Effects of Cell Wall Structure on Tensile Properties of Hardwood : Effect of down-regulation of lignin on mechanical performance of transgenic hybrid aspen. Effect of chemical degradation on mechanical performance of archaeological oak from the Vasa ship.

Wood is a complex material and the mechanical properties are influencedby a number of structural parameters. The objective of this study has been toinvestigate the relationship between the structure and the mechanical propertiesof hardwood. Two levels were of special interest, viz. the cellular stru...

Full description

Bibliographic Details
Main Author: Bjurhager, Ingela
Format: Doctoral Thesis
Language:English
Published: KTH, Fiber- och polymerteknik 2011
Subjects:
Online Access:http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-32190
http://nbn-resolving.de/urn:isbn:978-91-7415-914-1
id ndltd-UPSALLA1-oai-DiVA.org-kth-32190
record_format oai_dc
spelling ndltd-UPSALLA1-oai-DiVA.org-kth-321902013-01-08T13:07:22ZEffects of Cell Wall Structure on Tensile Properties of Hardwood : Effect of down-regulation of lignin on mechanical performance of transgenic hybrid aspen. Effect of chemical degradation on mechanical performance of archaeological oak from the Vasa ship.engBjurhager, IngelaKTH, Fiber- och polymerteknikStockholm : KTH Royal Institute of Technology2011tensile strengthtransgenic hybrid aspenlignin down-regulationthe Vasa shipchemical degradationlongitudinell draghållfasthettransgen hybridaspligninnedregleringVasaskeppetkemisk nedbrytningTECHNOLOGYTEKNIKVETENSKAPWood is a complex material and the mechanical properties are influencedby a number of structural parameters. The objective of this study has been toinvestigate the relationship between the structure and the mechanical propertiesof hardwood. Two levels were of special interest, viz. the cellular structureand morphology of the wood, and the ultra-structure of the cell wall. In thenext step, it was of interest to examine how the mechanical properties ofhardwood change with spontaneous/induced changes in morphology and/orchemical composition beyond the natural variation found in nature. Together, this constituted the framework and basis for two larger projects,one on European aspen (Populus tremula) and hybrid aspen (Populus tremulax Populus tremuloides), and one on European oak (Quercus robur). Amethodology was developed where the concept of relative density and compositemechanics rules served as two useful tools to assess the properties ofthe cell wall. Tensile testing in the longitudinal direction was combined withchemical examination of the material. This approach made it possible to revealthe mechanical role of the lignin in the cell wall of transgenic aspen trees,and investigate the consequences of holocellulose degradation in archaeologicaloak from the Vasa ship. The study on transgenic aspen showed that a major reduction in lignin inPopulus leads to a small but significant reduction in the longitudinal stiffness.The longitudinal tensile strength was not reduced. The results are explainableby the fact that the load-bearing cellulose in the transgenic aspen retained itscrystallinity, aggregate size, microfibril angle, and absolute content per unitvolume. The results can contribute to the ongoing task of investigating andpinpointing the precise function of lignin in the cell wall of trees. The mechanical property study on Vasa oak showed that the longitudinaltensile strength is severely reduced in several regions of the ship, andthat the reduction correlates with reduced average molecular weight of theholocellulose. This could not have been foreseen without a thorough mechanicaland chemical investigation, since the Vasa wood (with exception fromthe bacterially degraded surface regions) is morphologically intact and witha micro-structure comparable to that of recent oak. The results can be usedin the ongoing task of mapping the condition of the Vasa wood. QC 20110420Doctoral thesis, comprehensive summaryinfo:eu-repo/semantics/doctoralThesistexthttp://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-32190urn:isbn:978-91-7415-914-1Trita-CHE-Report, 1654-1081 ; 2011:14application/pdfinfo:eu-repo/semantics/openAccess
collection NDLTD
language English
format Doctoral Thesis
sources NDLTD
topic tensile strength
transgenic hybrid aspen
lignin down-regulation
the Vasa ship
chemical degradation
longitudinell draghållfasthet
transgen hybridasp
ligninnedreglering
Vasaskeppet
kemisk nedbrytning
TECHNOLOGY
TEKNIKVETENSKAP
spellingShingle tensile strength
transgenic hybrid aspen
lignin down-regulation
the Vasa ship
chemical degradation
longitudinell draghållfasthet
transgen hybridasp
ligninnedreglering
Vasaskeppet
kemisk nedbrytning
TECHNOLOGY
TEKNIKVETENSKAP
Bjurhager, Ingela
Effects of Cell Wall Structure on Tensile Properties of Hardwood : Effect of down-regulation of lignin on mechanical performance of transgenic hybrid aspen. Effect of chemical degradation on mechanical performance of archaeological oak from the Vasa ship.
description Wood is a complex material and the mechanical properties are influencedby a number of structural parameters. The objective of this study has been toinvestigate the relationship between the structure and the mechanical propertiesof hardwood. Two levels were of special interest, viz. the cellular structureand morphology of the wood, and the ultra-structure of the cell wall. In thenext step, it was of interest to examine how the mechanical properties ofhardwood change with spontaneous/induced changes in morphology and/orchemical composition beyond the natural variation found in nature. Together, this constituted the framework and basis for two larger projects,one on European aspen (Populus tremula) and hybrid aspen (Populus tremulax Populus tremuloides), and one on European oak (Quercus robur). Amethodology was developed where the concept of relative density and compositemechanics rules served as two useful tools to assess the properties ofthe cell wall. Tensile testing in the longitudinal direction was combined withchemical examination of the material. This approach made it possible to revealthe mechanical role of the lignin in the cell wall of transgenic aspen trees,and investigate the consequences of holocellulose degradation in archaeologicaloak from the Vasa ship. The study on transgenic aspen showed that a major reduction in lignin inPopulus leads to a small but significant reduction in the longitudinal stiffness.The longitudinal tensile strength was not reduced. The results are explainableby the fact that the load-bearing cellulose in the transgenic aspen retained itscrystallinity, aggregate size, microfibril angle, and absolute content per unitvolume. The results can contribute to the ongoing task of investigating andpinpointing the precise function of lignin in the cell wall of trees. The mechanical property study on Vasa oak showed that the longitudinaltensile strength is severely reduced in several regions of the ship, andthat the reduction correlates with reduced average molecular weight of theholocellulose. This could not have been foreseen without a thorough mechanicaland chemical investigation, since the Vasa wood (with exception fromthe bacterially degraded surface regions) is morphologically intact and witha micro-structure comparable to that of recent oak. The results can be usedin the ongoing task of mapping the condition of the Vasa wood. === QC 20110420
author Bjurhager, Ingela
author_facet Bjurhager, Ingela
author_sort Bjurhager, Ingela
title Effects of Cell Wall Structure on Tensile Properties of Hardwood : Effect of down-regulation of lignin on mechanical performance of transgenic hybrid aspen. Effect of chemical degradation on mechanical performance of archaeological oak from the Vasa ship.
title_short Effects of Cell Wall Structure on Tensile Properties of Hardwood : Effect of down-regulation of lignin on mechanical performance of transgenic hybrid aspen. Effect of chemical degradation on mechanical performance of archaeological oak from the Vasa ship.
title_full Effects of Cell Wall Structure on Tensile Properties of Hardwood : Effect of down-regulation of lignin on mechanical performance of transgenic hybrid aspen. Effect of chemical degradation on mechanical performance of archaeological oak from the Vasa ship.
title_fullStr Effects of Cell Wall Structure on Tensile Properties of Hardwood : Effect of down-regulation of lignin on mechanical performance of transgenic hybrid aspen. Effect of chemical degradation on mechanical performance of archaeological oak from the Vasa ship.
title_full_unstemmed Effects of Cell Wall Structure on Tensile Properties of Hardwood : Effect of down-regulation of lignin on mechanical performance of transgenic hybrid aspen. Effect of chemical degradation on mechanical performance of archaeological oak from the Vasa ship.
title_sort effects of cell wall structure on tensile properties of hardwood : effect of down-regulation of lignin on mechanical performance of transgenic hybrid aspen. effect of chemical degradation on mechanical performance of archaeological oak from the vasa ship.
publisher KTH, Fiber- och polymerteknik
publishDate 2011
url http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-32190
http://nbn-resolving.de/urn:isbn:978-91-7415-914-1
work_keys_str_mv AT bjurhageringela effectsofcellwallstructureontensilepropertiesofhardwoodeffectofdownregulationofligninonmechanicalperformanceoftransgenichybridaspeneffectofchemicaldegradationonmechanicalperformanceofarchaeologicaloakfromthevasaship
_version_ 1716509546535452672