scholarly journals THERMAL CHARACTERISTIC EVALUATION OF DIFFERENT ASCORBIC ACID CRYSTAL HABITS

2018 ◽  
Vol 3 (1) ◽  
pp. 50-59
Author(s):  
S. Hassan ◽  
F. Adam ◽  
M.R. Abu Bakar
Keyword(s):  
Thermal Stability ◽  
Hydrogen Bond ◽  
Ascorbic Acid ◽  
Thermal Characteristic ◽  
Intermolecular Forces ◽  
Crystal Habit ◽  
Gravimetric Analysis ◽  
High Hydrogen ◽  
Acid Crystal ◽  
Thermal Stability Of

Melting temperature (Tmelt) and enthalpy of fussion (ΔHf ) are important parameters to determine the quality and the thermal stability of active pharmaceutical ingredient (API) crystals. In this study, different habit of ascorbic acid was prepared by using different polar solvents namely water, methanol, ethanol and 2-propanol. Ascorbic acid crystal was then been physically and thermally characterised by using microscopic analysis, thermo gravimetric analysis (TGA) and differential scanning calometry analysis (DSC). This provides an insight into the formation of crystal habit across four different polar protic solvents. The ascorbic acid is found to grow as a cubic or prism crystal when grown in water that provides high hydrogen bond between solvent and solute. As the polarity of the solvents decrease, the hydrogen bond weaken and the width of the crystal become narrower, forming almost a needle like crystal. The thermal stability of ascorbic acid crystal is found to be the most stable when ascorbic acid is crystallized from water (prism) and the weakest from 2-propanol (needle) due to the molecule arrangement in crystal lattice in which resulted from decreasing intermolecular forces in the liquid phase

scholarly journals The Thermal Properties of Polyurethane/Neoprene Blends on Prosthetic Foot

2020 ◽  
Vol 990 ◽  
pp. 106-110
Author(s):  
Mohd Zulkifli Mohamad Noor ◽  
Mohamad Anas Mohd Azmi ◽  
Mohd Shaiful Zaidi Mad Desa ◽  
Mohd Bijarimi Mat Piah ◽  
Azizan Ramli
Keyword(s):  
Thermal Stability ◽  
Thermal Properties ◽  
Low Cost ◽  
Decomposition Temperature ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Prosthetic Foot ◽  
Reinforced Polymer ◽  
New Material ◽  
Thermal Stability Of

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.

Effect of Alkali and Silane Treatment on the Thermal Stability of Hemp Fibers as Reinforcement in Composite Structures

2011 ◽  
Vol 415-417 ◽  
pp. 666-670 ◽  
Author(s):  
Na Lu ◽  
Shubhashini Oza ◽  
Ian Ferguson
Keyword(s):  
Thermal Stability ◽  
Composite Structures ◽  
Natural Fiber ◽  
Alkali Treatment ◽  
Thermo Gravimetric Analysis ◽  
Natural Fibers ◽  
Gravimetric Analysis ◽  
Silane Treatment ◽  
Hemp Fibers ◽  
Thermal Stability Of

Natural fiber reinforced composites are being used as reinforcement material in composite system due to their positive environmental benefits. Added to that, natural fibers offer advantages such as low density, low cost, good toughness, high specific strength, relatively non-abrasive and wide availability. However, the low thermal stability of natural fibers is one of the major challenges to increase their use as reinforcing component. In this study, a thorough investigation has been done to compare the effect of two chemical treatment methods on the thermal stability of hemp fibers. 5wt% sodium hydroxide and 5wt% triethoxyvinylsilane was used for the treatment of hemp fibers. Fourier transform infrared spectroscopy, scanning electron microscopy and thermo gravimetric analysis were used for characterization of untreated and treated fiber. The results indicated that 24 hours alkali treatment and 3 hours silane treatment time enhanced the thermal stability of the hemp fiber. However, alkali treatment shows better improvement compared to silane treatment.

Palm Kernel Shell Filled Recycled High-Density Polyethylene: Effect of Filler Loading

2016 ◽  
Vol 857 ◽  
pp. 191-195 ◽  
Author(s):  
A. Nadiatul Husna ◽  
Bee Ying Lim ◽  
H. Salmah ◽  
Chun Hong Voon
Keyword(s):  
Thermal Stability ◽  
High Density Polyethylene ◽  
Thermo Gravimetric Analysis ◽  
Palm Kernel ◽  
Filler Loading ◽  
High Density ◽  
Gravimetric Analysis ◽  
Melt Mixing ◽  
Palm Kernel Shell ◽  
Thermal Stability Of

Palm kernel shells (PKS) filled recycled high density polyethylene (rHDPE) biocomposites were produced using melt mixing. The biocomposites were prepared on Brabender Plasticorder at temperature of 185 °C and rotor speed of 50 rpm by varying filler loading (0 to 40 phr). In this study, the effect of PKS loading on rheological properties and thermal stability of rHDPE/PKS were investigated. Rheological study of the biocomposites was carried out by means of capillary rheometer under temperature of 190 °C, 200 °C and 210 °C. Thermal properties of biocomposites were studied by using thermo gravimetric analysis (TGA). The rheological results showed that the flowability of the composite increased with increasing temperature. Meanwhile, the result of TGA showed that at higher PKS loading, rHDPE/PKS biocomposites had lower total weight loss. The thermal stability of the biocomposites was reduced due to the addition of filler loading.

Study on the thermal stability of Controlled Permeability Formwork

2011 ◽  
Vol 374-377 ◽  
pp. 1426-1429
Author(s):  
Xiao Meng Guo ◽  
Jian Qiang Li ◽  
Xian Sen Zeng ◽  
De Dao Hong
Keyword(s):  
Thermal Stability ◽  
Thermal Properties ◽  
Dynamic Mechanical Analysis ◽  
Thermo Gravimetric Analysis ◽  
Mechanical Analysis ◽  
Gravimetric Analysis ◽  
Construction Work ◽  
Thermo Gravimetric ◽  
Excellent Thermal Stability ◽  
Thermal Stability Of

In this study, the thermal properties of a kind of new geotextile materials, so called controlled permeable formwork (CPF), were studied. Thermo-gravimetric analysis showed that the weight of CPF didn’t change much between 0~350 °C. Dynamic mechanical analysis showed that the storage modulus of CPF reduced from 25 MPa to around 10 MPa when the temperature rose to above 100 °C. The strength of sample decreased slightly with the increase of the temperature. The breaking elongation changed slightly with a maximum at 80 °C. The CPF showed excellent thermal stability and was suitable for general use in construction work.

Synthesis of Stable Oil Dispersions of Silver Nanoparticles

2011 ◽  
Vol 694 ◽  
pp. 73-78
Author(s):  
Dan Li
Keyword(s):  
Thermal Stability ◽  
Silver Nanoparticles ◽  
Ascorbic Acid ◽  
Spectral Analysis ◽  
Oleic Acid ◽  
Aqueous Medium ◽  
Aqueous Phase ◽  
Thermal Stability Of

Hydrophobic silver nanoparticles have been carried out by use of ascorbic acid in cyclohexylamine and aqueous medium. Nanosilver can be effectively coated with oleic acid and possesses oil-soluble property. Oleic acid as an extractant is also effective at stabilizing particles of similar size in an oil phase when the AgNO3 is reduced in a coexisting aqueous phase. Stable spherical silver nanoparticles 15~25 nm in diameter with a well-crystallized structure were obtained at 120 °C. The thermal stability of surface-coated silver prepared in cyclohexylamine solution was monitored by UV-vis spectral analysis.

Preparation and Properties of Silane-Terminated Poly(urethane-Imide)

2013 ◽  
Vol 690-693 ◽  
pp. 1577-1580
Author(s):  
Xiao Xi Hu ◽  
Yun Wang
Keyword(s):  
Thermal Stability ◽  
Water Resistance ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Silane Coupling ◽  
Ft Ir ◽  
And Storage ◽  
Thermal Stability Of

A serious of silane-terminated poly (urethane-imide) (Si-PUI) was synthesized via prepolymer method using polycarbonatediols (PCDL), 2,4-tolylene diisocyanate (TDI), 4,4'-Oxydiphthalic Anhydride (ODPA) and silane coupling agent KH-550. The structure of the products was characterized by FT-IR. The thermal properties were measured by thermal gravimetric analysis (TGA). The thermal mechanical behavior was investigated by dynamic mechanical analysis (DMA).The mechanical characteristic was measured by tensile tests. The water absorption (Wa) was also been tested. With the imide content increasing, the thermal stability, tensile strength and storage modulus of poly (urethane-imide) improve significantly, and the glass transition temperature rises. The introduction of silanes improves the water resistance and further enhances the thermal stability of poly (urethane-imide).

Thermal Gravimetric Analysis of Unsaturated Polyesters Filled with Alumina Trihydrate and Silica Aerogel

2017 ◽  
Vol 264 ◽  
pp. 116-119 ◽  
Author(s):  
Zulhelmi Alif Abdul Halim ◽  
Muhamad Azizi Mat Yajid ◽  
Mohd Hasbullah Idris ◽  
Halimaton Hamdan
Keyword(s):  
Thermal Stability ◽  
Thermal Gravimetric Analysis ◽  
Silica Aerogel ◽  
Polyester Resin ◽  
Unsaturated Polyester ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Polyester Matrix ◽  
Alumina Trihydrate ◽  
Thermal Stability Of

Thermal degradation of the composite blend consisting unsaturated polyester resin, alumina trihydrate and silica aerogel was studied using thermal gravimetric analysis. Composite filled with silica aerogel show lower density and slightly improve the thermal stability of the pure polymer. The addition of alumina trihydrate slows down the degradation of the polymer due to the release of bond water while the combination of silica aerogel and alumina trihydrate in polyester matrix does not interrupt the function of alumina trihydrate due to inert properties of silica aerogel.

Mechanical and thermal behavior of cellulose nanocrystals-incorporated Acrodur® sustainable hybrid composites for automotive applications

2020 ◽  
Vol 54 (22) ◽  
pp. 3159-3169 ◽  
Author(s):  
Ezatollah (Nima) Amini ◽  
Mehdi Tajvidi
Keyword(s):  
Thermal Stability ◽  
Impact Strength ◽  
Flexural Strength ◽  
Cellulose Nanocrystals ◽  
Flexural Modulus ◽  
Natural Fibers ◽  
Cellulose Nanocrystal ◽  
Gravimetric Analysis ◽  
Automotive Applications ◽  
Thermal Stability Of

Utilization of cellulose nanocrystals as an additive in the formulation of biocomposites made with Acrodur® resin is presented. Natural fibers/polyethylene terephthalate mats were impregnated with Acrodur® and hot-pressed into the final thickness of 3 mm after drying. Biocomposites with 2 wt.% and 5 wt.% cellulose nanocrystal (dry-basis) were also produced. The produced biocomposite panels were then tested to determine the flexural strength, flexural modulus and Izod impact strength. The results revealed that adding cellulose nanocrystal to the composite formulation increased flexural modulus significantly up to 970 MPa (17.5% increase) at a panel density of 0.5 g/cm3, while it did not significantly affect flexural strength values. A slight reduction was observed in the impact strength of the samples by adding cellulose nanocrystal. The fractured samples of impact test were observed under a scanning electron microscope. It was shown that in all cases, the fracture happened due to the failure of the fibrous system and in particular natural fibers. Thermal stability of the composites was also investigated using thermo-gravimetric analysis. It was found that adding cellulose nanocrystal slightly reduced the thermal stability of the biocomposites. Potential compatibility of cellulose nanocrystal particles with Acrodur® resin is promising and the improvement in flexural modulus can lead to the design of lighter parts for automotive applications such as door panels, headliners, and underbody shields.

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