Rodrigo Llano-Ponte

Effects of fibre treatment on wettability and mechanical behaviour of flax/polypropylene composites

Abstract Chemical treatment of natural reinforcements can enhance their adhesion to polymer matrices. This work reports the effects of different treatments on the fibre–matrix compatibility in terms of surface energy and mechanical properties of composites. The composites were compounded with two kinds of flax fibres (natural flax and flax pulp) and polypropylene. The applied treatments were maleic anhydride (MA), maleic anhydride-polypropylene copolymer (MAPP) and vinyl trimethoxy silane (VTMO). The treatment effects on the fibres have been characterised by Infrared Spectroscopy. Two techniques have been used to determine the surface energy values: the Dynamic Contact Angle method for the long flax fibres and the Capillary Rise method for the irregular pulps. The use of different methods involves a small discordance in the wettability values. Nevertheless, the three treatments reduce the polar component of the surface energy of the fibre. Composites containing MAPP-treated did the highest mechanical properties, whilst the MA and VTMO-treated fibre gave similar values to that for the untreated ones.

Ultrasound-assisted fractionation of the lignocellulosic material

In the present work the effectiveness of different lignocellulosic biomass fractionation processes based on ultrasounds technology was evaluated. Organosolv (acetic acid 60% v/v), alkaline (sodium hydroxide 7.5% w/w) and autohydrolysis treatments were applied at low temperature and the fractionation effectiveness was measured at different sonication conditions of the raw material. The obtained solid fractions were characterized using TAPPI standard methods, and the liquid fractions main components were quantified with the purpose of studying the effect that the treatment conditions had on the obtained by-products quality. Therefore, obtained lignin samples were characterized by ATR-IR spectroscopy and their thermal behaviour by TGA technique. The results showed that ultrasounds application improved the yield and selectivity of the studied processes and that the obtained lignin did not suffer significant modifications in its physicochemical properties.

Strain rate and temperature effects on the mechanical behaviour of epoxy mixtures with different crosslink densities

Abstract The microstructure and the flexural behaviour of two highly crosslinked mixtures have been investigated. Besides the usual α and β relaxations appearing for any epoxy mixture, an additional ω relaxation, located slightly above room temperature, was evident for the mixture with higher crosslink density. This relaxation, which seems to be related to microstructural variations originating in a free volume increase, permits us to explain the lower mechanical properties of the larger higher crosslinked mixtures in the temperature range between the β and α relaxations. Whilst at room temperature the flexural modulus did not show any significant variation upon testing rate and the strength slightly increased for both epoxy mixtures.

Energy Optimization of a Kraft Pulp Mill

Abstract New regulations, economical and environmental requirements urge industrial companies to continuously improve the efficiency of their production technologies. The application of process integration tools for process retrofit is a must whenever energy or raw material intensive processes are considered. Since pulp and paper processes use a large amount of energy and water, the application of process integration techniques in this area is essential and can contribute to the protection of the environment to a great extent. CadSim Plus simulation software has been used to simulate several sections of a kraft pulp mill. Based on the process flow sheet and the developed simulation, pinch analysis was undertaken using the software Aspen HX-Net 2006. Potential of energy savings has been identified and the feasibility of the associated heat exchangers network (HEN) modification has been evaluated by the process simulation. The combination of both computer tools, has allowed to carry out the study of energy optimization of the process, maintaining the conditions of operation and evaluating the feasibility of the possible changes in the design of the heat exchangers network that allow minimizing the energy consumption.

Energy and Economic Assessment of Soda and Organosolv Biorefinery Processes

The paper industry is facing the necessity of improving process efficiency, especially in terms of energy and raw materials consumption. In most of the cases, the production of pulp and paper generates an energy surplus that is often not conveniently used. The actual trend is to convert traditional pulp and paper processes in biorefineries where all components of lignocellulosic materials can be converted in added value products such as bioethanol, lignin, cellulose whiskers and other chemicals than can replace the common petroleum based products. In the present work, the energetic and economical efficiencies of two biorefinery processes were studied using the simulation software Aspen Plus. Soda and organosolv processes were used for raw material delignification. The simulation design and treatment sequences (reaction, solid fraction washing, products recovery and liquid fraction processing) are similar for both processes. Mass and energy balances were established and the processes were compared in terms of yield, solvents/reactants recovery and energy consumption based on the same amount of processed raw material. In this way, the development of rigorous simulations allowed to determine the economical feasibility of both biorefinery models, and to establish the optimal operation conditions for both processes.

Effect of wood drying and heat modification on some physical and mechanical properties of radiata pine

ABSTRACT To evaluate evolution of physical and mechanical properties due to drying and heat modification, a load of radiata pine wood was selected and properties were measured after each drying process. The results revealed interesting correlations between intrinsic factors and properties; the values of density were highly dispersed after drying or thermal treatment and uncorrelated with other parameters, but the minimum density values were kept constant after heat treatment. Moreover, weight loss (WL) and moisture content (MC) were decreasing proportionally to the treatment intensity, due to wood–water interactions, cell wall changes, and thermal degradation of wood fractions. WL and MC were reasonably correlated with the dimensional stability, improving the dimensional stability after drying treatments, but keeping the same order of anisotropy. Regarding the wood stiffness (modulus of elasticity, MOE), it was unaffected by the drying temperature, and the correlations between MOE and MC or WL appear to be acceptable, and the values of MC or WL did not adversely affect the MOE. However, the modulus of rupture was dropped during the drying process, obtaining three differentiated groups with a decrease in around 59% after thermal modification.