Thesis /

ROMDOC-THESIS-2017-887

Nanocompozite polimerice armate cu nanotuburi de carbon

Petrea, Celina Maria
2011-07-29

Abstract: FACULTATEA DE CHIMIE APLICATA SI STIINTA MATERIALELOR DEPARTAMENTUL DE BIORESURSE SI STIINTA POLIMERILOR Nanocompozite polimerice armate cu nanotuburi de carbon Conducator de doctorat: Prof.dr.ing. Horia IOVU Doctorand: Celina Maria PETREA (cas. DAMIAN) Teza de doctorat începe cu un amplu studiu de literatura cuprins în trei capitole: primul capitol urmareste dezvoltarea domeniului nanotuburilor de carbon (CNT), al doilea capitol trateaza subiectul rasinilor termoreactive de tip epoxidic, iar al treilea capitol este o sinteza a celor mai imporante date din domeniul nanocompozitelor polimerice pe baza de nanotuburi de carbon. Primul capitol de contributii originale intitulat “Functionalizarea Nanotuburilor de Carbon” prezinta îndeplinirea primului obiectiv si anume dezvoltarea unei o metode de introducere a gruparilor de tip carboxil atât pe suprafata nanotuburilor de carbon cât si prin deschiderea capetelor semisferice ale tuburilor prin oxidare. Metoda a fost optimizata pentru a evita scurtarea excesiva a tuburilor si deteriorarea peretilor laterali prin crearea defectelor prea mari în structura grafenei. A doua etapa a acestui obiectiv a constat în functionalizarea covalenta cu diferite amine a nanotuburilor de carbon SWNT si MWNT pornind de la gruparile carboxilice. A fost abordata metoda acilarii cu clorura de tionil (SOCl2) pentru atasarea moleculelor de amina, dar si metoda activarii gruparilor carboxilice cu ajutorul carbodiimidelor. S-au studiat agenti de functionalizare din clasa aminelor, atât monoamine cât si diamine, alifatice si aromatice, acestea fiind cunoscute ca grupari compatibile cu rasinile epoxidice folosite ulterior ca matrice polimerica. Noua abordare a celui de-al doilea obiectiv a fost comparatia metodelor de functionalizare de tip covalent si respectiv noncovalent prin utilizarea drept agenti de functionalizare a trei tipuri de surfactanti nonionici cu diferite caracteristici. S-a urmarit îmbunatatirea compatibilitatii dintre suprafata nanotuburilor de carbon si rasina epoxidica, deci o crestere a termostabilitatii si optimizarea proprietatilor mecanice a nanocompozitelor epoxidice. Al doilea capitol de contributii originale „Compozite polimerice armate cu nanotuburi de carbon functionalizate” studiaza al treilea obiectiv al tezei constând în sinteza si caracterizarea avansata a nanocompozitelor epoxidice armate cu nanotuburile de carbon functionalizate anterior. Studiul mecanismelor de reticulare a matricii epoxidice DGEBA cu noul agent de reticulare numit PXDED de tip amina aromatica si influenta functionalizarii nanotuburilor în obtinerea unor materiale nanocompozite cu proprietati fizicomecanice îmbunatatite sunt abordari de o deosebita importanta. Compatibilitatea dintre gruparile functionale atasate de structura nanotuburilor de carbon si rasina epoxidica utilizata drept matrice polimerica, s-a tradus prin observarea unei dispersii avansate a agentului de armare si implicit o crestere a proprietatilor fizico-mecanice a materialelor obtinute. FACULTY OF APPLIED CHEMISTRY AND MATERIALS SCIENCE DEPARTMENT OF BIORESOURCES AND POLYMER SCIENCE Polymeric nanocomposites reinforced with carbon nanotubes Coordinator Professor: Prof.dr.ing. Horia IOVU PhD student: Celina Maria PETREA (DAMIAN) The thesis begins with an extensive literature study divided into three chapters: the first chapter follows the development of carbon nanotubes (CNTs) domain, the second chapter handle with epoxy type thermosetting resins and the third chapter is a summary of the most important data from carbon nanotubes polymeric nanocomposites field. The first chapter from the original contributions part entitled „Carbon Nanotubes Functionalization” presents the fulfillment of the first objective namely the development of a method to introduce carboxyl groups on the surface of carbon nanotubes and also the endcap opening by oxidation. This method was optimized in order to avoid excesive shortening of the tubes and damage of the sidewalls by creating large deffects in the graphene structure. The second stage of this objective was the covalent functionalization with different amines of the SWNTs and MWNTs starting from carboxyl groups. Acylation method was addressed using thionyl chloride (SOCl2) to attach amine molecules and a second method was the activation of carboxyl groups by carbodiimide chemistry. Monoamines and diamines, aliphatic and aromatic functionalization agents were studied, these groups being compatible with the epoxy resin used afterwards as polymeric matrix. A new approach was the comparison of covalent and noncovalent functionalization methods using three nonionic surfactants with different features as functionalization agents. It was followed the improvement of the compatibility between the surface of carbon nanotubes and the epoxy resin, therefore a higher thermostability and optimization of mechanical properties of the epoxy nanocomposites The second original contribution chapter „ Polymeric composites reinforced with functionalized carbon nanotubes” studies the third objective of the thesis consisting in the synthesis and advanced characterization of epoxy nanocomposites reinforced with the previously functionalized carbon nanotubes. The study of the crosslinking mechanisms of the DGEBA type epoxy resin with the new aromatic amine type hardener named PXDED and the influence of the functionalization of nanotubes in the obtaining of nanocomposite materials with improved physico-mechanical properties are approaches of particular importance . Compatibility between the functional groups from the nanotubes and the epoxy resin matrix was translated in a high dispesity of the reinforcing agents and enhanced physico-mechanical properties of the obtained materials

Keyword(s): Nanotuburi -- Teză de doctorat ; Compozite polimerice -- Nanoparticule -- Teză de doctorat
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