mprovements in thermal and mechanical properties of composites based on thermoplastic starch and Kraft Ligni

Autor(es)

de Freitas, Amanda de S. M. ^[1] ; Rodrigues, Jessica S. ^[2] ; Maciel, Cristiane C. ^[3] ; Pires, Ariane A. F. ^[2] ; Lemes, Ana Paula ^[1] ; Ferreira, Marystela ^[2] ; Botaro, Vagner R. ^[2]

Afiliação do(s) autor(es)

^[1] Fed Univ Sao Paulo UNIFESP, Polymers & Biopolymers Technol Lab TecPBio, Inst Sci & Technol ICT, BR-12231280 Sao Jose Do Campos, SP - Brazil

^[2] Fed Univ Sao Carlos UFSCar, Sci & Technol Ctr Sustainabil CCTS, Lignocellulos Mat Lab, Km 110, BR-18052780 Sorocaba - Brazil

^[3] Sao Paulo State Univ, UNESP, Sci & Technol Inst Sorocaba ICTS, Av Tres de Marco 511, BR-18087180 Sorocaba - Brazil

• Tipo de documento: Artigo Científico
• Fonte: International Journal of Biological Macromolecules; v. 184, p. 863-873, AUG 1 2021.
• Citações Web of Science: 1

Resumo

Thermoplastic starch (TPS) is a widely studied biopolymer as an alternative to the use of conventional polymers. In this sense, the incorporation of fillers or reinforcements coming preferably from other substances of natural origin, can be an alternative to try to improve some mechanical and thermal properties of starch polymers. Thus, Kraft Lignin (KL), can be an excellent filler to be incorporated, since it presents mechanical and thermal properties and reduces the cost and weight of the final compounds. TPS films were prepared by casting using dimethyl sulfoxide (DMSO) as solvent and additives with 2, 4 and 8% KL. Characterization of TPS films and compositions with KL were carried out by Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM), Thermogravimetric Analysis (TGA), Dynamic Thermomechanical Analysis (DMTA), tensile testing and contact angle. Samples were also analyzed for biodegradation and for the ability to remove contaminants in water, Metil Orange (MO), by Ultraviolet-Visible Spectroscopy (UV-Vis). The FT-IR spectra of the films showed bands typical of functional groups derived from starch and lignin, with the intensity of these bands varying among the samples studied. Micrographs revealed slightly different morphologies among the films, but all showed irregular shapes with structures that appeared as plots. Increasing the percentage of KL led to an increase in contact angle values, showing a more hydrophobic behavior. In the TGA analysis, it was possible to observe a change in the main degradation event of the films for lower temperatures, especially of TPS - 4 and 8% KL compared to the TPS film. Films with KL had the peak of maximum degradation shifted to temperatures below the starch film, where the decrease in intensity of the main peak in the TPS - 4% KL and TPS - 8% KL samples demonstrates that there was less mass loss in the event. There was also in the percentage of residue as the addition of KL was increased The DMTA analyses allowed for the conclusion that presence of KL in TPS film allowed for an increase in its energy storage property, and that the loss modulus followed a decreasing order of storage modulus values to TPS - 8% KL from TPS. For the tensile strength property only TPS - 4% KL has significant improvement, and the elongation at break showed an increase for TPS - 4 and 8% KL compared to TPS. Samples showed a continuous and progressive biodegradation process, being completely biodegraded within 10 days. The monitoring of the ability to remove contaminants from water by UV-Vis, also showed promising results of compounds for this application. The best results were obtained, in most tests, for the TPS- 4% KL films. (AU)

• Processo FAPESP: 19/19401-1 - Desconstrução dos tecidos vegetais: possibilidades de obtenção de materiais de maior valor agregado
• Beneficiário: Vagner Roberto Botaro
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 19/15976-0 - Biodegradação como proposta para tratamento e recuperação de nanotubos de carbono oriundos de resíduos de nanocompósitos poliméricos biodegradáveis
• Beneficiário: Ana Paula Lemes
• Modalidade de apoio: Auxílio à Pesquisa - Regular