Temperature Stage used for Biodegradable and Biocompatible Polymer Research at the CNR

Linkam Scientific Instruments report on the use of their popular THMS600 stage for polymer research at the Institute of Chemistry and Technology of Polymers (CNR), Italy.

A group of scientists from the CNR is investigating the melting kinetics of poly(3-hydroxybutyrate) (PHB), a natural thermoplastic polymer with mechanical properties comparable to synthetic polymers.

The Linkam THMS600 stage fitted to a Zeiss polarised light microscope was used to study PHB. Initially samples were heated above the melting point, at 185°C, 190°C, 192°C, or 195°C, in order to erase previous thermal and mechanical history followed by cooling at 5°C/min after 3 minutes at the high temperature. It was observed that a high number of spherulites develop when the polymer is melted at 185°C for 3 minutes but contrasted to very low spherulite development at >192-193°C. It was concluded that melting below 192°C does not result in complete melting of the crystals, and so the nucleation density is very high in the subsequent crystallisation step. It is theorised that the partially unmelted polymer retains a large memory of previous crystal order, and so the residual chain portions act as nucleation centres and result in a high nucleation density and a small spherulite size.

The team has found that some of the effects reported in literature as caused by degradation are actually related to non-completely melted structures. They found the chain degradation attained upon exposure at high temperatures has much lesser influence on crystallisation kinetics than incomplete melting, with some effects detectable on the spherulitic morphology and on the final degree of crystallinity.

Dott.ssa Maria Laura Di Lorenzo, one of the scientists working on the PHB research, added "the best feature of our Linkam stage is the fast heating/cooling rates, not accessible with other stages that we have in our laboratory."

The Linkam THMS600 stage is one of the most widely used microscope stages on the market and is used in many applications where high heating/freezing rates and 0.1°C accuracy are needed.