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    • br Model fitting methods Model fitting

    2018-10-29


    Model fitting methods Model fitting methods are based on the different models fittings at a particular temperature obtained from DTG curve and also determine the values of activation energy and pre-exponential factor. Many non-isothermal model fitting methods are available but Kissinger model is the most popular among all [11].
    Experimental design, materials and methods PLA and PLA/CH-g-OLLA bionanocomposite films were prepared by well-known solution casting method with the help of various combinations of PLA and CH-g-OLLA bionanocomposite [1].
    Acknowledgements Authors are very much thankful to Ministry of Food Processing Industries, Government of India, Centre of Excellence for Sustainable Polymers funded by Department of Chemical and Petrochemical, GOI (project sanction no. SERB/F/3839/2012-13), Department of Chemical Engineering and Central Instruments Facility, Indian Institute of Technology Guwahati, Assam, India for providing research facilities.
    Data There are three tables used to describe the numerical approximation of the Ae temperature: Table 1 gives the maximum valid composition range based on the model alloys used. Table 2 lists the contribution of each AGI-5198 to the polynomial coefficients in the derived function given in Eq. (6) in Ref. [1]:where Ae temperature is expressed in °C and concentrations in wt. %. Under para-equilibrium conditions carbon is the only chemical element that changes its concentration during transformation and to avoid repetitive calculations it is advantageous to write Ae3 as a polynomial in carbon, [C], as follows: The relationships of to the constants, c, are listed in Table 3.
    Experimental design, materials and methods The approximation of the Ae3 temperature was constructed in two steps: in the first step a large number of compositions with the associated Ae3 temperatures were generated; this was followed by multiple regression to find a suitable approximation. For each run, a total of 100,000 Ae3 temperatures were generated with [C]<0.8wt. % and within the range of validity for all other chemical elements given in Table 1. The value of each chemical element was chosen independently of all the other elements and was taken from a uniform distribution between 0 and the maximum allowed content. The SAS procedure ‘reg’ with the option ‘selection=stepwise’ chose terms from a large bank that contributed significantly to Ae3. Terms that did not improve the fit to the data were not included. The bank of terms consisted of: [C]4, [C]5, and [C]6. The product of [C]2, [C]3, [C]4, Mn2, Al2, and Si2 with the other elements. Since the starting temperature for the model is 910°C, all calculated Ae3 temperatures higher than this value are assigned the starting value. Calculated Ae3 temperatures higher than 910°C should be approached with caution, because some extrapolation will have taken place. This is especially true for Al and Si compositions at the upper end of the valid range. A measure of success of the approximation is the difference between the full MTDATA expressions and the values obtained from the approximation. The standard deviation of the approximation is 4.9°C, which is much smaller than the undercooling at which nucleation is assumed to take place, with an offset of 0.0°C. The fit for Ae3 was also determined for a second, independent set of 100,000 Ae3 temperatures. The differences between the two sets were small; the differences with Andrews׳ expression, Eq. (1) are somewhat larger, with an average difference of 11°C and a standard deviation of 22°C.
    Acknowledgments This work was made possible by the facilities and support of Tata Steel, the Diamond-Manchester Collaboration and the Research Complex at Harwell, funded in part by the EPSRC (EP/I02249X/1).
    Data Hydrolytic degradation of PLLA blends with biological safe oligomers, PML and PAL, at physiological conditions was investigated in the present study. Change in differential scanning calorimetry (DSC) thermograms (Fig. 1) and the water uptakes (Fig. 2) upon hydrolytic degradation was shown.