  Shearing test is carried out on the joint which bonded under different pre
curing processes with two component adhesives of acrylic and epoxy resin
respectively. The pre curing strength is obtained, which used to analyze the
relationship between the pre curing strength and time. The hoods with different
pre curing strength are baking with high temperature. The deformation of
different areas of the hood is measured with gauges, and the deformation
characteristics of the hood after baking are acquired with comparative
analysis. Combining the components of two component adhesives and DSC test, the
pre curing mechanism of different adhesive systems are studied. Therefore, the
key factors and regular pattern of the deformation for the hood are obtained.
The results indicate that, finally deformation of the hood after high
temperature baking varies with the pre curing time. The key of the pre curing
time of acrylic adhesives lies in the chain initiation stage of the free
radical polymerization reaction. Due to the influence of the chemical
properties of methyl acrylate and its initiator, the pre curing reaction
induced by free radical polymerization is very fast. The shear strength of this
joint can reach to 3.67 MPa with a pre curing time of 1 h, which quickly
achieving the pre cure strength required for deformation control. For epoxy
adhesives, the rate determining step in pre curing process is the
esterification reaction. Due to the influence of the structure of carboxylic
acid, the esterification process is relatively long. Shear strength of this
joint can only reach 0.87 MPa after pre curing for 4 h without external
heating.
