Nanocomposite with oriented mechanical properties

Table 3. Mechanical Properties of Track-Etched Membranes and Nanocomposites with Oriented Polyelectrolyte Nanodomains...

However, when compared with pure copolymer, the highly stretched nanocomposite exhibited a higher amount of unoriented crystals, a lower degree of crystal orientation, and a higher amount of 7-crystals. This behavior indicated that polymer crystals in the filled nanocomposite experienced a reduced load, suggesting an effective load transfer from the matrix to MCNF. At elevated temperatures, the presence of MCNF resulted in a thermally stable physically cross-linked network, which facilitated strain-induced crystallization and led to a remarkable improvement in the mechanical properties. For example, the toughness of the 10 wt% nanocomposite was found to increase by a factor of 150 times at 55°C. Although nanofillers... 

The main reason for the recent popularity of nanotechnology is that the reduction of the dimensions of a material to nanosize leads to new specific properties [82]. It is crucial to understand the intrinsic mechanical properties of CNFs in order to incorporate them into polymer resins to fabricate CNFs-reinforced nanocomposites. Because of the structural complexity of CNFs derived from variations in inner and outer wall thickness, cone angle, orientation of graphite plane, and C-C bonds, determination of their mechanical properties had posted considerable difficulties. To date, direct measurement of tensile properties of CNFs is accessible only with the aid... 

Gleason and coworkers have demonstrated that the surface coating of carbon nanotubes (CNTs) by hot filament CVD of tetrafluoroethylene and by plasma enhanced CVD of MMA provide surface-modified CNTs having a stable/ superhydrophobic surface and good compatibility with PMMA, respectively [91, 92]. The superhydrophobic CNT indicated superior water repellency, whereby essentially spherical and micrometer-sized water droplets were suspended on top of the nanotube forest. The multiwall-CNT/PMMA nanocomposites were dispersed into PMMA via melt mixing. The orientation of CNT in the blend was achieved by melt drawing. The dispersed CNT in the blend indicated a significant effect on mechanical properties of the blend even at a 1% concentration of CNT. 

On the basis of the above analysis, the following discussion will focus on the influence of different processing factors on the mechanical properties of the PP homopolymer-PP co]X)l5rmer composite with nanocomposite as reinforcement. As a matter of convenience, the content of the oriented PP reinforcements filled with 1 wt% nano-Si02is fixed at 72.1 wt%. 

Cellulose is a fascinating biopolymer that has always been used in the production of textile fibers. Due to environmental concerns intense research has been conducted in the past decades in order to substitute traditional carbon or glass fibers used in the production of composites with eco-friendly cellulose fibers. The research in cellulose-based biocomposites is now focused on the concept of self-reinforced nanocomposites. In this sense all-cellulose composites have been investigated showing mechanical properties comparable or even better than those of traditional composites. Cellulose and its derivatives may also show liquid crystalline mesophases, which can be used to produce new and biomimetic materials with distinctive mechanical and optical properties. Most likely, enhanced mechanical properties will be obtained in all-cellulose nanocomposites by taking full advantage of the orientational order, when both the matrix and the fibers are in a liquid crystalline state. 

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