Banca de DEFESA: LUCAS RICARDO FERNANDES FIGUEIREDO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : LUCAS RICARDO FERNANDES FIGUEIREDO
DATA : 15/12/2017
HORA: 14:00
LOCAL: Sala de aulas do PPGCEM
TÍTULO:

ADHESIVE PROPERTIES OF BIODEGRADABLE POLYMERS WITH ADDITION OF CELLULOSE NANOWHISKERS


PALAVRAS-CHAVES:

Composites; Cellulose Nanowhiskers; Biodegradable Adhesives; Degradation.


PÁGINAS: 114
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
RESUMO:
Green adhesives are of great scientific and technological interest as an alternative to conventional commercial products, which often release toxic substances and take long time to degrade.  However, the poor mechanical properties and fast degradation of some biodegradable polymers limit their use in most practical applications.  In the present work, novel biodegradable composites were prepared using biodegradable polymers and cellulose nanowhiskers (CNW) for their use as wood adhesives.  The goal of the investigation was to study the effect of the addition of CNW on the mechanical properties and degradation of the polymers.  The biodegradable polymers synthesized by polycondensation based on glycerol and acids were poly(glycerol adipate) - PGA, poly(glycerol maleate) - PGM, poly(glycerol citrate) - PGC, poly(glycerol phthalate) - PGPh, poly(glycerol succinate) - PGSu and poly(glycerol sebacate) - PGS.  In addition, the copolymers synthesized were poly(glycerol succinate-co-maleate) - PGMSu, poly(glycerol succinate-co-adipate) – PGASu and poly(glycerol adipate-co-maleate) – PGMA.  Cellulose nanowhiskers (CNW) were added to the polymers as an approach for improving the mechanical properties and controlling the degradation rate.  Composites were produced with the addition of 0, 5, 10 and 20 wt.% of CNW.  The neat polymers and composites were analyzed by Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR).  Adhesively bonded joints were produced in test specimens of slash pine (Pinus elliottii) and angelim (Vatairea heteroptera Ducke) and tested under shear by tensile loading and for accelerated aging degradation.  Bonded joints produced with polyvinyl acetate - PVAc and cyanoacrylate based adhesives were also tested under the same conditions for comparison purposes. Thermal analyses showed that most of the biodegradable glycerol-based polymers tested are stable up to about 260°C and the addition of CNW increased the thermal stability (Tonset) of some polymers by 26°C up to 48°C, while others were not affected.  Analyses of the fracture surface after the shear tests by Scanning Electron Microscopy (SEM) suggest less ductile fracture with the incorporation of CNW to the adhesive.  Adhesion measurements indicated that the green adhesives developed from glycerol polymers with 10 and 20% CNW addition showed shear strength superior to the commercial PVAc based adhesive and the best results were obtained for PGASu 20 wt.% CNW (2.57 ± 0.36 MPa) and PGM 20 wt.% CNW (2.33± 0.43), while the shear strength for polyvinyl acetate - PVAc is 1.58 ± 0,18 MPa.  Aging improved the shear strength of some adhesives. The best improvement was obtained for PGMA 20 wt.% CNW, which reached (3.89 ± 0.74 MPa) after 250h of aging, thus greater than the shear strength of cyanoacrylate (3.12 ± 0.53).  Ultimately, the results presented in this work suggest that the addition of cellulose nanowhiskers (CNW) is a viable approach to tailor mechanical properties and degradation rate of biodegradable polymers.

MEMBROS DA BANCA:
Interno - 2042234 - ANA PAULA CYSNE BARBOSA
Externo à Instituição - ELITON SOUTO DE MEDEIROS - UFPB
Externo à Instituição - HENRIETTE CORDEIRO MONTEIRO DE AZEREDO - EMBRAPA
Presidente - 1202134 - JOSE DANIEL DINIZ MELO
Externo à Instituição - JULIANO ELVIS DE OLIVEIRA - UFLA
Interno - 1755267 - MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
Notícia cadastrada em: 05/12/2017 07:46
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