材料をその使用目的に応じて的確に選択するには，その構造ならびに熱物性が重要な意味を持つ。圧力・体積・温度制御熱容量測定（scanning transitiometry）によって得られる相図は，温度，圧力，圧力媒体などの様々な条件下における材料選択を行うための基礎データとして有用である。Scanning transitiometryでは，一定温度での圧力走査（PCSC）ならびに一定圧力での温度走査（TCSC）によって，転移エンタルピーと転移体積を測定することが可能である。さらに様々な気体を圧力媒体として利用することで，熱物性データに加えて高分子－気体間相互作用に関する情報を得ることができる。二酸化炭素を圧力媒体として用いた場合の熱物性に対する圧力依存性を，原油輸送の安全性に関係する二種類の結晶性高分子（中密度ポリエチレン，ポリフッ化ビニリデン）のPCSC測定による体積膨張係数の評価と，TCSC測定による液晶型両親媒性ブロック共重合体の等方性転移を例に解説した。
Materials selection is usually made according to their thermophysical and structural properties. To provide a useful guide to the utilization of materials in a given set of conditions (temperature T, pressure P and pressurizing conditions), PVT-Controlled scanning calorimetry named scanning transitiometry permits to well document phase diagrams. The type and extent of {polymer/gas} interactions as well as thermophysical properties are obtained from thermal and mechanical measurements resulting from the methodology controlling precisely the temperature and pressure. Scanning transitiometry permits to scan one of the independent variables (P, V, or T) while the other independent variable is kept constant. Simultaneous change of the dependent variable is recorded together with the associated thermal effect. The effect of pressure on the thermophysical properties, especially using carbon dioxide as a pressurizing fluid, is investigated along two types of runs. Pressure-Controlled Scanning Calorimetry (PCSC) run is employed to determine the global cubic thermal expansion coefficients‡ of semicrystalline polymers in interaction with a fluid. Temperature-Controlled Scanning Calorimetry (TCSC) run is employed to investigate the isotropic transitions of amphiphilic liquid crystalline di-block copolymers under a pressurizing fluid. These polymers play an essential role as regards the safety of transport of petroleum products and are promising candidates as templates for microelectronics and biotechnology.
