Claudiane Ouellet-Plamondon

Enhanced plastic deformations of nanofibrillated cellulose film by adsorbed moisture and protein-mediated interactions.

Biological composites are typically based on an adhesive matrix that interlocks rigid reinforcing elements in fiber composite or brick-and-mortar assemblies. In nature, the adhesive matrix is often made up of proteins, which are also interesting model systems, as they are unique among polymers in that we know how to engineer their structures with atomic detail and to select protein elements for specific interactions with other components. Here we studied how fusion proteins that consist of cellulose binding proteins linked to proteins that show a natural tendency to form multimer complexes act as an adhesive matrix in combination with nanofibrillated cellulose. We found that the fusion proteins are retained with the cellulose and that the proteins mainly affect the plastic yield behavior of the cellulose material as a function of water content. Interestingly, the proteins increased the moisture absorption of the composite, but the well-known plastifying effect of water was clearly decreased. The work helps to understand the functional basis of nanocellulose composites as materials and aims toward building model systems for molecular biomimetic materials.

Mechanical unfolding of a fluorescent protein enables self-reporting of damage in carbon-fibre-reinforced composites

Carbon-fibre-reinforced polymer composites with an enhanced yellow fluorescent protein (eYFP) at the interface of fibres and resin were prepared. The protein was immobilized on the carbon fibres by physisorption and by covalent conjugation, respectively. The immobilized eYFP fluoresced on the carbon fibres, in contrast to non-protein fluorophores that were fully quenched by the carbon surface. The fibres were embedded into epoxy resin, and the eYFP remained fluorescent within the composite material. Micromechanical tests demonstrated that the interfacial shear strength of the material was not altered by the presence of the protein. Immunostaining of single fibre specimen revealed that eYFP loses its fluorescence in response to pull-out of fibres from resin droplets. The protein was able to detect barely visible impact damage such as fibre–resin debonding and fibre fractures by loss of its fluorescence. Therefore, it acts as a molecular force and stress/strain sensor at the fibre–resin interface and renders the composite self-sensing and self-reporting of microscopic damage. The mechanoresponsive effect of the eYFP did not depend on the type of eYFP immobilization. Fibres with the physisorbed protein gave similar results as fibres to which the protein was conjugated via covalent linkers. The results show that fluorescent proteins are compatible with carbon fibre composites. Such mechanophores could therefore be implemented as a safety feature into composites to assure material integrity and thereby prevent catastrophic material failure.

The Maya blue nanostructured material concept applied to colouring geopolymers

Maya blue is an ancient nanostructured pigment synthetized by assembling indigo, a natural dye, with palygorskite, a microfibrous clay mineral. The novelty of our approach is to mimic “pre-Columbian nanotechnology” and to functionalize geopolymers with a sepiolite-based hybrid organic–inorganic nanocomposite inspired from the Maya blue. It is acid- and UV-resistant, as confirmed by the stability of Maya mural paintings over time. We synthesized analogous pigments, using methylene blue (MB) and methyl red (MR) as organic dyes and sepiolite as fibrous clay mineral. We used an aqueous and a solid-state method, both leading to encapsulation of dye monomers into the clay micropores, as confirmed by UV-vis spectroscopy. This nanostructured pigment was then included into a geopolymer matrix at room temperature. The stability of the new material to UV and acid was tested. It was confirmed that it is the prior encapsulation of the dye into sepiolite that leads to the stability of the pigment in the geopolymer matrix. This first study opens the way to numerous possibilities for functionalizing inorganic binder materials with organic elements that would be otherwise sensitive to thermal treatment in conventional ceramic processing.

Nanocrystalline Cellulose as Effect Pigment in Clear Coatings for Wood

Nanocrystalline cellulose (CNC) is a renewable material with high potential in many applications. Due to its unique self-assembly and optical properties, CNC tends to behave as an iridescent pigment. The aim of this research was to explore the potential of CNC as an effect pigment in wood coatings. CNC-based coatings were developed from an aqueous CNC solution, a UV-curable water-based clear coating formulation, several colorants, and specialized additives. In this paper, the morphology of the resulting CNC films was investigated through circular dichroism and optical microscopy under polarized light. The effect of the CNC surface charge changes was monitored through zeta potential measurements. Color changes, or travel, and flop index were used to assess the iridescent effect of the coatings containing CNC. The experimental wood coatings contained CNC showed that the enhancement of the iridescent effect depends on the distribution and alignment of the CNC rod-like particles in order to generate the right pitch in the helical structure and their interaction with the polymer matrix as well with the additives. In conclusion, CNC could be successfully used as effect pigment in finishing systems, which can enhance the attractiveness and bring out the special grain of various types of wood.

Impact of nature and preparation method of graphene on the electrical behavior of LDPE/Graphene composites

In this paper, the effect of nature and preparation method of two different functionalized graphenes on the dielectric properties of Low Density Polyethylene (LDPE)/Graphene composites was investigated. The first type of composites contains only a single additive, a multilayer graphene purchased from an industrial supplier. The second type of composites was multiphase composites, where another type of graphene composed of 20% carbon and 80% clay, was fabricated at the university. The composites samples were then obtained by melt blending using a mini-extruder. For the comparative study, LDPE composites containing many contents ranging from 1 to 12wt% of two types of graphenes were prepared. All specimens were characterized by Broadband Dielectric Spectroscopy and DC conduction current measurements. The single phase LDPE/Graphene composites with an electrical percolation threshold found at 12wt%, revealed significantly higher electrical conductivities than the multiphase composites.

EFFECT OF MACROPHYTE SPECIES ON SUBSURFACE FLOW WETLAND PERFORMANCE IN COLD CLIMATE

Horizontal subsurface flow constructed wetlands (HSSCW) allows organic matter and nitrogen removal of fish farm effluent prior to streams discharge. The effect of macrophyte species on HSSCW efficiency was tested in ten units in a greenhouse experiment, in summer and winter. Eight units were individually planted with Phragmites australis, Typha angustifolia, Phalaris arundinacea and Calamagrostis canadensis (two units per species) and the remaining two units were left unplanted. The units were fed with a reconstituted effluent made from trout farm sludge. The sludge was diluted to obtain an average of 15 g COD/m2/d, 3 g BOD5/m2/d, 6 g TSS/m2/d, 0.50 g N/m2/d, 0.15 gP/m2/d and a resulting hydraulic loading of 3 cm/m2/d. Water quality was analysed in summer 2002 and winter 2003 for COD, BOD, TSS, TNK, NH4+, NO2- + NO3-, TP and o-PO4. Planted units were at least 5% more efficient in pollutant removal than unplanted units in summer and at least 10% in winter. The increase in removal efficiency for planted units was small, mainly because of the low loading conditions of the fish farm effluent. TKN (96% in summer and 88% in winter) and COD (96% in summer) removal were more efficient for Phragmites and Typha, the two species with large rhizomes. Phalaris was more efficient than the others with COD and BOD removal at 95% in winter. Calamagrostis was the least efficient species, with the largest difference being for winter nutrient removal. It was also the species with the lowest belowground: aboveground biomass ratio, around 0.25 compared to above 2 for Typha. Units planted with macrophytes with large belowground biomass showed less seasonal variability.

Alkali-activated binder containing wastes: a study with rice husk ash and red ceramic

In addition to several positive aspects in technical properties, geopolymeric binders have considerable advantages in the environmental point of view, with lower energy consumption and lower CO2 emission. In this study, it was conducted an overview about the utilized materials by some Brazilian researchers in geopolymers production, and also an experiment employing two types of wastes (red ceramic waste and rice husk ash). The compressive strength of the resulting material developed very fast, reaching a value of 11 MPa after one day. The microstructure was evaluated by scanning electron microscopy, revealing a compact microstructure and the presence of starting materials from the red ceramic waste that not completely reacted. The results indicated the feasibility of producing geopolymeric material without using commercial sodium silicate and cured at room temperature, showing an option for building materials production with lower environmental impacts.

Soil mix technology for integrated remediation and ground improvement: From laboratory work to field trials

Relatively new in the UK, soil mix technology applied to the in-situ remediation of contaminated land involves the use of mixing tools and additives to construct permeable reactive in-ground barriers and low-permeability containment walls and for hot-spot soil treatment by stabilisation/ solidification. It is a cost effective and versatile approach with numerous environmental advantages. Further commercial advantages can be realised by combining this with ground improvement through the development of a single integrated soil mix technology system which is the core objective of Project SMiRT (Soil Mix Remediation Technology). This is a large UK-based R&D project involving academia-industry collaboration with a number of tasks including equipment development, laboratory treatability studies, field trials, stakeholder consultation and dissemination activities. This paper presents aspects of project SMiRT relating to the laboratory treatability study work leading to the design of the field trials.

Corn Stover Fractions during Extended Harvest

Two corn hybrids were sampled weekly at each of three research farms in Quebec, Canada between September 4 and November 19. The Saint-Augustin site (AUG) was in a 2500 crop heat unit (CHU) zone while the two other sites, Sainte-Rosalie (ROS) and Sainte-Anne-de-Bellevue (ANN), were in 2900 CHU zones. At AUG, grain yields of hybrids 46T07 RR and 30A27 RR were 3.35 and 4.25 Mg of dry matter (DM)/ha in early September and reached 7.69 and 7.55 Mg DM/ha by the end of October, respectively. Meanwhile, stover yield declined to 7.71 and 7.04 Mg DM/ha by the end of October, with an average loss rate of 25 and 12 kg DM/ha/d, respectively. At ROS, grain yield of hybrids 46T07 RR and 25T19 RR were 4.41 and 4.72 Mg DM/ha in early September and reached 9.85 and 10.88 Mg DM/ha by mid-November, respectively. Meanwhile, stover yield declined to 8.29 and 8.33 Mg DM/ha by mid-November, with an average loss rate of 41 and 40 kg DM/ha/d, respectively. At ANN, grain yields of hybrids 39D85 and 38M59 were 7.59 and 9.27 Mg DM/ha in early September and reached 8.59 and 14.44 Mg DM/ha by mid-November. These hybrids had less stover loss (2 and 6 kg/ha/d) and less total stover yield (5.76 and 6.74 Mg DM/ha, respectively, at the end of sampling) than the other hybrids. At a standardized harvest time (171 d after planting), grain, cob, husk, leaf and stalk averaged 55, 10, 4, 12 and 19% of the overall plant biomass, respectively. On average at 171 d after planting, 56 % of the corn fibre was located above the point of junction between the first ear and the stalk. The average moisture content of fibre ranged between 68 to 76 % during September and declined to as low as 28 % by mid-November.

Conductive clay containing graphene layers

Clays were used as a template to produce graphene-like layers from sugar, a natural renewable resource. Raman spectroscopy showed that the synthesis with five times more sugar than clays produced multilayered graphene better ordered than when starting with a lower proportion of sugar. At 6.5 MPa, the clay graphene-like nanostructured materials are as conductive as commercially available graphene. The scanning electron microscopy images of conductive clay with higher sugar content featured more uniform structure with higher porosity. The thermal conductivity increased with higher initial sugar content.