Formation of craze-like pattern in polypropylene UV-induced surface cracking

Autor(es)

De Freitas, Amanda De S. M. ; Rodrigues, Jessica S. ; Botaro, Vagner R. ; Lemes, Ana Paula ; Cruz, Sandra Andrea ; Waldman, Walter R.

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF POLYMER RESEARCH; v. 29, n. 12, p. 8-pg., 2022-12-01.

Resumo

Polypropylene (PP) samples were exposed to accelerated aging with UV-C light and showed a morphology inside the crackings like that of thermoplastic polymers under stress, known as craze. Herein we used the well-established photodegradation of polypropylene to build the relationship between the phenomenon of fibrillation inside the crackings and the microvoid formation during the evolution of the craze process. The basis of our proposition is the similarity of the processes but the stress source: whereas an external tensile stress load drives the craze, in photodegradation the stress comes from the changes caused by the crystallization, which reduces volume, creating tensions and forming cracks. We followed the polypropylene photodegradation using Scanning Electron Microscopy (SEM), tensile tests, Dynamic Mechanical Thermal Analysis (DMTA), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffractometry (XRD) to prove the correlation between the cracking evolution and the craze mechanism. From this similarity, we paved the way to applying the current knowledge about the craze phenomenon to understand better the cracking evolution on polypropylene surfaces. (AU)

• Processo FAPESP: 16/24936-3 - Desenvolvimento de filmes finos depositados a plasma para fotoproteção de materiais poliméricos
• Beneficiário: Walter Ruggeri Waldman
• 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
• 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