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Flax unidirectional (UD) fabrics and polyamide 11 (PA11) are used to create a 100% bio-sourced composite. The fabrication process is hot press moulding. Different configurations are studied by varying process parameters and composite constituents. Three temperature values (190°C, 200°C and 210°C) are combined with three pressure levels (35, 65 and 100 bars). In addition, two types of flax fabric (A and B) are tested and two types of PA11 (in the form of powder or film) are used. The two forms of PA11 are characterized using differential scanning calorimetry and rheological methods. Ten different composites are then manufactured. They are compared by means of tensile tests and dynamic mechanical analysis (DMA). Results are correlated with microstructural study: measurements of porosity degree and scanning electron microscopic observations are also performed. Finally, an optimum configuration is determined: the composite flax B/PA11 film manufactured with a temperature value of 210°C and using gradual levels of pressure (25 bars during 2 min, 40 bars during 2 min and 65 bars until the end of cycle). This configuration leads to a Young’s modulus value of 36 GPa and a tensile strength of 174 MPa, with the highest storage modulus and the lowest damping factor values measured by DMA.

The successful formulation of two-part condensation-curing silicone materials via purely organic catalysis is here developed and investigated as fouling-release coating. Several non-toxic organic catalysts and their ‘onium’ salts were studied as potential purely organic catalysts on the silicone condensation reaction but also on the properties of the resulting cured resins. The trifluoroacetic acid was pointed suitable for the production of condensation-curing silicone coatings. To assess favorable fouling-release properties, multi-wall carbon nanotubes (0.05–0.2 wt-%) were added to the resin. Interestingly, the catalytic activity of the trifluoroacetic acid proved not affected by the presence of the nanocharge. The properties of the coatings prepared using 0.1 wt-% acid revealed constant degree of crosslinking independently of the carbon nanotubes loading and pronounced surface nanostructuring suitable for fouling release. This final property was tested against Ulva linza sporelings and revealed ...

A series of novel fluorinated amphiphilic stabilizers of different architectures (diblock, grafted, or palm tree copolymers) were successfully prepared by reversible addition–fragmentation chain transfer. The surfactant properties of these copolymers were first evidenced by measuring the interfacial tension at the H2O/trifluorotoluene (TFT) interface, and the results were correlated with their stabilizing efficiency in the dispersion polymerization of 2-hydroxyethyl methacrylate (HEMA) in trifluorotoluene. The effects of the architecture and concentration of the stabilizer on the morphology, size and stability of the obtained polyHEMA particles were investigated. Whatever the architecture of the stabilizer, conditions could be adapted to produce submicronic spherical poly(HEMA) particles with diameters around 300 nm and a quite narrow size distribution.

Poly(dimethylsiloxane) (PDMS)/organomodified montmorillonite (OMMT) nanocomposites have been prepared, characterised and the fouling-release properties of these materials have been studied through laboratory assays involving a representative soft-fouling species, the green alga, Ulva. The bulk mechanical properties of the polymer matrix have been slightly changed by the addition of OMMT, i.e., to a higher Young's modulus value. The surface properties of the nanocomposites were modified after immersion in water. Indeed, it appears that the surface topography, as observed with AFM, is affected by the presence of OMMT after immersion in water. The data indicate that the modified surface affects the fouling release behaviour of sporelings (young plants) of Ulva; percentage removal by hydrodynamic shear stress increases from 28% for the unfilled PDMS control to 78% for the 2 wt% filled coating.

Among the various issues pertaining to the use of composite polymeric materials based on nanoparticles, the dispersion of the nanofillers in the matrix and the nature of the fillerpolymer interface are central. In many cases, poor dispersion results in agglomeration or phase separation, leading to a dramatic loss of the materials properties. To overcome this problem, a number of strategies have been developed with various degrees of success. They usually come at a high price, due to the necessity of modifying the surface state of the filler. Here, we report on novel carbon nanotubes-reinforced poly(dimethyl)siloxane nanocomposites and surprisingly, for which the use of “self pure” multiwall carbon nanotubes, i.e., without any surface functionalization or specific surface treatment, turns out to be the most efficient approach to impart new key-properties to the silicone matrix. Viscometric, rheological and theoretical studies have been performed that demonstrate the remarkable potential of dispersing a very tiny amount of “self pure” carbon nanotubes in silicone, paving the way to unexpected applications, e.g., in the field of fire endurance. Very interestingly, only tiny amounts of MWCNTs are required: usually less than 0.5 wt %. Those properties all rely on the nature of the nanotube-silicone interface interactions, which are dominated by additive CH-p interactions between the methyl groups of the polymer and the nanotube surface. Polydimethylsiloxane (PDMS) is the most common silicone elastomer owing to its ease of fabrication and advantageous chemical/physical properties, such as low surface energy, low glass transition temperature and high chain mobility. [1] Currently, to compensate for their poor mechanical properties, silicone materials have to be reinforced by incorporation of particulate materials, silica being the most commonly used filler. To date, the in situ filling process, where silica is generated into the elastomeric matrix, is the most efficient way to fill PDMS materials. [2] However, this reinforcement still re

Polydimethylsiloxane/HTiNbO 5 nanocomposites were prepared through four different routes: melt intercalation of the pure mineral, melt intercalation of the organically modified mineral, grafting by a sol–gel process, and grafting by anionic ring-opening polymerization. The four nanocomposites were characterized using wide-angle X-ray scattering and rheometry, at different solid fractions. No exfoliated structure was observed, for any system prepared, but in situ polymerization techniques, especially the ionic polymerization process, were shown to lead to the more structured nanocomposites. This study mainly shows that PDMS master batch made of in situ synthesized systems is probably a well-suited route to achieve high performance silicon elastomer nanocomposites.

Several routes were used to achieve silicon nanocomposites. The first and second one are the melt intercalation of polydimethylsiloxane (PDMS), which is a mechanical blending of the polymer in the molten state with the untreated inorganic filler or intercalated nanoparticles. The last one is an in situ polymerization, which previously requires the intercalation of hexamethylcyclotrisiloxane (D 3 ) followed by a subsequent polymerization step. We used synthetic mineral oxide HTiNbO 5 as nanofiller. These systems were investigated by differential scanning calorimetry (DSC) and solid state NMR in order to better understand the relation between the nanocomposites dynamics, and crystallisation. The efficiency of grafting reactions was studied by 29 Si CP/MAS NMR. The nature of the interfacial interactions seems to play the major role. Indeed, the nanocomposites 1 and 2 for which only physical interactions are expected do not exhibit any Tg deviation whereas the nanocomposite 3, for which chemical grafting is achieved, increases strongly the Tg. Crystallization is more sensitive to density and strength of interfacial interactions which are maximum for the pristine filler.

The present work reports on the influence of the dispersion quality of multiwall carbon nanotubes (MWCNTs) in a silicone matrix on the marine fouling-release performance of the resulting nanocomposite coatings. A first set of coatings filled with different nanofiller contents was prepared by the dilution of a silicone/MWCNTs masterbatch within a hydrosilylation-curing polydimethylsiloxane resin. The fouling-release properties of the nanocomposite coatings were studied through laboratory assays with the marine alga (seaweed) Ulva, a common fouling species. As reported previously (see Ref. [19]), the addition of a small (0.05%) amount of carbon nanotubes substantially improves the fouling-release properties of the silicone matrix. This paper shows that this improvement is dependent on the amount of filler, with a maximum obtained with 0.1 wt% of multiwall carbon nanotubes (MWCNTs). The method of dispersion of carbon nanotubes in the silicone matrix is also shown to significantly (p = 0.05) influence the fouling-release properties of the coatings. Dispersing 0.1% MWCNTs using the masterbatch approach yielded coatings with circa 40% improved fouling-release properties over those where MWCNTs were dispersed directly in the polymeric matrix. This improvement is directly related to the state of nanofiller dispersion within the cross-linked silicone coating.

The objective of the present study is the introduction of well known and readily accessible analytical methods as FTIR, thermogravimetric (TGA) and evolved gas analysis (EGA) for quantitative determination of the degree of polymerization (DP) and degree of quaternization (DQ)/betainization (DB) of amino-based amphiphilic block copolymers. For this purpose a series of amphiphilic poly(dimethylsiloxane)-b-poly[2-{dimethylamino)ethyl methacrylate] (PDMS-b-DMAEMA) diblock copolymers with DP of the PDMAEMA-block ranging from 22 to 162 was synthesized by atom transfer radical polymerization and analyzed by 1H NMR, ATR-FTIR and TGA-co-EGA. The determined composition results have shown linear correlation between the FTIR or TGA and the 1H NMR data and equations allowing the quantitative calculation of PDMAEMA-block DP were found. The errors estimated by ATR-FTIR were less than 1.5%. Further, the PDMAEMA-block was quaternized (or betainized) with DQ (or DB) from 25 % to 100 % and analyzed by TGA-co-EGA. Again, a linear correlation between the quaternized (betainized) PDMAEMA-block mass fraction and the DQ (DB) degrees was obtained by 1H NMR.