To improve the interfacial adhesive strength between cellular matrix and filler in rigid polyurethane foam, lower viscous TDI was added to the MDI as a cellular matrix. Compressive properties of polyurethane foam were investigated varing MDI/TDI blending ratio and mica content. The variation of MDI/TDI ratio was 10/0, 8/2, 5/5, 2/8 and 0/10, and the range of mica content was 5∼20%. The effects of blending ratio on the compressive properties of polyurethane foams were investigated by combining Pada wer & Beecher''s and Rusch''s equations : the former equation could be applied to the matrix filled with discontinuous platelet filler and the latter generally to the foams. In case of blending MDI with TDI, both compressive modulus and compressive strength of unreinforced foam were found to increase with the increase in MDI content. When mica flake was filled, however, the compressive modulus and strength increased with increasing TDI content as the mica content was in the range of 10∼20%. It was found that cell structure of polyurethane foam was gradually changed into open cell with the increase in mica and TDI content. A tendency to form this open cell, however, showed to be relaxed by increasing TDI content when mica was filled in the range of 10∼20% in the reinforced foam.

경질 polyurethane foam의 cellular matrix와 보강제인 mica-flake의 계면접착력을 향상시키기 위하여 기재인 MDI에 점도가 낮은 TDI를 혼합사용하였다. MDI/TDI의 혼합비를 10/0, 8/2, 5/5, 2/8 및 0/10의 5가지로 변화시키고, mica의 함량을 5∼20%까지 충전시켜 혼합비와 충전재 함량에 따른 압축특성을 조사하였다. 불연속 판상충전재를 matrix안에 충전시킬 때의 Padawer & Beecher식을 foam에 대한 Rusch식에 복합한 식을 이용하여 압축 탄성율을 비교하고 압축강도는 일반적인 식을 이용하였다. MDI와 TDI를 혼합한 무충전 foam의 경우에는 MDI의 혼합량이 증가할수록 압축탄성율과 압축강도가 모두 크게 나타났다. 그러나 mica를 충전시킨 경우에는 mica 함량이 10%∼20%에서부터 TDI의 혼합량이 많을수록 open cell화되나, mica 충전시 TDI혼합량의 증가로 open cell 화되는 경향을 완화시킬 수 있었다.