Thermal expansion control employing platelet fillers

摘要

Bilayer platelet fillers are employed to compensate for a positive coefficient of thermal expansion (CTE) of an embedding polymeric material, or even to provide a composite structure having a negative CTE to eliminate or alleviate thermomechanical stress and/or delamination during thermal cycling. A bilayer platelet includes two joined layers having different CTEs. The CTE mismatch induces bending of the bilayer platelets, thereby causing cavities at temperatures lower than the joining temperature at which the bilayers are joined. The decrease in the volume of the polymeric material and the bilayer platelets at low temperatures is compensated by an accompanying increase in the volume of the cavities so that the composite structure has a temperature independent volume, a low net CTE, or even a negative CTE.

主权项

1. A composite structure comprising a polymeric matrix and a bilayer platelet embedded therein, wherein said bilayer platelet comprises a pair of material layers joined to each other and having mismatched coefficients of thermal expansion (CTEs), wherein at least one cavity is present between said bilayer platelet and a surface of said polymeric matrix in a temperature range within which surfaces of said bilayer platelet have a non-zero curvature, wherein boundary surfaces of one of said at least one cavity consist of at least one surface of said polymeric matrix and at least one surface of said bilayer platelet, wherein a plurality of cavities is present between said bilayer platelet and surfaces of said polymeric matrix in said temperature range.