Discussion CHAPTER - 5

Transcription

1 CHAPTER - 5 Discussion The chapter deals with discussion of the results. The thesis ends with this chapter. The chapter interpretates and discusses the results of the investigation on the physical properties of mineral and biological waxes, and animal fat. The chapter starts with brief introduction on waxes. The results of the investigations have been discussed, correlating with biological and medical and technological aspects. At the end of this chapter, the important conclusions drawn from the investigations are presented.

2 The different waxes such as Mineral wax (Microcrystalline wax and Paraffin wax); biological wax (Beeswax); and animal Fat are taken for study of physical properties using the techniques like FTIR, NMR, GC-MS, XRD, microwave bench, network analyzer and impedance analyzer. The results obtained are tabulated for comparison and discussion. The case wise critical review of results from various methods revealed the behavior of different waxes and fat at wide range of frequencies, which is useful in medical discipline and also in technology electronics. From the present investigation, it is noticed that the density of the samples is considerably less when compared with that of water. Further, among the wax samples, the density of paraffin wax is less, while the density of Beeswax and animal fat is high. The heat treatment increases the density, irrespective of type of wax (Table 5.1). The visible region of electromagnetic radiation extends from 0.38 to 0.78 µm. The infrared region extends from the end of the visible region at 0.78 µm to the microwave region with a wavelength of ~1mm. The infrared region is usually divided into three sections. The section used mostly by material scientist is the mid infrared region extending from 2.5 µm or 4000 cm -1 to ~ 50 µm or

3 200 cm -1. The region between the visible and mid infrared is called near infrared region. This region of the infrared has been used for many applications, especially for quantitative analysis. The region beyond ~50 µm (200 cm -1 ) is called the far infrared region. This region is used for studying the low frequency vibrations and some molecular rotations. Common infrared spectrophotometers cover wave numbers raging from 4000 to 200 cm -1. The spectrum is a plot of sample absorbance or percent transmittance versus wave number. A grating or several prisms are used for changing wavelengths and for monochromatisation. Sodium Chloride prisms are used for the 4000 to 600 cm -1 range, while cesium bromide prisms are used for 600 to 200 cm -1 range. However, the wavelength scale usually changes with use, and therefore, frequent calibration is necessary. Biological samples can be studied as mulls in Nujol. The mull is prepared by grinding the sample to a fine powder and mixing with a mulling agent to maker a paste. A thin layer of the paste is studied between Nacl and other plates. Another method is the KBr disc method in which the powdered sample is mixed with KBr and is pressed into a clear disk which is mounted and examined directly.

4 Care must be taken while analyzing infrared spectra, because of spurious bands present in IR spectra. A list of such bands have been prepared, some of which are presented in Table 5.2. (Launer, 1962). In the present investigation, the infrared spectra of powdered samples of different waxes and animal fat were recorded at the room temperature of 30 0 C with a JASCO 3500 FTIR spectrophotometer. In general, spectral analysis of tissues of biological systems depends upon the material present and the analyze being sought. The tissue itself is dominated by the spectrum of the macromolecular components, which are present to the largest amount. If living tissue is being examined, it is dominated by the water spectrum. For the spectroscopic analysis, the biological material can be classified into Four types: 1. Organic tissues such as muscle, brain, liver, kidney, heart, etc. 2. Mineralized tissues such as bone, calculi, gallstones, horn, hoof, teeth and nail, etc. 3. Body fluids such as blood, urine, saliva, bile, spinal fluid, etc. 4. Waxes (mineral and biological) and fats The main aim of the IR spectroscopic analysis of the tissues is the determination of structure and combinations of organic and inorganic constituents of the tissues. Further, it is an attempt to investigate

5 what variation has occurred in the spectrum of normal tissue. What is the effect of some physiological change, and what change might occur in the normal composition with ageing? It might be of interesting to analyze for a particular component which changes in response to some physiological stress. Finally, infrared spectra of tissues may be utilized to determine whether there are changes in the structure of various components as part of the study of the mechanism of the reactions within the living cell. The present investigation is aimed to analyze the principal constituents of some waxes in normal and heat treated conditions, and fat in normal condition. For the convenience of analysis the IR spectrum can be divided into three regions. The first region 4000 to 3000 cm -1 concerned with water and hydroxyl group. This region is of considerable interest to present study because it reveals the nature of hydrogen bonding. The second region is 3000 to 1500 cm -1, wherein bands for functional groups are seen. In this region, major IR absorptions of waxes and fat occur. The third region ( cm -1 ) has significant importance in the context of biological apatite and other salts. The spectra of

6 waxes and fat indicate the presence of bands characteristics of some functional groups concerned with the waxes and fat. These are the major bands which can be attributed to the organic component of the waxes and fat. In the case of waxes and fat of the present investigation, FTIR Spectroscopy confirms that some functional groups are absent after heat treatment. Even after heat treatment, the main compounds are present. The presence of peaks at 2920 cm -1, cm -1, cm -1, cm -1, cm -1 is characteristic of wax. The additional peaks such as cm -1, cm -1, cm -1 and cm -1 suggest the sample is a beeswax. Similarly, the presence of cm -1 peak which refers to triglycerides tells that the sample is a fat (Table 5.3). Beeswax, microcrystalline wax, paraffin wax and animal fat contain large number of compound as evident from the data obtained from gas chromatography and mass spectrum (GC-MS). The provision is made for the temperature to go up to C. The pressure is maintained low such that the compounds having higher boiling point can easily eluded. The data of GC-MS of beeswax signifies that it contains alkenes, acid and alkane groups. Similarly the data of GC- MS of microcrystalline wax and paraffin wax shows that it contains only alkanes. The GC-MS report of animal fat tells that it contains acids and alkanes (Table 5.4).

7 The spectra of 1 H1 (proton) and 13 C NMR justify the same by showing the peaks at aliphatic region for all waxes and fat. For beeswax and fat, the peaks are seen at 4 ppm in 1 H1 and in between ppm for 13 C NMR, indicating the presence of acid group. The 1 H1 NMR of microcrystalline wax and paraffin wax indicates the presence of triplet at the end, which specifies the end molecule contains 3 hydrogen atoms. X-ray diffraction of waxes signifies that they are crystalline in nature (Figures to 4.5.7). The crystalline nature of wax is also proved from the GC-MS data. The physical properties of eluded compounds are gathered, which reveals the crystalline nature of waxes under study (Table 5.4). Further, it is found that more number of the compounds are crystalline in nature. The components of animal fat, which are predicted by GC-MS, reveal that only few compounds are crystalline in nature. From x-ray diffractograms (XRD) of waxes of the present investigation, it is evident that mineral waxes (microcrystalline wax and paraffin wax) exhibit sharp peaks, when compared to beeswax and animal fat. The sharp peaks indicate that more number of compounds are crystalline in nature. The peaks present in beeswax are found to be little bit wider than the mineral wax. It shows some compounds of the beeswax are crystalline in nature. The above Table reveals the information on the percentage of crystalline compound, out of eluded compound. In conclusion, one

8 can say that the wax, whether it can be mineral wax or biological wax, contains a large number of amorphous and crystalline compounds. Therefore it is not worth to draw conclusion that the wax or fat is only crystalline or amorphous material. The XRD of heat treated waxes and animal fat shows a decrease in the inter planer distance, which indicates the shifting of the molecules. As the inter planer distance decreases the volume of the molecule is also decreases, which reveals that the density decreases after heat treatment. The V-I characteristic curves are linear and pass through the origin (Figures to ). As the curves are linear, they are ohmic in nature. It is noticed from the present study on electrical properties that after heat treatment the resistance decreases. In other words, one can say that the conductivity increases. It is in accordance with the general theory of resistivity that the resistivity decreases as density increases. The waxes follow the same rule. After heat treatment, the increase of density shows the decrease in resistivity. The resistance of microcrystalline wax is found to be more, which indicates it is a good insulator compared to the other samples. The dielectric data of different samples that obtained by using the microwave bench at 8.9 GHz shows a decrease in dielectric constant of beeswax and paraffin wax after heat treatment, where as

9 the dielectric constant is increasing for microcrystalline wax after heat treatment. It is interesting to note that the values of dielectric constant at the frequency of 8.9 GHz that are measured using microwave bench and sophisticated network analyzer are in good agreement. This reveals the fact that in the absences of sophisticated expensive instrumentation (network analyzer), an inexpensive microwave bench solves the purpose. The study of dielectric constant of different samples at microwave range frequencies in x-band and p-band regions reveals that dielectric constant is decreasing with the increase of frequency in all cases (Tables 5.9). The dielectric data of different samples, studied using impedance analyzer, reveals a decrease in impedance and dielectric constant with the increase of frequency (Table 5.10). The dielectric study on waxes and fat in wide range of frequencies staring from 10 khz to 18 GHz presents some following interesting features:

10 There is no significant dielectric decrement in the frequency range of 10 khz to 1MHz. Further, it seems that electrical polarization mechanisms are not so pronounced. Also same is the observation in x- band frequency region. But a significant decrease in dielectric constant of wax and fat samples is noted as frequency in p-band (12.4 GHz -18 GHz) region increases. In general, it is obvious from the dielectric spectra of waxes and animal fat under study that the value of dielectric constant is low, varying from about 8 to 3 in the wide frequency range of 10 khz to 18 GHz. Table 5.1 Density of different wax samples using single pan balance S.No Sample name Condition of sample Density, ρ (gm/cm 2 ) 1 Beeswax normal Beeswax heat & cool Microcrystalline wax normal Microcrystalline wax heat & cool Paraffin wax normal Paraffin wax heat & cool Fat normal

11 S.NO Table 5.2 some common spurious absorption bands in infrared spectra Wave number (Cm -1 ) Wave Length (μm) Compound or group Source H2O Any Source H2 Any Source H2O Hydrogen bonding in water, usually in KBr discs CO2 Atmospheric absorption H2O Atmosphere H2 Water of crystallization CO NO3 Contaminant in halide window. Contaminant in halide window SiCH3 Silicon oil or grease SiO Glass CO2 Atmosphere

12 Table 5.3 Comparison of FT IR data of wax samples S.NO Sample name Condition of sample Range of characteristic wave numbers in cm -1 1 Beeswax normal 3605, 3449, 3390, 2966, 2646, 2334, 2150, 1896, 1732, 1454, 1377, 1180, 1122, 958, 920, 837, Beeswax heat & cool 3 Microcrystalline wax normal 3390,2956, 2851, 2636, 2357, 1738, 1464, , 2733, 2334, 1633, 1462, 1377, 1180, 889, Microcrystalline wax heat & cool 2928, 2339, 1599, 1462, 1377, 1180, 889, Paraffin wax normal 6 Paraffin wax heat & cool 7 Fat normal 2918, 2336, 1898, 1462, 1379, 1128, 889, , 2339, 1898, 1469, 1379, 889, ,2918, 2332, 1730, 1468, 1161, 968, 891, 721

13 Table 5.4 Comparison of different samples with reference to compounds present through GC-MS S.No. Sample name Condition of sample Name of the compounds present within the sample 1 Beeswax normal Cyclohexadecane, palmitic acid, octadecane, Heneicosane, octadecenoic acid, stearic acid, Docosane, Tricosane, Tetracosane, Pentacosane, Hexacosane, Heptacosane, Octacosane, Nonacosne, Triacontane 2 Microcrystall ine wax normal Hexadecane, Octadecane, Nanodecane, Eicosane, Heneicosane, Docosane, Tricosane, Tetracosane, Pentacosane, Hexacosane, Heptacosane, Nonacosne, Triacontane, Hentriacontane, Dotriacontane, Tritriacontane. 3 Paraffin wax normal 4 Fat normal Heneicosane, Docosane, Tricosane, Tetracosane, Pentacosane, Hexacosane, Octacosane Nonacosne, Triacontane, Dotriacontane, Tritriacontane, decyltetracosane. n-hexane, acetic acid, Tetradecanoic acid, palmitoleic acid, palmitic acid, Margaric acid, Oieic acid, Stearic acid, Tetratetracontane.

14 Table 5.5 Data on crystalline compound in wax and fat samples S.NO Sample name 1 Beeswax(nor) 2 Microcrystalline wax (nor) Name of the crystalline compounds present within the sample Cyclohexadecane, Heneicosane Docosane, Tricosane, Tetracosane, Hexacosane, Heptacosane, Nanodecane, Eicosane, Heneicosane, Docosane, Tricosane, Tetracosane, Hexacosane, Heptacosane, Hentriacontane % of crystalline compounds present within the sample Paraffin wax (nor) Heneicosane, Docosane, Tricosane, Tetracosane, Hexacosane, Dotriacontane, decyltetracosane 58 4 Fat (nor) Margaric acid 11 Table 5.6 A Comparison on resistivity of different samples. S.NO Sample name Condition of sample Resistivity ρ(x10 7 Ω.m) 1 Beeswax normal Beeswax heat & cool Microcrystalline wax normal Microcrystalline wax heat & cool Paraffin wax normal Paraffin wax heat & cool Fat normal

15 Table 5.7 Data on Dielectric constant of different wax samples obtained from Microwave bench at 8.9 GHz. S.NO Sample name Condition of sample Dielectric constant (ε') 1 Beeswax normal Beeswax heat & cool Microcrystalline wax normal Microcrystalline wax heat & cool Paraffin wax normal Paraffin wax heat & cool Fat normal 6.55 Table5.8 Comparison of dielectric constant of different samples using microwave bench and network analyzer at 8.9 GHz. S.NO Sample name Condition of sample Dielectric constant from microwave bench (ε') Dielectric constant from Network analyzer (ε') 1 Beeswax normal Beeswax heat & cool Microcrystalline wax normal Microcrystalline wax heat & cool Paraffin wax normal Paraffin wax heat & cool Fat normal

16 Table 5.9 Percentage decrement of dielectric constant of different samples at frequency range 8.2 GHz 18 GHz. S.No Sample Dielectric constant Percentage At At decrease 8.2GHz 18.0GHz Difference 1. Beeswax (nor) Beeswax (h&c) Microcrystalline wax (nor) Microcrystalline wax (h&c) Paraffin wax (nor) Paraffin wax (h&c) Fat (nor) Table 5.10 Variation of dielectric parameters with increase of frequency range( ) Hz computed through Impedance Analyzer. Variation of Variation of Variation of Dielectric S.NO Sample name Condition Impedance, Z Capacitance, C p Constant (x10 6 Ω) (x10-12 F) ε' 1 Beeswax normal Beeswax heat & cool Microcrystalline wax normal

17 4 Microcrystalline wax heat & cool Paraffin wax normal Paraffin wax heat & cool Fat normal Table 5.11 Percentage decrement of dielectric constant of different samples at frequency range 10kHz 1MHz. Dielectric constant Percentage S.No Sample At 10kHz At 1MHz Difference decrease 1. Beeswax (nor) Beeswax (h&c) Microcrystalline wax (nor) Microcrystalline wax (h&c) Paraffin wax (nor) Paraffin wax (h&c) Fat (nor)

18 Figure 5.1 density of different types of waxes and fat

19 8.2 GHz Figure 5.2 variation of dielectric constant of different types of waxes and fat at 8.2 GHz using network analyzer.

20 Figure 5.3 variation of dielectric constant of different types of waxes and fat at 18 GHz using network analyzer.

21 Figure 5.4 comparision of dielectric constant of different types of waxes and fat at 8.9 GHz using microwave bench and network analyzer.

22 Figure 5.5 variation of dielectric constant of different types of waxes and fat at 10 khz using impedance analyzer.

23 Figure 5.5 variation of dielectric constant of different types of waxes and fat at 10 khz using impedance analyzer. Conclusion From the present study the following conclusions are drawn. The density or specific gravity of waxes and of animal fat is found to be less than that of water. After heat treatment, the density increases in all types of waxes of the investigation. From FTIR study, it is concluded that all waxes and animal fat are heterogeneous in nature. Beeswax and animal fat contains alkanes, alkenes and acid group, while in mineral wax (paraffin and microcrystalline wax) alkanes and alkenes groups are present. The above statement is also confirmed by 1 H 1 and 13 C NMR study.

24 Also GC-MS technique strongly confirms the result obtained from spectra of FTIR and NMR studies. XRD study suggests that beeswax of the present investigation are crystalline nature. However, the typical crystal structure combines crystalline and amorphous characteristics. The wax, whether it is mineral wax or biological wax, contains a large number of amorphous and crystalline compounds. It is noticed from the present study on electrical properties that after heat treatment the resistance decreases. The resistance of microcrystalline wax is found to be more, which indicates it is a good insulator compared to the other wax samples. There is no significant dielectric decrement in the frequency range of 10 khz to 1MHz. Further, it seems that electrical polarization mechanisms are not so pronounced. Also same is the observation in x- band frequency region. But a significant decrease in dielectric constant of wax and fat samples is noted as frequency in p-band (12.4 GHz -18 GHz) region increases. In general, it is obvious from the dielectric spectra of waxes and animal fat under study that the value of dielectric constant is low, varying from about 8 to 3 in the wide frequency range of 10 khz to 18 GHz.