*3.1.1 Analysis of rheological properties*

It is clear from **Figures 3** and **4** that the dynamic viscosities of PO at various temperature range is inferior w.r.t commercially available SAE 20W40 (**Figures 3** and **4**). Hence, the dynamic viscosity of PO is enhanced using different weight percentages of EVA and SBR polymers. The variation of viscosity is studied from 25–100°C [20–22].

From **Figure 3**, it is observed that the plain PO is having the lowest viscosity both at lower as well as higher temperatures. The viscosity is found to be improving on addition of EVA in different weight percentages to PO. PO with 2.5% w.t. EVA has shown the highest change in viscosity both at lower as well as higher temperatures.

From **Figure 4**, it is found that SBR tends to show better improvements in viscosity than EVA at different weight percentages. The curve of SBR at 2.5% w.t. in PO is found to be close enough to reference oil SAE20W40. However, from the results obtained from **Figures 3** and **4**, at equal weight percentages of the additives PO + SBR combinations have shown higher viscosity enhancements. Hence, SBR has been selected as the viscosity enhancer in the current study.


#### **Table 3.**

*Fatty acid profile of PO and sesame oil.*

**209**

**Figure 5.**

*Biolubricant from Pongamia Oil*

*3.1.2 Analysis of oxidation stability*

**Figure 4.**

excellent oxidation stability.

*Change in dynamic viscosities of oil samples at 40°C after HOOT.*

High oxidation stability of TBHQ is because of the longer alkyl chains present in it [23]. Oxidation stability of the oil samples are estimated by measuring the change in viscosity at 40°C after hot oil oxidation test (HOOT) from the fresh sample without subjected to HOOT [24]. Change in dynamic viscosity of neat PO, PO oil samples blended with different weight percentages of TBHQ and SAE20W40 at 40°C are calculated and plotted as shown in **Figure 5**. From the analysis of different oil samples blended with different weight percentages of TBHQ , PO + 2.5% TBHQ showed the least change in viscosity. It is observed that for the weight percentage of TBHQ beyond 2.5%, it is difficult to dissolve in PO. The change in viscosity at 40°C of PO + 2.5% TBHQ is found to be very lesser than neat PO comparable with that of SAE20W40. Thus PO + 2.5% TBHQ have

*Dynamic viscosity v/s temperature curve for PO with SBR compared against SAE20W40.*

*DOI: http://dx.doi.org/10.5772/intechopen.93477*

*Tribology in Materials and Manufacturing - Wear, Friction and Lubrication*

has been selected as the viscosity enhancer in the current study.

thermal degradation of at 204.39°C [9].

the pour point of the lubricants.

*3.1.1 Analysis of rheological properties*

the loss of moisture content and volatile components from it [19]. Thus, by observing the TGA, it is evident that PO is a well suited environment-friendly base stock for a wide range of temperatures. The thermal compared to SAE20W40 which have

**Table 3** shows the fatty acid profile of PO, compared with that of sesame oil and coconut oil. High amount of oleic acid present in the PO can improve the tribological properties [10]. A larger proportion of saturated fatty acids can adversely affect

It is clear from **Figures 3** and **4** that the dynamic viscosities of PO at various temperature range is inferior w.r.t commercially available SAE 20W40 (**Figures 3** and **4**). Hence, the dynamic viscosity of PO is enhanced using different weight percentages of EVA and SBR polymers. The variation of viscosity is studied from 25–100°C [20–22]. From **Figure 3**, it is observed that the plain PO is having the lowest viscosity both at lower as well as higher temperatures. The viscosity is found to be improving on addition of EVA in different weight percentages to PO. PO with 2.5% w.t. EVA has shown the highest change in viscosity both at lower as well as higher temperatures. From **Figure 4**, it is found that SBR tends to show better improvements in viscosity than EVA at different weight percentages. The curve of SBR at 2.5% w.t. in PO is found to be close enough to reference oil SAE20W40. However, from the results obtained from **Figures 3** and **4**, at equal weight percentages of the additives PO + SBR combinations have shown higher viscosity enhancements. Hence, SBR

**Constituent Pongamia oil [10] Sesame oil [9] Coconut oil [9]** Oleic acid 62.98% 42% 5% Linoleic acid 16.84% 38% 1% Palmetic acid 9.1% 13% 7.5%

**208**

**Figure 3.**

**Table 3.**

*Fatty acid profile of PO and sesame oil.*

*Dynamic viscosity v/s temperature curve for PO with EVA compared against SAE20W40.*

**Figure 4.** *Dynamic viscosity v/s temperature curve for PO with SBR compared against SAE20W40.*
