Papers by Keyword: TGA

Abstract: In this study, the effect of SBR concentration (10 Phr, 20 Phr & 30 Phr ) on the thermal behavior of EPDM/SBR blends was studied. Thermogravimetric analysis (TGA) was used to check weight loss of samples as function of temperature by heating upto 600^°C. X-ray diffraction (XRD) was performed to determine quality and % crystallinity of the elastomer blends. It was seen that % crystallinity improved with an increase in the content of SBR in EPDM/SBR blends. TGA revealed that the thermal stability of EPDM/SBR blends has improved by 17% than neat EPDM. Carbon nano-coatings produced by sputtering have no beneficial influence on thermal behaviour of elastomers.

Abstract: The composites between polyamide 11 (PA11) and functionalized graphene nanoplatelets (GNP) were prepared to compare influence of GNPs content and functionalities; hydroxyl (GO) and carboxylic acid (GC); on mechanical and thermal properties. The composites were melt compounded and injection molded into specimens with the final GNP content of 1, 3, 5, 7 and 9 wt%. It was found in XRD that these plasma-exfoliated GNPs acted as the nucleating agents that changed the crystal form of PA11, but did not have significant influence on crystallinity content. DSC analysis confirmed the nucleating effect of GNPs, which the degree of crystallinity was not affected by the presence of GNPs. The functionalities of GNP did not reduce the degradation temperature of the composites compared to neat PA11. Young's modulus and tensile strength at yield of the composites were higher with respect to the GNP content. This was attributed to stretching restriction of polymer chains by GNPs during the elastic deformation. The composites adding GO had higher tensile properties than those adding GC. In contrast, the composites adding GC showed higher impact strength than those adding GO. SEM micrographs indicated the failure of the composites occurred at the interphase between PA11 matrix and GNPs.

Abstract: Micro-fibrillated celluloses (MFCs) are made from oil palm empty fruit bunches (EFB). EFB is processed through several stages of the process, including washing, alkalization, and bleaching to remove impurities, lignin, and hemicellulose. Each treatment stage was characterized by differential scanning calorimeter (DSC) and thermogravimetric (TGA) analysis. Morphological analysis was characterized using Scanning Electron Microscope (SEM). The process results show that MFC has an average length and thickness of 450 and 80 microns for coarse fibers respectively, averaging 50 and 5 microns for fine fibers, respectively. Fibrillation fibers appear on the surface of fibers which are treated using alkalization and bleaching processes. The TGA results showed a decrease in weight occurred at a temperature of 40 to 109 °C for the first stage of the heating process and at a temperature of 247 to 382 °C for the second stage. The decrease in fiber weight is caused by evaporation of water content and degradation of cellulose compounds at each stage. The glass transition temperature of MFC was obtained at 236 °C. The thermal stability of cellulose from fibers treated using alkalization and bleaching processes proved the formation of cellulose crystals. Removal of lignin and hemicellulose is shown by the absorption of O-H and C-C bonds in FTIR spectroscopy. From these results, it is stated that micro-fibrillation cellulose is formed well through a series of processes given.

Abstract: In this study, raw wood (RW) samples were impregnated with a mixture of furfural alcohol (FA), styrene (ST), and nanoclay of varying concentration of FA and ST. These impregnated wood and RWsamples were then subjected to FTIR, water uptake (WU), and thermal studies. The FT-IR results at 1600-1800 cm^-1 showed that the ST/FA/clay-WPNCs had different peak numbers with different positions compared with the RW. So, there was an interaction between RW, FA, ST and clay. The WU of ST/FA/clayimpregnated wood is lower than RW. In thermo gravematric result, below 100 °C the impregnated wood samples had less weight lost compared to RW.

Abstract: Neoprene reinforced polymer has become an attraction in current research and development of new material blend. In this invention, neoprene was chosen to be enhance to polyurethane because of their superior properties that possess extraordinary mechanical, electrical, optical and thermal properties on prosthetic foot. In this research, polyurethane was chosen due to good rigidity, easy processing and low cost. The reinforcement polyurethane with neoprene is expected to improve the properties of polyurethane. The objective of this research was conducted to investigate the effect of neoprene contents on thermal properties of polyurethane reinforced neoprene on prosthetic foot. The effect of neoprene on thermal properties neoprene reinforced polyurethane was analysed in term of its thermal stability by thermal gravimetric analysis (TGA). Moreover, the visual of small topographic details on the surface of polyurethane/neoprene blends will be examined by scanning electron microscope (SEM). Based on result, the thermal properties show the great enhancement at high neoprene contents which is 1.0wt%. The thermal stability of polyurethane reinforced neoprene improves when the temperature where decomposition starts to occurs are higher than decomposition temperature of pure polyurethane. Then, thermal conductivity of polyurethane shows the great improvement after the addition of neoprene. Lastly, the smooth surface and visible of sheets pattern on surface represent the present of neoprene disperse into polymer that enhance brittleness. Thus, the presence of neoprene has clearly enhanced the thermal stability of the polyurethane. Table 1 shows formulation of neoprene and polyurethane.

Abstract: Poly (diethylene glycol) adipate diol, tolylene-2,4-diisocyanate, 1,3-bis (3',4-dicarboxylphenoxy) benzene and 1,4-bis (4'-aminophenoxy) biphenyl were used as monomers to form statistical copoly (urethane-imide) s with variable content of imide blocks (from 37 to 65% (wt)). The copolymers imide blocks on the T_g and T_m values relative content increasing effect was traced, which is associated with the phase separation of hard imide and flexible polyester blocks in the systems studied.

Abstract: This paper presents the effect of nanosilica (NS) on compressive strength and microstructure of cement paste containing high volume slag and high volume slag-fly ash blend as partial replacement of ordinary Portland cement (OPC). Results show that high volume slag (HVS) cement paste containing 60% slag exhibited about 4% higher compressive strength than control cement paste, while the HVS cement paste containing 70% slag maintained the similar compressive strength to control cement paste. However, about 9% and 37% reduction in compressive strength in HVS cement pastes is observed due to use of 80% and 90% slag, respectively. The high volume slag-fly ash (HVSFA) cement pastes containing total slag and fly ash content of 60% exhibited about 5%-16% higher compressive strength than control cement paste. However, significant reduction in compressive strength is observed in higher slag-fly ash blends with increasing in fly ash contents. Results also show that the addition of 1-4% NS improves the compressive strength of HVS cement paste containing 70% slag by about 9-24%. However, at higher slag contents of 80% and 90% this improvement is even higher e.g. 11-29% and 17-41%, respectively. The NS addition also improves the compressive strength by about 1-59% and 5-21% in high volume slag-fly ash cement pastes containing 21% fly ash+49%slag and 24% fly ash+56%slag, respectively. The thermogravimetric analysis (TGA) results confirm the reduction of calcium hydroxide (CH) in HVS/HVSFA pastes containing NS indicating the formation of additional calcium silicate hydrate (CSH) gels in the system. By combining slag, fly ash and NS in high volumes e.g. 70-80%, the carbon footprint of cement paste is reduced by 66-76% while maintains the similar compressive strength of control cement paste. Keywords: high volume slag, nanosilica, compressive strength, TGA, high volume slag-fly ash blend, CO₂ emission.

Abstract: Multifunctional fibrous systems were developed within this research work, giving special importance to the electrical conductivity and antibacterial activity. The functionalization of several natural fibres (jute, sisal, coir, flax and cotton) with silver nanoparticles (Ag NPs) was successfully achieved using a sustainable and eco-friendly method, namely polyethylene glycol (PEG) reduction. FESEM images, GSDR and ATR-FTIR analysis show that the Ag NPs were incorporated onto the fibres surface. The resistivity values obtained by analysing the fabrics without functionalization was about 1.5x10⁷ Ω.m while with the Ag NPs functionalization the resistivity values decreased almost 15000 times, to 1.0x 10³ Ω.m. Jute fibres’ antibacterial efficiency was also studied using the fibres with incorporated nanoparticles. Jute/Ag NPs showed some activity against E. Coli and S. Aureus. Polylactic acid (PLA) was used to develop flexible biodegradable composites with the functionalized jute. The compatibilization of the jute with PLA was successful and the characterization of the final composites was performed by GSDR, ATR-FTIR and TGA.

Abstract: The effect of Pd-TiO₂ nanoparticle doping on structural, optical and thermal properties of the PVA polymer has been investigated using FTIR, UV-Visible, TGA and FESEM analysis. nanosized Pd-TiO₂ particles were synthesized using standard method. Pure and Pd-TiO₂/PVA nanocomposite films were prepared using solution casting technique. The FTIR study confirmed that the Pd-TiO₂ nanoparticles interacts with the OH group of PVA polymer and forms the complex. The presence of these complexes affects the optical and thermal properties the composite. The change in the optical properties was studied using UV-Vis absorption method. The effect of doping on the thermal properties was studied using TGA method and the modified surface morphology using FESEM.

Abstract: Titanium dioxide has a special feature: anatase, to rutile transformation which was considered in our investigations. It is especially important to keep anatase form of titanium dioxide for photocatalytic materials, different ceramics with tribo-chemical properties, self-cleaning coatings and self-sterilizing coatings. For that only one of the titanium dioxide forms is more suitable – anatase, which is more active but not stable, because it transforms to rutile during the time or with the temperature increase loses its activity. Different methods of stabilising anatase have been considered in the paper. Several doping agents have been determined and it was chosen fluorine ion to modify titanium dioxide. Stabilization of anatase is achieved by preparing the reaction mixture by a sol-gel method with hydrofluoric acid. It has shown thermodynamic data, results of experiment, temperatures of anatase to rutile transformation of non-doped and doped titanium dioxide, its X-Ray diffraction and TGA. It is proved that titanium dioxide doped by fluorine ion keeps anatase form till the temperature is more than 1000 °C.