Papers by Keyword: Miscibility

Abstract: Miscibility between poly (butylene succinate) [PBS], a semi-crystalline polymer with a natural gum extracted from the pine tree (Pinus Caribaea – Hondurensis), was investigated in solution cast blends using Differential Scanning Calorimetry [DSC] and Fourier Transform Infrared Spectroscopy [FTIR]. The spherulite morphology of PBS in the blends was observed with polarized optical microscopy [POM]. Depression in the equilibrium melting temperature of PBS in the blends was determined using the Hoffman-Weeks plot method. The depression in the crystallization temperature of the blends with increasing pine gum ratio and the emergence of extinction rings in the spherulites of the blends confirmed the blends to be miscible at the molecular level. Infrared spectroscopy indicated that interactions occurred between the hydroxyl groups of the pine-gum and the carbonyl group of PBS.

Abstract: The poly (ethylene terephthalate)/poly (trimethylene terephthalate) (PET/PTT) blends were prepared and their phase morphology, mechanical and thermal properties were investigated by scanning electron microscopy (SEM), polarized optical microscopy (POM), universal material testing machine, differential scanning calorimetry (DSC), wide-angle X-ray (WAXD), respectively. The glass transition and SEM results suggest apparently that the PET and PTT have good miscibility at amorphous state. The blends with more PET content less likely undergo a melting/recrystallization process during DSC heating scan. In the blends, PET component with higher supercooling degree crystallizes first, and then the crystallites of PET will be the nucleating agents for PTT, which greatly improves the crystallization rate of PTT. Because of the interaction between the PET and PTT, there are much smaller spherulites formed in blends with increasing PET component. The blend with more PET contents has larger tensile strength and modulus.

Abstract: Polylactic acid (PLA) is the most promising material in the biodegradable category. However, brittleness and poor thermal stability restrict its application. To overcome this limitation, PLA may be blended with other biodegradable materials to tailor its properties while maintain biodegradability. In this study a series of blends of PLA and poly (ε-caprolactone) (PCL) with various mass fractions were prepared by solution method and solvent casting. Films of each blend were formed when the solvent evaporated. Subsequently, tensile test samples were punched out of the film for testing and tensile testing, Fourier transform infrared spectrometry (FTIR), Differential scanning Calorimetry (DSC) and contact angle measurements were carried out. Since PCL is a ductile material, the two materials were blended together in an effort to improve the mechanical properties. However, on thermal analysis of the blends, two individual melting peaks were observed in the DSC thermograms. Furthermore, no significant shift in peaks was observed on the FTIR spectra, and clear droplets and boundaries between two components of the blend can be observed in morphology study, all indicated the immiscibility of PLA and PCL. Tensile test showed poor mechanical properties due to the poor adhesion of the two immiscible components of the blend, and the addition of PCL did not influence the wettability of the surface of the blends as there were no significant differences in contact angle measurements.

Abstract: Due to the increasing growth of fuel consumption and also its price, alcohols begin to show a real interest for their use as fuel at compression ignition engines. Tightening the requirements on reducing the level of pollutant emissions and greenhouse effect gases has led to the increasing of research on using alcohols as alternative fuel for diesel engine. Among the primary alcohols, butyl alcohol (butanol) is considered to be of great perspective in its use as fuel in diesel engines, due to its properties close to those of diesel fuel. The overall objective of the paper represents using butanol at an automotive diesel engine in order to reduce BSFC, to reduce engine emissions and replace fossil fuels. This paper presents some aspects of the operation of diesel engine fuelled with blends of diesel fuel and butanol. Results of theoretical and experimental investigations done on a 1.5 L diesel engine fuelled with butanol are presented. At the use of butanol in mixture with diesel fuel in different proportions (10% and 20% butanol vol.), brake specific energetic consumption of the engine was reduced by about 2.5% and respectively 5%, NO_x emissions decreased by about 15% and respectively 20%, CO₂ emission by about 5% for 20% butanol, at the engine running at full load and maximum torque engine speed. The results of experimental investigations have validated the physical-mathematical model used for the simulation of thermo-gas-dynamics processes from the inside engine cylinder. The paper brings real contributions in the field making available to specialists new information related to the use of butanol at the diesel engines.

Abstract: Thin films of poly (ethylene oxide) (PEO), poly (methyl methacrylate) (PMMA) and selected blends of PEO/PMMA with and without the addition of LiClO₄ were prepared using solution casting technique. The presence of a single T_g which corresponds closely to that of the Gordon Taylor equation confirms the miscibility of both the salt-free and salt-doped blends. The T_gs and the ion conductivity (σ) at room temperature of PEO, PMMA and the PEO/PMMA blends generally increase with ascending salt concentration (Y). Variations in the σ value as a function of Y for all the three systems correlate closely with their respective T_g results. PMMA-salt complex records the lowest σ value at all salt concentrations. PEO/PMMA/LiClO₄ blend with 75 wt% PEO exhibits the highest σ value of 5 x 10^-7 S cm^-1 at Y = 0.10. The σ value of the blend-salt system is observed to be slightly lower than that of the PEO-salt system. This is due to reduced segmental motion cause by increased T_g of the blend and a decrease in free ions in the amorphous phase of PEO as a small amount of the salt is solvated by PMMA in the blend. Therefore, the percolation path lies in the amorphous PEO rich phase of the blend.

Abstract: The miscibility of chitosan / methylcellulose (CH/MC) blends was studied by FT IR, wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA), and scanning electronic microscopy (SEM). The regular changes of FT IR and WAXD spectra of CH/MC blend powder indicated the miscibility of the blends. TGA curves and SEM images of cross-sections of the blends films showed partly miscibility.

Abstract: The miscibility and thermal properties of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/poly(ethylene oxide) blends were investigated by differential scanning calorimetry (DSC). The results indicated that PHBHHx showed complete miscibility with PEO for PHBHHx/PEO 95/5, 90/10 and 80/20 blends as evidenced by the single composition-dependent glass transition temperature and the depression of the melting temperature of PHBHHx. However, PHBHHx showed partial miscibility with PEO for the other three blends as shown by the existence of unchanged composition independent glass transition temperature. The incorporation of PEO may improve the performances of PHBHHx to meet the different need in biomedical applications.

Abstract: Being interested in the development of lignin-containing polymeric materials had been investigated in this paper and the lignin/LDPE-EVA blends compatibilized with LDPE-g-MAH prepared in rheometer were characterized by rheological properties. The experimental results indicated that the maximum, balanced torque and plasticized time were lowest to 53.7N.m-1 and 11.7N.m-1 75s, respectively, with compatibilizer additon of 10 parts. In addtion, mechanical properties, FT-IR, SEM and DSC-TG were measured and the results revealed that the compatibility and miscibility of lignin/LDPE-EVA blends were improved obviously.

Abstract: The miscibility of chitosan/ethylcellulose (CH/EC) blends was studied by FT IR, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and scanning electronic microscopy (SEM). The regular changes of FT IR and WAXD spectra of CH/EC blend powder indicated the miscibility of the blends. DSC curves and SEM images of cross-sections of the blends films showed partly miscibility. CH/EC blends could form anisotropic phase in their formic acid solutions observed on a polarizing light microscope (PLM).

Abstract: Miscibility of ternary polymer blends composed of poly(ethyleneimine) (PEI), poly(ethylene glycol) (PEG), and carboxymethyl chitosan (CMCS) was investigated by dilute-solution viscometry, FTIR spectrum, and scanning electron microscope (SEM) techniques. The results of these measurements indicate that PEG is immiscible in the ternary CMCS/PEI/PEG polymer blend.