英语专业学位文写作规范

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论文中英文摘 要

作者姓名:任俊莉

论文题目:蔗渣和麦草半纤维素分离,改性及其应用

作者简介:任俊莉,女,1978年4月出生,2004年9月师从于华南理工大学孙润仓教授,于2016年6月获博士学位.

中文摘 要

随着石油等化石资源储量的逐渐减少,以农业废弃物等可再生资源为原料生产化工新材料,用来补充和替代以石油为原料的化工产品,正成为一种新的发展趋势.很多国家特别是发达国家已将此列为经济和社会发展的重大战略.对我国这样一个化石资源短缺,人口众多,经济持续快速发展的大国,推动农林废弃物的高效转化利用,具有更突出的迫切性,这将是我国新世纪的工业结构调整与升级的重点战略.本论文以高附加值利用的农业废弃物蔗渣和麦草秸秆可再生资源为出发点,系统地研究了蔗渣和麦草秸秆半纤维素的分离以及结构鉴定,在此基础上研究了分离得到的半纤维素的醚化反应和酯化反应如:季铵化反应,羧基化反应,均相乙酰化反应以及月桂酰化反应等,并对得到的半纤维素衍生物作为湿部助剂在造纸中的应用做了初步探讨,得到的结论如下:1.提出了以蔗渣半纤维素为原料,3-氯-2-羟丙基三氯化氨CHMAC)为反应试剂,乙醇/水为反应介质,在碱的作用下合成出水溶性好,取代度低的阳离子型半纤维素聚合物的方法.系统地研究了碱的加入及用量,反应温度,反应时间,反应试剂用量对阳离子半纤维素取代度的影响.结果发现通过改变反应条件可以制备出一系列白色粉末状的取代度为0.0030.19的阳离子型半纤维素聚合物.采用傅立叶红外光谱FT-IR)和13C核磁共振13C-NMR)表征了改性半纤维素的结构,发现半纤维素在异相体系中的季铵化反应主要发生在半纤维素木聚糖单元C3位的羟基上.凝胶渗透色谱GPC)和热分析结果表明改性后的半纤维素有一定程度的降解,并且热稳定性有所降低.2.提出了一种在碱性水溶液中制备水溶性好,取代度高的阳离子型半纤维素聚合物的方法.以蔗渣半纤维素为原料,以3-氯-2-羟丙基三氯化铵CHMAC)或2,3-环氧丙基三氯化铵ETA)为反应试剂,在碱性水溶液中通过季铵化反应合成出取代度为0.010.54的阳离子型半纤维素.发现采用两次加碱的方法比一次加碱的方法得到的改性半纤维素的取代度高.另外,在相同条件下与CHMAC作季铵化试剂相比,发现使用ETA合成的阳离子半纤维素的取代度较高.凝胶渗透色谱分析结果改性过程中半纤维素发生明显的降解,比未改性半纤维素的重均分子量降低了33.0%46.8%.另外,热分析结果表明改性后半纤维素的热稳定性下降.JournalofAppliedPolymerScience,2007,105:3301-3308.)

英语专业学位文写作规范参考属性评定
有关论文范文主题研究: 关于纤维素的论文范文资料 大学生适用: 高校大学论文、硕士学位论文
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所属大学生专业类别: 本科论文怎么写 论文题目推荐度: 优质选题

3.发现了一种能够减少半纤维素降解且能够提高半纤维反应活性的溶剂体系.以二亚砜为均相反应介质,蔗渣半纤维素在催化剂碱的作用下与2,3-环氧丙基三氯化铵反应制备出一系列水溶性的,取代度为0.060.24的阳离子型半纤维素聚合物.通过红外光谱和核磁共振表征了改性前后半纤维素的结构,发现蔗渣半纤维素在均相二亚砜体系中季铵化反应主要发生在半纤维素木聚糖单元C2位的羟基上.另外,凝胶渗透色谱分析显示了改性后半纤维素的重均分子量有所降低,其降解程度较小,相比而言,比未改性的半纤维素的分子量降低了6.8%12.9%.热分析结果表明改性后半纤维素的热稳定性降低.4.提出了一种异相体系合成羧半纤维素的方法.以蔗渣半纤维素为原料,氯乙酸钠为反应试剂,乙醇/水为反应介质,通过醚化反应制备出水溶性的羧半纤维素聚合物.研究发现通过改变反应温度,反应时间,催化剂用量及反应试剂用量可以得到取代度为0.100.56的羧半纤维素.通过碳谱分析发现半纤维素的羧醚化反应主要发生在半纤维素大分子链木聚糖单元C3位的羟基上.与分离的蔗渣半纤维素相比,改性后半纤维素的重均分子量都有所降低,比未改性的半纤维素的分子量降低了25.7%45.9%,这说明在羧醚化反应中半纤维素发生了明显的降解.热分析结果发现改性后的半纤维素热稳定性增加,并且取代度高的羧半纤维素的稳定性要比取代度低的羧半纤维素高.5.基于不同介质制备的阳离子半纤维素以及羧半纤维素,初步探讨了不同取代度的阳离子半纤维素和羧半纤维素对马尾松漂白硫酸盐浆BKP),旧瓦楞纸箱OCC)废纸浆和马尾松热磨机械浆TMP)抄造的纸张增强的影响.还考察了阳离子半纤维素和羧半纤维素在BKP和OCC废纸浆中对阴离子松香胶辅助施胶效果的影响.结构发现阳离子半纤维素和羧半纤维素对BKP,OCC和TMP抄造的纸张均有较好的增强作用,尤其对OCC和TMP纸张强度的影响尤为显着.另外,阳离子半纤维素与羧半纤维素具有协同作用,能够提高纸页的物理强度.此外,还发现阳离子半纤维素对阴离子松香胶的辅助施胶效果显着,能够明显改善阴离子松香胶对纸页的施胶效果.press).)

6.提出了一种超声波预处理和碱分级抽提相结合的分离蔗渣半纤维素的方法.探讨了不同碱处理方法对半纤维素制备物性质的影响.研究发现,脱木素和超生波预处理后的蔗渣在25oC下分别用15%和18%的KOH抽提2h,用15%和18%的NaOH抽提2h,用8%和10%KOH抽提15h,用8%和10%NaOH抽提15h,可分别得到89.6%,92.8%,94.9%和97.3%的原本半纤维素.通过13C-NMR证实了半纤维素制备物的结构主要是L-阿拉伯糖-(4-O--D-葡萄糖醛酸)-D-木聚糖.通过GPC检测了半纤维素制备物的分子量,发现强碱15%和18%KOH,15%和18%NaOH溶出的四种半纤维素具有较低的聚合度,重均分子量在21700―28700g/mol之间,弱碱8%和10%KOH,8%和10%NaOH溶出的四种半纤维素制备物分枝度较高,呈酸性,重均分子量在23100―34500g/mol之间.热分析结果发现强碱分离的半纤维素比弱碱分离的半纤维素的热稳定性高.JournalofAgriculturalandFoodChemistry,2006,54:5742-5748.E-Polymers,2006,067:1-12.)

7.提出了一种以分子碘为新型催化剂,在绿色离子液体1-丁基-3-氯化咪唑盐BMIMCl)均相溶剂系统中,温和条件下,对麦草半纤维素进行均相化学改性的方法.产物的产率及取代度分别为70.5%90.8%和0.491.53.随着催化剂浓度从5%增加到15%,反应温度从85oC增加到100oC,反应时间从10min增加至30min,乙酸酐用量从10.0增加到20.0乙酸酐与半纤维素木聚糖单元羟基的摩尔比,产率和取代度随之增加.在研究半纤维素在离子液体中溶解机理时,发现功能化离子液体是半纤维素的直接溶剂,在溶解过程中没有发生半纤维素的衍生化反应.通过FT-IR和13C-NMR对乙酰化半纤维素的结构进行了表征.热分析结果表明改性的乙酰化产物热稳定性增加,这在生产环境友好的热塑性材料方面具有广泛的应用前景.8.提出了一种在微波辐射的作用下,以N,N-二甲酰胺DMF)/氯化锂LiCl)为均相溶剂系统,麦草半纤维素与月桂酰氯发生酯化反应的方法.考察了反应条件对改性半纤维素取代度的影响,例如:月桂酰氯浓度1:1―1:4,半纤维素大分子链上木聚糖与酰氯的摩尔比,4-二甲氨基吡啶DMAP)浓度2―10%),反应时间1―8min),反应温度78oC,半纤维素大分子链上木聚糖单元与三乙胺的摩尔比1:2)等.通过优化条件可以得到取代度为1.63的改性半纤维素,对应的反应条件为木聚糖与酰氯的摩尔比是1:3,半纤维素大分子链上木聚糖与三乙胺的摩尔比是1:2,DMAP浓度控制在5%,反应温度为78oC,反应时间为5min.通过红外光谱和和核磁共振表征了改性前后半纤维素的结构.发现在均相DMF/LiCl体系中酯化反应主要发生半纤维素大分子链上木聚糖单元C3位上.热分析结果表明取代度低的改性半纤维素热稳定性比天然半纤维素低,然而,取代度高的改性半纤维素的热稳定性比天然半纤维素的热稳定性有所提高.热分析结果还显示与传统的加热方法相比,微波辐射可导致酯化反应中聚合物轻微降解.这种酯化的半纤维素可用于食品包装或可降解薄膜.9.提出了一种通过一步合成手段制备带有两种不同官能团的新型半纤维素衍生物的方法.以氢氧化钠为催化剂,在不同介质中,麦草半纤维素与丙烯酰胺发生化学反应,生成白色粉末状,水溶性的带有乙基甲酰胺和羧基基团的新型半纤维素衍生物.通过优化条件如:丙烯酰胺用量,催化剂用量,反应温度,不同介质,反应时间等合成出取代度为0.58的新型半纤维素衍生物.发现随着丙烯酰胺用量的增加,产物的取代度也随之增大.通过FTIR,NMR和元素分析仪检测了半纤维素衍生物的结构及其特性.热分析结果表明改性后的半纤维素热稳定性降低.AgriculturalandFoodChemistry,2016,56:11209-11216.CarbohydrateResearch,2016,343:2776-2782.E-Polymers,2016,003:1-11.)

关 键 词:蔗渣,麦草,半纤维素,分离,改性,增强剂,

Isolation,modification,andapplicationofhemicelluloseromwheatstrawandsugarcanebagasse

RenJunli

ABSTRACT

Thereisagrowingurgenttrendtoproducerenewableproducts,chemicalsandfuels,fromagriculturalresidues,suchassugarcanebagasse,andcerealstraws,tosubstituteonesproducedfromfossilresources,becauseofthedecreasingreservesoffossilfuels.Inmanycountries,particularlyinthedevelopedcountrieslikeU.S.andsomecountriesinEurope,theagricultural,forestry,lifesciences,andchemicalmunitieshedevelopedastrategicvisionforusingagriculturalandforestresidues.Inparticular,inourcountry,duetoitslimitednaturalresource,largepopulation,andhighspeedofeconomy,theuseofrenewablematerialsioreimportantandcannotbeignorednowadays,andisalsoasignificantstrategyforadjustingandupgradingindustrialstructureinthenewcentury.Inordertousethishighvalueutilizationofagriculturalresiduessuchassugarcanebagasseandwheatstraw,inthisstudy,theisolationandstructuralcharacterizationofhemicelluloseromagriculturalresiduessuchassugarcanebagasseandwheatstrawwereinvestigatedindetail.Importantly,theetherificationandesterficationofhemicellulosessuchasquaternization,carboxymethylation,acetylationandlauroylationandsoonwerestudied.Inaddition,theapplicationofhemicellulosicderivativesaswetendadditiveinpapermakingwaspreliminarystudied,andtheresultsaredescribedaollows:

1.Quaterniztionofhemicellulosesisolatedfromsugarcanebagassewith3-chloro-2-hydroxypropyltrimethylammoniumchloride(CHMAC)usingalkalineascatalystwasachievedinethanolasreactionsystem.ThereactionparametersincludingthemolarratioofNaOH/CHMAC,themolarratioofCHMACtoanhydroxyloseunitsinhemicelluloses,themethodofalkalineadded,reactiontime,andreactiontemperaturewereoptimizedandtheextentofquaternizationwaeasuredbyyieldanddegreeofsubstitution(DS).ByvaryingthereactionconditionsaseriesofcationichemicellulosespresentingwhitepowerwithDSvaluerom0.003to0.19wereobtained.ThestructureofthecationichemicellulosicderivativeswascharacterizedbyGPC,FT-IR,and13C-NMRspectroscopyaswellasthermalanalysis.ItwaoundthatthequaternizationofhemicellulosesoccurredmainlyatC-ositionofxylose,andthethermalstabilityandweight-eragemolecularweightofthemodifiedhemicellulosesdecreasedafterchemicalmodification.(CarbohydratePolymers,2007,67:347-357.NewTechnologiesinNon-woodFiberPulpingandPapermaking,2006:20-24.JournalofSouthChinaUniversityofTechnology(NaturalScienceEdition),2007,35:86-90.)

2.Cationichemicellulosicderivativeswitharelativelyhighdegreeofsubstitution(0.01–0.54)containingquaternaryammoniumgroupswerepreparedbyetherificationwith3-chloro-2-hydroxypropyltrimethylammoniumchloride(CHMAC)orpreferablywith2,3-epoxypropyltrimethylammoniumchloride(ETA)usingsodiumhydroxideasacatalystinaqueoussolution.TheDSvaluesoftheproductscouldbecontrolledbyadjustingthereactioncondition.Atthesameconditions,theproductswithhigherDScouldbeobtainedbythewaytoaddalkalinetwicethanonce.ComparedtoCHMAC,thereactionpreferredtouseETAaschemicalreagents.ThestructureoftheproductswascharacterizedbyFT-IRand13C-NMR.BytheanalysisofGPC,itwaoundthatasignificantdegradationofthehemicellulosepolymersoccurredduringetherificationunderthealkalineconditionsused.Thethermalstabilityoftheetherifiedhemicelluloseswaslowerthanthatoftheunmodifiedhemicellulosepolymers.(PolymerDegradationandStability,2006,91:2579-2587.JournalofAppliedPolymerScience,2007,105:3301-3308.)


3.Aseriesofwater-solublecationichemicellulosicderivativeswithDSfrom0.06to0.24werepreparedbyincorporatingacationicmoiety2,3-epoxypropyltrimethylammoniumchlorideontothebackboneofhemicellulosesinthepresenceofNaOHasacatalystinhomogeneousdimethylsulfoxide(DMSO)media.ThecharacterizationoftheproductswasanalyzedbyFT-IR,solution-state13C-NMRspectroscopy,andGPCaswellasthermalanalysis.13CNMRspectragetheevidenceforetherificationreactionandthequaternizationofhemicellulosesoccurredmainlyatC-2positionofxylose.Itwaoundthatalightdegradationofthehemicellulosepolymersoccurredduringetherification,andthemolecularweights(Mw)ofmodifiedhemicelluloseswaslowerthanthatofunmodifiedhemicelluloses,by6.8%–12.9%.Inparison,nosignificantdegradationofthehemicellulosicderivativesoccurredduringtheetherificationofthepolymersinthehomogeneousDMSOsystem.Thethermalstabilityofthemodifiedhemicellulosesdecreasedafterchemicalmodification.Therefore,DMSOisanefficientsolventtoenhancethereactionactivityofhemicelluloseorquaternization,andoidthedegradationofhemicellulosesduringquaternizationassoonaspossible.(JournalofAppliedPolymerScience,2016,109:2711-2717.E-Polymers,2007,061:1-9.)

4.Hemicellulosesisolatedfromsugarcanebagassewereconvertedtocarboxymethylhemicelluloses(CMH)bycarboxymethylationusingsodiummonochloroacetateandsodiumhydroxideinethanol/watermedium.Thereactionwasperformedundervarioustemperatures,timesofalkalineactivation,thewaysoftheadditionofalkali,andtheamountsofsodiumhydroxideandsodiummonochloroacetate.Theproductswiththedegreeofsubstitution(DS)from0.1to0.56wereobtainedbyvaryingthereactionconditions.ThestructureoftheresultingpolymerswascharacterizedwithFouriertranorminfrared(FT-IR)and13Cnuclearmagicresonance(NMR)spectroscopy.Destructivemethodssuchasthermalanalysisandnon-destructivetechniquessuchasgelpermeationchromatography(GPC)wereusedtocharacterizethecarboxymethylhemicellulosepreparations.Itwaoundthatthemolecularweights(Mw)ofmodifiedhemicelluloseswaslowerthanthatofunmodifiedhemicelluloses,by25.7%–45.9%,whichcouldbeimpliedthatasignificantdegradationofthepolymersoccurredduringcarboxymethylation.Thethermalstabilityofcarboxymethylhemicelluloseswashigherthanthatofthenativehemicelluloses.(PolymerDegradationandStability,2016,93:786-793.ModernChemicalIndustry,2006,S1:68-71.)

5.TheinfluenceofcationichemicelluloseswithdifferentDSandcarboxymethylhemicelluloseswithdifferentDSaswetendadditivesonthephysicalpropertiesofhandsheetsofbleachedkraftpulp(BKP)ofmassonpine,oldcorrugatedcartons(OCC)pulp,andthermo-mechanicalpulp(TMP)ofmassonpinewasstudiedindetail.Inaddition,theeffectofcationichemicellulosesandcarboxymethylhemicellulosesontheassistantsizingofanionicrosininBKPpulpofmassonpineandOCCpulpwasparativelyinvestigated.ItwaoundthatcationichemicellulosesandcarboxymethylatedhemicellulosesobviouslyimprovedthephysicalpropertyofsheetromBKP,OCCandTMP,especiallyforBKPandOCC.Inaddition,cationichemicellulosesandcarboxymethylatedhemicelluloseshadthegoodcooperationfortheenhancementinthephysicalpropertyofsheets.ItalsowaoundthatcationichemicellulosescouldimprovethesizingdegreeofhandsheetsofBKPandOCCpulpunderthesizingofanionicrosin.(CarbohydratePolymers,2016,75:338-342.JournalofBiobasedMaterialsandBioenergy,2016,3:62-68.CelluloseChemistryandTechnology,2006,40:281-289.AppitaJournal(inpress).)

6.Hemicellulose-typepolysaccharideswereisolatedfromthedelignifiedandultrasonicirradiatedsugarcanebagassebyasequentialtwo-stepalkalineextraction.Itwaoundthatthesuccessiveextractionsat25oCwith15%and18%KOHfor2h,15%and18%NaOHfor2h,8%and10%KOHfor15h,andwith8%and10%NaOHfor15hresultedinatotaldissolutionof89.6%,92.8%,94.9%,and97.3%oftheoriginalhemicelluloses,respectively.Thestructuralstudiesby13C-NMRspectroscopyshowedthatL-arabino(4-O-methyl-D-glucurono)xylanswerethemajorconstituentsofthehemicellulosicpolymers.Furthermore,thecurrentresultsalsoshowedthatthefouralkali-solublehemicellulosicfractions,isolatedduringthefirststeptreatmentwithrelativelylowerconcentrationsofalkalis,weremorebranchedandacidic,andhadlargermolecularweights(Mw,23100–34500),butlowerthermalstabilitythantheotherfouralkali-solublehemicellulosicpreparations(Mw,21700–28700),extractedduringthesecondstagetreatmentwithrelativelyhigherconcentrationsofalkalis.(JournalofAgriculturalandFoodChemistry,2016,57:6305-6317.JournalofAgriculturalandFoodChemistry,2006,54:5742-5748.E-Polymers,2006,067:1-12.)

7.Homogeneousacetylationofsugarcanebagassehemicelluloseswithaceticanhydrideusingiodineasanovelcatalystin1-butyl-3-methylimidzoliumchlorideionicliquid(IL)undermildconditionswasparativelystudied.Theyieldandthedegreeofsubstitutionrangedfrom70.5%and0.49to90.8%and1.53asafunctionofexperimentconditions.ItwaoundthattheyieldandDSincreasedwithiodineconcentrationbetween5%and15%(basedonthedryhemicelluloses),reactiontemperaturefrom85to100°C,andreactiontimebetween10and30min,andthedosageofaceticanhydridefrom10.0to20.0(Molarratioofaceticanhydridetohydroxylfunctionalityinhemicelluloses).Inaddition,thedissolutionmechaniofhemicellulosesinionicliquidwasinvestigated.Itwaoundthationicliquidwasonlyusedasasolvent,andnotactedwithhemicellulosesbytheFT-IRanalysisofregeneratehemicelluloses.FT-IRand13C-NMRspectroscopywereappliedtocharacterizeacetylatedhemicellulosesindetail.Thethermalstabilityofthemodifiedhemicelluloseswashigherthanthatoftheunmodifiedhemicellulosepolymers.Suchpolymerscouldbefoundpromisingformakingenvironmentallyfriendlythermoplastics.Itisthefirsttimethatwehedemonstratedthationicliquidcouldbeusedasanenvironmentallyfriendlysolventforthechemicalmodificationofhemicelluloses.(CarbohydratePolymers,2007,70:406-414.BioresourceTechnology,2016,100:3906-3913.CarbohydratePolymers,2016,78:609-619.)

8.LauroylationofwheatstrawhemicellulosesintheN,N-dimethylformamide/lithiumchloridesystemundermicroweirradiationwasstudied.Theparametersoptimizedincludedlauroylchlorideconcentrationasthemolarratioofxyloseunitinhemicelluloses/lauroylchloride(1:1–1:4),4-dimethylaminopyridineconcentration(2–10%),reactiontime(1–8min),molarratioofxyloseunitinhemicelluloses/triethylamine(1:2),andreactiontemperature(78°C).Thereactionefficiencywaeasuredbytheyieldanddegreeofsubstitution(DS).Underanoptimumreactioncondition(molarratioofxyloseunitinhemicelluloses/lauroylchloride1:3,molarratioofxyloseunitinhemicelluloses/triethylamine1:2,5%4-dimethylaminopyridine,78°C,5min),aDSof1.63wasobtained.ChangesinthestructureofhemicelluloseswereverifiedbyFT-IRand1Hand13CNMRspectroscopy.TheresultsshowedthatthelauroylationoccurredpreferentiallyattheC-ositionofthexyloseunitinhemicelluloses.Thebehiourofthelauroylatedhemicelluloseswaonitoredbymeansofthermogrimetric(TG)anddifferentialthermogrimetric(DTG)analysis.ItwaoundthattheproductwithlowDShadalowerthermalstabilitythanthenativehemicelluloses,whereasthelauroylatedpolymerswithhighDSshowedahigherthermalstabilitythantheunmodifiedhemicelluloses.(JournalofAgriculturalandFoodChemistry,2016,56:1251-1258.CarbohydrateResearch,2016,343:2956-2962.E-Polymers,2016,0108:1-11.)

9.Wheatstrawhemicelluloseswereconvertedtonovelbifunctionalhemicellulosicderivativesbyone-stepetherificationusingacrylamideasreactantandsodiumhydroxideascatalyst.Thedegreeofsubstitutioncanbemonitoredbyalteringthemolarratioofacrylamidetoxyloseunitinhemicellulosesintherangeof1.0–10.0andthemolarratioofsodiumhydroxidetoxyloseunitinhemicellulosesintherangeof0.5–1.6withoutchangingthestructureofthehemicelluloses.Comparisonofthereactionindifferentmediaisdiscussedindetail.TheoptimizedproductwithahighDSvalueof0.58wasobtainedbyvaryingtheconditionparameters.NovelhemicellulosicderivativescontainingcarbamoylethylandcarboxyethylgroupscouldbeconfirmedbyFT-IR,1HNMR,and13CNMRspectroscopy.Thebehiourofhemicellulosicderivativeswaonitoredbymeansofthermogrimetry(TG)anddifferentialthermalanalysis(TGA).ItwaoundthattheproductwithahighDShadalowerthermalstabilitythanthenativehemicelluloses.(JournalofAgriculturalandFoodChemistry,2016,56:11209-11216.CarbohydrateResearch,2016,343:2776-2782.E-Polymers,2016,003:1-11.)Keywords:sugarcanebagasse,wheatstraw,hemicelluloses,isolation,modification,strengtheningagents

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