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Nail Holding Performance of Self-Tapping Screws on Masson Pine and Chinese Fir Dimension Lumbers

Journal of Renewable Materials 2023年第10期11卷 3725-3738页

作者： De Li Bengang Zhang Yuan Tu Guoming Xiao Meifen Tian Xiaoxue Xu Xiao Zhong Qiaoyan Zhang Zhigang Wu jiankun liang College of Forestry Guizhou UniversityGuiyang550025China Forestry Science and Technology Promotion Station Xifeng County Bureau of Natural ResourcesGuiyang551100China Forest Park Management Section Zhazuo State-Owned Forest FarmGuiyang550299China College of Civil Engineering Kaili UniversityQiandongnan556011China

Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects of the diameter of the self-tapping screw and the guiding bores on the nail holding performance on different sections of Masson pine and Chinese fir dimension lumbers were mainly explored.The results showed that:(1)The nail holding strength of the tangential section was the maximum,followed by that of the radial section,and that of the cross section was the minimum.(2)The nail holding strength of Masson pine was higher than that of Chinese fir.(3)The nail holding strength grew with the increase in the diameter of self-tapping screws,but a large diameter would lead to plastic cracking of the timber,thus further affecting the nail holding strength.Masson pine and Chinese fir reached the maximum nail holding strength when the diameter of self-tapping screws was 3.5 mm.(4)Under a large diameter of screws,prefabricated guiding bores could mitigate timber cracking and improve its nail holding strength.(5)Prefabricated guiding bores were more necessary for the screw connection of Masson pine.The results obtained could provide a scientific basis for the screw connection design of Masson pine and Chinese fir timber structures.

关键词： Masson pine Chinese fir self-tapping screws nail holding performance

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Study on the Soy Protein-Based Adhesive Cross-Linked by Glyoxal

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Journal of Renewable Materials 2021年第2期9卷 205-218页

作者： Zhigang Wu jiankun liang Hong Lei Bengang Zhang Xuedong Xi Lifen Li Yunnan Provincial Key Laboratory of Wood Adhesives and Glued Products Southwest Forestry UniversityKunming650224China College of Forestry Guizhou UniversityGuiyang550025China Kaili University Qiandongnan556011China

Based on the ESI-MS and ^(13)C-NMR analysis of the forms of glyoxal in acidic and alkaline solutions,the soy-based adhesive cross-linked by glyoxal was prepared in this work.The results showed that glyoxal existed in water in different forms at different pH levels.Under alkaline conditions,glyoxal transformed to glycolate through the intramolecular disproportionation reaction.Under acidic conditions,although some of glyoxal transformed to glycolate as what happened under alkaline conditions,most of glyoxal molecules existed in the form of fiveor six-membered cyclic ether structure.No ethylene tetraol or free aldehyde group was actually detected under these conditions.Although glyoxal reacted with soy protein under both acidic and alkaline conditions,alkaline conditions were more favorable for the improvement of mechanical performance and water resistance of soybased adhesives than acid conditions.

关键词： Glyoxal soy protein-based adhesive cross-link

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Plasma Treatment Induced Chemical Changes of Alkali Lignin to Enhance the Performances of Lignin-Phenol-Formaldehyde Resin Adhesive

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Journal of Renewable Materials 2021年第11期9卷 1959-1972页

作者： Zhigang Wu Sicheng Chen jiankun liang Lifen Li Xuedong Xi Xue Deng Bengang Zhang Hong Lei College of Forestry Guizhou UniversityGuiyang550025China Kaili University Qiandongnan556011China ENSTIB-LERMAB University of LorraineEpinal88051France Yunnan Provincial Key Laboratory of Wood Adhesives and Glued Products Southwest Forestry UniversityKunming650224China

Alkali lignin was processed by plasma and then used in modification of phenol formaldehyde resin in this study.Chemical structural changes of lignin which was processed by plasma as well as bonding strength,tensile property,curing performance and thermal property of the prepared phenol formaldehyde resin which was modified by the plasma processed lignin were analyzed.Results demonstrated that:(1)Alkali lignin was degraded after the plasma processing.The original groups were destroyed,and the aromatic rings collected abundant free radicals and oxygen-containing functional groups like hydroxyls,carbonyls,carboxyls and acyls were introduced into increase the reaction activity of lignin significantly.(2)The introduction of alkali lignin decreased the free formaldehyde content and increased bonding strength and toughness of the prepared phenol formaldehyde resin,especially after the introduction of lignin treated with plasma.(3)The introduction of alkali lignin led to high curing temperature for the prepared phenol formaldehyde resin,but that was reduced by the plasma processed alkali lignin.(4)The introduction of alkali lignin could also increase thermal stability of phenol formaldehyde resin,but that was modified by plasma processed alkali lignin was better than the unprocessed lignin.Based on the results,the plasma processed lignin was used to modify phenol formaldehyde resin,which could increase the strength and toughness of phenol formaldehyde resin significantly.

关键词： Alkali lignin plasma phenol formaldehyde resin bonding performance tensile property

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Competitive polycondensation of model compound melamine-urea-formaldehyed(MUF)resin system by^(13)C NMR

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Journal of Bioresources and Bioproducts 2020年第1期5卷 60-66页

作者： jiankun liang Quan Li Zhigang Wu Guanben Du Taohong Li Hong Lei Lifen Li Kaili University Qiandongnan 556011China College of Forestry Guizhou UniversityGuiyang 550025China Yunnan Provincial Key Laboratory of Wood Adhesives and Glued Products Southwest Forestry UniversityKunming 650224China

Melamine-urea-formaldehyde(MUF)resin is an excellent adhesive in the field of wood adhe-sives,however the competition mechanism is questionable which affects the structure control and performance optimization of the resin.In this study,the competitive resin synthesis poly-condensation reaction of MUF system under alkaline condition was studied based on the model compound 1,3-dihydroxymethyl urea(UF_(2))and melamine(M)system,and the competitive reac-tion mechanism in the system was deduced by^(13)C NMR quantitative analysis.The results show that the energy barrier of hydroxymethylation of melamine is lower than that of urea,and the priority of hydroxymethylation is lower;the addition of melamine results in a large amount of hy-drolysis of UF_(2),and the formed free formaldehyde,resulting in hydroxymethylation of melamine;there is obvious polycondensation reaction in UF_(2)+M system,mainly from the relationship be-tween hydroxymethylurea and melamine or hydroxymethylmelamine.The type I bridge bond structure of polycondensation mainly comes from the reaction of UF_(2) and M,which is difficult to form the type II bridge bond.At low molar ratio,the formation of bridge bond is superior to that of ether bond.With the increase of molar ratio,the formation of ether bond shows advantages,but there is obvious competition between them.There may be competitive presence of the UF self-condensation products,melamine-formaldehyde(MF)self-condensation products and MUF co-condensed products after the polycondensation reaction.

关键词： Model compound Melamine-urea-formaldehyde(MUF) Copolycondensation Competitiveness

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Crosslinking Mechanism of Soy Protein-based Adhesives based on Glyoxal and a Compound of Protein Model

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Journal of Wuhan University of Technology(Materials Science) 2023年第4期38卷 942-950页

作者：曹龙 liang jiankun ZHANG Qiaoyan XI Xuedong 吴志刚雷洪 Yunnan Provincial Key Laboratory of Wood Adhesives and Glued Products Southwest Forestry UniversityKunming650224China College of Civil Engineering Kaili UniversityQiandongnanKaili556011China Zhazuo State-owned Forest Farm Guiyang550299China College of Forestry Guizhou UniversityGuiyang550025China School of Chemistry Materials Engineering Zhejiang A&F UniversityHangzhou311300China

The crosslinking mechanism of glyoxal and asparagine was analyzed,and the relationship between the mechanism and practical performances of soy protein-based adhesives was also discussed.It is shown that when pH=1 and 3,glyoxal reacted with asparagine in the form of major cyclic ether compounds.When pH=5,glyoxal reacted with asparagine in two structural forms of sodium glycollate and cyclic ether compounds.However,amidogens of asparagine were easy to develop protonation under acid conditions.Supplemented by the instability of cyclic ether compounds,the reaction activity and reaction degree between glyoxal and asparagine were relatively small.Under alkaline conditions,glyoxal mainly reacted with asparagine in the form of sodium glycollate.With the increase of pH,the polycondensation was more sufficient and the produced polycondensation products were more stable.The reaction mechanism between glyoxal and asparagine had strong correspondence to the practical performances of the adhesives.Glyoxal solution could develop crosslinking reactions with soy protein under both acid and alkaline conditions.Bonding strength and water resistance of the prepared soy protein-based adhesives were increased significantly.When pH>7,glyoxal had relatively high reaction activity and reaction intensity with soy protein,and the prepared adhesives had high crosslinking density and cohesion strength,showing relatively high bonding strength,water resistance and thermal stability.

关键词： soy protein wood adhesives glyoxal model compounds crosslinking

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The Crosslinking Mechanism of Camellia Oleifera Protein Adhesive with Amine Resins by ^(13)C-NMR and ESI-MS

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Journal of Wuhan University of Technology(Materials Science) 2023年第2期38卷 460-466页

作者： DENG Xue ZHANG Bengang liang jiankun LI Lifen WU Zhigang LEI Hong College of Forestry Guizhou UniversityGuiyang550025China Yunnan Provincial Key Laboratory of Wood Adhesives and Glued Products Southwest Forestry UniversityKunming650224China College of Civil Engineering Kaili UniversityQiandongnan556011China

A new protein wood adhesive was studied with Camellia oleifera protein.Formaldehyde and N-(2)-L-Ala-L-Gln(LAG)were used as the model compounds of amino resins and Camellia oleifera protein,aiming to provide scientific foundations for the improvement and applications of Camellia oleifera protein adhesive by the reaction of model compounds.The experimental results demonstrate that,under alkaline conditions,formaldehyde is easier to react with Camellia oleifera protein by quicker reaction and lower curing temperature.Under acid conditions,amino hydroxymethylated structure of aliphatic series from LAG is difficult to form stable reactive intermediates and further polycondensation.Hydroxymethylation of end acylamino and peptide bond amino from LAG is relatively weak.Under alkaline conditions,the free aliphatic amino and acylamino of LAG both can make hydroxymethylation reaction with formaldehyde.In the polycondensation,hydroxymethyl amide is the initial structure and the reactive intermediate is produced by E1cb reaction of hydroxymethyl amide.Methylene bridge bonds and methylene ether bonds are structures of the polycondensation products,which are competing reactions.The former is mainly formed by the reaction between alkaline reactive intermediate and amino of aliphatic series,and the latter is produced by the reaction of reactive intermediate and amino of hydroxymethyl aliphatic series with hydroxymethyl amide.

关键词： Camellia oleifera protein wood adhesive ESI-MS NMR

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近二十年我国高尔夫学术研究热点及趋势演变分析——基于CiteSpace的图谱化分析

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中州大学学报 2024年第1期41卷 83-89页

作者：梁建坤姚洁张芸芸张佩佩郑州工业应用技术学院体育学院河南郑州451100 四川科技职业学院体育学院四川眉山620500

为揭示近二十年国内高尔夫研究的热点与趋势演变,借助CiteSpace对CNKI数据库2000至2020年间国内高尔夫研究核心期刊文献及学位论文的题录信息进行统计和可视化分析。结果显示:在作者合作网络中,韩烈保、郁小平、刘照辉等处于核心位置,... 详细信息

为揭示近二十年国内高尔夫研究的热点与趋势演变,借助CiteSpace对CNKI数据库2000至2020年间国内高尔夫研究核心期刊文献及学位论文的题录信息进行统计和可视化分析。结果显示:在作者合作网络中,韩烈保、郁小平、刘照辉等处于核心位置,辐射带动效应明显。近二十年国内高尔夫研究的热点主题分为高尔夫球场治理、高尔夫运动技术优化、高尔夫球产业发展以及休闲体育人才培育四个方面。国内高尔夫研究的趋势演变为2000—2009年(高尔夫球场治理)、2010—2015年(高尔夫球产业发展及人才培育)、2016—2020年(高尔夫运动技术研究),其中对于高尔夫球员的技术动作,采用高新设备进行分析是近年来研究的前沿问题,需进行重点关注。

关键词： CiteSpace 高尔夫球运动可视化分析

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Study on Camellia Oleifera Protein based Wood Adhesive by Epoxy Resin and Its Crosslinking Mechanism

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Journal of Wuhan University of Technology(Materials Science) 2021年第4期36卷 607-613页

作者：陈思成 liang jiankun ZHANG Bengang 吴志刚雷洪 LI Lifen YANG Shoulu College of Forestry Guizhou UniversityGuiyang 550025China School of Architectural Engineering Kaili UniversityQiandongnan 556011China Yunnan Provincial Key Laboratory of Wood Adhesives and Glued Products Southwest Forestry UniversityKunming 650224China Guizhou Academy of Forestry Guiyang 550005China

Epoxy resin (EPR) was used to crosslink with Camellia oleifera Abel.protein to prepare wood adhesive,and the bonding performance and curing characteristics of which were mainly investigated,and the synthesis mechanism was also discussed by using model compounds.The experimental results show that EPR can significantly improve the bonding performance of Camellia oleifera Abel.protein-based adhesive,and the maximum of which reaches 0.72 MPa satisfies the strength requirement of Type II plywood in GB/T 17657-2013.After alkali treatment,the protein can more easily crosslink with EPR at low curing temperature,and the adhesive has high degree of crystallinity of curing products,high degree of crosslinking reaction,and high bonding strength.The reaction mechanism of EPR-modified Camellia oleifera Abel.protein adhesive can be divided into resinification phase and curing phase.

关键词： Camellia oleifera protein epoxy resin crosslinking wood adhesive

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儿童梨状窝瘘的诊断和治疗

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中华医学杂志 2016年第39期96卷 3156-3159页

作者：刘涛温哲梁奇峰刘斐王哲梁鉴坤广州市妇女儿童医疗中心小儿外科 510623

目的探讨儿童梨状窝瘘的诊断和治疗方法.方法回顾性分析广州市妇女儿童医疗中心2013年5月至2015年8月收治的8例梨状窝瘘患儿的临床资料,患儿年龄11个月～12岁,中位年龄4岁6个月;本组患儿的临床表现为反复颈部感染（典型的红、肿、热... 详细信息

目的探讨儿童梨状窝瘘的诊断和治疗方法.方法回顾性分析广州市妇女儿童医疗中心2013年5月至2015年8月收治的8例梨状窝瘘患儿的临床资料,患儿年龄11个月～12岁,中位年龄4岁6个月;本组患儿的临床表现为反复颈部感染（典型的红、肿、热、痛表现）,其中2例伴随急性甲状腺炎;术前影像学检查主要为上消化道钡剂造影检查和颈部CT检查（平扫、增强和重建）;术中联合使用喉内镜检查并行外科手术治疗.结果术前影像学检查明确7例患儿瘘管为单侧,且均位于左侧,1例患儿为双侧（左侧发病）;术中进一步明确瘘管位于下角下3例、下角前5例;8例患儿均行瘘管切除术,其中1例双侧瘘管患儿因右侧无症状,仅行左侧瘘管切除术.所有患儿术中均无食管损伤、无神经损伤,术后患儿均无声音嘶哑、无呛咳症状发生.术后随访7个月～2年10个月,患儿均恢复良好,无复发.其中双侧瘘管患儿右侧未再发,无声音嘶哑、呛咳等术后并发症发生.结论术前联合上消化道钡剂造影检查和颈部CT检查可以提高儿童梨状窝瘘的术前诊断率.术中联合经喉内镜检查可进一步明确瘘管内口位置、辨别瘘管走行,达到一次性根治的目的.

关键词：儿童消化系统瘘体层摄影术,螺旋计算机喉镜检查

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单宁-糠醇-异氰酸酯热固性树脂砂轮片的制备与性能分析

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功能材料 2016年第6期47卷 228-234页

作者：张俊杜官本梁坚坤席雪冬北京林业大学材料科学与技术学院北京100083 西南林业大学云南省木材胶黏剂及胶合制品重点实验室昆明650224

通过单宁、糠醇与异氰酸酯共缩聚树脂(TFI)为基质,氧化铝颗粒为研磨材料制备新型天然可回收砂轮片,研究了树脂的热性能及砂轮片的力学性能。结果表明,单宁、糠醇与异氰酸酯共缩聚树脂具有很高的玻璃转化温度,并且固化后硬度大。用其制... 详细信息

通过单宁、糠醇与异氰酸酯共缩聚树脂(TFI)为基质,氧化铝颗粒为研磨材料制备新型天然可回收砂轮片,研究了树脂的热性能及砂轮片的力学性能。结果表明,单宁、糠醇与异氰酸酯共缩聚树脂具有很高的玻璃转化温度,并且固化后硬度大。用其制备的砂轮片抗压强度较实验室制备酚醛树脂砂轮片高,同时与商业砂轮片(taber calibrate wheel H-18)相比,单宁-糠醇-异氰酸酯砂轮片具有更好的耐磨性能。因此未来采用TFI为基质制备的砂轮片替代酚醛树脂基砂轮片是可行的。

关键词：天然砂轮片单宁树脂力学性能耐磨性能氧化铝颗粒

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