SAXS and DSC studies of the crystallization and melting phenomena of poly(epsilon-caprolactone)

The relationships between the crystallization temperature, T,, the crystal thickness, d(c) and the melting peak temperature, T-m of poly(epsilon -capr olactone)have been determined by carrying out time- and temperature-depende nt small angle x-ray scattering experiments. A two-step melting has been su ggested, resulting in the occurrence of two well defined independent bounda ry lines, indicating the transformation from melt into the partially crysta lline state. For crystallization temperatures lower than 40 degreesC, durin g heating, more pronounced peak shifts are observed with the final melting of the crystallites having the same thickness of d(c) approximate to 7 nm. In this region, it is evident that crystals have relatively good stabilitie s, since they have fairly uniform thickness. At higher temperatures, above 40 degreesC, T-m increases with T-c, together with the thickness. The trans formation of the melt into the partially crystalline state depicts a two-st ep process, beginning with the formation of a well defined initial structur e with lower order, which is subsequently stabilized.