Poly(dimethyl phosphazene) displays, upon crystallization, a polymorphic behaviour showing two crystalline modifications, form I with a chain periodicity of 4.9 Å and a melting point of 146°C and form II with a chain periodicity of 5.85 Å and a melting point of 76°C. Form I, the only crystalline modification that is observed upon melting and recrystallization, has been completely characterized from a structural point of view through the study of X-ray diffraction patterns from oriented fibres and powder samples. A final structural refinement was carried out with the Rietveld method. The unit cell is monoclinic, space group P21c and the cell parameters are a = 6.345(2), b = 13.805(4), c = 4.887(2)Å, β = 110.45(3)°.
THE POLYMORPHIC BEHAVIOR AND THE CRYSTAL-STRUCTURE OF ONE MODIFICATION OF POLY(DIMETHYLPHOSPHAZENE)
MEILLE, STEFANO VALDO;GALLAZZI, MARIA CARMELA;
1992-01-01
Abstract
Poly(dimethyl phosphazene) displays, upon crystallization, a polymorphic behaviour showing two crystalline modifications, form I with a chain periodicity of 4.9 Å and a melting point of 146°C and form II with a chain periodicity of 5.85 Å and a melting point of 76°C. Form I, the only crystalline modification that is observed upon melting and recrystallization, has been completely characterized from a structural point of view through the study of X-ray diffraction patterns from oriented fibres and powder samples. A final structural refinement was carried out with the Rietveld method. The unit cell is monoclinic, space group P21c and the cell parameters are a = 6.345(2), b = 13.805(4), c = 4.887(2)Å, β = 110.45(3)°.| File | Dimensione | Formato | |
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Pub045 PDMP Bruck Polym 1992.pdf
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