|Budget Amount *help
¥1,700,000 (Direct Cost : ¥1,700,000)
Fiscal Year 1996 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1995 : ¥1,100,000 (Direct Cost : ¥1,100,000)
1.Copolyesters of PET (polyethylene terephthalate) and PEN (polyethylene-2,6-naphthalene dicarboxylate) with composition of PET/PEN=100/0,95/5,90/10,85/15,70/30,50/50,30/70,10/90,0/100 were prepared. The mechanical propertiesof uniaxial stretching films were examined at 83 K and 296 K.PET/PEN=90/10 copolymer film possessed especially excellent cryogenic properties. It was found to withstand elongations in excess of 40% at stress levels about 400 MPa at 83 K for 5 times uniaxial stretching PET/PEN=90/10 film.
DSC (Differential Scanning Calorimeter) curves of samples before and after tensile test at 83 K were compared for 5 times uniaxial stretching PET/PEN=90/10 film. After tensile test at 83 K,the peak position of cold-crystallization shifted and the peak area between the curve and a baseline decreased, indicating that crystallization is allowed to take place during tensile test at 83 K.Dielectric loss tangent was measured in the temperature range from 18 K to the glass transition temperature. The increase of loss level below 100 K in addition to the pronounced relaxation maximum at around 230 K of PET and its Copolymers was observed with dependence on the morphology. On the basis of the results obtained, relationship between the structure of polymers and their cryogenic properties will be discussed.
2.The mechanical and dielectric properties of several polyimide films (Upilex-S and-R (Ube Industries), Kapton (duPont), and Regulus (Mitsui Toatsu Chemicals) were measured. All samples had prominent mechanical properties at cryogenic temperatures. This is partly because, even when their segmental motions are frozen out at cryogenic temperatures, these polymers could undergo deformation, and hence could still flexible by changing the main chain bond angles. Such polymers may, therefore, include those whose main chains are composed of oxygen (ether linkage) or various heterocyclic linkages.