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(Reference retrieved automatically from SciELO through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Influence of Surface Crystalline Structures on DSC Analysis of PTFE

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Author(s):
Vinicius Fiocco Sciuti [1] ; Caiuã Caldeira Melo [2] ; Leonardo Bresciani Canto [3] ; Rodrigo Bresciani Canto [4]
Total Authors: 4
Affiliation:
[1] Universidade Federal de São Carlos. Programa de Pós-Graduação em Ciência e Engenharia de Materiais - PPGCEM. Departamento de Engenharia de Materiais - Brasil
[2] Universidade Federal de São Carlos. Programa de Pós-Graduação em Ciência e Engenharia de Materiais - PPGCEM. Departamento de Engenharia de Materiais - Brasil
[3] Universidade Federal de São Carlos. Programa de Pós-Graduação em Ciência e Engenharia de Materiais - PPGCEM. Departamento de Engenharia de Materiais - Brasil
[4] Universidade Federal de São Carlos. Programa de Pós-Graduação em Ciência e Engenharia de Materiais - PPGCEM. Departamento de Engenharia de Materiais - Brasil
Total Affiliations: 4
Document type: Journal article
Source: MATERIALS RESEARCH-IBERO-AMERICAN JOURNAL OF MATERIALS; v. 20, n. 5, p. 1350-1359, 2017-07-31.
Abstract

The physical and mechanical properties of polytetrafluorethylene (PTFE) are greatly dependent on the degree of crystallinity and this is extremely important for the modeling of PTFE processing which is complex and costly. Differential scanning calorimetry (DSC) is one of the most important techniques for the determination of the degree of crystallinity and powder granules of the sample are generally used in the analysis. This procedure provides samples with a high surface-to-volume ratio, resulting in the formation of a considerable number of surface crystalline structures, called warts, along with the bulk crystallization, as shown by scanning electron microscopy. The presence of warts has a significant effect on the PTFE melting enthalpy and thus hinders the correct estimation of the degree of crystallinity of industrial PTFE parts, in which bulk crystallization prevails. In this study, we propose a procedure which does not lead to the formation of warts in the DSC sample and thus allows a more accurate determination of the melting enthalpy (or the degree of crystallinity) of industrial PTFE parts. We demonstrate that samples must be extracted from the core of dense (well-pressed) parts previously sintered in an oven, and the use of powder granules and/or sintering in DSC is not recommended. (AU)

FAPESP's process: 13/00256-5 - Improvement and validating of numerical models for PTFE powder compaction
Grantee:Caiuã Caldeira de Melo
Support type: Scholarships abroad - Research Internship - Scientific Initiation
FAPESP's process: 12/25374-8 - Modeling of mechanical behavior of PTFE
Grantee:Vinicius Fiocco Sciuti
Support type: Scholarships abroad - Research Internship - Scientific Initiation
FAPESP's process: 10/20925-0 - Experimental system for validation of numerical models for the compaction process of polytetrafluoroethylene (PTFE) powder
Grantee:Caiuã Caldeira de Melo
Support type: Scholarships in Brazil - Scientific Initiation
FAPESP's process: 12/10319-1 - Mechanical behavior of polytetrafluoroethylene (PTFE) in tensile and compressive tests at different strain rates.
Grantee:Vinicius Fiocco Sciuti
Support type: Scholarships in Brazil - Scientific Initiation