VCL#53 Part 2

Abstract

Polyethylene Terephtalate (PET) is chosen for modeling the complexity of the effect of crystallization because this polymer crystallizes from the melt when cooled slowly, yet remains amorphous when quenched. Additionally, its viscosity and crystallization is very sensitive to thermal history, especially under melt oscillation.

TMA is a technique of analysis very appropriate to discern the presence of both b-grains (which stiffen up the modulus of the melt) and crystallization. We present a way to quantitatively relate the TMA curve to the determination of the amount of b-conformers and crystals. We show that for these samples, obtained from non-equilibrium melts, many discrepancies appear when characterizing and following the total crystallization in the sample, or comparing the heat capacity in the glassy and in the melt state with their theoretical values (see part 1). The samples show a lack of free volume in the liquid and solid states which cannot be attributed to the crystalline phase.

Analysis of TMA results

links to download VCL #53 part 2

(45.4 MB; 59 min): inquire @ :Beltzeki@eknetcampus.com