The Thermogravimetric,Microscopic and Mechanical Analyses of PBT and PET yarns(4)

2.2 Methods

2.2.1 Microscopic Analyses
The morphologic features of various modified and unmodified yarns were studied with the help of light microscope (Leica L5 FL stereomicroscope) and SEM (Phillips XL-30S FEG).

2.2.2 Thermogravimetric Analysis
The TGA of the fabric sample was carried out using a Perkin-Elmer Diomand in the temperature range of 30–500°C under nitrogen atmosphere. The heating rate was maintained at 10°C/min. The measurements were made under a constant nitrogen flow rate of 20 ml/min.
2.2.3 Mechanical Analyses (Tensile Properties)
The tensile strength and elongation at break properties of the samples were measured using a Statimat material testing machine and tests were conducted according to DIN EN ISO 2062 method.

3. RESULTS AND DISCUSSION
To investigate the microstructure of the samples, SEM and polarized light microscope were used. The SEM and microscopic images of the samples are shown in Figure 1 and 2.

From the SEM images, it was clearly seen that the polyester fibre generally had a smooth surface. After the modification processes, it was detected that there were some particles on surface of the fibers and the surfaces were rougher. Also, cross section of the fibres and incorporated materials (e.g. silver particles in Figure 1b) on the fiber surface differed due to change in the spinning process and in the additive material. From the light micrographs, the cross sectional shapes of the fibres were clearly observed. It was seen that regular and UV additive polyester fibres had circular cross section whereas antibacterial and flame retardant polyester fibres and PBT had pentalobal cross section. It was also seen that PBT fibre had a smooth surface like PET based fibres and this fact confirmed the previous study of Mathew et al (11).

Writen by Buket ARIK1, Ebru BOZACI1, Asli DEMIR2, Esen ÖZDOGAN1