抄録
The thermal conductivity and thermal expansion curves of glass fiber reinforced rigid polyurethane foam (PRU) were determined experimentally, and the interaction between matrix and fiber was examined to analyze the thermal expansion behaviour.
(1) The thermal conductivity of molded FRU in the thickness direction was independent of the glass fiber content (8.5 to 9.5 volume%), and the value was same as that of matrix PUF itself.
(2) The thermal expansion behaviours of FRU and PUF were essentially the same, but their behaviours were peculiar because the matrix had a foam structure.
(3) The thermal expansion coefficient increased with increasing apparent density of the matrix for FRU having the same volume content of glass fiber, and decreased with increasing volume content of glass fiber or with increasing fiber length for the matrix having the same density.
(4) Young's modulus was calculated by using the efficiency factor according to the theoretical equation of Shapery. The results agreed well with the experimentally measured tensile moduli. From this fact, it becomes apparent that the thermal expansion behaviour can be analyzed with the mechanism analogous to that of the mechanical tensile behaviour.
(5) The critical fiber length of glass fiber was calculated theoretically from the thermal expansion coefficient according to the method of Marom. The values obtained agreed approximately with the values calculated by using the interlaminar shear strength of FRU.
