Untitled in english

Author(s)

Lincoln Silva Gomes

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola Politécnica (EP/BC)
• Defense date: 2001-11-20

Examining board members

Nicole Raymonde Demarquette; Renato Norio Shimizu; Maria Lucia Pereira da Silva

• Advisor: Nicole Raymonde Demarquette

Abstract

Liquid-crystalline polymer (LCPs) have been the subject of intensive research in the past few decades, due to their various applications such as: high-strength fibers, processing aids and electro-optical devices. Due to their applications in various areas, it\'s very important to the evaluate their properties such as the surface tension. In this work, one equipment based on the Pendant Drop method to measure the surface tension of LCPs was developed. The apparatus developed in this work was tested regarding their temperature control and optical distortion. The influence of temperature on the surface tension of LCPs (Vectra A950 e PB-n) and PET was evaluated using the pendant drop method. The experimental data of surface tension were compared to theoretical predictions using Dee and Sauer theory. Dee and Sauer theory infers surface tension from PVT (Pressure, Volume, Temperature) experimental data. The experimental data showed that the surface tension of PET decreases linearly with increasing temperature and that the surface tension of PB-11 increases with increasing temperature for temperatures, above the nematic to isotropic transition temperature, and that, above 240°C, the surface tension decreases when temperature increases. The comparison between the theoretical and experimental data, showed that the absolute values of tension did not corroborate. This discrepancy may result from the fact that the values of m and bDS (inherent parameters of theories) used for the predictions were not adapted for LCPs. (AU)