Yi Xing Liu

Hydrophobic Modification of Natural Cellulose Fiber with MMA via Surface-Initiated ARGET ATRP

To convert the hydrophilic cotton fiber into hydrophobic, grafting methyl methacrylate (MMA) on cotton fiber surface using ARGET (activators regenerated by electron transfer) ATRP (atom transfer radical polymerization) was studied in this paper. Four parallel experiments with different reaction time (2h/4h/6h/8h) were designed. The modified cotton fibers and the untreated control were examined using FTIR, SEM and contact angle analysis. The results show that as the reaction time prolonged, the peak of carbonyl stretching band of 2-bromoester at 1730cm-1 was stronger and the surface of cotton fiber was rougher, which demonstrates MMA has been grafted on the surface of cotton fiber successively and its amount increases with the reaction time. As the results of contact angle measurement, it shows that the hydrophilicity of cotton fiber can easily be modified by grafting of MMA, but the increasing amount of grafting chain had no obvious effects on further improving its hydrophobicity.

Fabrication, Characterization and Photocatalytic Activity of TiO2/Cellulose Composite Aerogel

nanoTiO2/cellulose composite gels have been uniformly blended during the dissolving process of cellulose in ionic liquids (ILs). After the regeneration process, the obtained hydrogel was finally dried through supercritical CO2 to obtain the TiO2/cellulose composite aerogel. The structure and properties of the composite aerogel were characterized by XRD, SEM, FT-IR, UV-vis, and photocatalytic degradation tests. The porous structure and hydroxyl groups in the regenerated cellulose matrix provided cavities and affinity for the immobilization of TiO2 in the cellulose gels through electrostatic and hydrogen bonding interactions. The TiO2/cellulose composite gels exhibited a good photocatalytic activity for photodegradation of Rhodamine B (RhB) under UV light irradiation. This research highlights another opportunity for the development of the portable and flexible photocatalyst.

Structure and Property of PGMA/Wood Composite

In order to prepare a wood-based composite material which, as a type of multifunctional and natural bio-based material, possesses satisfactory mechanical properties, excellent durability (i.e., decay resistance and dimensional stability), and Aenvironmental characteristic, the study presents a new method which is based on the cellular structure of wood by initiating polymerizable monomers for in situ polymerization. Glycidyl methacrylate (GMA) as a multifunctional and polymerizable monomer was chosen, and impregnated into the porous structure of wood. After a thermal-catalyst process, the wood-based composite, PGMA/Wood, was prepared. The structure of this material was analyzed by SEM, FTIR and XRD; and its performance was also determined. The analyzing results show that GMA not only polymerized in the cellular structure in a solid form and amorphous form, which fully and uniformly filled in wood cell lumen, but also sufficiently grafted onto wood cell walls in a chemical level, resulting in tight contact between wood cell walls and resultant polymers (PGMA) without any obvious cracks. The test results of mechanical properties show that the modulus of rupture (MOR), modulus of elasticity (MOE), compression strength, and hardness of PGMA/Wood increased by 82%, 122%, 139%, and 348% over those of untreated wood, respectively. The test results of durability show that the dimensional stability and decay resistance of PGMA/Wood improved 44% and 91% than those of untreated wood, respectively. Such composite could be widely applied in the fields of construction, furniture and traffic.

Preparation, Characterization and Biocompatibility of Regenerated Cellulose/PVA Blend Membranes in 1-Allyl-3-Methyimidazolium Chloride

Regenerated cellulose/polyvinyl alcohol (PVA) blend membranes were prepared from a solution of cellulose and PVA in an ionic liquid of 1-allyl-3-methyimidazolium chloride (AMImCl). SEM images showed that the phase separation on the mixture was severely formed when the content of PVA was higher than 10% by volume. However, when the content of PVA in the mixture was lower than 6%, the cellulose and PVA were well-distributed. The regenerated blend membranes using the AMImCl presenting reasonable crystallinity were superior to those of regenerated pure cellulose membrane. In conclusion, the compatible properties of blend membranes from regenerated cellulose/PVA (6%) were improved and the blend membranes kept original biodegradability.

Performance of Wood-Polymer Composite Prepared by In Situ Polymerization of Styrene

A new material was prepared by formation of polystyrene in situ wood porous structure from styrene monomer through thermal-catalyst treatment. And the performance of such wood-polymer composite, containing mechanical properties and durability, was also tested. The SEM results showed that polymer was generated inside wood, and filled in wood cellular structure. The mechanical properties of such wood-polystyrene composite including modulus of rupture (MOR), modulus of elasticity (MOE), compression strength and hardness, were respectively improved 38%, 77%, 21% and 97% over untreated wood. And the durability of the novel composite involving dimensional stability, decay resistance and stability against weather erosion were remarkably improved than those of untreated wood. Such composite can be widely used in fields of construction, traffic and interior decoration, which greatly enhanced the utilization of low-valued wood material instead of high-quality wood.

Durability Improvement of Bio-Based Material by Polymer

Bio-based materials such as wood, bamboo, bio-straw material are vulnerable to degradation by microorganisms and susceptible to change in dimension under humidity, which greatly reduced their service life. In this study, a novel thought was inspired from the unique porous structure of bio-based material that durability of wood may be capable of being improved by generating polymer in situ the special structure. Maleic anhydride (Man) and Styrene (St) were used to penetrate into wood for further copolymerization. SEM observation shows that polymer filled in wood porous structure and tightly contacted wood matrix (i.e. biopolymers), indicating strong interaction between them. FTIR analysis indicates that polymer chemically grafted onto wood matrix by reaction of anhydride group and hydroxyl group. As the amount of hydroxyl groups greatly reduced for their reacting with polymer, the dimensional stability of wood immersing in water was improved; and as the reaction of wood with polymer, the biopolymers were wrapped by resultant polymer, preventing the sample from attack of microorganisms, thus decay resistance of treated wood against microorganisms was greatly improved. Both of them contributed to the improvement of wood durability.

Study on the Mechanism of the NaCl Influenced on the Movement of Water Molecular in the Wood

This paper aimed to investigate the influence of NaCl to water molecular movement. The interpretation is that NaCl could change structure of microscopic capillary in wood and increase energy consumption for water movement in capillary. Crystallized of NaCl in capillary made the pipe diameter diminished, resulted in the reduce of movement velocity for water, at the same time the adsorbed water increased, which leaded to consume more energy to destroy this bond force between adsorbed water and wood or NaCl.

Performance of Wood-Polymer Composite Prepared by In Situ Synthesis of Terpolymer within Wood

In order to improve the value-added applications of low-quality wood, a novel composite, wood-polymer composite, was fabricated by in-situ terpolymerization of MMA, VAc and St within wood porous structure. The structure of the composite and the reaction of monomers within wood were both analyzed by SEM and FTIR, and the mechanical properties were also evaluated. The SEM observation showed that the polymer mainly filled up wood pores, suggesting good polymerizating crafts. The FTIR results indicated that under the employed crafts, three monomers terpolymerized in wood porous structure, and grafted onto wood matrix through reaction of ester group from monomers and hydroxyl group from wood components, suggesting chemical combination between the two phases. The mechanical properties of the wood-polymer composite involving modulus of rupture, compressive strength, wearability and hardness were improved 69%, 68%, 36% and 210% over those of untreated wood, respectively. Such method seems to be an effective way to converting low-quality wood to high-quality wood.

Green Chemical Treatment of Natural Wood Material for Decay Resistance by 3-iodo-2-propynyl butyl carbamate (IPBC) with Supercritical CO2 as a Carrier Solvent

In order to improve the decay resistance of wood as the renewable natural material of biological origin, an organic preservative, 3-iodo-2-propynyl butyl carbamate (IPBC), was penetrated into wood matrix by supercritical CO2 as a carrier solvent. And the effectiveness of penetrating IPBC into wood matrix through SC-CO2 was also examined in terms of preservative distribution, leachability resistance of preservative as well as decay resistance of wood. The results indicate that the optimum penetration craft under the adopted conditions was pressure: 19MPa, temperature: 35°C, pressure time: 2.5h and time for releasing pressure: 20min. And under the optimum condition, the mechanical properties of SC-CO2 treated wood were not significantly affected. SEM-EDX analysis indicate that IPBC mainly distributed in wood matrix due to the higher penetration of supercritical CO2 as a carrier solvent, and its leachability was remarkably reduced after such penetration. The decay resistance of SC-CO2 treated wood against fungi attack was improved 90.96% over untreated wood, indicating effective decay resistance of wood after preservative penetration with SC-CO2.

Preparation and Characterization of Nanofibriled Cellulose via High Frequency Ultrasonication from Cornstalk

To obtain nanofibriled cellulose (NFC) with uniform diameter and high aspect ratio, chemical pretreatment was employer to remove the hemicellulose and lignin of cornstalks with further ultrasonic treatment. The prepared samples were characterized by SEM, TEM, FTIR, XRD, and TG. Results showed: The obtained NFC possessed the uniform diameter of about 25 nm and high aspect ratio (>300). The crystalline type of NFC was cellulose I type. The NFC with high crystallinity, high aspect ratio, and nanoscale is a newly great potential nanomaterial in different fields.