Thermomechanical relaxation and different water states in cottonseed protein derived bioplastics

Thermomechanical relaxation events and different water states in cottonseed protein bioplastics are presented whilst investigating the effects of aldehyde cross-linking agents. Thermomechanical relaxation of cottonseed protein bioplastics associated with protein denaturation, moisture absorption and broad glass transitions (Tg) were observed from DSC and DMA measurements. It was shown that variation of the aldehyde influences the storage modulus at very low temperature (below Tg). From measurements of the water fusion point, enthalpy, vaporisation, and weight loss, three water states in the water-absorbed bioplastics are suggested; namely strongly-bound-to-polymer, weakly-bound-to-polymer and bulk-like water. The water content and unreacted cross-linking agents are influential factors in controlling formation of the different water states, whilst the selection of different aldehydes was found to be negligible. These results could be valuable for adjusting the thermomechanical relaxations of protein based bioplastics, and tailoring their properties in wet environments

Identification of high performance solvents for the sustainable processing of graphene

Nanomaterials have many advanced applications, from bio-medicine to flexible electronics to energy storage, and the broad interest in graphene-based materials and devices means that high annual tonnages will be required to meet this demand. However, manufacturing at the required scale remains unfeasible until economic and environmental obstacles are resolved. Liquid exfoliation of graphite is the preferred scalable method to prepare large quantities of good quality graphene, but only low concentrations are achieved and the solvents habitually employed are toxic. Furthermore, good dispersions of nanomaterials in organic solvents are crucial for the synthesis of many types of nanocomposites. To address the performance and safety issues of solvent use, a bespoke approach to solvent selection was developed and the renewable solvent Cyrene was identified as having excellent properties. Graphene dispersions in Cyrene were found to be an order of magnitude more concentrated than those achieved in N-methylpyrrolidinone (NMP). Key attributes to this success are optimum solvent polarity, and importantly a high viscosity. We report the role of viscosity as crucial for the creation of larger and less defective graphene flakes. These findings can equally be applied to the dispersion of other layered bi-dimensional materials, where alternative solvent options could be used as drop-in replacements for established processes without disruption or the need to use specialized equipment. Thus, the discovery of a benign yet high performance graphene processing solvent enhances the efficiency, sustainability and commercial potential of this ever-growing field, particularly in the area of bulk material processing for large volume applications

Elastic relaxation during 2D epitaxial growth: a study of in-plane lattice spacing oscillations

The purpose of this paper is to report some new experimental and theoretical results about the analysis of in-plane lattice spacing oscillations during two-dimensional (2D) homo and hetero epitaxial growth. The physical origin of these oscillations comes from the finite size of the strained islands. The 2D islands may thus relax by their edges, leading to in-plane lattice spacing oscillations during the birth and spread of these islands. On the one hand, we formulate the problem of elastic relaxation of a coherent 2D epitaxial deposits by using the concept of point forces and demonstrate that the mean deformation in the islands exhibits an oscillatory behaviour. On the other hand, we calculate the intensity diffracted by such coherently deposited 2D islands by using a mean model of a pile-up of weakly deformed layers. The amplitude of in-plane lattice spacing oscillations is found to depend linearly on the misfit and roughly linearly on the nucleation density. We show that the nucleation density may be approximated from the full-width at half maximum of the diffracted rods at half coverages. The predicted dependence of the in-plane lattice spacing oscillations amplitude with the nucleation density is thus experimentally verified on V/Fe(001), Mn/Fe(001), Ni/Fe(001), Co/Cu(001) and V/V(001).Comment: 39 pages, 10 figure

Generalized oscillator strength for Na 3s-3p transition

Generalized oscillator strengths (GOS's) for the Na $3s -3p$ transition have been investigated using the spin-polarized technique of the random phase approximation with exchange (RPAE) and the first Born approximation (FBA), focussing our attention on the position of the minimum. Intershell correlations are found to influence the position of the minimum significantly, but hardly that of the maximum. The RPAE calculation predicts for the first time the positions of the minimum and maximum at momentum transfer, $K$ values of 1.258 a.u. and 1.61 a.u., respectively. The former value is within the range of values extracted from experimental measurements, $K=1.0-1.67$ a.u.. We recommend careful experimental search for the minimum around the predicted value for confirmation.Comment: 11 pages, 2figure

Bio-based carbonaceous composite materials from epoxidised linseed oil, bio-derived curing agent and starch with controllable functionality

Development of biomass-derived materials using sustainable practices has been one of the major scientific aims over the last few decades. A new class of bio-derived nanocomposite derived from epoxidised linseed oil, a bio-derived crosslinker and a starch based carbonaceous mesoporous material (Starbon®) has been developed. The use of Starbons® technology enables the incorporation of carbonaceous materials with tuneable surface functionality (from hydrophilic to hydrophobic). The resulting composite demonstrated good thermal stability up to 300 °C, good low temperature modulus, flexibility and uniformity, as demonstrated by TGA, DMA and SEM studies, respectively. Furthermore, the thermoset composites' swelling behaviour in solvents with a high polar index through to non-polar ones was investigated, revealing initially that non polar solvents have a greater impact on swelling than polar solvents and that in all cases the addition of filler reduces the extent of swelling. The inclusion of this carbonaceous material with hierarchical pore structure and high BET surface area may further aid the use of such composites in membrane separation applications

Inertial Tracking System for Monitoring Dual Mobility Hip Implants In Vitro

Dual mobility (DM) implants are being increasingly used for total hip arthroplasties due to the additional range of motion and joint stability they afford over more traditional implant types. Currently, there are no reported methods for monitoring their motions under realistic operating conditions while in vitro and, therefore, it is challenging to predict how they will function under clinically relevant conditions and what failure modes may exist. This study reports the development, calibration, and validation of a novel inertial tracking system that directly mounts to the mobile liner of DM implants. The tracker was custom built and based on a miniaturized, off-the-shelf inertial measurement unit (IMU) and employed a gradient-decent sensor fusion algorithm for amalgamating nine degree-of-freedom IMU readings into three-axis orientation estimates. Additionally, a novel approach to magnetic interference mitigation using a fixed solenoid and magnetic field simulation was evaluated. The system produced orientation measurements to within 1.0° of the true value under ideal conditions and 3.9° with a negligible drift while in vitro, submerged in lubricant, and without a line of sight

Controllable production of liquid and solid biofuels by doping-free, microwave-assisted, pressurised pyrolysis of hemicellulose

Batch, pressurised microwave-assisted pyrolysis of hemicellulose in the absence of any external microwave absorber was found to be a promising route for the production of bio-based chemicals and biofuels. The experiments were conducted in a 10 mL batch reactor using a fixed power of 200 W employing different initial masses of xylan (0.1–0.7 g) for a maximum time, temperature and pressure of 10 min, 250 °C and 200 psi, respectively. The gas, bio-oil and solid (char) yields varied by 16–40%, 2–21% and 40–82%, respectively. Char production is preferential using a low amount of xylan (<0.25 g), while bio-oil production is favoured using a high amount of xylan (0.25–0.7 g). The effect of the sample mass is accounted for by the different physical state of the volatiles released during pyrolysis depending on the pressure attained during the experiment. This permits the process to be easily customised for the selective production of liquid (bio-oil) or solid (bio-char). Regarding the bio-oil, it is composed of a mixture of platform chemicals such as aldehydes, alkenes, phenols, polyaromatic hydrocarbons (PAHC), cyclic ketones and furans, with the composition varying depending on the initial mass of xylan. The char had a higher proportion of C together with a lower proportion of O than the original feedstock. Energy efficiencies of 100 and 26% were achieved for char and bio-oil production, respectively; thus leading to an increase in the HHV of the products (with respect to the original feedstock) of 52% for char and 19% for bio-oil