DSC Data (dsc + data)

Distribution by Scientific Domains

Selected Abstracts

Calorimetric study of milk fat/rapeseed oil blends and their interesterification products

Mario Aguedo
Abstract Milk fat (MF) and rapeseed oil (RO) blends were analyzed by differential scanning calorimetry (DSC). It was shown that peak and onset temperatures can be used to determine the percentage of each fat in the blend and that the relative enthalpy of one peak assigned to low-melting triacylglycerols (TAG) can also be used to determine the percentage of RO in the blend. A linear relation was also established between MF content of the blend and its dropping point (DP), indicating that DP can be linearly related with the above DSC data. A blend of MF/RO 70,:,30 (wt/wt) was then chosen as a model system for enzymatic interesterification (EIE). The applicability of DSC analyses to EIE products was checked and a correct correlation could be established between DSC values and the interesterification degree and DP. Among the data from the DSC profiles, the peak associated with low-melting TAG was the best indicator of the reaction course. In the same way, a high-melting MF stearin fraction was interesterified with RO. In that case, onset temperatures and peak "a" were better reaction indicators than for the interesterified MF/RO blend. We therefore suggest that values from DSC endotherms could be used to monitor EIE of fat blends. [source]

Effect of boron-containing materials on the flammability and thermal degradation of polyamide 6 composites containing melamine

Mehmet Do
Abstract Three different boron-containing substances,zinc borate (ZnB), borophosphate (BPO4), and a boron- and silicon-containing oligomer (BSi),were used to improve the flame retardancy of melamine in a polyamide 6 (PA-6) matrix. The combustion and thermal degradation characteristics of PA-6 composites were investigated with the limiting oxygen index (LOI), the UL-94 standard, thermogravimetric analysis (TGA)/Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC). A slight increase was seen in the LOI values of a sample containing BSi (1 wt %). BPO4 at high loadings showed a V0 rating (indicating the best flame retardancy) and slightly lower LOI values in comparison with samples with only melamine. For ZnB and BSi, glassy film and char formation decreased the dripping rate and sublimation of melamine, and this led to low LOIs. According to the TGA,FTIR results, the addition of boron compounds did not change the decomposition product distribution of melamine and PA-6. The addition of boron compounds affected the flame retardancy by physical means. The TGA data showed that boron compounds and melamine reduced the decomposition temperature of PA-6. According to the DSC data, the inclusion of boron compounds increased the onset temperature of sublimation of melamine and also affected the flame retardancy negatively. 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]


ABSTRACT In the present work, rice starch was studied by differential scanning calorimetry (DSC) and electrical conductivity as a function of temperature. The gelatinization temperature was calculated using both methods. Three stages of electrical conductivity were found. When the logarithm of conductivity was plotted versus temperature, the data have been well adjusted to the linear equation, indicating that a model for conductivity may be created using an Arrhenius-type expression to obtain kinetic parameters such as onset, peakset, endset temperatures and gelatinization energy (Eg). The conductivity Eg was calculated and compared to the enthalpy H calculated from the DSC data. It was found that Eg and enthalpy are similar processes. We conclude that electrical conductivity is an alternative method for the study of starch,water mixtures. PRACTICAL APPLICATIONS This research provides a new methodology to obtain kinetic parameters such as temperature of the beginning, medium and ending of gelatinizaiton, which are important for determining the cooking range needed to obtain desired characteristics in a processed starch-containing food. [source]

Estimation of the fragility index of indomethacin by DSC using the heating and cooling rate dependency of the glass transition

Joaquim J. Moura Ramos
Abstract In this study we have investigated the features of the glass transition relaxation of indomethacin using Differential Scanning Calorimetry (DSC). The purpose of this work is to provide an estimation of the activation energy at the glass transition temperature, as well as of the fragility index, of amorphous indomethacin from DSC data. To do so, the glass transition temperature region of amorphous indomethacin was characterized in both cooling and heating regimes. The activation energy for structural relaxation (directly related to glass fragility) was estimated from the heating and cooling rate dependence of the location of the DSC profile of the glass transition. The obtained results were similar in the heating and in the cooling modes. The results on the fragility index of indomethacin obtained in the present study, m,=,60 in the cooling mode and m,=,56 in the heating mode, are compared with other values previously published in the literature. 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:1503,1507, 2004 [source]

Crystallization Behavior of Poly(, -caprolactone) Grafted onto Cellulose Alkyl Esters: Effects of Copolymer Composition and Intercomponent Miscibility

Ryosuke Kusumi
Abstract Graft copolymers of CA and CB with PCL were prepared at compositions rich in PCL. Kinetic DSC data were analyzed in terms of a folded-chain crystallization formula expanded for a binary mixing system of amorphous/crystalline polymers. The order of crystallization rates was plain PCL,>,CA- g -PCL (DS,=,2.98),>,CB- g -PCL (DS,=,2.1,2.95),>,CA- g -PCL (DS,=,2.1,2.5), and the fold-surface free energy of the PCL crystals obeyed the reverse order. POM revealed a generally tardy growth of spherulites for all the graft copolymers. The slower crystallization process may be ascribed primarily to the compulsory effect of anchoring PCL chains onto the semi-rigid cellulose backbone. Intercomponent miscibility of the CA/PCL and CB/PCL pairs was also taken into consideration. [source]

Functionalization of Shortened Single-Walled Carbon Nanotubes with Poly(p -dioxanone) by "Grafting-From" Approach

Kuk Ro Yoon
Abstract Summary: It has been a real challenge to form carbon nanotube (CNT)/polymer composites where CNTs are well-dispersed in the polymer matrix and the interactions between CNTs and polymers are effectively strong. In this paper, we applied surface-initiated, ring-opening polymerization (SI-ROP) of p -dioxanone (PDX) to shortened single-walled carbon nanotubes (s-SWCNTs) and successfully formed s-SWCNT/PPDX composites (see Figure). Due to intimate interactions between s-SWCNTs and PPDX, we observed dramatic changes in PPDX properties upon the formation of the composites: 10%-weight-loss-temperature of PPDX increased by 20,C (measured by thermogravimetric analysis) and the patterns of Tg and Tm were greatly altered. We did not observe any noticeable peaks from the composite up to 120,C in differential scanning calorimetry (DSC), while DSC data of PPDX itself showed Tg and Tm at ,13.4 and 103,C respectively. Schematic representation of the procedure for formation of s-SWCNT/PPDX composites. [source]

Kinetic parameters estimation for unsaturated polyester-styrene systems

Chao-Ming Lin
A model modified from the traditional kinetic model is proposed for the determination of the kinetic parameters describing the autocatalytic reaction of polyesterstyrene systems. The proposed method utilizes three experimental data values from the vs. , curve,the initial value, the peak value, and the maximum value,to solve the kinetic parameters. The curing reaction of a thermosetting polyester was investigated by using the isothermal and dynamic techniques of differential scanning calorimetry (DSC). The results show that the reaction orders m, n and the ultimate conversion are not constant, and instead are functions of temperature. The estimated kinetic curves agree well with the experimental DSC data. [source]

Synthesis and characterization of homo- and copolymers of 3-(2-cyano ethoxy)methyl- and 3-[methoxy(triethylenoxy)]methyl-3,-methyl-oxetane

Lin Ye
Abstract Two oxetane-derived monomers 3-(2-cyanoethoxy)methyl- and 3-(methoxy(triethylenoxy)) methyl-3,-methyloxetane were prepared from the reaction of 3-methyl-3,-hydroxymethyloxetane with acrylonitrile and triethylene glycol monomethyl ether, respectively. Their homo- and copolyethers were synthesized with BF3 Et2O/1,4-butanediol and trifluoromethane sulfonic acid as initiator through cationic ring-opening polymerization. The structure of the polymers was characterized by FTIR and1H NMR. The ratio of two repeating units incorporated into the copolymers is well consistent with the feed ratio. Regarding glass transition temperature (Tg), the DSC data imply that the resulting copolymers have a lower Tg than pure poly(ethylene oxide). Moreover, the TGA measurements reveal that they possess in general a high heat decomposition temperature. The ion conductivity of a sample (P-AN 20) is 1.07 10,5 S cm,1 at room temperature and 2.79 10,4 S cm,1 at 80 C, thus presenting the potential to meet the practical requirement of lithium ion batteries for polymer electrolytes. Copyright 2005 Society of Chemical Industry [source]