Investigation of Physical Structure of Sudan III/PVK Film Composite Exposure to Acetone, and Alcohol Vapor by using XRD Method

Fabrication of Sudan III/PVK composite film for sensor technology application has been carried out by using casting method. The physical structure of Sudan III/PVK composite film exposure to acetone and alcohol vapor have been investigated by using XRD method. In this paper would be determined the interplanar distance of crystals plane, crystallinity index, the average crystallite size and the average polymer chain separation within the Sudan III/PVK composite film and also for pure Sudan III and PVK powder samples according to XRD experimental results.


Introduction
Development of a composite polymer material of Sudan III/poly (N-vinylcarbazole) as a sensing material for optical sensor technology application is an interesting subject research [1,2]. The optical sensor based on polymer optical fibre is important because of resulting lightweight sensor device, and without electrical power at the sensing point and is easily produced and low cost [3 ]. Sudan III molecule posseses azobenzene group and so that this molecule is well known very sensitively to its environmental especially in presence of other molecules such as alcohol, ethanol and acetone vapor [4].
PVK material have been used as matrix polymer for fabrication of TiO 2 -PVK composite film for gas sensor etahanol application. And aslo for development of composite material using inorganic nanocrystal such as PVK-LiNbO 3 . The properties sensing material of course is also determined by the physical structure such as the crystallinity. In this research we would like to determine the crystallinity content involving the crystal plane distance, the average crystal size, the average chain separation, and degree of crystallinity within the Sudan III/PVK composite film. In this paper the crystallinity of pristine Sudan III and PVK in form of powder also discussed.

EXPERIMENTAL
Fabrication of Sudan III/PVK composite film has been carryed out using solution casting method. This experiment aims to produce a good quality composite film which are homogeneously film and a smoothly surfaces film which are strongly depend on a solvent used.

Materials Sudan III molecule
Sudan III molecule is red disazo dye which possesses a hydroxyl group and two azo groups that are sensitively to interact with others molecule such as CO 2 . The Sudan III molecule structure is shown in figure 2.1.

a. Sample Preparation Preparation of Solution Sample
The solvent used in this experiment was CHCl 3 . Sudan III solution and PVK solution were prepared by disolving Sudan III powder and PVK powder in CHCl 3 respectively and then stirred for 12 hours using magnetic stirrer in order to obtain the missible solution. Next, the stock of Sudan III solution and stock of PVK solution were combining to obtain the Sudan III/PVK composite solution. The composition of Sudan III/PVK solution were 20/80 % wight and 20/40 % weight.

Preparation of Sudan III/PVK composite film.
Preparation Sudan III/PVK composite film was carried out using casting solution method. The Sudan III/PVK solution was deposited on a clean glass substrate and then dryed at room temperature. Next , it was covered to avoid contamination from unwanted material such as dust.   The experimental of Sudan III/PVK conposite film exposure to acetone vapor and alcohol vapor were worked out as shown in figure 2.5 and 2.6. The composite film was placed at about 10 cm above the jar which is containing of 5 ml acetone and alcohol liquids. And then it was vaporized at 23 o C for 12 hours.

Sample Characterization
Characterization of the samples namely Sudan III molecule and PVK and Sudan III/PVK composite film were carried out by using XRD measurement.
The XRD (X-Ray Diffraction)measurement is intended to investigate the structural physics of the samples. From the XRD sectra can be then determined the crystal plane distance, degree of crystallinity, the average polymer chain/molecule separation, the average crystal size. The XRD measurement using Philips Diffractometer. In this experiment XRD diffraction patern is recorded with

RESULTS AND DISCCUSION
The result of XRD measurement of PVK powder is shown in figure 3.1. From XRD spectra can be calculated the crystal plane distance according to the Bragg formula : [ 7 ]. From the XRD spectra (figure 3.1) the average polymer chain separation for PVK sample in powder form was calculated by choosing peak with maximum intensity 2 = 19.3 (d hkl = 4.6 Angstrom). By using the formula S=5/8 sin where S is separation polymer chain, is X-ray wavelength ( 1.5406 Angstrom) and is diffraction angle at maximum intensity from halo amorf . So we get S = 5.744 Angstrom atau 57.44 nm.  The average polymer chain separation of PVK sample film (figure 3.3) was calculated from to the amorf peak with a maximum intensity. By using the formula 3.2 is obtained S = nm.
Next, the average polymer chain separation of Sudan III/PVK (1/2) composite film is calculated from XRD spectra as shown in   Identification of XRD spectra of Sudan III pristine powder is shown in table (3.2).
The results of XRD measurement for PVK film and for Sudan III/PVK composite film without exposure to the vapor is shown in figure 3.3 and 3.4.      The crystallinity index (CI) is calculated according to Segal peak height [9] with intensity method calculation is: CI = (I c -I am )/I c 3.3. From figure 3.4 can be calculated the crystallitnity index [9] that is CI=(I c -I am )/I c = (634-420)/634=0.337.      The XRD spectra of Sudan III/PVK composite film exposure to alcohol vapor is shown in figure 3.7.   The average polymer chain separation (S) for Sudan III/PVK composite film exposure to alcohol vapor was found to be 56.6 nm . And this is the same value of S for Sudan III/PVK composite film exposure to acetone vapor.
Crystallinity index (CI) for Sudan III/PVK composite film exposure to alcohol vapor was found to be 0.64. Meanwhile for Sudan III/PVK composite film exposure to acetone vapor is 0.52. So CI for Sudan III/PVK composite film exposure to alcohol vapor is higher around 19% c.f CI for Sudan III/PVK composite film exposure to acetone vapor.