Matrix/fiber composites of

β

-form isotactic polypropylene (

i

PP) matrix and

α-i

PP or PA6 fibers were prepared by laminating technique under different preparation temperatures. The mechanical properties and interfacial morphologies of these composites were studied by tensile test

optical microscopy and scanning electron microscopy

respectively. The experimental results show that the tensile yield load and tensile modulus of

β-i

PP/PA6 matrix/fiber systems increased significantly at the expense of elongation at break. These mechanical properties show essentially no dependence on the sample preparation temperature. On the other hand

the mechanical properties of

i

PP matrix/fiber single polymer composites depend strongly on the sample preparation temperature. At low sample preparation temperature

e.g.

172 ℃

the solid

α-i

PP fiber induces

α-i

PP crystallization

leading to the formation of

α-i

PP transcrystalline layer around the fiber. This results in a remarkable increment of the tensile yield load and tensile modulus. The elongation at break is also much better than that of the

i

PP/PA6 matrix/fiber system. It reflects a better interfacial adhesion of the single polymer composite compared with the

i

PP/PA6 composite. At higher sample preparation temperature

e.g.

174 ℃ or 176 ℃

the partial surface melting of the oriented fiber allows interdiffusion of

i

PP molecular chains in the molten fiber and matrix melt. The penetration of matrix chains into the molten

i

PP fiber results in some

i

PP molecular chains being included partially in the recrystallized fiber and the induced

β

-transcrystalline layers. This kind of configuration leads to an improvement of interfacial adhesion between the fiber and matrix

which causes a simultaneous increase of the tensile yield load

tensile modulus and elongation at break of

β-i

PP.