Influence of microstructure on space charges of polypropylene

Abstract

The correlation of chemical structure, crystalline morphology, and space charge distribution under a dc electrical field was investigated with three kinds of poly(propylene) (PP) with a different chemical structure, that is, homogeneous PP and block copolymer and random copolymer of PP. The space charge distribution of the samples was prominently affected by their chemical sequence structure and crystalline microstructure. Among samples of different PPs, all isothermally crystallized at 140°C, the sample of random coPP represents the most well proportional space charge distribution and the smallest number of space charges. The effect of thermal history on the space charge distribution was also investigated by the samples of block coPP. The sample thermally treated at 50°C clearly represents a better proportional distribution than that at higher temperature of 140 and 100°C. Subsequent experiments indicate that the better proportional distribution attributes to imperfect and fine sperulites with the fine distribution of the "amorphous" region. The imperfect and fine sperulites originate from the random incorporation of ethylene segments or units into PP chains or from the low annealing temperature, and play an important role in the formation of shallow traps and transportation of space charges.

Sensitivity of intermediate mass fragment flows to the symmetry energy

“…For example, the radii of neutron stars are related to the pressure of isospin asymmetric nuclear matter, which is proportional to the slope of the symmetry energy [4]. Additionally, the proton fraction as a function of density for a neutron star in β equilibrium has been shown to be very sensitive to the density dependence of the symmetry energy, E sym (ρ) [5,6]. The proton fraction of the neutron star, and therefore E sym (ρ), defines whether the neutron star will cool quickly through the direct URCA process or more slowly through the standard URCA process.…”

Transverse collective flow and midrapidity emission of isotopically identified light charged particles

“…Recent experimental results are being used to apply constraints to the asymmetric part of the EoS, or density dependence of the symmetry energy (E sym (ρ)) [3][4][5][6]. Constraining the density dependence of the symmetry energy is essential for understanding the fundamental nucleon-nucleon interaction and has important astrophysical implications [3,5,[7][8][9][10][11][12][13].…”

“…Differences between the free neutron and free proton transverse collective flows have been predicted to be strongly sensitive to E sym (ρ) [43][44][45]. However, obtaining accurate energy and angular measurements of free neutrons, along with charged particles, is a difficult task.…”

Research progress on space charge characteristics in polymeric insulation

“…The imperfect and fine crystalline morphology eventually contributes to the formation of considerable shallow traps, which is more remarkable at low annealing temperature. 81 …”