Crystallization of poly(ethylene-co-octene): II. Melt memory effects on first order kinetics

Area of Science:

• Polymer Science
• Materials Science
• Physical Chemistry

Background:

• Crystallization kinetics in polymers is crucial for material properties.
• Melt memory effects, where prior thermal history influences subsequent behavior, are observed in various polymers.
• Understanding these effects in poly(ethylene-co-octene) is key to controlling its structure and performance.

Purpose of the Study:

• To investigate the melt memory effects on the crystallization kinetics of poly(ethylene-co-octene).
• To determine the temperature range and underlying mechanisms of these memory effects.
• To analyze the relationship between melt temperature and crystallization process characteristics.

Main Methods:

• Dilatometric experiments to measure volume changes during crystallization.
• X-ray scattering to probe structural evolution during the phase transition.
• Systematic variation of melt temperatures prior to cooling to crystallization temperatures.

Main Results:

• Pronounced melt memory effects were observed in poly(ethylene-co-octene) crystallization kinetics.
• The effect is temperature-dependent, occurring within a specific range of melt temperatures (T(m)l to T(m)h).
• The characteristic crystallization time varies systematically with pre-cooling melt temperature, indicating a first-order process.

Conclusions:

• Melt memory effects in poly(ethylene-co-octene) are attributed to variations in the characteristic time of a first-order crystallization process.
• The crystallization process involves the in-filling of crystallites into a pre-existing precursor structure.
• The findings provide insights into controlling polymer crystallization through thermal history manipulation.