Composites of polypropylene melt blended with synthesized silica nanoparticles

Sandwich panels were fabricated with nanoclay-filled polyurethane foams and glass fiber-reinforced polyamide and polypropylenes face sheets. Nanoclay-filled foam cores, with organophilic montmorill...

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Effect of nanofillers on low energy impact performance of sandwich structures with nanoreinforced polyurethane foam cores.

The use of copolymer and polymer blends widened the possibility of creating materials with multilayered architectures. Hierarchical polymer systems with a wide array of micro and nanostructures are generated by thermally induced phase separation (TIPS) in partially miscible polymer blends. Various parameters like the interaction between the polymers, concentration, solvent/non-solvent ratio, and quenching temperature have to be optimized to obtain these micro/nanophase structures. Alternatively, the addition of nanoparticles is another strategy to design materials with desired hetero-phase structures. The dynamics of the polymer nanocomposite depends on the statistical ordering of polymers around the nanoparticle, which is dependent on the shape of the nanoparticle. The entropic loss due to deformation of polymer chains, like the repulsive interactions due to coiling and the attractive interactions in the case of swelling has been highlighted in this perspective article. The dissipative particle dynamics has been discussed and is correlated with the molecular dynamics simulation in the case of polymer blends. The Cahn-Hillard-Cook model on variedly shaped immobile fillers has shown difference in the propagation of the composition wave. The nanoparticle shape has a contributing effect on the polymer particle interaction, which can change the miscibility window in the case of these phase separating polymer blends. Quantitative information on the effect of spherical particles on the demixing temperature is well established and further modified to explain the percolation of rod shaped particles in the polymer blends. These models correlate well with the experimental observations in context to the dynamics induced by the nanoparticle in the demixing behavior of the polymer blend. The miscibility of the LCST polymer blend depends on the enthalpic factors like the specific interaction between the components, and the solubility product and the entropic losses occurring due to the formation of any favorable interactions. Hence, it is essential to assess the entropic and enthalpic interactions induced by the nanoparticles independently. The addition of nanoparticles creates heterogeneity in the polymer phase it is localized. This can be observed as an alteration in the relaxation behavior of the polymer. This changes the demixing behavior and the interaction parameter between the polymers. The compositional changes induced due to the incorporation of nanoparticles are also attributed as a reason for the altered demixing temperature. The particle shape anisotropy causes a direction dependent depletion, which changes the phase behavior of the blend. The polymer-grafted nanoparticles with varying grafting density show tremendous variation in the miscibility of the blend. The stretching of the polymer chains grafted on the nanoparticles causes an entropy penalty in the polymer blend. A comparative study on the different shaped particles is not available up to date for understanding these aspects. Hence, we have juxtaposed the various computational studies on nanoparticle dynamics, the shape effect of NPs on homopolymers and also the cases of various polymer blends without nanoparticles to sketch a complete picture on the effect of various particles on the miscibility of LCST blends.

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Nanoparticle induced miscibility in LCST polymer blends: critically assessing the enthalpic and entropic effects

The Influence of Multiscale Fillers Reinforcement into Impact Resistance and Energy Absorption Properties of Polyamide 6 and Polypropylene Nanocomposite Structures

Novel pentafunctional epoxy resin, mainly based on pentaglycidyl ether pentabisphenol A of phosphorus (PGEPBAP) has been synthesized and characterized through different spectroscopic methods (FTIR, 1H NMR, 13C NMR and 31P NMR) Moreover, the analysis of the viscosity of (PGEPBAP/Methanol) system was determined by using viscosimeter VB-1423 of the Ubbelohde type Furthermore, the analysis of the rheological properties of the matrix PGEPBAP and their (PGEPBAP/MDA/PN) elaborated composite was performed according the RHM01-RD HAAKE rheometer In addition, the morphology of different (PGEPBAP/MDA/PN) prepared composite was determined by using the polarizing optical microscope

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Investigation of structure and rheological behavior of a new epoxy polymer pentaglycidyl ether pentabisphenol A of phosphorus and of its composite with natural phosphate

BACKGROUND: A new processing method for polypropylene-untreated precipitated silica (PP/SiO2) Composites based on the incorporation of a second polymer phase of polyamide 6 (PA6) is presented and compared with a more classic one making use of compatibilizers: glycerol monostearate (GMS), ethylene acrylic acid ionomer (IAAZE) and maleic anhydride grafted polypropylene (NIA-graft-PP). The effects of processing methods and conditions on the microstructure and properties Of PP/SiO2 Composites prepared by melt compounding are investigated with a view to reduce the size of aggregates of silica from the micrometre to the nanometre scale and to improve the link between filler and matrix. RESULTS: On the one hand, the presence of GMS and LAAZE compatibilizers significantly improves the dispersion of the silica particles. On the other hand, when using a PA6 second phase, the SiO2 particles are dispersed in PA6 nodules. Within these nodules, SiO2 appears dispersed at the nanoscale but with larger particles ('aggregates') of about 200 nm. Significant improvements in tensile strength and modulus are obtained using MA-graft-PP compatibilizer. An increase in impact strength is observed in the case of GMS compatibilizer. Thermal parameters indicate also that silica plays the role of nucleation agent for PP matrix. All improvements (tensile strength, modulus and impact strength) increase with the addition of compatibilized PA6 second phase. CONCLUSION: By the incorporation of masterbatch of silica in PA6 as a second polymer polar phase, a successful new production method for PP/SiO2 nanocomposites has been developed. Interestingly, this method does not require any (expensive) pre-treatment of the silica. (c) 2007 Society of Chemical Industry.

Effect of compatibilizer on the dispersion of untreated silica in a polypropylene matrix

In this study, polypropylene/silica (PP/SiO2) composites containing 5 wt% of untreated precipitated silica were compatibilized with different coupling agents like maleic anhydride-grafted polypropylene, glycerol monostearate (GMS), ethylene acrylic acid zinc ionomer and a second polymer phase of polyamide 6 (PA6). The composites were melt-compounded by two different processes: either by direct melt mixing or by dilution of a masterbatch (two-step mixing) in a twin screw extruder using both injected water and high shear stress as a new processing method. The various samples were characterized by Fourier transform infrared spectroscopy (FTIR), thermal analysis, morphological and rheological measurements in order to determine the compatibilizers effects between the matrix and the untreated filler. Hence, atomic force microscopy observations revealed that the untreated silica was dispersed more homogeneously in the presence of PA6 and GMS compatibilizers when water injection is used as one. However, the roughness values are lower in this case. FTIR analysis confirmed the existence of interfacial interactions between OH groups of SiO2 and polar groups of compatibilizers. The storage (G′), loss moduli (G″) and the dynamic viscosity of PP/SiO2 composites increased with the incorporation of PA6. Furthermore, the thermal stability of the compatibilized PP/SiO2 compounds enhanced significantly in the presence of water. An improvement in decomposition temperature of about 50 °C was obtained compared to uncoupled composites.

Celine Vanzeveren

Papers

Effect of compatibilizer on the dispersion of untreated silica in a polypropylene matrix

Rheological properties and thermal stability of compatibilized polypropylene/untreated silica composites prepared by water injection extrusion process