smolama i modifikovanim nanočesticama silicijum-dioksida i celuloze

Abstract

Dve grupe nanokompozitnih materijala baziranih na nezasićenim poliestarskim (NZPE) smolama ispitivano je u ovoj doktorskoj disertaciji. Jedna grupa nanokompozita bazirana je na NZPE smolama sintetisanim iz produkata katalitičke depolimerizacije poli(etilen tereftalata) (PET) u višku dipropilen-glikola (DPG) sa ojačanjem od alkil modifikovanih komercijalnih nanočestica silicijum-dioksida (SiO2), Aerosil® R812S, R805 i R816, i fenil modifikovanih Aerosil® R200 nanočestica. Polimernu matricu nanokompozita sa ojačanjem od vinil modifikovanih nanočestica SiO2 (Aerosil® 380) i celuloze (NC) predstavlja NZPE smola sintetisana iz produkata katalitičke depolimerizacije PET-a u višku 1,2-propilen glikola (PG). Uticaj alkil, fenil i vinil modifikovanih nanočestica SiO2, kao i vinil modifikovanih čestica NC na dinamičko-mehanička i termička svojstva nanokompozita proučavan je u ovom radu. Vinil reaktivne grupe koje mogu kopolimerizovati sa poliestarskim lancima NZPE smola uvedene su na površinu nanočestica SiO2 hemijskim vezivanjem organo-silana sa slobodnim vinil ili metakriloil grupama, ili vezivanjem metil estara masnih kiselina izolovanih iz lanenog ulja (BD). Površinske kopolimerizujuće vinil grupe NC uvedene su direktnim hemijskim vezivanjem oleinske kiseline i masnih kiselina izolovanih iz lanenog ili suncokretovog ulja, kao i indirektnim vezivanjem metil estara masnih kiselina izolovanih iz ulja preko reaktivnih nezasićenih mostova od anhidrida maleinske kiseline i etilen diamina. Ispitivan je i uticaj post-tretmana (sušenja) natkritičnim ugljen(IV)-oksidom na teksturalna, morfološka i termička svojstva čestica NC i mogućnost primene tretiranih čestica NC u nanokompozitima poboljšanih fizičko-mehaničkih svojstava. NZPE smole sintetisane su iz produkata katalitičke depolimerizacije PET-a u višku DPG-a ili PG-a, sa ili bez azeotropskim izdvajanjem etilen-glikola, i anhidrida maleinske kiseline (AMK). Reakcije depolimerizacije PET-a, u prvom stupnju, i polikondenzacije sa AMK u drugom, katalizovane su tetrabutoksi-titanatom. Proizvodi katalitičke depolimerizacije PET-a sa terminalnim hidroksilnim grupama (glikolizati) kao i sintetisane NZPE smole strukturno su okarakterisane određivanjem vrednosti kiselinskog, hidroksilnog i ii jodnog broja i primenom FTIR i NMR spektroskopskih metoda. Strukturna karakterizacija nanokompozita, urađena primenom transmisione elektronske mikroskopije, pokazala je da čestice SiO2 formiraju lančane agregate u poliestarskoj matrici...

Two groups of unsaturated polyester resin (UPe)-based nanocomposites were prepared. One was prepared of UPe, obtained from depolymerisation product of waste poly(ethylene terephthalate) (PET) and dipropylene glycol (DPG), and fumed silica Aerosil® R812S, R805 and R816 and phenyl modified R200. The second group was prepared of UPe, obtained from depolymerisation product of waste PET and 1,2-propylene glycol (PG) and vynil modified R380, as well as vynil modified cellulose nanocrystals (NC). Influences of the alkyl, phenyl and vinyl modified nanosilica, i.e., vinyl and methacryloyl silane coupling agent and linseed oil fatty acids (BD) reactive residues, as well as vynil modified NC on the dynamic-mechanical properties of the UPes based nanocomposites, were studied. Surface vynil moiety was introduced by modification of NC on two ways: the first one represents the modification with oleic acid (OA), linseed and sunflower oil fatty acids (FALO and FASO, respectively), and the second with methyl ester of linseed, sunflower and soybean oil fatty acid attached by maleic acid/ethylene diamine cross-linker to NC surface. Also, the influence of supercritical carbon(IV)-oxyde (CO2) drying of the NC was investigated, especially on their morphology, structural and thermal stability and the possibility of applying them as reinforcement for high-performance thermosetting composites. UPe resins were synthesized from maleic anhydride and products of glycolysis, obtained by PET depolymerization with DPG or PG, with and without separation of ethylene glycol, in the presence of tetrabutyl titanate catalyst. The hydroxyl terminated PET depolymerization products (glycolyzates) and obtained UPes were characterized by acid, hydroxyl, and iodine values and by FTIR and NMR analysis. The microstructural analysis of the prepared nanocomposites, performed by using transmission electron microscopy, confirmed that silica nanoparticles formed chain-like aggregates in the polymer matrix. Cross-linking density, storage modulus (G'), tanδ hight and glass transition temperature (Tg) of the nanocomposite were determined from the dynamic-mechanical testing and discussed in relation to the structure of silica and NC modification. The presence of modified silica nanoparticles had no influence on the Tg and thermal stability of polyester matrix. The tensile iv modulus and stress at break (σb) of cured products increased with increasing silica content. The highest increase from 195 to 247% of σb of UPes based nanocomposites was obtained for 1 wt% addition of vynil modified silica, while increase of σb for vynil modified NC/polymer based nanocomposites for 1 wt% addition of modified NCs was from 137 to 193%...