作者机构：
[孙振宇; 张源; 左迎峰; 吴义强; 王张恒; 吕建雄] College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha;410004, China;Research Institute of Wood Industry, Chinese Academy of Forest, Beijing;100091, China;[孙振宇; 张源; 左迎峰; 吴义强; 王张恒] 410004, China
摘要：
This study was designed to solve the problem of large waste volume from bamboo processing residues in recent years. Using magnesium oxychloride (MO) cementitious material as the main material and bamboo residue (BR) as the reinforcing material, a BR/MO composite material was prepared. The effects of BR amount on the molding properties, mechanical strength, and water resistance of BR/MO composites were examined and discussed. Scanning electron microscopy (SEM), X-ray diffractometry (XRD), and thermogravimetric analysis were used to characterize composite microscopic morphology, crystalline structure, and heat resistance. The results showed that, when the BR content was 1.00% (by wt), the flowability of MO paste was beneficial to composite molding. Composite mechanical properties and water resistance were greatly affected by BR addition. When the BR content was 1.00%, composite compressive and bending strengths and softening coefficient all reached maximum values. Meanwhile, increases in water absorption by 24 h and decreases of contact angle were small. These results suggested that, when the BR content was 1.00%, composite mechanical properties and water resistance were the best and the mechanical strength also improved with extended composite storage time. SEM analysis indicated that BR played the role of a reinforcing phase in MO matrices. However, when the BR content exceeded 1.00%, interfacial bonding between BR and MO became less. XRD analysis showed that, with 1.00% BR content, composites showed more 5-phase crystals with high strength. This further explained the reason why this composite's mechanical properties were the best and the heat resistance not deteriorated due to BR, which was easily decomposed.
作者机构：
[周亚; 李萍; 张源; 袁光明; 吴义强; 左迎峰] College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha;410004, China;[王向军] Tianying (Guangdong) Wood Industry Technology Limited Company, Jiangmen;529700, China;[周亚; 李萍; 张源; 袁光明; 吴义强; 左迎峰] 410004, China
通讯机构：
College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha, China
期刊：
Journal of Materials Research and Technology,2020年9(1):1043-1053 ISSN：2238-7854
通讯作者：
Zuo, Yingfeng;Wu, Yiqiang
作者机构：
[Wu, Yiqiang; Yuan, Guangming; Zuo, YF; Li, Ping; Zuo, Yingfeng; Zhang, Yuan] Cent South Univ Forestry & Technol, Coll Mat Sci & Engn, Changsha 410004, Hunan, Peoples R China.;[Li, Ping] Xiangnan Univ, Coll Art & Design, Chenzhou 423000, Hunan, Peoples R China.;[Lu, Jianxiong] Chinese Acad Forestry, Res Inst Wood Ind, Beijing 100091, Peoples R China.
通讯机构：
[Zuo, YF; Wu, YQ] C;Cent South Univ Forestry & Technol, Coll Mat Sci & Engn, Changsha 410004, Hunan, Peoples R China.
关键词：
Chinese fir wood;Sodium silicate;Phenol formaldehyde oligomer;Respiratory impregnation;Comparative study
摘要：
To improve the properties and added value of Chinese fir wood, sodium silicate-modified Chinese fir wood (SSMCF) was prepared by respiratory impregnation method. Phenol formaldehyde oligomer-modified Chinese fir wood (PFOMCF) as control sample, the impregnation and reinforcement effects, water resistance of PFOMCF and SSMCF were compared. The results showed that the weight percentage gain, density growth rate, bending strength, compressive strength, and dimensional stability of SSMCF were clearly higher than those of PFOMCF, and the SSMCF showed a lower water absorption rate within 60 h. The impregnation and reinforcement effects, for SSMCF were better than those for PFOMCF. FT-IR, XRD, CONE, oligomer and TGA examinations were used to analyze the chemical structure, crystalline structure, flame retardancy, and heat resistance of these modified woods. The results indicated that Si-O-Si chemical bonding with high bond energy was formed in SSMCF, and there are possessed more hydrogen bonds in SSMCF than PFOMCF and that Si-O-Si chemical bonding with high bond energy was formed. Meanwhile, the weakened degree of the diffraction peak of SSMCF was much less than that of PFOMCF. These results explained the better mechanical properties and water resistance of SSMCF. Compared with PFOMCF, SSMCF had lower heat release rate (HRR), peak-HRR, mean-HRR, total heat release, smoke production rate, and total smoke production, and showed higher thermal decomposition temperature and residual rate. Inorganic sodium silicate was shown to be a better flame retardant, while SSMCF had good smoke suppression effects, thermal stability, and safety performance in the case of fire. (C) 2019 Published by Elsevier B.V.
摘要：
To improve the hydrophobicity and thermoplastic processability of starch, lactic acid esterified starch (LA-e-starch) was prepared by in-situ solid phase esterification with corn starch as the raw material and LA as the esterifying agent. Fourier transform infrared spectroscopy confirmed that the esterification reaction was successful. The optimal esterification efficiency of LA-e-starch was obtained when the LA proportion was 20% by mass, catalyst ratio at 3%, reaction temperature 80 degrees C and reaction time 2.5 h. LA-e-starch was characterized by scanning electron microscopy (SEM), contact angle (CA) analysis, X-ray diffractometry (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) as well as its water absorption rate evaluated. Results showed that in-situ solid phase esterification mainly occurred on starch granule surfaces and did not destroy the starch granularity. LA-e-starch surfaces were covered with a layer of polylactic acid resin, which caused starch granules to stick together. The initial contact angle of LA-e-starch was clearly larger than that of native starch and the water absorption rate lower than native starch in a 168 h test time, which showed that esterification effectively improved the hydrophobicity of starch. This esterification destroyed the crystalline structure of starch to some extent, resulting in a crystallinity reduction to 25.16%. In addition, the gelatinization temperature and enthalpy were lower than those of native starch. XRD and DSC analyses indicated that esterification modification increased starch thermoplasticity. Also, LA-e-starch exhibited better thermal stability than native starch, from which it was inferred that this application of esterification could improve the thermoplastic processability of starch modify the interfacial compatibility between starch and polymer resins.
摘要：
To improve the properties of polylactic acid-grafted-bamboo fiber/polylactic add (PLA-g-BF/PLA) composite, a compatible interface was constructed by adding nano-silica (nano-SiO2). The results showed that, with increased nano-SiO2 mass ratio, the composites' mechanical strength and water resistance were significantly improved. The composite with a 1.5% nano-SiO2 mass ratio exhibited the best mechanical properties and water resistance. Strain scanning results showed that the strain value at which the storage module (G') of the composite began to decrease was the largest with 1.5% nano-SiO2 and the G' and complex viscosity (eta*) of the composite also reached the best state at this point. The interfadal compatibility between PLA-g-BF and PLA was also confirmed to be the best at this mass ratio. SEM and TEM analyses indicated that, when the mass ratio of nano-SiO2 was 1.5%, nanoparticles were uniformly dispersed in the composite and PIA-g-BF and PLA in a state of integration. The addition of nano-SiO2 was beneficial for the crystallization and nucleation of PLA, and composite crystallinity with 1.5% nano-SiO2 reached the maximum value. With increased interfacial compatibility and crystallinity of the composite, the thermal stability was also best when the mass ratio of nano-SiO2 was 1.5%. (C) 2020 Elsevier B.V. All rights reserved.
通讯机构：
[Zuo, YF; Li, XJ] C;Cent South Univ Forestry & Technol, Coll Mat Sci & Engn, Changsha 410004, Peoples R China.
关键词：
Chinese fir wood;Sodium silicate;Fluorine sodium silicate;Reinforced;Leach resistance
摘要：
The mechanical properties, dimensional stability, and fire resistance of fast-growing Chinese fir wood was improved using a silicate-impregnation modification of Chinese fir as a green, safe and non-toxic method. However, the high leaching rate of silicate from impregnated wood has remained a problem. This study was aimed to prepare sodium silicate (Na2SiO3)-modified Chinese fir wood with leaching resistance using a cyclic increasing-pressure method, with sodium fluorosilicate (Na2SiF6) solution as the curing agent. Scanning electron microscopy and weight percentage gain results indicated that silicate effectively adhered to the wood interior and leaching tests showed that the weight leaching ratio of Na2SiO3/Na2SiF6-modified wood was increased by 25.97% and the water absorption rate reduced by 15.80%, compared to Na2SiO3-modified wood. Compressive and bending strength enhancements of 210 and 40.1%, over than that of natural wood, were observed. In addition, silica impregnation inside the cell walls and lumens were confirmed using Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). Thermogravimetric analysis (TGA) and cone calorimetry (CONE) analyses showed that the addition of sodium fluosilicate alleviated thermal decomposition and complete combustion of this treated wood and enhanced its flame retardancy. (C) 2020 The Author(s). Published by Elsevier B.V.
作者机构：
[左迎峰; 屠茹茹; 李萍; 周亚; 吴义强] College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha;410004, China;[左迎峰; 屠茹茹; 李萍; 周亚; 吴义强] 410004, China
通讯机构：
[Wu, Y.] C;College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha, China
作者机构：
[张源; 袁光明; 左迎峰; 吴义强] College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha, 410004, China;College of Art and Design, Xiangnan University, Chenzhou, 423000, China;Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing, 100091, China;[李萍] College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha, 410004, China, College of Art and Design, Xiangnan University, Chenzhou, 423000, China;[Lü J.] College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha, 410004, China, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing, 100091, China
通讯机构：
[Zuo, Y.] C;College of Materials Science and Engineering, China
摘要：
The in-situ reactive interfacial compatibilization and properties of polylactic acid-g-bamboo fiber (PLA-g-BF)/polylactic acid (PIA) composites, produced by blending with a three-component plasticizer, glycerol/formamide/tributyl citrate, were investigated. The PLA-g-BF/PLA composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermal gravimetric analyzer (TGA) and rotational rheometer, and the bending, tensile, and water resistance properties were also tested. The bending strength and elongation at break of PLA-g-BF/PLA composite reached 35.6 MPa and 5.59%, which increased by 19.3% and 30.1% relative to the ungrafted composites. The initial contact angle of the PLA-g-BF/PLA composite was 74.3 degrees, which was larger than that of the ungrafted composite (41.2 degrees), and the water absorption ratio reached 4.3% after 24 h, which was less than the unmodified material (6.1%). SEM results showed that PIA matrix showed smooth surfaces and the interfacial adhesion between modified BF and matrix PLA was greatly improved after grafting modification. The crystal structure results proved that the grafting treatment of BF strengthened the interfacial interactions between the filler BF and matrix PLA, and reduced the mobility of PLA molecular chain. The rotational rheometer illustrated that the initial storage modulus of PLA-g-BF/PLA composites was the largest and decreased slowly, which improved the processing properties of composites. (C) 2019 Elsevier B.V. All rights reserved.
摘要：
Three kinds of hydrophobic groups grafted starches of maleic anhydride grafted starch (MAH-g-starch), lactic acid grafted starch (LA-g-starch), and methyl acrylate grafted starch (MA-g-starch) were prepared by in situ solid phase polymerization. The results of Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) confirmed successful grafting. The grafting ratios of MAH-g-starch, LA-g-starch, and MA-g-starch were 6.50%, 12.45%, and 0.57%, respectively. Influenced by the grafting ratio, LA-g-starch had the best relative hydrophobicity and the largest molecular weight, and those for MA-g-starch were the worst. The surfaces of grafted starches were covered with graft polymer, with obvious surface roughness and bond degree of MAH-g-starch and LA-g-starch. The crystalline structure of grafted starches showed some damage, with LA-g-starch exhibiting the greatest decrease in crystallinity, and less of a change for MA-g-starch. Overall, the grafting reaction improved thermoplasticity, with LA-g-starch the most improved, followed by MAH-g-starch, and then MA-g-starch.
作者机构：
[李萍; 吴义强; 刘文杰; 左迎峰; 屠茹茹] College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha;410004, China;[吕建雄] Research Institute of Wood Industry, Chinese Academy of Forest, Beijing;100091, China;[李萍; 吴义强; 刘文杰; 左迎峰; 屠茹茹] 410004, China
通讯机构：
[Zuo, Y.] C;College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha, China
