PSI - Issue 28

Anurag Singh et al. / Procedia Structural Integrity 28 (2020) 2218–2227 Anurag Singh/ Structural Integrity Procedia 00 (2019) 000–000

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Figure 4: SEM mages of PGLA fibres

Table 1: PGLA concentration and filament diameter

13.84 μm PLA 323.1 μm PGA

PGLA (Multifilament) Diameter

Concentration of various blends

Single Fibre Multifilament

10 % 90 %

2.3. Mechanical testing Uniaxial quasi-static tensile tests with five different strain rates chosen as 10 -4 , 10 -3 , 10 -2 , 50x10 -2 , and 10 -1 1/s for mechanical characterisation, up to failure at room temperature on undegraded and degraded PGLA samples. Instron® ElectroPuls E1000 (High Wycombe, England) is used to perform these tests using a 2 kN load cell. Gauge length is 100 mm. 2.4. Differential Scanning Calorimetry DSC was performed in a DSC 214 Polyma (NETZSCH). The material was heated to 250 °C at a heating rate of 10 °C/min, then cooled down to 10 °C at a cooling rate of 10 °C/min and then reheated to 250 °C in the N 2 atmosphere. Equation 1 shows the formula to calculate the degree of crystallinity from the enthalpy of melt and enthalpy of melt of 100% crystalline sample. *100 100%    esample crystallin melt H H y ystallinit DegreeofCr (1)

   

   

Where, 

(∆H) melt is the enthalpy of melting,

 (∆H) 100% crystalline sample is the enthalpy of melt of a fully crystallised sample.  Enthalpy of melt of 100% crystalline PGLA sample is 181.44 J/g. 3. Results and Discussions 3.1. Mechanical properties vs degradation time

Figure 6 shows the tensile test results of PGLA fibres, five different strain rates and at each strain rates six stages of degradation; viz. 0, 5, 10, 15, 20 and 30 days at room temperature. Only last staged degraded PGLA fibres showed inferior mechanical properties than the dry PGLA fibres. Mechanical properties of the PGLA fibres increases till 15 days of degradation; the last two stages of degradation show a decrease in terms of toughness of the PGLA fibres.