Differential scanning calorimetry

About: Differential scanning calorimetry is a research topic. Over the lifetime, 50315 publications have been published within this topic receiving 1152335 citations. The topic is also known as: DSC.

Effect of crystallization temperature on crystal modifications and crystallization kinetics of poly(L-lactide)

Abstract: The crystalline structure of poly(L-lactide) (PLLA) have been found to quite depend on the crystallization temperatures (Tcs), especially in the range of 100−120°C, which is usually used as the crystallization temperature for the industrial process of PLLA. The analysis of wide-angle X-ray diffraction and Fourier transformed infrared spectroscopy revealed that 110°C is a critical temperature for PLLA crystallization. At Tc < 110°C and Tc ≥ 110°C, the α′ and α crystals were mainly produced, respectively. Besides, the structural feature of the α′-form was illustrated, and it was found that the α′-form has the larger unit cell dimension than that of the α-form. Moreover, the crystallization kinetics of the α′ and α crystals are different, resulting in the discontinuousness of the curves of spherulite radius growth rate (G) versus Tc and the half time in the melt-crystallization (t1/2) versus Tc investigated by Polarized optical microscope and Differential scanning calorimetry, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Nucleating agent for poly(L‐lactic acid)—An optimization of chemical structure of hydrazide compound for advanced nucleation ability

Abstract: A series of compounds having hydrazide groups was prepared and evaluated as nucleating agent for poly(L-lactic acid) by differential scanning calorimetry. Hydrazide compounds derived from benzoic acid, 2-hydroxybenzoic acid, 3-tert-butylbenzoic acid, and 2-aminobenzoic acid, where two of hydrazide compounds connected by four methylene chain were evaluated in series. Benzoylhydrazide type was found to be more effective on the enhancement of crystallization of poly(L-lactic acid). Effects of connecting length of methylene chain numbers between two of benzoylhydrazide on the nucleation ability were also evaluated. Benzoylhydrazide-type compound having 10 methylenes, that is, decamethylenedicarboxylic dibenzoylhydrazide demonstrated excellent nucleation ability, and the resulted crystallization temperature and enthalpy of PLA with the compound of 1 wt % loading were 131°C and 46 J g−1. The achieved crystallization temperature and enthalpy were over 10°C and over 10 J g−1 higher than PLA with conventional nucleating agents, such as talc and ethylenebis (12-hydroxystearylamide). Thus, the improvement in processability, productivity, and heat resistance of PLA is suggested to be achieved by using decamethylenedicarboxylic dibenzoylhydrazide as a nucleating agent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 198–203, 2007

Glassy Dynamics and Glass Transition in Nanometric Thin Layers of Polystyrene

Abstract: Broadband dielectric spectroscopy (BDS), spectroscopic vis-ellipsometry (SE), X-ray reflectometry (XRR), and alternating current (ACC) as well as differential scanning calorimetry (DSC) are combined to study glassy dynamics and the glass transition in nanometric thin (≥5 nm) layers of polystyrene (PS) having widely varying molecular weights (27 500−8 090 000 g/mol). For the dielectric measurements two sample geometries are employed, the common technique using evaporated electrodes and a recently developed approach taking advantage of nanostructures as spacers. All applied methods deliver the concurring result that deviations from glassy dynamics and from the glass transition of the bulk do not exceed margins of ±3 K independent of the layer thickness and the molecular weight of the polymer under study. Our findings are discussed in the context of the highly controversial literature and prove that an appropriate sample preparation is of paramount importance.