A method using a combination of ball milling, acid hydrolysis, and ultrasound was developed to obtain a high yield of cellulose nanofibers from flax fibers and microcrystalline cellulose (MCC). Poly(vinyl alcohol) (PVA) nanocomposites were prepared with these additives by a solution-casting technique. The cellulose nanofibers and nanocomposite films that were produced were characterized with Fourier transform infrared spectrometry, Xray diffraction, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy. Nanofibers derived from MCC were on average approximately 8 nm in diameter and 111 nm in length. The diameter of the cellulose nanofibers produced from flax fibers was approximately 9 nm, and the length was 141 nm. A significant enhancement of the thermal and mechanical properties was achieved with a small addition of cellulose nanofibers to the polymer matrix. Interestingly, the flax nanofibers had the same reinforcing effects as MCC nanofibers in the matrix. Dynamic mechanical analysis results indicated that the use of cellulose nanofibers (acid hydrolysis) induced a mechanical percolation phenomenon leading to outstanding and unusual mechanical properties through the formation of a rigid filler network in the PVA matrix. X-ray diffraction showed that there was no significant change in the crystallinity of the PVA matrix with the incorporation of cellulose nanofibers.

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Conductive plastics are new generation functional materials with potential application in electronics, space and aviation industries. Polypropylene (PP) and polyethylene (PE) being most common, widely available and cheapest thermoplastic, if made conductive, can be revolutionary in the field of engineering thermoplastics. The article deals with the fabrication of electrically conductive PP and PE for electromagnetic interference/ radio frequency (EMI/RF) shielding applications and protection against electrostatic discharge (ESD). It reviews different fillers used by researchers to fabricate conductive PP and PE, several factors that affect the electrical conductivity of thermoplastic composites and various processing methods that can be adopted to prepare such composites. It exhaustively covers the preparation of such conductive composites, the processing methods involved therein, and the electrical properties of the end material. Emphasis has been given to comprehend the percolation threshold and means to reduce the latter in order to achieve high electrical conductivity in PP-and PE-based composites at relatively low filler loading. POLYM. COMPOS., 35:900-914,

A procedure is described for preparing polyamide-6 (PA-6) reinforced with cellulose nanofibres. The cellulose nanofibres were obtained from flax and microcrystalline cellulose (MCC) using combinations of acid hydrolysis, ball milling and ultrasound, then characterised by transmission electron microscopy (TEM) in order to determine their size and geometry. The nanofibres produced from the different feedstock sources were of a similar order with lengths ranging from 21 to 300 nm and diameters between 2 and 22 nm. PA-6 nanocomposite films were subsequently prepared from these nanofibres using a solution casting technique. Their chemical and physical structure was analysed using Fourier transform infrared analysis (FTIR) and TEM. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were also applied to compare their thermal properties with unfilled polymer. Dynamic mechanical thermal analysis and tensile measurements demonstrated a significant enhancement in mechanical properties was possible with a low addition of cellulose nanofibres to the polymer matrix.