Application of Metal-Organic Framework as Reactive Filler in Bisphenol-A-Based High-Temperature Thermosets

Excellent thermoset monomers, bisphenol-A-based biscyanate ester (BADCy) and bispropargyl ether (BPEBPA), are synthesized and thermally cured to high-temperature thermosetting polymers. The nanoporous aluminum fumarate (Al_FA_A), an interesting Metal-Organic Framework (MOF), is synthesized in an eco-friendly manner and used as a reactive nanoparticle filler. The interaction of fumarate π bonds (trans -CH=CH-) in MOF with the reactive end functional groups (-O-C ≡ N) in cyanate ester (CE) and (-CH2-C ≡ CH) in bispropargyl (BP) ethers is focused in these hybrid nanocomposites. The % decrease in enthalpy of curing in the organic and the inorganic blends (~60% for CE and ~ 10% for BP) indicates the interaction exciting between the MOF and the organic component. The addition of the aluminum fumarate MOF increases the glass transition temperature of the polymers. The amount of heat released for every increase in 1°C during the temperature window of curing (ΔHc/TE-TS) of the neat BADCy resin is approximately 2.4 times higher than the blend (BADCy+Al_FA_A). But BPEBPA shows only a 1% higher temperature curing window compared to its blend with MOF. The metal hotspots present in the hybrid nanocomposites may be the reason for the decrease in the thermal stability, and the % char residue is noted at 700°C. The TG-FTIR studies are done to predict the gaseous products (CO2) evolved during thermal degradation

Green composite material made from Typha latifolia fibres bonded with an epoxidized linseed oil/tall oil-based polyamide binder system

Here, we report the mechanical and water sorption properties of a green composite based on Typha latifolia fibres. The composite was prepared either completely binder-less or bonded with 10% (w/w) of a bio-based resin which was a mixture of an epoxidized linseed oil and a tall-oil based polyamide. The flexural modulus of elasticity, the flexural strength and the water absorption of hot pressed Typha panels were measured and the influence of pressing time and panel density on these properties was investigated. The cure kinetics of the biobased resin was analyzed by differential scanning calorimetry (DSC) in combination with the iso-conversional kinetic analysis method of Vyazovkin to derive the curing conditions required for achieving completely cured resin. For the binderless Typha panels the best technological properties were achieved for panels with high density. By adding 10% of the binder resin the flexural strength and especially the water absorption were improved significantly

Influence of thermo-analytical and rheological properties of an epoxypowder coating resin on the quality of coatings on medium densityfibreboards (MDF) using in-mould technology

Powder coating of engineered wood panels such as medium density fibreboards (MDF) is gaining industrial interest due to ecological and economic advantages of powder coating technology. For transferring powder coating technology to temperature-sensitive substrates like MDF, a thorough understanding of the melting, flowing and curing behaviour of the used low-bake resins is required. In the present study, thermo-analysis in combination with iso-conversional kinetic data analysis as well as rheometry is applied to characterise the properties of an epoxy-based powder coating. Neat resin and cured powder coating films are examined in order to define an ideal production window within which the resin is preferably applied and processed to yield satisfactory surface performance on the one hand and without exposing the carrier MDF too high a temperature load on the other hand to prevent the panel from deteriorating in mechanical strength. In order to produce powder coated films of high surface gloss – a feature that has not yet successfully been realized on MDF with powder coatings – a new curing technology, in-mould surface finishing, has been applied

Microfibrillated Lignocellulose Enables the Suspension-Polymerisation of Unsaturated Polyester Resin for Novel Composite Applications

A new route towards embedding fibrillated cellulose in a non-polar thermoset matrix without any use of organic solvent or chemical surface modification is presented. It is shown that microfibrillated lignocellulose made from cellulose with high residual lignin content is capable of stabilising an emulsion of unsaturated polyester resin in water due to its amphiphilic surface-chemical character. Upon polymerisation of the resin, thermoset microspheres embedded in a microfibrillated cellulose network are formed. The porous network structure persists after conventional drying in an oven, yielding a mechanically stable porous material. In an application experiment, the porous material was milled into a fine powder and added to the polyester matrix of a glass fibre-reinforced composite. This resulted in a significant improvement in fracture toughness of the composite, whereas a reduction of bending strength and stiffness was observed in parallel

Characterization of Cellulose/Polyvinyl Alcohol/Expanded Graphite 3D Porous Foam and Adsorption of Methylene Blue

The cellulose/polyvinyl alcohol (PVA)/expanded graphite (EG) 3D porous foam, which has wide application prospects in cost-effective dye removal, was prepared by physical crosslinking and foaming technology. The prepared foam material has an obvious 3D network and porous structure, exhibiting excellent removal efficiency for methylene blue (MB) in an aqueous solution. The largest MB adsorption capacity of the foam is 110.81 mg/g. The adsorption process follows the pseudo-2nd order kinetics and the Freundlich isotherm model, indicating that the adsorption process is controlled by active surface sites and the physical adsorption process. Thermodynamic studies have shown that the adsorption process is a spontaneous and exothermic reaction. After five cycles of adsorption experiments, the composite material still exhibited a more than 70% dye removal rate. Results show that cellulose/PVA/EG 3D porous foam is an effective, promising, and recyclable adsorbent, which can be used to remove MB from aqueous solutions

Carbon Microparticles from Organosolv Lignin as Filler for Conducting Poly(Lactic Acid)

Carbon microparticles were produced from organosolv lignin at 2000 °C under argon atmosphere following oxidative thermostabilisation at 250 °C. Scanning electron microscopy, X-ray diffraction, small-angle X-ray scattering, and electro-conductivity measurements revealed that the obtained particles were electrically conductive and were composed of large graphitic domains. Poly(lactic acid) filled with various amounts of lignin-derived microparticles showed higher tensile stiffness increasing with particle load, whereas strength and extensibility decreased. Electric conductivity was measured at filler loads equal to and greater than 25% w/w