**3.2 Strength characteristics in unaged condition**

Second, we will compare the tensile properties of PCR with virgin or conventional PC at time zero and without any aging. Here breaking strengths of 50 and 75% PCR grades were compared with conventional PC. **Figure 4** shows the loadextension curve of three grades of PC and PCR-PC.

From **Figure 5(a)**, both the PCR grades have comparable tensile strength (at breakage) when compared with a virgin PC of the same MFR. The strength is around 67, 65 and 71 MPa for Virgin PC, 50% PCR and 75% PCR respectively. For comparison, it was made sure the resin color is white for all the grades of PC and PCR. In **Figure 5(b)**, tensile strain at breakage for Virgin PC, 50% PCR and 75%

*Effect of Environmental Aging on Tensile Properties of Post-Consumer Recycled (PCR)… DOI: http://dx.doi.org/10.5772/intechopen.99528*

**Figure 3.** *% change in dimension after aging: (a) width and (b) thickness.*

PCR have been compared. The strain follows a very similar pattern as the strength in **Figure 4(a)**. Strain value of 210%, 200% and 213% were recorded respectively for Virgin PC, 50% PCR and 75% PCR. The strain at breakage confirms the ductile behavior for all these three grades of polycarbonates.

#### **3.3 Strength characteristics after aging**

Secondly, we studied strength degradation with aging. First, all the three grades were compared at 100, 200 and 300 cycles of the -20<sup>o</sup> to 60<sup>o</sup> C thermal cycling. Based on the data recorded in **Figure 6(a)**, temperature cycling does not have a strong effect as the strength did not degrade appreciably for any of the grades.

**Figure 4.** *Load - extension for virgin PC, 50% PCR and 75% PCR before aging.*

**Figure 5.**

*Comparison between virgin PC and two grades of PCR for (a) tensile strength, (b) tensile strain at breakage.*

*Effect of Environmental Aging on Tensile Properties of Post-Consumer Recycled (PCR)… DOI: http://dx.doi.org/10.5772/intechopen.99528*

**Figure 6.**

*Effect of thermal cycling on (a) tensile strength, (a) tensile strain and (c) life distribution of virgin PC, 50% PCR and 75% PCR.*

Similar results were observed in strain at breakage 6(b). None of the grades show any significant reduction in strain and no pattern was observed for all three grades which indicates that the tensile bars retained the ductile behavior. The reliability performance was evaluated by B10 (where 10% of the population fails), β (slope of the curve), and *α* (characteristic life). **Figure 6(c)** and **Table 3** shows that the B10
