1,720,985 research outputs found
Hydrophobation of Silica Surface by Silylation with New Organo-Silanes Bearing a Polybutadiene Oligomer Tail
No full textTo enhance dispersion of silica into styrene-butadiene emulsion copolymer (e-SBR), used in tyres production, two new modifiers, characterized by 3-mercaptopro pyltrimethoxysilane grafted onto polybutadiene oligomers of 5900 (sb1) and 5000 (sb3), were used. Silica was modified with several degrees of the two new silanes. Thermodynamic surface properties of the modified silicas were estimated by inverse gas chromatography as a function of the grafting degree of sb1 and sb3. e-SBR/silica compounds, with silica pre-modified and in situ modified during the mixing, were prepared and characterized using vulcanization tests, dynamicmechanical analysis, and morphological observations by TEM. At degree of silylation lower than 10 wt%, the method of pre-modification allows a better dispersion of the silica within the elastomeric matrix and the best results were obtained using sb3. In particular, the lowest Payne effect, similar to that of a sample containing silica modified with bis-triethoxysilylpropyltetrasulfide, usually used in tyre production, was found for the sample containing silica grafted with about 10 wt% of sb
Oxygen and water vapor barrier properties of MMT nanocomposites from low density polyethylene or EPM with grafted succinic groups
No full textLDPE, EPM and their derivatives containing a moderate amount (0.08–1.8 by mol) ofdiethylsuccinate or succinic anhydryde groups were used as
matrices in blending with different amount of organophilic montmorillonites and the resulting composite morphology and structure (by XRD, SEM,TEM microscopy, DSC analysis and selective solvent extraction) were studied with reference to the polar groups/MMT ratio. Exfoliated, intercalated and mixed morphologies were achieved. High concentrations ofpolar groups grafted to the polyolefin and montmorillonite loading not larger than 5% wt were favourable for obtaining high exfoliation degree. Particularly in the exfoliated MMT composite LDPE had lower crystallinity degree, while EPM showed increased glass transition temperature and reduced solubility in hot toluene. Moreover, oxygen and water vapor barrier property improvement was observed in films where MMT exhibits either exfoliated or intercalated morphologies. Strong interactions with the montmorillonite particle surface through the polar groups grafted to the polyolefin seems to be the basic effect responsible for the morphology and peculiar properties. A model based on the reduced mobility ofthe polymer located near the particle surface or inside the MMT gallery (confined phase) was proposed to explain the observed oxygen permeability reduction, the Tg increase and solubility ofpoly(ethylene-ran-propylene)/MMT nanocomposites
Morphology and viscoelastic behaviour of silica filled styrene/butadiene random copolymer
No full textBiobased Janus molecule for the facile preparation of water solutions of few layer graphene sheets
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Valorizzazione di fibre di canapa non tessili per la preparazione di compositi a base di poliestere biodegradabile
No full textPyrolysis of bulk molding compound: Mechanisms, products characterization, and recovery potential
No full textThermosetting composite materials pose challenges for recycling due to their complex composition and crosslinked structure. Moreover, energy recovery is hindered by the low calorific value of highly filled and flame-retarded composites. This study focuses on Bulk Molding Compound (BMC), a thermosetting composite based on Unsaturated Polyester Resin, reinforced with glass fibers, and using Aluminum Hydroxide as a flame retardant. Thermal degradation mechanisms of BMC were investigated using Thermogravimetric Analysis coupled with Fourier Transform Infrared Spectroscopy. A lab-scale pyrolysis test was also conducted to explore the recovery and potential applications of pyrolysis products. The pyrolysis process yielded oil (31 % by weight), gas (10 %), and solid residue (59 %). The oil phase contained a notable concentration of styrene (more than 40 %). Analysis of the pyrolysis gas revealed a composition primarily consisting of carbon dioxide, carbon monoxide, hydrogen, and lower hydrocarbons, with a Gross Calorific Value of 7.5 MJ/m3. Additionally, the solid residue obtained from pyrolysis presented opportunities for closed-loop recycling as filler in BMC, and as aggregate in the construction sector. The findings underscore pyrolysis as a promising approach for BMC waste management, offering opportunities for resource recovery
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