On the minimum of Poisson's ratio in polymers
The calculation ofPoisson's ratio from the complexYoung's modulus and the complex shear modulus of polyvinylchloride as function of the temperature through the entire glass transition leads to curves with comparatively deep minima. It is shown that the shape of thePoisson's ratio curve depends on the rate of temperature change during the measurements. No minima were found in direct measurements ofPoisson's ratio.
Application of quartz crystal microbalance (QCM) sensors for odor sensing has been an important research topic. Proper performance of odor sensing systems with QCM sensors requires good discrimination among odor samples. Recently we have been studying pegylated lipopolymers - composed of lipid and poly(ethylene glycol). (PEG) The materials allowed for very good discrimination among odorants of different functional groups. Here we study lipopolymers with various molecular weight of PEG moiety. Our results indicate that the PEG chain length is an important factor influencing lipopolymer's sensing properties.