Physical aging behavior of a series of biodegradable polymers as a function of the pendent-chain length

The physical aging behavior of a series of tyrosine-containing polyarylates was investigated as a function of the length of the alkyl pendent chain. The experiments were performed in a differential scanning calorimeter (DSC) at corresponding aging temperatures. It was found that the physical aging efficiency was strongly affected by small changes in the length of the pendent chain (2, 6, or 8 methylene units). For similar cooling rates from above T/sub g/ to below T/sub g/ and identical aging times, the enthalpy relaxation decreased with the length of the pendent chain. A free volume based explanation is suggested.<
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