We report on the mechanical properties of optically curable stereolithographic resins (SLRs) which were reinforced through the addition of small amounts of cellulose nanocrystals (CNCs). The resin/filler mixtures are readily accessible via simple mixing processes. A detailed rheological investigation of such mixtures and the successful processing of these materials on a commercial SLR machine show that at low filler concentrations (below 5%) the processability of the materials is barely impacted. The storage modulus, E', increased steadily with increasing CNC content in the regimes below and above the glass transition. A remarkable modulus enhancement was observed in the rubbery regime, where E' increased by 166, 233, and 587% for CNC/SLR nanocomposites with 0.5, 1.0, and 5.0% w/w CNC, respectively. The modulus increase was less pronounced in the glassy state, where E' increased by 21, 32 and 57%, for the same compositions. The increase in tensile strength was of similar magnitude. In comparison to previously reported CNC and carbon-nanofiller based nanocomposites, the presently investigated nanocomposites display a comparably large increase of stiffness and strength, which appear to originate from the high level of dispersion and the intimate contact of the CNCs with the SLR matrix. Through the fabrication of 3-dimensional parts, it was shown that the CNC-filled resins can be processed with standard equipment in a stereolithographic process that is widely used for rapid prototyping and rapid manufacturing.
Land-use/land-cover (LU/LC) change is an important component of global environmental change. The need to understand LU/LC change is essential for regional development and land use management towards sustainable development. To understand LU/LC change, the different LU/LC categories and their spatial as well as temporal variability in Tiruchirappalli city has been studied over a period of eight years (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006), using the analysis of Indian Remote Sensing Satellite (IRS) images. In this, an attempt was made to adopt Markov model for obtaining and understanding LU/LC dynamics. Model performance was evaluated between the empirical LU/LC map extracted from CARTOSAT-1 PAN image and the simulated LU/LC map obtained from the Markov model. The future landscape distribution in the year 2014 and 2022 was derived using a Markov model. This result shows that Markov model and geospatial technology together are able to effectively capture the spatio-temporal trend in the landscape pattern associated with urbanization in this region.
We investigated how different processing methods affect the morphology and mechanical properties of nanocomposites made from poly(vinyl acetate) (PVAc) and cellulose nanocrystals (CNCs). Homogeneously mixed reference PVAc/CNC nanocomposites of various compositions were first prepared by solution casting. These materials were post‐processed by mixing in a roller blade mixer (RBM) or a twin‐screw extruder (TSE) and subsequent compression molding. Transmission electron microscopy was used to elucidate the dispersion and size distribution of the CNCs and these data were correlated with the materials' mechanical properties. While RBM processed composites are virtually indistinguishable from the solution‐cast reference materials, TSE processing led to mechanical degradation of the CNCs and resulted materials with inferior mechanical properties. Direct RBM mixing of PVAc and CNCs was also explored. This process afforded materials that are much stiffer than the neat matrix, but did not reach the levels of the reference series.
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