Microfibrillar reinforced composites - the role of the chemical interactions at the fibril - matrix interface

The preparation, structure and some of the properties of microfibrillar reinforced composites (MFC) based on polyamide-6 (PA6) as a polymer matrix and poly(ethylene terephthalate) (PET) in the form of reinforcing microfibrils are briefly discussed. It is demonstrated that the PA6-PET MFC displays comparable or even better mechanical properties than a conventional composite consisting of short glass fibers in a PA6 matrix. This effect is attributed to the interface between the PA6 polymer matrix and the PET microfibrils resulting in the formation of a new phase - a PET-PA6 copolymer which plays the role of a selfcompatibilizer. The progress of the chemical interactions between PET and PA6 amorphous phases leads ultimately to the involvement of the entire amount of PA6 into a block copolymer, thus changing the orginal homopolymeric PA6 matrix into a copolymeric PET-PA6 one. In such a way it is possible to overcome the immiscibility of the MFC components and to obtain control over mechanical properties of the PA6-PET MCF.