**4.3 Instrumentation**

174 Recent Advances in Plasticizers

dielectric constant of 7.6. Another virtue of this solvent is its good solvent properties. It can dissolve a wide range of non–polar and polar chemical substances. Therefore, it is being chosen as solvent as it shows a well–dissolution with PVC, Li2B4O7 and PC in this study. It is

O

These plasticized–polymer electrolytes were prepared by solution casting technique. It is the simplest and cost–effective method to produce thin films from solution by evaporating the

High molecular weight poly (vinyl chloride) PVC was obtained from Fluka, while lithium tetraborate (Li2B4O7) and propylene carbonate (PC) were obtained from Aldrich.

Prior to the preparation of the polymer electrolytes, Li2B4O7 was dried at 100 °C for 1 hour to eliminate trace amounts of water in the material. Appropriate amount of PVC, Li2B4O7 and PC were dissolved in anhydrous THF. The mixture was then stirred continuously for 24 hours at room temperature to achieve a homogenous solution. The resulting solution was cast on a Petri dish and was allowed to evaporate slowly in a fume hood. This procedure yields free standing films eventually. The designations of polymer film are listed in Table 1. The weight ratio of PVC (70%) to Li2B4O7 (30%) had achieved the maximum ionic conductivity in the preliminary step which is not being shown here. As a result, the ratio of

**Designation Composition of materials [PVC: Li2B4O7: PC (wt%)]** 

Table 1. The nomenclature of samples with different stoichiometric amounts of materials

SPC1 70.0:30.0:0.0 SPC2 66.5:28.5:5.0 SPC3 63.0:27.0:10.0 SPC4 59.5:25.5:15.0 SPC5 56.0:24.0:20.0 SPC6 52.5:22.5:25.0 SPC7 49.0:21.0:30.0 SPC8 45.5:19.5:35.0 SPC9 42.0:18.0:40.0

also a heterocyclic compound with chemical formula of (CH2)4O, as shown in Figure 4.

Fig. 4. Chemical structure of tetrahydrofuran.

volatile solvent. No technology is required in this technique.

Tetrahydrofuran (THF) was obtained from J.T. Baker.

PVC to Li2B4O7 was fixed as 70 wt% to 30 wt% in this study.

**4. Experimental** 

**4.1 Materials** 

**4.2 Sample preparation** 

added into polymer electrolytes.

After the samples were prepared, the characterizations have been employed to investigate the electrical, structural and thermal properties of the samples. These analytical and evaluative methods include ac–impedance spectroscopy, Fourier Transform Infrared spectroscopy (FTIR) and thermogravimetry analysis (TGA).
