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Differential scanning calorimetry can be used to measure a number of characteristic properties of a sample. Using this technique it is possible to observe fusion and crystallization events as well as glass transition temperatures T g. DSC can also be used to study oxidation, as well as other chemical reactions. [15] [16] [19]
HDPE is known for its high strength-to-density ratio. [4] The density of HDPE ranges from 930 to 970 kg/m 3. [5] Although the density of HDPE is only marginally higher than that of low-density polyethylene, HDPE has little branching, giving it stronger intermolecular forces and tensile strength (38 MPa versus 21 MPa) than LDPE. [6]
(Differential thermal analysis) (DTA) and (differential scanning calorimetry) (DSC): Analyzing the heating effect of polymer during the physical changes in terms of glass transition, melting, and so on. [7] These techniques measure the heat flow associated with oxidation.
Characteristic DSC curve for a polyethylene, the OIT is measured. Oxidation induction time or OIT is a standardized test performed in a DSC which measures the level of thermal stabilization of the material tested. The time between melting and the onset of decomposition in isothermal conditions is measured.
The melting point for average commercial low-density polyethylene is typically 105 to 115 °C (221 to 239 °F). These temperatures vary strongly with the type of polyethylene, but the theoretical upper limit of melting of polyethylene is reported to be 144 to 146 °C (291 to 295 °F). Combustion typically occurs above 349 °C (660 °F).
Ultra-high-molecular-weight polyethylene (UHMWPE, UHMW) is a subset of the thermoplastic polyethylene. Also known as high-modulus polyethylene ( HMPE ), it has extremely long chains, with a molecular mass usually between 3.5 and 7.5 million amu . [ 1 ]
The detection of the melting can be done by sensing the transient heat flows during phase transitions using differential scanning calorimetry – DSC thermoporometry, [1] measuring the quantity of mobile liquid using nuclear magnetic resonance – NMR cryoporometry (NMRC) [2] [3] or measuring the amplitude of neutron scattering from the imbibed ...
Additional energy is released upon melting a semicrystalline polymer. This energy can be measured with differential scanning calorimetry and compared with that released upon melting of the standard sample of the same material with known crystallization degree. [6] [20] X-ray diffraction