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Optical emission spectroscopy
Optical emission spectroscopy was used to characterise plasma in the empty discharge chamber and in the chamber containing fibers. Fibers were placed approximately 1 cm from the glass tube at the height of 19 cm measured from the bottom of the glass tube. Optical emission spectra were recorded by Avantes Ava Spec 3648spectrometer. The device is based on Ava Bench 75 symmetrical Czerny Turner design with a 3648 pixel CCD detector with the focal length of 75 mm. The range of measurable wavelengths is from 200 nm to 1100 nm and the wavelength resolution is 0.5 nm. The spectrometer has USB 2.0 interface, enabling high sampling rates of up to 270 spectra per second. Signal to noise ratio is 350:1. Integration time is adjustable from 10 s to 10 min. At integration times below 3.7 ms, the spectrometer itself performs an internal averaging of spectra before transmitting them through the USB interface. For our particular case, the spectra were averaged over three sub-sequent measurements.
Water absorption studies
The water absorption capacity of the untreated and plasma-treated coir fibers was performed according to the standard ISO9073-6:2003 by measuring the water absorbency time and water absorptive capacity. The water absorbency time test measures the time required for the complete wetting of a specimen which is rolled into a cylindrical wire basket and is dropped on the surface of the liquid from 25 mm height. The water absorptive capacity method provides a measure of the amount of liquid held within a test piece after specified times of immersion and drainage. To perform the measurements the untreated and plasma-treated fibers were prepared according to standard. A sample of coir fibers (5 g) was inserted into wire basket of defined dimensions (height 80 mm, diameter 50 mm, thickness of wire 0.4 mm, mesh 20 mm). The basket with the sample was released sideways from 25 mm height into the round vessel of 110 mm diameter containing distilled water with temperature 200C and height 100 mm. The time taken for the basket to completely sink to the bottom of the vessel was measured. The samples were left in the water for 60 s and afterwards hung freely and vertically to drain for 120 s. Without squeezing the water from the sample, the sample was weighted. For each sample, fresh conditioned water was set. The water absorptive capacity (LAC) of fibers was calculated according to the equation: [ ]…………………………………………….. (2.1) Where, mw is the mass of a wet sample and md is the mass of a dry sample.
Scanning Electron Microscope (SEM) Analysis
Surface features of pristine and plasma-treated coir fibers were analysed by scanning electron microscopy, Jeol JSM 7600 FEG. Coir fibers were sputtered with gold and operated at 8 kV. The samples were examined at 500× and 1000× magnification, and the changes of morphology were examined after 30 s and 60 s of plasma treatment in a large discharge chamber. The changes of morphology were examined after 10 s of plasma treatment for the case when small chamber was used for plasma generation.
Atomic Force Microscope (AFM) Analysis
Topographic features of fibers were monitored by atomic force microscopy (AFM, Solver PRO, NT-MDT, Russia) technique in the tapping mode in air. Samples were scanned with the standard Si cantilever with a force constant of 22 N/m and at a resonance frequency of 325 Studies on O2 plasma modification and fluoroalkyl functional siloxane (FAS) coating effects on natural lignocellulosic coir fibers… Praveen Kosappallyillom Muraleedharan 2018 kHz (tip radius was 10 nm and the tip length was 95 m). The imaging was done on 5 × 5 m2 and 2 × 2 m2 areas on the untreated sample and the one treated in oxygen plasma for 30 s for the case where large chamber was used.
X-ray photoelectron spectroscopy (XPS) Analysis
Surface of fibers were analysed with an XPS instrument TFA XPS Physical Electronics. The base pressure in the XPS analysis chamber was about 6 × 10−8 Pa. The samples were excited with X-rays over a 400μm spot area with a monochromatic Al Kα1, 2 radiation at1486.6 eV. The photoelectrons were detected with a hemispherical analyser positioned at an angle of 450 with respect to the normal of the sample surface. The energy resolution was about 0.5 eV. Survey scan spectra were obtained at a pass energy of 187.85 eV, while the C1s, O1s and N1s individual high-resolution spectra were taken at a pass energy of 29.35 eV and a 0.1-eV energy step. All spectra were referenced to the main C1s peak of the carbon atoms which was assigned a value of 284.8 eV. The XPS spectra were measured on pristine coir fibers and on on fibers treated with oxygen plasma at 50 Pa and 75 Pa for 10 s (the samples were analysed immediately after plasma treatment)in the case of when small chamber is used for plasma treatment. The concentration of the different chemical states of carbon in the C1s peak was determined by fitting the curves with symmetrical Gauss–Lorentz functions. The spectra were fitted using MultiPak v7.3.1 software from physical electronics, which was supplied with the spectrometer. A Shirley-type background subtraction was used.
Fluoroalkyl functional siloxane (FAS) Sol-Gel coating on coir fibers
The surface modification of lignocellulosic coir fibers was done with the use of low-pressure oxygen plasma, followed by the application of a spray-dry-cure sol–gel coating with the water and oil repellent organic–inorganic hybrid precursor fluoroalkyl-functional siloxane (FAS), with the aim of creating the extremely hydrophobic coir fiber surface. The plasma pre-treatment increased the effective concentration of the FAS network on the lignocellulosic coir fibers.
Table of contents :
Chapter 1: Introduction
1.1 Introduction
1.2 Polymer surfaces and Interfacial problems
1.2.1 Surface phenomena in polymers
1.2.2 Adhesion phenomena in bonding of polymers
1.3 Surface modification strategies in polymer multiphase systems
1.4 Plasma processing of polymeric materials
1.5 Plasma treatment of fibers
1.5.1 Plasma treatment of synthetic fibers
1.5.2 Plasma treatment of Natural fibers
1.6 Organo functional siloxanes
1.6.1 Fluoroalkyl functional siloxane (FAS)
1.7 Lignocellulosic coir fiber
1.8 Impact Toughening of Polypropylene
1.9 Objectives of the work
1.10References
Chapter 2: Materials and methods
2.1 Experimental
2.1.1 Materials used
2.1.2 Methodology
2.1.2.1 Preparation of fibers
2.1.2.2 Plasma modification of fibers
2.1.2.2.1 Optical emission spectroscopy
2.1.2.2.2 Water absorption studies
2.1.2.2.3 Scanning Electron Microscope (SEM) Analysis
2.1.2.2.4 Atomic Force Microscope (AFM) Analysis
2.1.2.2.5 X-ray photoelectron spectroscopy (XPS) Analysis
2.1.2.3 Fluoroalkyl functional siloxane (FAS) Sol-Gel coating on coir fibers
2.1.2.3.1 Wettability analysis
2.1.2.3.2 Water absorption studies
2.1.2.3.3 Scanning Electron Microscope (SEM) Analysis
2.1.2.3.4 Atomic Force Microscope (AFM) Analysis
2.1.2.3.5 X-ray photoelectron spectroscopy (XPS) Analysis
2.1.2.4 Melt blending
2.1.2.5 Preparation of test specimens
2.1.2.6 Breaking strength analysis and Pull-out stress of coir fibers
2.1.2.6.1 Pull-out test of coir fibers
2.1.2.7 Mechanical property analysis
2.1.2.7.1 Impact analysis
2.1.2.7.2 Tensile analysis
2.1.2.7.3 Flexural analysis
2.1.2.8 Morphological Analysis
2.1.2.8.1 High resolution transmission electron microscopy (HRTEM)
2.1.2.8.2 Scanning Electron Microscopy (SEM)
2.1.2.9 Differential Scanning Calorimetry
2.1.2.9.1 Non-isothermal Crystallization Kinetics
2.1.2.9.2 Determination of glass transition temperature (Tg)
2.1.2.10 Thermo gravimetric analysis
2.1.2.11 Rheological Analysis
2.2 References
Chapter 3: Plasma surface modification of lignocellulosic natural coir fibers
3.1 Plasma surface treatment
3.2 Optical Emission Spectroscopy
3.3 Water Absorption Studies
3.4 Scanning Electron Microscope (SEM) Analysis
3.5 Atomic Force Microscope (AFM) Analysis
3.6 X-ray photoelectron spectroscopy (XPS) Analysis
3.7 Inferences
3.8 Conclusions
3.9 References
Chapter 4: Development and Characterisation of Fluoroalkyl functional siloxane (FAS) based hydrophobic coating on lignocellulosic natural coir fibers
4.1 FAS Sol–gel coating
4.2 Wettability analysis
4.3 Water Absorption Studies
4.4 Scanning Electron Microscope (SEM) Analysis
4.5 Atomic Force Microscope (AFM) Analysis
4.6 X-ray photoelectron spectroscopy (XPS) Analysis
4.7 Tensile Analysis of uncoated and FAS coated coir fibers
4.8 Conclusions
4.9 References
Chapter 5: Mechanical, morphological, rheological and thermal properties of PP/EPDM blends
5.1 Polypropylene (PP) and high-molecular grade ethylene-propylene-diene rubber (EPDM) blends
5.2 Mechanical property (Impact, Tensile and Flexural) analysis of PP/EPDM blends
5.2.1 Impact analysis of PP/EPDM blends
5.2.2 Tensile analysis of PP/EPDM blends
5.2.3 Flexural analysis of PP/EPDM blends
5.3 Morphological analysis of PP/EPDM blends
5.3.1 High-resolution transmission electron microscopy (HRTEM)
5.3.2 Scanning Electron Microscopy (SEM) Analysis
5.4 Rheological analysis of PP/EPDM blends
5.4.1 Low shear rate rheology
5.4.2 Dynamic viscoelastic property analysis
5.5 Non-isothermal crystallisation kinetics of PP/EPDM blends
5.5.1 Nucleation Activity
5.5.2 Glass transition temperature
5.6 Thermo gravimetric (TGA) analysis
5.7 Conclusions
5.8 References
Chapter 6: Mechanical, morphological, rheological and thermal properties of PP/EPDM 7.5/coir composites
6.1 Determination of critical length of coir fibers
6.2 Polypropylene (PP) / Ethylene-propylene-diene rubber (EPDM) / Coir composites Studies on O2 plasma modification and fluoroalkyl functional siloxane (FAS) coating effects on natural lignocellulosic coir fibers… Praveen Kosappallyillom Muralee
6.3 Mechanical property (Impact, Tensile and Flexural) analysis of PP/EPDM/Coir composites
6.3.1 Impact analysis PP/EPDM/Coir composites
6.3.2 Tensile analysis of PP/EPDM/Coir composites
6.3.3 Flexural analysis of PP/EPDM/Coir composites
6.4 Determination of pull-out stress
6.5 Morphological analysis of PP/EPDM/Coir composites
6.5.1 Morphology of impact-fractured samples
6.6 Rheological analysis of PP/EPDM/Coir composites
6.6.1 Low shear rate rheology
6.6.2 Dynamic viscoelastic property analysis
6.7 Non-isothermal crystallisation kinetics of PP/EPDM7.5/Coir composites
6.7.1 Nucleation Activity
6.7.2 Glass transition temperature
6.8 Thermo gravimetric (TGA) analysis
6.9 Conclusions
6.10References
Chapter 7: Conclusions and Future work
7.1 Conclusions
7.2 Future Work
