Cure kinetics and the final performance of styrene–butadiene–styrene block copolymer (SBS)/silica nanocomposites followed by vulcanization are analyzed. The results indicated that the presence of silica affects the curing reaction of SBS, and additional heating is required for complete vulcanization of SBS/silica nanocomposites due to their higher activation energy. The samples were characterized using scanning electron microscopy/energy dispersive X-ray spectroscopy, atomic force microscopy, and tensile test methods. The tensile strength, hardness, and wear resistance of SBS/silica nanocomposites show considerable increases by incorporating different silica nanoparticle contents in the SBS matrix; however, silica nanoparticles cause a decrease in modulus and elongation at break compared to cured neat SBS.
In this work, cure behaviour and cure kinetic parameters of unsaturated polyester (UP) resin containing Na-Montmorillonite (Cloisite 30B) is investigated. The state of nanoclay dispersion is analysed by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Addition of 1-5 wt-% nanoclay results in decreasing gel time, exothermic peak and increasing cure rate. Cure kinetic parameters are determined employing Borchardt-Daniels method. The modelling results also prove: decreased curing reaction starting temperature, higher reaction rate and higher conversion ratio. Besides decreased activation energy ratio and shorter curing cycle are also observed as the main results of incorporating Cloisite 30B to neat UP resin.
A linear diblock copolymer [Polystyrene-b-Poly(4-vinyl-pyridine)] (PS-b-P4VP) was successfully prepared through Atom Transfer Radical Polymerization (ATRP). This synthesis is performed in two successive steps: using the (1-bromoethyl) benzene as initiatorand and Hexamethyl tris [2(dimethylamino)ethyl] amine as ligands in a protic solvent. The first step of the synthesis allows the realization of block polystyrene having a terminal function; however, Bromine (Br) permits the grafting of the second successive block P4VP. RMN-1H demonstrates that the P4VP block has been grafted onto the PS block. The molecular weight of PS-b-P4VP is determined by size exclusion chromatography, and its thermal stability is examined by TGA. The surface and the thermodynamic properties of this copolymer are studied by inverse gas chromatography (IGC). The new Hamieh Model shows that the synthesized copolymer PS-P4VP has an amphoteric behavior with rather very basic character that is six times stronger than acidic character (in Lewis terms), reflected the presence of acidic and basic groups in the structure of the PS-P4VP copolymer, more particularly the presence of benzenic, methyl and vinylpyridine groups.
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