X-ray powder diffraction analyses were carried out over polylactide (PLA)/graphene nanocomposites, prepared by a facile and low-cost method of solution blending of PLA with liquid-phase exfoliated graphene using chloroform as a mutual solvent [27]. The dispersion of graphene in a PLA matrix has been examined by physical methods as SEM, XRD and TEM. The authors reported that the XRD pattern of PLA-based nanocomposites loaded with 0.1 wt% graphene sheets (GSs) was almost the same as that of pure PLA, in which two characteristic diffraction peaks are shown at 16.3 and 18.7\({}^{\circ}\), corresponding to (200)/(110) and (203) planes of crystalline PLA, respectively. The diffraction peak at 26\({}^{\circ}\) corresponding to graphite layer structure (002) was not observed in GSs due to the exfoliation. The scattering intensity profile did not reveal the presence of the diffraction peak of graphite, suggesting that the GSs do not aggregate in a PLA matrix. As suggested by some authors, this result indicates that the dispersion of GSs in a PLA matrix is close to single-sheet level. In another paper [28], [PERSON] et al. made research over the diameter dependence of interwall separation and strain in multiwalled carbon nanotubes probed by X-ray diffraction and Raman scattering studies. The authors did a systematic study on the diameter dependent spectral features in X-ray diffraction (XRD) and Raman scattering studies of multiwalled carbon nanotubes (MWCNTs) of various diameters in the range 5\(-\)100 nm. Analysis of the XRD patterns showed an exponential decrease in d\({}_{002}\) interlayer spacing with increasing tube diameter, in close agreement with the HRTEM results. Analysis of Raman and XRD data disclosed that the lowest diameter (7 nm) MWCNTs have features similar to those of the single walled nanotubes, while the spectral features are distinctly different for higher diameter MWCNTs. Relationships between structure and properties of nanocomposite materials can be made through a combination of structural investigations (such as Raman spectroscopy and X-ray diffraction) and mechanical tests in order to have better understanding of these nanocomposites. The effects of increasing filler content on the macro-mechanical properties of polymer nanocomposites can be investigated through tensile, flexural or impact tests. Some previous results for mechanical properties of PLA reinforced with carbon nanostructures as graphene [29; 30], carbon nanotubes [31] and both nanofillers [32] have been reported in the literature. The incorporation of carbon fillers in a polymer matrix is expected to improve the mechanical properties, especially when carbon nanotubes are used as a reinforcing material [33]. The aim of the present study was to estimate the influence of two different carbon nanofillers and the relevant loading amount on the structure and homogeneity of PLA-based nanocomposites. Another challenge was to elucidate the dispersion degree of both carbon nanofillers at all composites loadings, as well as to study the effect of GNP and MWCNTs on the crystal structure of PLA (at high filler contents). The novelty in this study is related to an important detail in the preparation method consisting of preliminary grinding of PLA and then using PLA as a powder during melt mixing of the polymer with the carbon nanofiller.