木材皺縮動力機制的初步探討——液體張力的測量及外力對皺縮的影響.pdf

1、南京林業(yè)大學碩士學位論文木材皺縮動力機制的初步探討——液體張力的測量及外力對皺縮的影響姓名：陳振興申請學位級別：碩士專業(yè)：木材科學與技術指導教師：莊壽增20070601Studyonthedynamicmechanismofwoodcollapse——measurementofliquidtensionandeffectofexternalforceoncollapseAbstractSincelongago，thewoodcollap

2、sesourcedynamicisthoughttoresultfromthetensilecapillaryforcescausedbytheairwatermeniscusonpitmembraneThistensilecapillaryforcemayamounttoseveralmegapascals，whichcausesthewoodcellcollapseHoweverrecentlysomeresearchresults

3、ofthebotanyandthephysicsactuallyindicatedthatthedirectlymeasuredliquidnegativepressurevalueinthexylemislowerthantheoreticalvalue，andpossiblythenegativepressureinxylemmaynotbelowerthan1MPaTheseresearchresultsproposedchall

4、engetocapillarytensiontheoryinthewoodcollapsemechanismresearchItisnecessarytofurtherstudythecapillarytensiontheorywiththenewangleofviewThispaperisaboutresearchofthewoodcollapsedynamicmechanismattheearlierperiodreferstoth

5、eglassplateliquidtensionmeasuringtechniquewhichisprovidedbythepredeeessorstudiesandfurtherstudiestherelationshipbetweenradiusofcurvatureofairwatermeniscusandthefiquidtensionTheexperimentalresultindicatesthatalthoughthera

6、diusofcurvatureofairwatermeniscusdifferentgreatlythereisnotremarkabledifferencebetweenvaluesofthewatt“filmtensionandthereisnoinevitablerelationbetweenthewaterfilmtensionandtheradiusofcurvatureofairwatermeniscusThisresear

7、chresultsproposesoppugntopointofviewthatnegativepressurecausedbytensilecapillaryforcesistheSOUlV：cdyuamicofwoodcollapseandthedynamicvalueofwoodcollapsedependedontheapertureofporeonpitmembraneTheexperimentalresultalsoshow

8、sthatthewatertensiondifferenceisnotremarkablewhentheradiusofcurvatu把ofairwatermeniscusdifferentgreatlyandwithrelativelythesamewaterfilmthickness。andthewaterfilmtensionispossiblyrelatedwiththewaterfilmthicknessThisphenome

9、nonwaitsforthefurtherthoroughresearchThispaperalso∞lectsthedombeyiasthestudyobjeetwhichiseasytocollapse，andinspectseffectofexternalforceonwoodcollapseTheexperimentalresultindicatesthatwhenwatersaturatedwoodisdriedtofiber

10、saturationpointunder70℃dryingconditionsthe04MPatensilestresscausedthewoodcollapsequantitydrop277％：andwhenthecollapsedwoodistreatedunder9095。Csteaming，the04MPacompressedstresshasbeencompletelysuppressedcollapserestoration

11、Thisindicatesthatthebiggesttensionwhichcauseswoodcollapsecertainlyisnottobepossiblybig，andtheaveragecollapserestoresdynamicispossiblysmallerthan04MPa芻，Keyword：collapse；dynamicmechanism；liquidtension；effectofexternalf，orc