Tensile Strength of PP Fibres
Since there is no specific tensile test guidelines for fibres in Australian Standards, tests for tensile strength and Young’s modulus were performed on the virgin and recycled PP fibres according to ASTM D3822-07 (ASTM 2007). The tensile test instrument used for the tests was United STM ‘Smart’ Test System (STM-50KN) from United Calibration Corporation and was equipped with a 2 kN load cell and data acquisition software (Fig. 3.2). Distance between the clamps was adjusted to obtain a gauge length of 25.4 mm, and extension speed was set as 60% of the gauge length/min (15.24 mm/min). 30 specimens were tested for each sample. Testing temperature was 20 ± 2 °C.
Fourier Transform Infrared Spectroscopy
Fourier transform infrared spectroscopy (FTIR) measurements were carried out with a Perkin-Elmer spectrum 100 FTIR Spectrometer. FTIR is a technique which is used to obtain an infrared spectrum of absorption, emission, photoconductivity or Raman scattering of a material, as shown in Fig. 3.3. Since the FTIR measures how well a sample absorbs light at each wavelength, molecular orientation of the recycled PP fibre and its raw material can be measured by using FTIR spectra with radiation parallel and perpendicular to the fibre and raw material. Through this test, we can see how the melt spinning and hot drawing process affect the molecular chains of the PP fibres. The intensity of absorption brands at 998 and 1153 cm 1 were used to
Fig. 3.2 Test apparatus for fibre tensile test
Fig. 3.3 Mechanism of FTIR (Myllari et al. 2015)
calculate the contents of crystal and amorphous, respectively (Parthasarthy et al. 2002). For quantitative estimation of orientations, the dichroic ratios of 998 and 1153 m-1 bands, R998 and R1153, were calculated with dividing the intensity of absorption brands in parallel direction (Aparallel) by the intensity in perpendicular direction (Aperpendicular), that is, R = Aparallel/Aperpendicular. The degree of orientation f of crystal and amorphous was further calculated through Eq. (3.1) (Li et al. 2014)