RESUMO
Polypropylene (PP) is a commodity material that has been increasingly used in different industries in the past two decades due to its versatile properties when enhanced with additives. Homo polypropylene, in general, has weak mechanical properties and limited chemical resistance; thus, using a different type of fillers to adjust such properties to fit the required applications opened a large market for this commodity. Understanding the interface constituent between the polymer matrix and the added filler and the nucleation behavior is a key to fine control of the enhancement of PP properties. In this study, PP was incorporated with nano calcium carbonate (CaCO3) at 2 and 5 wt% in the presence of maleic anhydride (MAH) to overcome the weak interface due to low polymer polarity. The mix was compounded in a twin screws extruder at a temperature range of 180-200 °C ; then, the prepared samples were left to dry for 24 h at 25 °C. Nuclear Magnetic Resonance (NMR) was used to study the interface adhesion of the nanofiller and the curved revealed that at 2% of nano CaCO3 PP structure remained the same and the nano experienced good adhesion to the polymer matrix. The mechanical impact resistance results showed a real enhancement to the polymer matrix of the nanocomposite by 37%. Moreover, DSC results showed a faster crystallinity rate due to the nanofiller acting as a nucleating agent and rheology tests indicated that low content of nano additive (2%) has better processability behavior, with suitable viscosity complex values at high frequencies.
RESUMO
This paper tackles the effect of reaction temperature on the apparent order of the hydrodesulfurization (HDS) reactions of an atmospheric residue (KEC-AR) derived from Kuwait Export Crude (KEC). Testing was carried out using a pilot plant consisting of five identical fixed-bed reactors arranged in series. A moderate-HDS-activity catalyst was used under a 120 bar (total) operating pressure, a feed flow rate of 120 mL per hour (mL/h), and a hydrogen-to-feed ratio of 1000 mL/mL. The liquid hourly space velocity (LHSV) varied by 4.0, 2.0, 1.0, 0.5, and 0.25 relative to the catalyst accumulative volumes in the five reactors. Testing was conducted between 360 and 420 °C with a temperature increase of 10 °C each time. Product samples were collected between the reactors using customized inter-reactor sampling systems that operate under the pilot plant's total pressure. The results showed that the HDS apparent order decreases with an increase in reaction temperature. The order dropped from 4.9 at 360 °C to 1.62 at 420 °C. Using the least-squares method (LSM), we demonstrated that the apparent overall orders are aggregates of several first-order reactions occurring consecutively at different rates and dependent on sulfur total disappearance. On the other hand, we showed that the apparent overall orders are aggregates of several reactions of different orders occurring simultaneously and independently of sulfur total disappearance. The first-order reactions' activation energy was found to be 22.1 kcal/mol and in total agreement with that reported in the literature for the sulfur removal from KEC-AR.