Tham khảo tài liệu 'thermal analysis of polymeric materials part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 646 6 Single Component Materials exotherm in the insert in Fig. . The following annealing of 70 min starts at 3 with only a slight increase in diffraction intensity. The subsequent heating to 433 K is shown in the lower part of Fig. . It reveals again a period of constant intensity 1 followed by an increase in crystallinity 2 which leads to the beginning melting at 3 which on annealing at 4 indicates some recrystallization and a further slight increase in crystallinity. The next heating leads to the main melting with disappearance of the crystalline diffraction pattern in accord with the DSC trace. Further analysis of the two samples of Fig. is done by TMDSC as seen in the left graphs of Fig. . A comparison of the two reversing heat capacities shows that the cold crystallization and the transition mesophase-to-a-monoclinic crystals do not show . they are nonreversing. There remains however a substantial reversing contribution which is larger for the quenched iPP than for the lamellar melt-cooled iPP. The upper limit of the devitrification of the RAF seems to occur at 320-330 K Fig. but cannot be separated fully from the reversing melting. The curves on the right in Fig. represent the latent-heat contributions of the apparent reversing cp obtained by subtracting the expected thermodynamic cp for the given crystallinity from the curves on the left. Results from quasi-isothermal experiments on heating are plotted also in Fig. . These are taken after the slow crystal perfection ceased and represent reversible latent heats. The slowly-cooled lamellar sample begins to show reversible melting at 320 K while the fast-cooled sample with globular morphology begins melting at the end of the glass transition. More qualitative data were generated throughout the melting peak and show a maximum in reversible melting on heating after fast cooling of J K 1 mol 1 and after slow cooling of J K 1 mol 1 52 . The same thickness in the chain .
