Influence of Surface Crystalline Structures on DSC Analysis of PTFE
AUTOR(ES)
Sciuti, Vinicius Fiocco, Melo, Caiuã Caldeira, Canto, Leonardo Bresciani, Canto, Rodrigo Bresciani
FONTE
Mat. Res.
DATA DE PUBLICAÇÃO
31/07/2017
RESUMO
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.
Documentos Relacionados
- The influence of storage method on the transparency of pig crystalline lens
- In vitro analysis of the influence of surface treatment of dental implants on primary stability
- Crystalline surface layers in procaryotes.
- Anisotropic surface chemistry of crystalline pharmaceutical solids
- Influence of Cross-Linker Concentration on Physical Properties of Main-Chain Liquid Crystalline Elastomers