この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。A novel acetylated cellulose called cellulose oligo-oxymethylene ether acetate, COAc, was prepared by the homogeneous reaction in Paraformaldehyde/DMSO medium. Measurements of thermal deformation for COAc series with different degree of substitution (DS) revealed that the asending deformation for all samples went off at about 170℃. Heat treatment above this temperature caused remarkable change in thermal properties of COAc. A large weight loss of COAc was also observed in the region above this temperature From these results, the side chain of COAc was concluded to decompose above 170℃

MOROOKA, Toshiro

SUBOWO, Wiwik S.

TARIGAN, Lucia I.

Kyoto University Research Information Repository

Title<Note>Thermal Properties of Newly Developed AcetylatedCelluloseAuthor(s)MOROOKA, Toshiro; TARIGAN, Lucia I.; SUBOWO, WiwikS.CitationWood research : bulletin of the Wood Research Institute KyotoUniversity (1990), 77: 42-48Issue Date1990-12-28URL http://hdl.handle.net/2433/53278RightType Departmental Bulletin PaperTextversionpublisherKyoto UniversityNoteThermal Properties of Newly DevelopedAcetylated CelluloseToshiro MOROOKA*l, Lucia 1. T ARIGAN*2and Wiwik S. SUBOWO*2(Received August 31, 1990)Abstract--A novel acetylated cellulose called cellulose oligo-oxymethylene etheracetate, COAc, was prepared by the homogeneous reaction in Paraformaldehyde/DMSOmedium. Measurements of thermal deformation for COAc series with different degreeof substitution (DS) revealed that the asending deformation for all samples went offat about 170°C. Heat treatment above this temperature caused remarkable changein thermal properties of COAc. A large weight loss of COAc was also observed inthe. region above this temperature From these resu Its, the side chain of COAc wasconcluded to decompose above 170°C.Key word~: acetylated cellulose, thermal deformation, homogeneous acetylation, thermaldecomposi tion1. IntroductionHomogeneous acetylation of cellulose in Paraformaldehyde (PF) /DMSO solventsystem is known to give a novel acetylated celluloseJ) called COAc, cellulose oligo-oxymethylene ether acetate. The COAc is somewhat different from the usual celluloseacetate in that it involves oxymethylene oligomer between glucopyranose ring andacetate group. The COAc gives off a clear and transparent films with flexibility,which indicates potential utility in various areas of application. For a series ofcellulose oligo-oxymethylene ether acylates including COAc, we have been studyingviscoelastic properties, and classified types of molecular motion present in them2- 4).From the practical point of view, however, it is necessary to obtain informationon the thermal properties, especially on the thermal stability of COAc, since suchproperties restrict temperature ranges of the materials to be used.In our present article, we describe the results of thermal degradation of COAcusing thermomechanical analyzer (TMA) and dynamic thermogravimeter (DTG).*1 Research Section of Wood Physics, Wood Research Institute, Kyoto University, Uji, Kyoto,611, Japan.*2 R&D Center for Applied Physics, LIPI, Bandung, Indonesia- 42-MOROOKA et at.: Thermal Properties of New Acetylated Cellulose2. Experimental2. 1 Preparation procedure of COAcDried cellulose power (What man cellulose CF-II) (2g) and paraformaldehycle(4 g) were well dispersed in DMSO (50 mI) at room temperature. The mixturewas then heated with stirring to 120°C in a 100 mi Erlenmyer flask equipped witha condencer. After being held at this temperature for 3 hr, the cellulose solutionso obtained was cooled to room temparature. To the cooled cellulose solution,triethylamine (6 mol/mol glucose) and specified amount of acetic anhydride (0"""-'6mol) were added. After the addition, the reaction mixture was allowed to standat room temperature for at least 5 hr. The reaction mixture was then poured intomethanol. The DS value of the sample obtained were determined by saponificationmethod.2. 2 Measurements of thermal softening and weight loss of samplesThe thermal softening of the sample was measured with thermomechanicalanalyzer (TMA), in which a column of the sample collapsed under a plunger whichsupported a constant load, when heated at a rate of 1°C/min. The weight lo'iSof the sample was observed using dynamic thermogravimeter (DTG) in which thesample is heated at a rate of 2°C/min. The heating rate of 5°C/min was adopted forcellulose oligo-oxymethylene ether butyrate. Powder samples were used for bothmeasurements.3. Results and DiscussionFig. I shows the diagram of thermal deformation versus temperature for COAcwith DS of about 2.8. In the diagram, the deformation is normalized: the defor-dP=oooooooooo/tPo00ooo2T X102(Oc)Fig. I. Diagram of thermal deformation versus temperaturefor COAc with DS=2.8- 43-WOOD RESEARCH No. 77 (1990)mation is null at room temperature and unity at the temperature at which theplunger in TMA reaches the bottom of the glass capillary, indicating completionof liquid flow of the sample. In the diagram, we observed two well-defined transi-tion regions. Regarding the transitiOn appearing in the higher temperature range,the deformation curve rises gradually, and reaches unity. This region is regardedto be the flow region, and the gradual deformation of the curve indicates the sampleto be almost amorphous in nature. This result is in accord with that of x-raydi ffractgram.On the other hand, the lower temperature transition can be ascribed to themicro-Brownian motion of the segment along the main chain, and thus the rapidlychanging deformation is associated with the glass transition of COAc.The information on the transition for COAc with DS =2.8 (i.e. triacetate) des-cribed above aids considerably in the assignment of transitions for COAc serieswith different DS values. Fig. 2 represents thermodiagram for a series of COAcwith DS =2.8 to 0, where the COAc with DS =0 corresponds to regenerated cellu-lose obtained from PF/DMSO solution. From the figure, we observe that the glasstransition region regularly shifts to higher temperature as the DS values decreasefrom 2.8 to 1.35. From this evidence, it is learned that the decrease in the amountof the COAc side groups which are randomly distributed along the cellulose chaincauses increased interaction between cellulose main chain, thus supressing the mainchain motion. The regularity of the change in the glass transition region observedabove is thought to be typical of cellulose derivatives prepared by homogeneou~reaction. It should be noted, however, that such glass transition disappears forCOAc with DS less than 0.74. Similar trends are recognized in the flow region,i.e., the flow region shifts to higher temperature with decreasing DS, and it (!isap-pears for the sample less than DS = 1.81. In connection with this, it can be seenfrom the diagrams at DS =2.10 and 2.04 that the ascending deformation curve inthe flow region goes down at about 170°C prior to the completion of liquid flow.Furthermore, the deformation in the glass transition region for the sample withDS = 1.35 also appears to be suppressed at about 170°C.From these facts, it is expected that some structural change in COAc mightoccur at around 170°C. For further information, we measured thermal deformationfor COAc with DS =2.8 after heat treatment at specified temperatures for I hr. Theresulting diagrams at 155, 182,200 and 220°C are shown in Fig. 3. It is known fromthe figure that the deformation curve of the sample after the treatment at 155°C isthe same as that of untreated one. However, all the curves treated at more than182°C are quite different in shape from those for untreated samples, though theirglass transition regions appear at a temperature comparable to that for untreated- 44-MOROOKA et ai.: Thermal Properties of New Acetylated Cellulose'I 00· 0 ..,---...."..'I l'0.32 ..oIl'I.........0.74.......'I ..-.1.35 "......"...·1z'I ....-----«= ....., t=c 1.59~ICC "....«=.....'I.....«=....,--r1.81 ....",.",.0·'I...,,--2.0400000<".11 ",r1f2.10 /1..el'I.·1•0 170°1:.02.8 ~oo.."°0 2 3 4-2T x10 (Oc)Fig. 2. Diagram of thermal deformation versus temperaturefor a series of COAs with DS=2.8 to 0sample. It should be emphasized that these samples do not exhibit flow region,but show apparent deformation due to the decomposition around 28DoC at which- 45-WOOD RESEARCH No. 77 (1990)0_oooo~oooo00o00155"C182_/,-_......------"'II............--'IIP""--~2000'-'-"pdI'#'__.. ......~00220-2T X10 (Oe)Fig. 3. Effect of heat treatment on thermal deformationcurves for COAc with DS=2.8cellulose itself decomposes. This point will be mentioned later using DTG data.In addition, the deformation magnitude in the glass transition region become smallerwith increasing temperature. From these facts, it is evident that the COAc chan-ged markedly in structure after heat treatment above ca. 170°C.In an effort to elucidate the significance of this structural change DTG measu-rements were made for COAc. Figs. 4a, 4b, 4c and 4d illustrate normalized weightloss (W) versus temperature curves for Whatman cellulose CF-II, regenerated cellu-lose, triacetylated COAc, and cellulose oligo-oxymethylene ether butylate, COB,respectively. In each figure, dW/dT curve is also shown for reference. Regardingcellulose (Fig. 4a), observable weight loss begins at around 280°C, accelerated untilan inflection point near 310°C, and levels off somewhat above 330°C. This loss isdue to the decomposition of cellulose chain. The similar curve i" obtained forregenerated cellulose (Fig. 4b), although slight decrease which can be attributed tothe evaporation of some contaminants such as formaldehyde involved begins around220°C. On the other hand, a remarkable weight loss for COAc (Fig. 4c) is observedbetween 170 and 280°C in advance of cellulose chain degradation. This differencein thermal properties between cellulose and COAc is thought to arise from different-46MOROOKA et at.: Thermal Properties of New Acetylated Cellulosechemical structure III the side chain. Thus, it is most probable that the drop inloss curve before main chain degradation stems from the decomposition of oligooxymethylene ether acetate side chain in COAc examined. If this is the case, th(~weight loss should become much greater when the alkyl portion in the COAc sidechain is replaced by butylate groups whose molecular weight is higher than that ofacetate. From Fig. 4d, we see that the drop in weight loss for COB occurs mar-kedly in the temperature range corresponding to the above, although higher heating. rate (5°C/min) is adopted in this case. Consequently, we may conclude that theCOAc side chain decomposes at around l70°C, and is reduced to the regeneratedcellulose prior to the disintegration of cellulose itself.••••••1 000000000 0000000000 oooo~00\ooooooo000o 0 0 00o 1 2 3 4Fig. 4a. Dynamic thermogravimetric trace of unmodified cellulose••••••o o o o 0 0 0 0 0 0 0 000 0 0 0 0 0000,\o000o 0 0o 00o 1 3 4Fig. 4b. Dynamic thermogravimetric trace of regenerated cellulose- 47-WOOD RESEARCH No. 77 (1990)•••1 o o-oo 3 4Fig. 4c. Dynamic thermogravimetric trace of COAc with DS=2.81 o o o o o 03o 2TX102(Oc)Fig. 4d. Dynamic thermogravimetric trace of Cellulose oligooxymethylene ether butyrate, COBReferences41) N. SHIRAISHI, T. KATAYAMA and T. YOKOTA: Cellulose Chem. Technol., 12, 429 (1978)2) T. MOROOKA, M. NORIMOTO, T. YAMADA and N. SHIRAISHI: j. Applied Polym. Sci., 27,4409 (1982)3) T. MOROOKA, M. NORIMOTO, T. YAMADA and N. SHIRAISHI: Wood Research, No. 72, 12(1986)4) T. MOROOKA, M. N ORIMOTO, T. YAMADA, S. TAKUMA and K. OKAMURA: J. Applied.Polym. Sci., 35, 717 (1988)- 48-

<Note>Thermal Properties of Newly Developed Acetylated Cellulose

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<Note>Thermal Properties of Newly Developed Acetylated Cellulose

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