Time filter

Source Type

Zhang Z.,Louisiana State University | Wu Q.,Louisiana State University | Song K.,Louisiana State University | Lei T.,Key Biomass Energy Laboratory of Henan Province | Wu Y.,Central South University of forestry and Technology
Cellulose | Year: 2015

Cellulose nanocrystals (CNCs) were used to improve the performance of poly(vinylidene fluoride) (PVDF), and the composite properties were characterized. The results showed that the prepared nanocomposites displayed the increases in mechanical properties. In particular, with the incorporation of 6 wt% CNCs, increases in tensile strength and dynamic storage modulus were observed. For hydrophilicity, the water contact angle decreased from 90° to 77° with the incorporation of only 3 wt% CNCs, indicating improved hydrophilicity. Addition of CNCs to PVDF also helped improve its thermal stability and crystallinity. It was suggested that CNCs played a nucleating role in the crystallization of PVDF, which was supported by the smaller size of PVDF spherulite observed from scanning electron microscopy analysis. Rheological results indicated that incorporation of CNCs also increased both melt storage modulus and shear viscosity of composites. Overall, our present work demonstrates that CNCs can provide PVDF with simultaneously improved properties. © 2015, Springer Science+Business Media Dordrecht.

Sun X.,Louisiana State University | Wu Q.,Louisiana State University | Ren S.,Key Biomass Energy Laboratory of Henan Province | Lei T.,Key Biomass Energy Laboratory of Henan Province
Cellulose | Year: 2015

Transparent cellulose films from 2,2,6,6-tetramethylpiperidine-1-oxyl radical oxidized cellulose nanocrystals (TOCNs) and 64 wt% sulfuric acid treated cellulose nanocrystals (SACNs) were prepared from bleached wood pulp. Film morphology, optical, mechanical, thermal, and surface wettability properties were characterized and compared. The results showed that TOCNs and SACNs had different average length (200.7 vs. 163.0 nm), diameter (5.8 vs. 15.6 nm), and aspect ratio (34.4 vs. 10.4). Compared with the SACN film, TOCN films exhibited higher optical transmittance (98.4 % at 900 nm) and larger tensile strength (236.5 MPa). SACN films exhibited better thermal stability (Tonset = 239 °C), higher crystallinity (73.4 %) and lower coefficient of thermal expansion (CTE = 8.38 ppm/k). Additionally, both films demonstrated good surface wettability. The results indicate that the TOCN and SACN films could be considered as a substrate material to replace traditional glass and plastic substrates for the next generation “Green” electronics. © 2015, Springer Science+Business Media Dordrecht.

Song K.,Louisiana State University | Wu Q.,Louisiana State University | Zhang Z.,Louisiana State University | Ren S.,Key Biomass Energy Laboratory of Henan Province | And 4 more authors.
Fuel | Year: 2015

Biomass pyrolysis and gasification are used to efficiently convert lignocellulosic materials to a variety of products that can substitute for petrochemical-derived energy and chemicals. Tar (heavy hydrocarbons) is inevitably produced from the thermochemical processes, and is often disposed as an industrial waste, leading to environmental pollution. To utilize the tar, a facile route to fabricate porous fibrous composite with antimicrobial capability was demonstrated by electrospinning tar and polyacrylonitrile (PAN) blends. Continuous fibers with an average diameter ranging from 422 to 948 nm without beads were prepared from tar and PAN blends. The electrospun Tar/PAN nanofibers exhibited a high porosity of 51-63% with an average pore diameter ranging from 5.6 to 7.1 nm, indicating a mesoporous structure. The Tar/PAN nanofibers showed higher antimicrobial activities (up to 39%) against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) in comparison with the neat PAN nanofibers, due to the presence of phenolic compounds in the tar. Aside from their antimicrobial capability, the electrospun nanofibers can also be applied in the manufacture of low-cost adsorption materials and carbon nanofibers. © 2015 Elsevier Ltd.

Ren S.,Key Biomass Energy Laboratory of Henan Province | Sun X.,Louisiana State University | Lei T.,Key Biomass Energy Laboratory of Henan Province | Wu Q.,Louisiana State University
Journal of Nanomaterials | Year: 2014

Cellulose nanoparticles were fabricated from microcrystalline cellulose (MCC) through combined acid hydrolysis with sulfuric and hydrochloric acids and high-pressure homogenization. The effect of acid type, acid-to-MCC ratio, reaction time, and numbers of high-pressure homogenization passes on morphology and thermal stability of the nanoparticles was studied. An aggressive acid hydrolysis was shown to lead to rod-like cellulose nanocrystals with diameter about 10 nm and lengths in the range of 50-200 nm. Increased acid-to-MCC ratio and number of homogenization treatments reduced the dimension of the nanocrystals produced. Weak acid hydrolysis treatment led to a network of cellulose nanofiber bundles having diameters in the range of 20-100 nm and lengths of a few thousands of nanometers. The high-pressure homogenization treatment helped separate the nanofiber bundles. The thermal degradation behaviors characterized by thermogravimetric analysis at nitrogen atmosphere indicated that the degradation of cellulose nanocrystals from sulfuric acid hydrolysis started at a lower temperature and had two remarkable pyrolysis processes. The thermal stability of cellulose nanofibers produced from hydrochloric acid hydrolysis improved significantly. © 2014 Suxia Ren et al.

Li M.-C.,Louisiana State University | Wu Q.,Louisiana State University | Song K.,Louisiana State University | Lee S.,Korea forest Research Institute | And 3 more authors.
ACS Applied Materials and Interfaces | Year: 2015

Wellbore instability and formation collapse caused by lost circulation are vital issues during well excavation in the oil industry. This study reports the novel utilization of soy protein isolate (SPI) as fluid loss additive in bentonite-water based drilling fluids (BT-WDFs) and describes how its particle size and concentration influence on the filtration property of SPI/BT-WDFs. It was found that high pressure homogenization (HPH)-treated SPI had superior filtration property over that of native SPI due to the improved ability for the plugging pore throat. HPH treatment also caused a significant change in the surface characteristic of SPI, leading to a considerable surface interaction with BT in aqueous solution. The concentration of SPI had a significant impact on the dispersion state of SPI/BT mixtures in aquesous solution. At low SPI concentrations, strong aggregations were created, resulting in the formation of thick, loose, high-porosity and high-permeability filter cakes and high fluid loss. At high SPI concentrations, intercatlated/exfoliated structures were generated, resulting in the formation of thin, compact, low-porosity and low-permeability filter cakes and low fluid loss. The SPI/BT-WDFs exhibited superior filtration property than pure BT-WDFs at the same solid concentraion, demonstrating the potential utilization of SPI as an effective, renewable, and biodegradable fluid loss reducer in well excavation applications. © 2015 American Chemical Society.

Discover hidden collaborations