Papers by Author: Yong Feng Li

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Authors: Yong Feng Li, Xiao Ying Dong, Yi Xing Liu
Abstract: The fast-growing poplar wood, Populus ussuriensis Kom, was prepared into wood-polymer composite by the in-situ polymerization of methyl methacrylate (MMA) and styrene (St) under vacuum/pressure and subsequent catalyst-thermal conditions. SEM observation, FTIR, XRD and DMA analysis indicated that the resulted polymer well filled up wood cell lumen in an amorphous form and physically reinforce wood matrix, which resulted in the improvement of glass transition temperature and storage modulus of wood. Such method could endow low-quality wood with potential value-added applications.
826
Authors: Yong Feng Li, Yi Xing Liu, Yun Lin Fu, Qing Lin Wu, Xiang Ming Wang
Abstract: 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.
495
Authors: Jian Li, Yong Feng Li, Xin Meng, Yi Xing Liu
Abstract: Wood-PMMA composite was manufactured by impregnating methyl methacralyte (MMA) monomers into wood porous structure, followed by in-situ polymerization through catalyst-thermal treatment. The structure was simply analyzed by SEM and FTIR, and its durability was also examined. The results indicate that PMMA polymer generated in wood cellular structure, and interacted with wood cell walls, resulting in chemical combination between them. The durability involving dimensional stability, water repellency, decay resistance as well as acid resistance was whole improved over untreated wood. Such composite enhancing wood values can be used as structural furniture material and traffic material.
830
Authors: Yong Feng Li, Duo Jun Lv, Chi Jiang, Yi Xing Liu, Hong Yue Zhang
Abstract: A new composite, wood-polymer composite, was fabricated by formation of poly (methyl methacrylate) in wood cellular structure. Methyl methacrylate (MMA) monomer and a few of 2,2'- azobisisobutyronitrile (AIBN) as an initiator, as well as several drops of pyrimidine as catalyst were first impregnated into wood porous structure under a pressure condition, and then initiated for thermal polymerization through a catalyst-thermal treatment. The mechanical properties of the composite were tested, and the composite was also analyzed by SEM and DSC to further correlate its performance. The results indicated that the modulus of rupture, modulus of elasticity, compression strength and hardness of Wood-PMMA Composite were improved by 68.28%, 110.27%, 62.43%, 357% over those of Untreated Wood, respectively. The SEM observations showed that PMMA generated and filled up wood pores under the employed conditions, and thus reinforced the mechanical properties of wood. DSC analysis suggested that Wood-PMMA Composite was more thermal stability than Untreated Wood as the formation of PMMA within wood pores.
640
Authors: Yong Feng Li, Xin Meng, Jian Li, Yi Xing Liu
Abstract: 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.
181
Authors: Yong Feng Li, Bao Gang Wang, Qi Liang Fu, Yi Xing Liu, Xiao Ying Dong
Abstract: 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.
1165
Authors: Yun Lin Fu, Yong Feng Li, Yi Xing Liu, Bao Gang Wang
Abstract: A novel Wood-Polymer Composite, Wood-PSt composite combining both advantages of wood and polystyrene was fabricated by determining the polymerization craft of monomer in wood porous structure through impregnating monomer into wood pores and followed by in-situ polymerization through a thermal-catalyst treatment. The performance was examined, and its structure was also characterized by SEM and FTIR. The results indicate that the optimum polymerizing craft is: 80oC, 8h and 3% AIBN. Under the optimum craft, the mechanical properties involving modulus of elasticity and compression strength were linearly increased with content of polystyrene. SEM and FTIR show that styrene polymerized under the employed polymerization craft, and the resultant polystyrene relatively full generated in wood cellular structure, in accordance with the results of the optimum polymerizing craft. Such composite having good mechanical properties and biomass features can be widely used in fields of construction, traffic and furniture.
1419
Authors: Yong Feng Li, Yi Xing Liu, Xiu Rong Li, Jian Li, Xiang Ming Wang
Abstract: A novel biomass composite, wood-polymer composite with potential good mechanical properties, durability and environmental characteristic capable of applying in fields of construction and traffic as structural material, was prepared by generating high-performance polymer from in situ polymerization of styrene in wood porous structure. The vinyl monomer, styrene, combing with 1wt% AIBN as an initiation, was first impregnated into wood porous structure under a vacuum/pressure condition, and then in situ polymerized through a thermal treatment. The structure of the resultant composite was characterized by SEM, FTIR and XRD. Results show that styrene polymerized into polystyrene through free radical polymerization, and the resultant polymer fully filled in wood porous structure in a column form, partly contacting wood matrix. FTIR analysis indicates that polystyrene generated into wood pores, indicating weak interaction between them. XRD analysis suggests that the polystyrene generated into wood pores mainly existed in an amorphous form.
491
Authors: Xin Meng, Yong Feng Li, Jian Li, Yi Xing Liu
Abstract: A new composite, wood-polymer composite, was fabricated by formation of poly (methyl methacrylate) in wood cellular structure. Methyl methacrylate (MMA) monomer and a few of 2,2'- azobisisobutyronitrile (AIBN) as an initiator, as well as several drops of pyrimidine as catalyst were first impregnated into wood porous structure under a pressure condition, and then initiated for thermal polymerization through a catalyst-thermal treatment. The structure of Wood-PMMA Composite was characterized by SEM, FTIR, XRD, and its thermal stability was also examined. The results indicate that PMMA polymer generated in wood cellular structure as an amorphous form, and interacted with wood cell walls, resulting in chemical combination between them. The thermal stability of Wood-PMMA composite was higher than untreated wood under 450°C.
971
Authors: Yong Feng Li, Yi Xing Liu, Feng Hu Wang, Duo Jun Lv, Chi Jiang
Abstract: Inspired from the natural porous structure of wood, a novel wood-polymer composite combining both advantages of wood with high strength-to-weight ratio as a natural renewable resource and polymer as a reinforcer was manufactured by synthesis of terpolymer of methyl methacrylate (MMA), Styrene (St) and Vinyl Acetate (VAc) inside wood. The three kinds of monomers with a few of 2,2'- azobisisobutyronitrile (AIBN) as an initiator, as well as some additives were first impregnated into wood porous structure under a pressure condition, and then initiated for terpolymerization through a catalyst-thermal treatment. The impregnating conditions containing pressure value and pressure time, and polymerizing crafts including heating temperature and heating time, as well as additive content were confirmed according to rate of monomer loading and rate of polymer loading inside wood. Results indicate that among these influencing factors, pressure and temperature were the significant influencing factors; and the rate of monomer loading and rate of polymer loading linearly positive correlated to them, respectively. SEM observation shows that the terpolymer fully filled in wood porous structure under the optimum manufacturing craft.
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