Method to reinforce polylactic acid with cellulose nanofibers via a polyhydroxybutyrate carrier system.

The elastic moduli of PLA reinforced with 5 and 10wt.% CNF with the carrier, at a frequency (ω) of 0.07, were 67% and 415% higher, respectively, than that of neat PLA. The shear viscosity at a shear rate of 0.01 (η0.01) for PLA+10wt.% CNF was 32% higher than that of the neat PLA matrix. The η0.01 of PLA reinforced with 5wt.% CNF and the PHB carrier was similar to neat PLA. The tensile and flexural moduli of elasticity of the nanocomposites continuously increased with increased CNF loading. The results of the mechanical property measurements are in accordance with the rheological data. The CNF appeared to be better dispersed (less-aggregated nanofibers) in the PLA reinforced with 5wt.% CNF and the PHB carrier. Possible applications for the composites studied in this research are packaging materials, construction materials, and auto parts for interior applications.

Electrically conductive nano graphite-filled bacterial cellulose composites.

A unique three dimensional (3D) porous structured bacterial cellulose (BC) can act as a supporting material to deposit the nanofillers in order to create advanced BC-based functional nanomaterials for various technological applications. In this study, novel nanocomposites comprised of BC with exfoliated graphite nanoplatelets (xGnP) incorporated into the BC matrix were prepared using a simple particle impregnation strategy to enhance the thermal properties and electrical conductivity of the BC. The flake-shaped xGnP particles were well dispersed and formed a continuous network throughout the BC matrix. The temperature at 10% weight loss, thermal stability and residual ash content of the nanocomposites increased at higher xGnP loadings. The electrical conductivity of the composites increased with increasing xGnP loading (attaining values 0.75 S/cm with the addition of 2 wt.% of xGnP). The enhanced conductive and thermal properties of the BC-xGnP nanocomposites will broaden applications (biosensors, tissue engineering, etc.) of BC and xGnP.

Biosynthesis of bacterial cellulose in the presence of different nanoparticles to create novel hybrid materials.

The unique micro-nano porous three-dimensional network of bacterial cellulose (BC) can facilitate the incorporation of nanoparticles (NPs) into the BC matrix to create advanced BC-based functional nanomaterials for diverse applications. In this study, novel nanomaterials comprised of bacterial cellulose (BC) synthesized in the presence of different NPs (cellulose nanofibrils (CNF), exfoliated graphite nanoplatelets (xGnP), and nanoclay (NC)) were prepared using an in situ approach. NPs at 0.5 wt.% loading were added into the BC culture medium and their effect on the resulting nanocomposite structure was studied by field emission scanning electron microscopy (FE-SEM), X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). All BC-based nanomaterials produced, exhibited good dispersion of the NPs within the BC matrix and the NPs were found embedded among the voids and microfibrils. The thermal stability and residual mass of BC-xGnP and BC-NC nanomaterials was significantly increased compared with the neat BC. CNF incorporation into the BC matrix did not change the thermal stability and residual mass of the BC matrix. This study also provides novel insights into the properties of the hybrid materials, and shows the approach used to make these materials which results in increased performance for chosen applications.

Synthesis of bacterial cellulose using hot water extracted wood sugars.

Bacterial cellulose (BC), a type of nanopolymer produced by Acetobacter xylinum is a nanostructured material with unique properties and wide applicability. However, a standard medium used for the cultivation of BC, the Hestrin-Schramm medium, is expensive and prevents wide scale extension of BC applications. In this research, a relatively low-cost culture media was successfully developed from wood hot water extracts for the Acetobacter xylinus 23769 strain. Hot water extract (HWE) is a residual material originating from pulp mills and lignocellulosic biorefineries and consists of mainly monomeric sugars, organic acids and organics. The effects of different pH (5, 6, 7 and 8) and temperatures (26, 28 and 30°C) were also examined in this research. There were no significant differences in the crystallinity and the recorded Iα fraction of cellulose produced between Hestrin-Schramm and the HWE medium. The maximum production of 0.15g/l of BC was obtained at a pH of 8 and temperature of 28°C. Glucose and xylose in the HWE were the main nutrient sources utilized in all BC cultivations based on high-pressure liquid chromatography (HPLC) results. HWE was shown to be a suitable carbon source for BC production, and a process was established for BC production from lignocellulosic feedstocks without using any modification of the HWE. HWE is an abundant and relatively inexpensive forest by-product. Using HWE for BC production could reduce burdens on the environment and also, achieve the goal of large scale BC production at low cost without using added culture nutrients.