Polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP) and cupric sulphate (CuSO₄) were procured from S D fine-chem. limited, Mumbai, India.

Samples were prepared using solution casting method. Stock solution PVA is prepared by dissolving 5 wt% of PVA in distilled water, stirred for 6 hours at room temperature using a magnetic stirrer, double filtered and allowed to settle for a day. Similarly stock solution of 3% of PVP is also prepared in distilled water. Different concentrations of PVA/PVP solutions cast on petri dishes and allowed to dry at room temperature. After complete drying the films were peeled out of these dishes. The film with 50/50 concentration was found to be blended well hence the solution of this percentage was used to prepare the different concentrations of cupric sulphate doped PVA/PVP films. The cupric sulphate was added to the 50/50 (PVA/PVP) stock solution with different weight concentrations of 0.2%, 0.4%, 0.6%, 0.8% and 1.0%, stirred at room temperature using magnetic stirrer for half an hour to get more homogeneous solution and then the solution was poured into petri dish placed on flat surface and allowed to dry completely at room temperature. The dried composite films were peeled out and cut in suitable sizes and were used in these studies.

XRD patterns of pure and CuSO₄ doped PVA/PVP polymer composite films of different concentrations were recorded using Rigaku Miniflex II Desktop X-ray Diffractometer equipped with CuK_α radiation (wavelength = 1.5406 Å) and a graphite monochromator. The samples were scanned in the 2θ range 6˚ - 80˚ and the specifications used for the recording are 30 kV and 15 mA with the scanning speed of 5˚/min. After correcting for instrumental broadening the microstructural parameters of these polymer composites were computed by employing whole powder pattern fitting method. Analysis of X-ray data is given in theory section. Fitted XRD pattern for the samples is as shown in Figure 1.

The absorbance of pure and CuSO₄ doped PVA/PVP polymer composites were recorded at room temperature in the UV-visible wavelength range using Labtronics MODEL LT-2800 double beam UV-Visible spectrophotometer. The recorded UV-Visible spectra of pure and CuSO₄ doped PVA/PVP films is as shown in Figure 2.

The Infrared transmission spectra of these polymer samples were recorded at room temperature in the wave number range of 4000 - 500 cm⁻¹ using Perkin Elmer Spectrum. The recorded FT-IR spectra of pure and CuSO₄ doped PVA/PVP polymer composite films are given in Figure 3.

Ac conductance measurements for these films were made using Hioki LCR 3532 Hi-tester in the frequency range from 50 Hz to 5 MHz at room temperature. Variation of conductivity calculated with log frequency is as shown in Figure 4.

Experimental and simulated XRD pattern of pure and CuSO₄ doped PVA/PVP polymer composite films are shown in Figure 1. From Figure 1 a broad peak at 20˚ and a less intense peak at 41˚ observed for pure PVA/ PVP film shows semicrystalline nature of the film. As the concentration of the dopant increases the peaks becomes more broad and less intense which are due to the disruption of the PVA/PVP crystalline structure by the added CuSO₄. Using this XRD data microstructural parameters were computed from line profile analysis [32] . The obtained data from the line profile analysis were further used in the refinement by whole powder pattern fitting method. These values are listed in Table 1. Figure 1 shows the goodness of the fit between the experimental and simulated XRD profile by whole powder pattern fitting method. From Table 1, it is seen that the average crystallite size varies with the concentration of dopant. Also the average lattice strain in these poly- mer composites are found to be vary between 0% and 1.5%, further the broadness of the peak which is generally

the measure of FWHM is also given in Table 1.

The crystalline shape ellipsoids are obtained by plotting experimentally obtained size values and it is given in Figure 5. Area under these ellipsoids gives the crystalline area and it changes with the concentration of cupric sulphate. Maximum crystallite area was obtained for pure sample and minimum for 0.8% cupric sulphate in PVA/PVP. This is only a graphical illustration of shape ellipsoids with percentage.

A casual glance at Figure 2 indicates that PVA/PVP has high transmission and it decreases with the increase in concentration of CuSO₄ in doped films. This is due to the formation of intermolecular hydrogen bonding between the ions of the dopant and the OH. The decrease in transmission for doped PVA/PVP films reflects the variation in the optical band gap which arises due to the change in polymer structure. We have made an attempt of evaluating optical band gap of these polymer composites using tauc plot. The derived tauc plot drawn against (αhν)^1/2 and hν is as shown in Figure 6. The calculated band gap values along with conductivity, electronic specific heat and statistical performance index are given in Table 2.

Since there are too many physical parameters have been experimentally determined, we have used multivariate analysis technique which is as follows. Each parameter that we have determined has been given a weightage. Then the sum of the weightage times the value of the physical parameters has been computed by normalising it with total sum of the weightage. This parameter has been identified as statistical performance index. In this work 35% weightage is given to crystallite size, 25% to each conductivity and energy gap and remaining 15% to electronic specific heat. From Table 2 it is found that the statistical performance index is high in the range