# Emulsion Polymerization of Tung Oil-Based Latexes with Asolectin as a Biorenewable Surfactant
## 3 Results and Discussion
The pure resin, containing 40 wt.% of tung oil, 30 wt.% of BMA, 20 wt.% of DVB, 10 wt.% of asoletin and an extra 5 wt.% of DTBP, was heated at 100 \({}^{\circ}\)C in a convection oven. The resulting DEA curve is displayed in Figure 5.  
Figure 4: 1:4 (xylene:water) by weight emulsion containing 200 mg of total monomer weight (**A**) immediately after sonication, (**B**) 15 min after sonication, and (**C**) 30 min after sonication. Figure 3: Emulsions of 1:4 (xylene:water) by weight containing (**A**) 200 mg of total monomer weight, (**B**) 400 mg of total monomer weight, and (**C**) 600 mg of total monomer weight. The pictures have been taken immediately after the samples were prepared. In Figure 5, the initial decrease in ion viscosity is due to an increase in ion mobility as the monomers start heating. After 20 min of heating, ion viscosity begins to increase as the polymerization process begins. Based on the stability experiment results (Figure 4), the onset polymerization time of 20 min is ideal for the cure of emulsions since within that time frame, the emulsion will still be intact. The continuous increase in the slope of the DEA curve for the remainder of the experiment indicates a continuous progress in the polymerization process. Over the course of 24 h, the DEA curve doesn't plateau, indicating that the resin isn't fully polymerized within the duration of the experiment. These results suggest that a post-cure step might be needed in order to complete the polymerization reaction. In order to investigate the effect of tung oil concentration in the cure of tung oil/asolectin-based emulsions, samples with varying concentrations of tung oil were prepared and cured at 100 \({}^{\circ}\)C for 24 h. Maintaining the concentration of asolectin constant at 10 wt.% and the BMA/DVB weight ratio set at 1.5, four samples containing 40 wt.%, 55 wt.%, 70 wt.%, and 80 wt.% of tung oil were prepared and cured at 100 \({}^{\circ}\)C for 24 h. The dried products from these samples were analyzed by DSC as shown in Figure 6.  
From the DSC curves in Figure 6, it can be seen that all samples exhibit an exothermic peak in the 150-160 \({}^{\circ}\)C regardless of the sample composition. Those peaks indicate an exothermic reaction occurring at that temperature, suggesting further crosslink of unreacted carbon-carbon double bonds. The presence of such peak in the DSC curves of all four compositions demonstrates that none of the dried products are fully polymerized when subjected to the cure conditions (100 \({}^{\circ}\)C, 24 h), revealing a need for a post-cure step after drying. Figure 5: Dielectric Analysis curve of 40 wt.% tung oil, 30 wt.% \(n\)-butyl methacrylate (BMA), 20 wt.% DVB, and 10 wt.% asolectin heated at 100 \({}^{\circ}\)C for 24 h.  
Figure 6: Differential Scanning Calorimetry results for dried products from emulsions containing (**A**) 80 wt.%, (**B**) 70 wt.%, (**C**) 55 wt.%, and (D) 40 wt.% of tung oil after heating at 100 \({}^{\circ}\)C for 24 h.  
Table 1 lists the enthalpy and the temperature for the maximum of the exothermic peaks observed for the samples in Figure 6. The enthalpy, calculated from the integration of the corresponding peaks is highest in the products containing the greatest amount of tung oil. This information suggests that samples with lower amounts of tung oil are polymerized to a higher extent during cure when compared to samples having a higher concentration of tung oil. This is most likely due to the relative reactivity of the oil and the other monomers. Due to its chemical structure, tung oil is expected to be less reactive towards free radicals than DVB or BMA. Therefore, increasing the amount of tung oil in the resin makes it less reactive and a higher portion of the monomers remains unreacted after the cure, generating higher enthalpies upon heating during the DSC experiments.