Search Results
Abstract
Plastics have been used in short-life products, which have presented harmful consequences for the nature, because of the low degradation rate reached by the most common polyolefins. This work evaluates the mechanical and thermal properties of pure iPP, plasticized starch (TPS) with biodiesel (TPSBio) or commercial (TPSCom) glycerols, and their blends (iPP/TPSPlas). The addition of TPSPlas caused an increasing on the cristallinity of iPP, mainly for the compositions 90/10 and 80/20, probably due to morphological alterations such as crosslinking, that may have modified the molecular arrangement of the iPP in the presence of glycerol.
Abstract
The thermal properties of caprolactam/long chain lactam copolymer were studied with a Perkin-Elmer DSC 7. The melting point (T m), heat of fusion (δH m), crystalline degree (X c), crystallization temperature (T c) and glass transition temperature (T g) of the copolymers increase with decrease of the content of the log chain lactam. From the changes in the mechanical properties with corresponding changes in the thermal properties, it is clear that the copolymers are thermal plastic and elastic. In addition, it is found that the results at a heating rate of 10 deg·min−1 are almost the same as that at 20 deg·min−1 after thermal history is erased.
Abstract
Waterborne polyurethane coatings were prepared by a polyaddition reaction using toluene diisocyanate (TDI), 2,2-di(hydroxy-methyl) propionic acid, soy-based polyols with different hydroxyl values, plus 2-hydroxyethyl methacrylate (HEMA) as chain termination agent, triethylamine as neutralization agent, and DBTDL as catalyst. Six soybean oil-based polyols were used in this study with hydroxyl values of 100, 115, 128, 140, 155, and 164 mg KOH g−1, respectively. The molar ratio of polyol hydroxyl to DMPA was varied from 1.6 to 2.6. The storage stability of the waterborne polyurethane coatings was greater than 6 months. The thermal properties of the coating films were investigated by TG and DCS. The results show that the soy-based polyurethane films decomposed in three stages. The glass transition temperatures, T g, of the soy-based polyurethane films increased with the hydroxyl number of the soy-based polyol.
Abstract
Vinylated polyhedral oligomeric silsesquioxane (POSS-M) was prepared by the reaction of POSS containing amine groups with acrylic acid. Azobenzene liquid crystalline copolymer (LCP-POSS) was then synthesized with 6.0 mol% POSS-M and 94.0 mol% acrylate monomer containing azobenzene liquid crystalline moiety (Azo-M) by free-radical copolymerization. Homopolymer of Azo-M (LCP) was also synthesized under the same conditions. Their thermal properties and liquid crystallinity were characterized by Thermal gravimetric analysis (TG), differential scanning calorimetry (DSC), Wide-angle X-ray diffraction experiments (XRD) and polarized optical micrographs (POM). The results showed that LCP-POSS has higher thermal stability and glass transition temperature than pure LCP due to the incorporation of the rigid cage-like POSS. Especially, LCP-POSS exhibits enantiotropic smectic and nematic liquid crystalline behaviors, its smectic-nematic transition temperature (T SN) and nematic-isotropic transition temperature (T NI) are higher than those of pure LCP, which may promote and extend its applications on stimuli-responsive materials and devices.
Abstract
In order to study the thermal properties of new type environment-friendly binary hydrate for cold storage in air-conditioning system, tests have been carried out by DSC comprehensively on the phase-change temperature and fusion heat of TBAB hydrate, THF hydrate, and TBAB–THF hydrate mixture. The results show a good trend that TBAB–THF hydrate has the superiority for more proper phase-change temperature and increased fusion heat. A broader and more developed view is that adding appropriate amount of hydrate with lower phase-change temperature to hydrate with higher one can make the hydrate mixture more suitable for cold storage (especially for 278–281 K); some hydrates with lower phase-change temperature can even make the fusion heat of mixture hydrate increased greatly. Several new environmental working pairs for binary gas hydrates have been listed to help to promote the application.
Abstract
The thermal properties (in the temperature range of 100–250°C) of N-ethyl-N-phenyldithiocarbamatecomplexes of Zn(II), Co(III), Ni(II), Cu(II) and Pb(II) and their influence on the kinetics of cure have been studied by differential scanning calorimetry (in nitrogen). It was found that Zn(II), Co(III) and Pb(II) dithiocarbamates melted without further effects, while the melting of Ni(II) and Cu(II) dithiocarbamates is accompanied with decomposition. From the kinetic point of view, the dithiocarbamates decrease the values of the reaction order and the values of rate constants follow this order (with respect to the metal ion): Zn(II)<Cu(II)<Pb(II)<Ni(II)<Co(III).
Abstract
Multiblock terpolymers -(PBT-b-PTMO-b-PA12.10)n- comprising the polymer systems in which one of the three blocks (PBT) is not soluble in the hard phase of PA12.10 blocks but is slightly soluble in the soft phase of PTMO blocks have been obtained. The DSC and DMTA method was applied to investigate the thermal properties of these polymers and it was found that the PBT block acts as an element that produce stiffness of -(PBT-b-PTMO-b-PA12.10)n- structure. The terpolymers were compared with the previously described [5] -(PBT-b-PTMO-b-PA12)n- elastomers, in which the rigid PBT block (DP > 7) dissolves in the hard phase of PA12 blocks and partly dissolves in the soft phase. It was found that even a small change in the chemical structure of the amide block influences significantly on the structure, phase separation and the properties of terpolymers.
Abstract
The dehydration and decomposition of the red mud from Seydięehir Aluminum factory, mixed with soda were investigated under dynamic and isothermal conditions. Soda was added to the red mud samples as much as 50, 100 and 150 mass% of Na2CO3 of the red mud sample's mass. To determine the effect of soda additive on the red mud's thermal properties, using TG and DTA techniques simultaneously under atmospheric conditions. Furthermore, the original red mud sample's XRD and IR spectrum curves were investigated. It seems that the temperatures of the endothermic peaks of the red mud decreased with the amount of soda added. However the endothermic peak's temperature readings showed that the melting of soda increased gradually with the quantity of soda used.
Abstract
The thermal properties of liquid silk from domestic and wild silkworms are investigated. Liquid silks obtained from the silk gland of the domesticated silkworm, Bombyx mori and four wild silkworms, Samia cynthia ricini, Dictyoploca japonica, Antheraea pernyi and Antheraea yamamai were used. The DSC curves for the liquid silk from the domestic silkworm have weak endothermic peaks corresponding to the breaking of hydrogen bonds in the β-form or to the untangling of physical network. The DSC curves for the wild silkworm silks, however, show clear exothermic peaks corresponding to a phase transition from the α-helix conformation to the β-form. Liquid silk from all the different silkworms undergoes a characteristic irreversible phase transition.
Abstract
In this study, the thermal properties of bio-flour-filled, polypropylene (PP) bio-composites with different pozzolan contents were investigated. With increasing pozzolan content, the thermal stability, 5% mass loss temperature and derivative thermogravimetric curve (DTGmax) temperatures of the bio-composites slightly increased. The coefficient of thermal expansion (CTE) and thermal expansion of the bio-composites decreased as the pozzolan content increased. The glass transition temperature (T g), melting temperature (T m) and percentage of crystallinity (X c) of the bio-composites were not significantly changed. The thermal stability, thermal expansion and X c of the maleic anhydride-grafted PP (MAPP)-treated bio-composites were much higher than those of non-treated bio-composites at 1% pozzolan content due to enhanced interfacial adhesion. X-ray diffraction (XRD) analysis confirmed the crystallinity of pozzolan-added bio-composites. From these results, we concluded that the addition of pozzolan in the bio-composites was an effective method for enhancing the thermal stability and thermal expansion.
