Abstract: This research proposed a novel combined glass fiber-reinforced microcellular foaming and double-sided in-mold decoration injection molding （GF-D-MIM/IMD） process. In this process， the mechanical properties of products were enhanced through adding glass fiber-reinforced （GF） matrix into polymer substrate to enhance， and the asymmetric temperature field on both sides of the mold cavity was suppressed and eliminated through applying two decorative films on both sides of plastic parts during single-sided IMD/MIM process（S-IMD/MIM）. This reduced the uneven bubble distribution and the warpage deformation of the molded parts. Taking the tensile test sample as an example， the mechanisms of bubble radius and quantity density were investigated and analyzed. Furthermore， the effects of double-sided decorative films and fiber contents on the warpage deformation and mechanical properties were investigated by using the numerical simulation method through GF with different fiber contents， which were added separately into polymer matrix during the D-MIM/IMD and S-IMD/MIM processes. The result indicated that compared to S-MIM/IMD， the double-sided films in GF-D-MIM/IMD process could balance the asymmetric temperature field effectively. When the fiber content was 20 wt%， the average bubble radius was the smallest， and the average quantity density was the largest in the test sample. Moreover， the tensile modulus and shear modulus of the products increased exponentially with an increase in the fiber content， and their Poisson’s ratio presented a decrease at first and then tended to increase.

Key words: microcellular foaming, in-mold decoration, bubble structure, warpage, mechanical performance