Banca de QUALIFICAÇÃO: GUILHERME ELIAS SALTARELLI GARCIA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : GUILHERME ELIAS SALTARELLI GARCIA
DATE: 05/12/2023
TIME: 14:00
LOCAL: BANCA VIRTUAL - CAMPUS SANTO ANDRÉ
TITLE:

ENDURECEDORES DE RESINAS EPÓXI BASEADOS EM FRAÇÕES DE LIGNINA KRAFT AMINADAS: INFLUÊNCIA DA MASSA MOLAR NAS PROPRIEDADES TERMOMECÂNICAS E ADESÃO PRÁTICA

PAGES: 151
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Polímeros, Aplicações
SUMMARY:

The use of aminated lignins as hardeners for epoxy resins has been growing in popularity recently, although the high chemical heterogeneity and polydispersity continue to pose challenges for the development of thermosetting materials based on technical lignins (TL). Enhanced control over the chemical structure and molecular weights (M_w) of TL can be achieved through fractionation processes. Fractions of TL with more homogeneous structures and narrower molecular weight distributions are desired for epoxy hardener applications, although most studies in the literature employ non-fractionated TL for this purpose. To contribute to this scenario, this study aimed to evaluate the influence of M_w and chemical structure of aminated Kraft lignin fractions (AKLF) on the thermomechanical properties of a DGEBA epoxy resin, with AKLF used as hardeners. Technical Kraft lignin (KL) was fractionated using a sequential solvent fractionation (SSF) protocol. Gel permeation chromatography coupled with multi-angle light scattering (GPC-MALS) was used to assess the molecular weights of KL and its fractions (KLF), which also had their chemical structures evaluated through phosphorus nuclear magnetic resonance spectroscopy (³¹P NMR) and two-dimensional heteronuclear single quantum coherence spectroscopy (2D NMR/HSQC). The lowest molecular weight fraction (F2), the highest molecular weight fraction (F3), and KL were modified via Mannich reaction using two aliphatic diamines: ethane-1,2-diamine (EDA) and butane-1,4-diamine (BDA). The amination of KLF was confirmed through X-ray photoelectron spectroscopy (XPS) and HSQC. The influence of the molecular weights of the diamines used in the amination of the fractions on the thermomechanical properties of the resin was also secondarily evaluated. XPS and HSQC results suggest that AKLF based on F2 are more reactive with EDA, while AKLF based on F3 demonstrated greater reactivity with BDA. This pattern may be attributed to the fact that F2 and F3 possess, respectively, the lowest and highest number of aliphatic hydroxyl groups, as confirmed by ³¹P NMR. Diamines with longer carbon chains tend to interact more favorably with the fraction exhibiting higher molecular weight and a greater number of aliphatic hydroxyl groups. Finally, an increase in thermal stability and glass transition temperatures (T_g) was observed with the increase in the molecular weights of KLF.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 1763443 - MARCIA APARECIDA DA SILVA SPINACE
Membro Titular - Examinador(a) Interno ao Programa - 1676364 - JULIANA MARCHI
Membro Titular - Examinador(a) Externo à Instituição - DIEGO LOMONACO VASCONCELOS DE OLIVEIRA - UFC
Membro Titular - Examinador(a) Externo à Instituição - LARA TAVARES DOS SANTOS
Membro Suplente - Examinador(a) Interno ao Programa - 1671298 - RENATO ALTOBELLI ANTUNES
Membro Suplente - Examinador(a) Externo ao Programa - 1730526 - SUEL ERIC VIDOTTI
Membro Suplente - Examinador(a) Externo à Instituição - NATHALIE MINAKO ITO