|Dr. Rahima Nasrin|
Materials Science, Thin Film, Composite Materials, Nanotechnology
Plasma polymerized n-butyl mehacrylate (PPnBMA) thin films of varying thicknesses were prepared at an optimized condition at room temperature by an AC plasma polymerization (PP) system using a capacitively coupled parallel plate reactor. The flat and defect free nature of thin films were confirmed by field emission scanning electron microscopy and atomic force microscopy images. A comparison between the micrographs of as-deposited and heat treated (at 473 K for 1 hour) PPnBMA thin films exhibited that no considerable variation in the surface morphology is detected due to heat treatment. With declining plasma power average roughness and root mean square (rms) roughness increases whereas with increasing deposition time the rms roughness of the PPnBMA thin films increases. From the energy dispersive X-ray spectra it is observed that the mass% of C increases accordingly with increament of thickness whereas mass% of O decreases. A comparative analysis of the elemental mass % of as-deposited and heat treated (at 473 K for 1 hour) PPnBMA thin films indicates the increament of mass% of C in heat treated PPnBMA compared to those of as-deposited PPnBMA which may be as a result of structural rearrangement during heat treatment. X-ray diffraction pattern confirms the amorphous nature of thePPnBMA thin films. Comparison of the fourier transform infrared (FTIR) spectra of nBMA with that of as-deposited and heat treated (at 473 K for 1 hour) PPnBMA demonstrated that structure of as-deposited PPnBMA is different to some extent from that of nBMA due to PP and further structural modification is observed owing to conjugation and/or cross-linking. The differential thermal analysis and thermogravimetric analysis show that PPnBMA was thermally stable up to about 476 and 500 K in air and N2 environments, respectively. Allowed direct transition energy gaps (Egd) were found to be 3.73 to 3.84 eV and 3.68 to 3.78 eV, respectively for as-deposited and heat treated PPnBMA thin films whereas the indirect transition energy gap (Egi) values were found to be 3.26 to 3.43 eV and 3.28 to 3.40 eV, respectively for as-deposited and heat treated PPnBMA thin filmsof thicknesses 150, 215, 320 and 450 nm. Values of Egdas well as Egi increase with the increase of film thicknesses. Extinction coefficient, Urbach energy, steepness parameter, refractive index and optical conductivity were also determined for these thin films. The current density – voltage and current density – film thickness characteristics of fabricated thin films of different thicknesses sandwiched between aluminum thin film electrodes indicate that the dominant conduction mechanism in the high-voltage region is space charge limited conduction in these films. The estimated carrier mobility, trap density and free carrier density decrease with the increase of thickness of the prepared thin films. The activation energy (ΔE) associated in low and high temperature regions were calculated for as- deposited and heat treated PPnBMA thin films of various thicknesses. For applied voltage of 10 V, at low and high temperature regions the ΔE are found to be around 0.21 - 0.36 eV and 0.43 – 0.78 eV for as -deposited whereas 0.17 – 0.47 eV and 0.35 – 0.88 eV for heat treated PPnBMA thin films of different thicknesses, respectively. On the other hand ΔE values in the low and high temperature region are found to be 0.14 - 0.39 and 0.47 - 0.64 eV for as deposited and 0.16 - 0.30 eV and 0.45 - 0.78 eV for heat treated PPnBMA thin films for an applied voltage 50 V. The low ΔE in the low temperature region indicate that the thermally activated hopping conduction is operative in this material. Frequency dependant AC electrical conductivity indicates Debye type conduction mechanism in low frequency and that in the high frequency other than Debye type. With increasing film thickness the peaks oftanδ shifts a little towards the lower frequency region indicating an increase of relaxation time.The ΔE value for dielectric relaxation is found to be 0.05 eV. Cole- Cole plot exhibits little distorted semicircle which also indicating nearly Debye type relaxation process in these films.
*This research was carried out in the Dept. of Physics , Bangladesh University of Engineering & Technology (BUET)
M. Phil. research:
In this research, the influences of adding talc particles on physical, mechanical, thermal,and electrical properties of compression molded polypropylene (iPP)/talc composites were investigated. The SEM micrographs of PP and composites with 10, 20, 30, 40 and 50 wt% talc content shows that PP, 10, 20, and 30Wt % talc surface is smooth comparison to 40 and 50 Wt % talc composites. The composites of 40 and 50 Wt % talc contain more crack, agglomerates or larger particles.Bulk density of the composites decreases with the increase of talc content. With the increase of percentage of talc, and with the increase period of immersion, the water absorption (WA) increases The tensile strength (TS) of composite decreases with the increase of talc addition.Elongation at break (EB%) of PP-talc composites decreases with the increase of talc content.Young modulus (YM) of the fabricated product increases with the increase of talc content. Its value is maximum for 30% talc. Therefore stiffness of the PP-talc composites increaseswith the increase of talc content.On the basis of the elastic modulus it appear that the talc filler can be used as an effictive reinfocement for the PP-talc composites for up to 30wt%. The flexural strength (FS) increases with the addition of talc up to certain percentageand after that it decreases. The maximum value of FS is 57.151 MPa for 30% talc Flexural break (FB %) of PP-talc composites decreases with the increase of talccontent. Flexural modulus increases slowly up to 20% talc and then it increases quickly for 30% talc. With the increase of talc content the microhardness (H) values decreases for PP- talccomposites. From the TGA, DTA, and DTG curves it is seen that composites become more thermally stable than neat PP. From I-V characteristics of the composites for different wt% of talc it is observedthat I-V curve shows ohmic behavior in the lower temperature region. With the increase% of talc the resistivity increases for PP-talc composites.In conclusions it is seen that a thermally stable with moderate strength PP-talc composite can be developed for industrial and scientific application.
*This research was carried out jointly in the Pilot Plant & Process Development Centre, Bangladesh Council of Scientific & Industrial Research (BCSIR), Dhaka and Dept. of Physics , Bangladesh University of Engineering & Technology (BUET), Dhaka
• PUBLISHED PAPER IN PEER-REVIEWED INTERNATIONAL JOURNALS
1. Rahima Nasrin, A. H. Bhuiyan, Synthesis of iodine doped n-BMA th n films via plasma polymerization technique: effect on optical properties, Surface Review and Letters (Publisher: World Scientific), 27(4), 1950133, 2020.
2. Humayun Kabir, Rahima Nasrin, M Mahbubur Rahman, A.H Bhuiyan, Heat treatment effect on the structural, morphological, and optical properties of plasma polymerized furan-2-carbaldehyde thin films, Results in Physics (Publisher: Elsevier),16, 103014, 2020.
3. Rahima Nasrin, A. H. bhuiyan, Thermal and AC electrical properties of thin films prepared from n-butyl methacrylate by a capacitively coupled plasma reactor, Surface Review and Letters(Publisher: World Scientific), 26 (2), 1850146, 2019.
4. Humayon Kabir, Rahima Nasrin, Kamrul Hasan, M. Mahbubur Rahman, A. H. bhuiyan, Synthesis and aging effect of plasma polymerized 2-Furancarboxaldehyde amorphous thin films, Materials Chemistry and Physics (Publisher: Elsevier), 232, 209–220, 2019.
5. Rahima Nasrin, A.H Bhuiyan,Effect of heat treatment on infrared and ultraviolet–visible spectroscopic studies of the PPnBMA thin films, Applied Physics A (Publisher: Springer), 124 (12), 856, 2018.
6. Rahima Nasrin, A. H. bhuiyan, Evaluation of electrical carrier transport mechanism in plasma polymerized n-butyl methacrylate thin films, Polymer Science Series A(Publisher: Springer), 60, 6, 882–889, 2018.
7. Rahima Nasrin, Sarmin Seema, Md. Abdul Gafur, Abu Hashan Bhuiyan, Study of dielectric behavior of titanium dioxide-filled polypropylene composites, American Journal of Materials Synthesis and Processing(Publisher: Science PG), 3(4), 56-61, 2018.
8. Rahima Nasrin, K.S Hossain, A.H Bhuiyan, Morphological, elemental, and optical characterization of plasma polymerized n-butyl methacrylate thin films, Applied Physics A (Publisher: Springer), 124, 1-8, 2018.
9. Rahima Nasrin, A.H Bhuiyan, M.A Gafur, Influence of talc filler content on the mechanical and dc electrical behavior of compression molded isotactic polypropylene composites, International Journal of Composite Materials(Publisher: Scientific & Academic Publishing), 5 (6), 155-161, 2015.
10. Rahima Nasrin, M. A Gafur, A.H Bhuiyan, Characterization of isotactic polypropylene/ talc composites prepared by extrusion cum compression molding technique, Materials Sciences and Applications(Publisher: Scientific Research Publishing), 6 (11), 925, 2015.
11. M.A Gafur, R. Nasrin, M. F. Mina, MAH Bhuiyan, Y. Tamba, T. Asano, Structures and properties of the compression-molded istactic-polypropylene/talc composites: Effect of cooling and rolling, Polymer Degradation and Stability(Publisher: Elsevier), 95 (9), 1818-1825, 2010.
• PUBLISHED PAPER IN PEER-REVIEWED NATIONAL JOURNALS
12. Rahima Nasrin, Salma Begum, M. A. Gafur, A. H. Bhuiyan, Effect of calcium carbonate filler and alkali treatment on physical and elastic properties of jute mat reinforced polyester resin composites, Bangladesh Journal of Physics, 26, 61-68, 2019.
13. Rahima Nasrin, S.M.T. Islam, KhorshedAlam, Generation and validation of a wimsd-5b multigroup constants library based on jendl-3.3 nuclear data. Barisal University Journal Part 1, 5, 195-201 , 2018.
14. Md. Khorshed Alam1, Md. Alauddin , Rahima Nasrin , Md. Imran Hossain , Md. Saif Ishtiaque, M. A. Islam, Surface structure and reduction processes of Ti doped CeO2: a ultra accelerated quantum chemical molecular dynamics study, Barishal University Journal Part 1, 5(1&2), 163-178, 2018.
15. Rahima Nasrin, A. H. Bhuiyan and M. A. Gafur, Mechanical and micromechanical studies on polypropylene composites filled with talc particles, Barisal University Journal, 4(1), 95-103, 2017.
16. Rahima Nasrin and A. H. Bhuiyan, Dc electrical behavior of plasma polymerized butyl ester thin films. Barisal University Journal 4(2), 377-388, 2017.
• CONFERENCE PROCEEDINGS / PRESENTATION
1. Rahima Nasrin and A.H. Bhuiyan, Thickness Dependent Surface Morphology and Dielectric Properties of Plasma Polymerized n-Butyl Methacrylate Amorphous Thin films, 6th International Conference on Nanotechnology, Nanomaterials & Thin Films for Energy Applications, Kuala Lumpur, Malaysia, 27-29 July, 2019.
2. Rahima Nasrin, Mental Health Problem of Adolescents and Adults, International Conference on Community and Mental Health: Connect, Communicate and Care Kolkata, India, 3-4th January, 2020.
3. Rahima Nasrin and A.H Bhuiyan, Structural and UV–Visible Spectroscopic Studies of Plasma Polymerized n-Butyl Methacrylate Thin Films, International Conference on Physics – 2020, Dhaka , Bangladesh,05-07 March, 2020.