Structural Changes in UHMWPE Reactor Powders during Sintering under Different Conditions

The change in the structure of the ultra-high-molecular-weight polyethylene (UHMWPE) nascent reactor powder during sintering at various temperatures and pressures was examined using the DSC method to elucidate the effect of processing parameters on the structure. Scanning electron microscopy revealed that the primary morphological units of the UHMWPE reactor powder investigated are crystalline lamellae. Because the heat flux dH/dT (where H is the melting enthalpy and T is the sample temperature) is proportional to the mass fraction of lamellae melting at a given temperature, data on the thickness distribution of the lamellae could be obtained by analysing the shape of the polymer melting peak on the DSC curves. The structure of UHMWPE has not yet been subjected to such scrutiny. The proportion of thick (>15 nm) and thin (10 nm) lamellae in compacted samples and those sintered at a temperature of 130oC (lower than the equilibrium melting temperature of an infinitely long polyethylene crystal T0 = 142oC) is found to be virtually identical. Significant variations in the composition of the lamellae of various thicknesses have been observed in the samples sintered at temperatures above the T0 of PE with subsequent cooling under various circumstances. At the same time, their melting points remained unaltered when the samples were heated from 130°C to 145°C while under pressure.

Author(s) Details:

L. P. Myasnikova,
IOFFE Institute, 26 Polytechnicheskaya, St. Petersburg 194021, Russia.

A. K. Borisov,
IOFFE Institute, 26 Polytechnicheskaya, St. Petersburg 194021, Russia.

Yu. M. Boiko,
IOFFE Institute, 26 Polytechnicheskaya, St. Petersburg 194021, Russia.

A. P. Borsenko,
A. A.Galkin Physical-Technical Institute, str. R. Luxemburg 72, Donetsk, 83114, Ukraine.

V. F. Drobot’ko,
A. A.Galkin Physical-Technical Institute, str. R. Luxemburg 72, Donetsk, 83114, Ukraine.

V. M. Egorov,
IOFFE Institute, 26 Polytechnicheskaya, St. Petersburg 194021, Russia.

E. M. Ivankova,
Institute of Macromolecular Compounds, 31 Bolshoy pr., St. Petersburg 199004, Russia.

E. I. Radovanova,
IOFFE Institute, 26 Polytechnicheskaya, St. Petersburg 194021, Russia.

V. A. Marikhin,
IOFFE Institute, 26 Polytechnicheskaya, St. Petersburg 194021, Russia.

Please see the link here: https://stm.bookpi.org/NTPSR-V3/article/view/6828

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