2023年12月2日發(作者:漢堡包的簡筆畫)

林業工程學報,2020,5(3):59-65JournalofForestryEngineeringDOI:10.13360/j.issn.2096-1359.201907037栓皮櫟軟木動態黏彈性研究畢俊杰,王慶國,吳世謙,宋孝周?(西北農林科技大學林學院,陜西楊凌712100)摘 要:軟木是從栓皮樹上采剝的樹皮,是一種天然可再生的生物質材料。通過對軟木的動態黏彈性進行研究,可以揭示許多關于軟木材料結構和分子運動的相關信息。本試驗主要運用動態力學分析技術研究了栓皮櫟軟木的動態黏彈性,并和國外栓皮櫧軟木進行了對比。結果表明:在不同測試頻率條件下,再生栓皮櫟軟木的儲能模量(E′)均隨溫度升高而呈現降低趨勢,損耗因子(tanδ)曲線主要出現了3個明顯的損耗峰,對應的3個損耗過程分別由軟木脂無定形區發生玻璃化轉變、軟木中有關成分發生熔融和吸著水的損失、纖維素和半纖維素發生熱軟化或降解所引起。再生栓皮櫟軟木分別沿軸向、徑向和弦向進行拉伸測試時,E′、損耗模量(E″)和tanδ曲線的變化趨勢基本一致,但在相同測試溫度下,E′和E″在3個方向存在明顯差異。在本試驗條件下,栓皮櫟和栓皮櫧軟木存在不同溫度的損耗峰,主要表現為初生和再生栓皮櫟軟木的tanδ曲線分別在-10和-19℃出現一個損耗峰,而再生栓皮櫧軟木對應的損耗峰出現在14℃。關鍵詞:栓皮櫟軟木;動態黏彈性;儲能模量;損耗模量;損耗因子中圖分類號:S781.3 文獻標志碼:A 文章編號:2096-1359(2020)03-0059-07開放科學(資源服務)標識碼(OSID):StudyondynamicviscoelasticityofcorkfromQuercusvariabilisBIJunjie,WANGQingguo,WUShiqian,SONGXiaozhou?(CollegeofForestry,NorthwestA&FUniversity,Yangling712100,Shaanxi,China)Abstract:CorkisthebarkmainlyfromQuercusvariabilisinChinaandQuercussurberinEuropeandAfrica.Itisalsoanaturalrenewablebiomassmaterialwithmanyappreciatedproperties,suchaslightweight,lowpermeability,lowther?malconductivity,soundabsorption,heatinsulation,wear?resistanceandchemicalstability.Themaincomponentofcorkissuber,lignin,polysaccharidesandextractables.Corkiswidelyusedinmanyfields,suchascorksealingmaterial,heatinsulationlayer,buildinganddecorationmaterials.Corkwouldbeaffectedbythechangingmagnitudeanddirectionofforceinthepracticalapplication,showingtwodifferentmechanismsofdeformation,namely,elasticityandviscosity,whichbelongstotheviscoelasticityofcork.Undertheactionofthecyclicalternatingstress(strain),therearestrain(stress)hysteresisandmechanicalloss,whichisthedynamicviscoelasticityofcork.Bystudyingthedynamicviscoelasticityofcork,thechangerulesofthestoragemodulus,lossmodulusandlossfactorwithtemperaturewerees?tablished.Theserulescanrevealtherelevantinformationofthecorkmaterialstructureandmolecularmovement.There?searchresultswereofgreatsignificancetodeterminetheprocessinganduseconditionsofcorkmaterials,beingusedtoevaluatetheimpactresistance,soundabsorptionanddampingcharacteristicsofthecork.ThedynamicviscoelasticityofthecorkfromQ.variabiliswasmainlyinvestigatedbythedynamicmechanicalanalysisandcomparedwiththatofthecorkfromQ.surber.TheresultsshowedthatthestoragemodulusofthereproductioncorkfromQ.variabilisdecreasedwiththeincreaseoftemperatureunderdifferenttestfrequencies,andtherewerethreeobviouspeaksinlossfactorcurves.Thethreelossprocesseswerecausedbytheglasstransitionintheamorphouszoneofsuberin,meltingofrelatedcomponentsinthecorkandlossofadsorbedwater,andthermalsofteningordegradationofcelluloseandhemicellulose,respectively.WhenthereproductioncorkfromQ.variabiliswastestedalongtheaxial,radialandtangentialdirections,respectively,thechangetrendsofstoragemodulus,lossmodulusandlossfactorcurveswerebasicallythesame.Whileatthesametesttemperature,thestoragemodulusandlossmoduluswereobviouslydifferentinthreedirections.ThecorkfromQ.variabilisandQ.surberhadlosspeaksatdifferenttemperaturesundertheexperimentalconditionsofthisre?search.ThelosspeaksofthevirgincorkandreproductioncorkfromQ.variabilisappearedat-10and-19℃,respec?收稿日期:2019-07-22 修回日期:2019-11-08基金項目:國家自然科學基金(31470583)。作者簡介:畢俊杰,男,研究方向為木材科學與技術。通信作者:宋孝周,男,教授。E?mail:xzhsong@163.com
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