Graphene should give a diffraction peak at 26°, characteristic of graphite that is usually present because the graphene will not be completely exfoliate; there may be another lower angle graphite peak if the graphite has been intercalated, hence expanding the lattice spacing.

You should obtain a characteristic diffraction pattern for the matrix polymer, superimposed upon the graphite peak(s). A powder or small pieces should give all peaks for the polymer since the pieces are likely randomly exposed to the X-ray beam and the type of camera being used (powder camera for instance). Otherwise, for oriented specimens only the diffractions peaks corresponding to the relative direction of specimen and beam will be detected.

Since you have observed no diffraction peaks the polymer may be amorphous. Annealing above glass transition temperature may result in crystallisation if the polymer is one that can form crystals. Spectroscopy including UV and Raman are sensitive to chemical structures, but not necessarily crystallinity. Differential scanning calorimetry (DSC) is a complementary technique for detecting crystallinity.

Apart from Robert's answer, I think that if the morphology of your graphene is small pieces, it may give very weak peak according to Scherrer's equation. Which means that your material is not ordered in long range but only in short range.

Ok Thanks Robert A. Shanks and Weiran Zheng

                                                             I think I get your point.....Thanks a lot