Polyamide 1010 and 2D nanomaterials-based hybrid multifunctional nanocomposites
Tipo
Tese
Data de publicação
2024-11-06
Periódico
Citações (Scopus)
Autores
Pinto, Gabriel Matheus
Orientador
Fechine, Guilhermino José Macêdo
Título da Revista
ISSN da Revista
Título de Volume
Membros da banca
Ribeiro, Hélio
Andrade, Ricardo Jorge Espanhol
Helal, Emna
Lee, Patrick
Andrade, Ricardo Jorge Espanhol
Helal, Emna
Lee, Patrick
Programa
Engenharia de Materiais e Nanotecnologia
Resumo
This PhD thesis focuses on the development of polymer nanocomposites using a bio-sourced
polyamide 1010 (PA 1010) matrix and various two-dimensional (2D) nanomaterials. PA 1010
was chosen for its diverse application potential across multiple domains and its
environmentally friendly character compared to traditional polyamides. The selected
nanofillers - graphene oxide (GO), hexagonal-boron nitride (h-BN), and molybdenum disulfide
(MoS2) - were chosen for their chemical compatibility with the polyamide's amide groups and
their 2D structures, which leads to their high surface area and exceptional properties. However,
a key challenge in utilizing 2D nanofillers is achieving proper dispersion within the polymer
matrix. Therefore, this thesis proposes a novel approach of combining different 2D fillers
within a single composite to enhance mutual dispersion and promote synergistic effects.
The nanocomposites were produced through melt blending in a twin-screw extruder. First, low
amounts (0.1, 0.3, or 0.5 wt%) of the previously exfoliated nanofillers were deposited on the
ground polymer particles by a technique called solid-solid deposition. Then, this powder
mixture was fed to the extruder to properly mix the polymer matrix with the nanofillers in the
melt, thus forming a homogeneous mixture. This process significantly facilitates scalability, as
it is compatible with existing industrial polymer processing infrastructure, enabling its
integration into current production lines and paving the way for commercial applications.
Molecular dynamics investigations were conducted to elucidate the interactions between the
nanofillers and the polyamide matrix, focusing on the polymer relaxation process at the glass
transition, the volume of chains involved in the Brill transition during melting, and the energy
required to separate polymer chains from the nanosheets. The results indicated that GO and h BN exhibit stronger interactions with the polymer matrix compared to MoS2, which is also
reflected in the performance of their respective hybrid composites.
The microstructure of the polymer matrix, a critical factor influencing the properties of
polymer-based materials, was examined through microstructural analyses. These analyses
revealed that the addition of the nanofillers affected the polymer matrix’s semi-crystalline
order. Although the phase transition from α to γ was not observed in the Polyamide crystals,
h-BN and MoS2 were found to decrease both the polymer’s overall crystalline fraction and the
organization of its crystalline domains. On the contrary, GO did not significantly affect the
polymer microstructure. However, with its larger sheets and strong chemical affinity, GO led
to the greatest enhancement in tensile toughness at room temperature (over 120% at 0.5 wt%).
Interestingly, this enhancement was not observed at low temperatures (-40 °C), where the
decreased microstructural order was the predominant reason for the toughening of PA 1010,
with only h-BN composites retaining some of the original toughening characteristics.
Finally, to demonstrate the multifunctionality of the developed nanocomposites, it has been
demonstrated that incorporating low amounts (less than 0.5 wt%) of these 2D nanofillers
allowed the nanocomposites to retain the original dielectric and tribological properties of PA
1010 while enhancing thermal conductivity by nearly 10%. These findings underscore the
potential of these nanomaterials as low-content additives for advanced applications, where
achieving specific properties without compromising others presents a significant challenge.
Descrição
Palavras-chave
polymer nanocomposites , polyamide 1010 , graphene oxide , hexagonal-boron nitride , molybdenum disulfide , multifunctional properties