TAP CHi HOA HOC T. 49(6)710-714 THANG 12 NAM 2011
PHU-aNG PHAP TACH VI SQ-J XENLULO TIJ CAY L U 6 N G VA LFNG DUNG D^ NANG CAO D 6 B ^ N M 6 I C O A C O M P O Z I T EPOXY
GIA CU-ONG BANG SOI T H O Y TINH
Nguyen Chau Giang'', Ta Thj Phuffng Hda', Toru Fujji^
'Trung Idm Nghien cim vgt liC'ii Polyme. Trin'mg Dgi hgc Bdch khoa Hd Npi. Vt?i Nam
^Boslmha University. Kyoianahe-cily. Kyoto 610-0349. Japan Den Tda sogn 18-5-2011
Abstract
MicrofibriHated cellulose (MFC) was isolated from bamboo by two different methods. The first one is a combination of a lliermomechanical treatment of bamboo culm called slcam explosion and a mechanical extraction by grinding In the second method, bamboo slabs were chemically treated with high concentration sodium hydroxide solution at elevated temperature following by grinding by stone miller. Obtained MFC were characterized in temiof chemical composition, morphology and crystallinity. Two kinds of epoxy composites (EC) reinforced by woven glass fiber with addition of MFC were prepared. Dy comparison of the mechanical properties of these composites with those of the EC wiihoui presence of MFC, it is showed that addition of MFC resulted in little increase in tensile strength but remarkable improvement in tension-tension fatigue strength.
Keywords. Microfibri Hated cellulose, chemical composition, morphology, crystallinity, polymer composite, fatigue life.
1. Gl6l THIEU Vi sgi xenlulo cd the dugc chl tgo tir rit nhiai ngudn nguyen lipu thyc vgt ciing nhu dpng vit khac Viec nghien ciru chl tao sgi xenlulo cd kich nhau, ma chu yeu li tir thyc vat nhu gd vi nhung thudc cd nanomet vi irng dyng chimg vio che tgo loai cay trdng khac nhu lanh, gai diu, sisal ... Mgt vit lieu compozit ngiy cing thu hut dugc nhieu sy sd cac sin pham phy cua ciy ndng nghiep cungco quan tim ciia cic nhi nghien ciru do chiing cd nhilu the sir dung de sin xuat cic logi sgi nanoxeniulo die tinh uu viet nhu do ben va dp ciing cao, khdi gom cd cic logi sin phim thu dugc trong qua trinb lugng rieng nhd vi cd khi ning phan huy sinh hpc thu hogch ngd, liia mi, ggo, dgi mgch, mia, dua.
cung nhu cd khi nang tii tgo. chuoi, dira. Nhu:ng logi thyc vgt phi gd nay nhin Mdi vi sgi don le la mgt tap hop cic mgch phin chung deu chira it lignin hem gd do dd khong nhai tu xenlulo sap xep song song vdi nhau tgo nen mpt thilt phii cd qui trinh tiy tring khi che tgo sgi^M?l ciu triic tinh the xen lin cic viing vd dinh hinh. Cic khac chung thudng cd cau triic don giin han gonfei vi sgi don le niy lgi cd xu hudng tu tip lgi vdi nhau qui trinh tich sgi v i vi sgi se cd nhieu thugn lgi hon thinh bd cic vi sgi trong nen hemixenlulo, lignin va Bii bio niy dl cgp din viec nghien curu tichyi pectin. Li thinh phin xuang sdng trong tat ci cac sgi xenlulo tCr cay ludng, mpt loai tre dugc tringtai logi thuc vat, xenlulo dugc hinh thinh trong mpt ciu phd biln d miln Bic Viet Nam, bing cic phuong triic cd trat ty d thinh te bio. Cic vi sgi tip hgp phip khic nhau. Vi sgi xenlulo thu dugc tir nhBnj trong thinh te bio cd tinh dinh hudng, dgc trung qui trinh tren se dugc ling dyng thii nghipm tronj bing gdc vi sgi, die tinh niy phu thupc vio Idp chl tgo polyme compozit cot sgi thuy tinh nham cai thinh te bio va logi thuc vat. Hudng ciia cic vi sgi thien mpt so tinh chat co hgc cua chung, dac bietia cd inh hudng Idn tdi tinh chat co hpc ciia nhilu logi dp bin mdi dgng.
sgi thyc vat, vi du gdc vi sgi nhd, nghTa li hiu hit
cac vi sgi djnh hudtig gin nhu song song vdi tryc 2. THVC NGHI$M sgi, lim tang ding ke mo dun din hdi trong khi gdc
vi sgi Idn se dan tdi viec lim tang dp dan dai khi diit 2.1. Vat lif u va hda chat
cua sgi. Nhd cd ciu triic dgng sgi vi mgt sd lugng i rat Idn cic lien kit hydro mi xenlulo cd dp bin keo Vi sgi xenlulo dugc chl tao tir cay luong %
rat cao, day chinh Ii thanh phin ciu true chju lyc binh 3 nam tudi, mot loii cd ham lugng xenlulot*
chinh cua sgi thuc vit khi thir keo [ 1, 3]. nhat trong cic loii cay thupc hg tre.
TCHH, T. 49(6), 2011
Vgt lieu polyme compozit (PC) dugc chl tgo tren ca hai logi nhya nin li nhua epoxy E-828 (Japan Epoxy Resin Co., Ltd) sii dyng chit ddng rin polyamin JER-113 (Japan Epoxy Resin Co,, Ltd), sgi gia cudng li vii lya thuy tinh (160 g/m^) 2.2. Phuromg phap che tao vi sgi xenlulo 2.2.1. Tach vi sgi tir sgi ludng bdng phirang phdp tach nd hai mrdc.
Thanh ludng dugc dua vio tich nd hai nudc trong thiet b| cao ip. Sgi ludng thu dugc dugc xir ly kiem, riia sgch vi tich vi sgi tren miy nghiin da MKCA 6-2 (Masuoka Sangyo). Qui trinh tich no dugc thyc hipn d dieu kipn 175°C vi ip suit la 0,8 MPa. Cii sau 5 phut ip suit trong thilt bj lgi dugc xi dot nggt mpt lin, ddng hai ndng dugc xa ra khdi thiet bj vdi mpt tdc dp cao tgo ra sy nd vi vipe \a ip nhu vgy dugc Igp lgi 9 lan. Vi sgi xenlulo tich dugc tir cay ludng theo phuong phip niy sau khi nghiin I dugc ky hipu li MFC ST..
Ciu tgo cua thiet bi nghien di MKCA 6-2 (supermasscoloider): Eg phgn chinh la hai khoi di mil O150, tim phia tren dat cd djnh trong khi tam phia dudi chuyen ddng nhd mpt d^ng ca 1.5 kW.
Tren be mit hai tam di cd xe ranh dugc dgt ip sit vio nhau va khe hd giifa chimg cd thi dilu chinh dugc. Khe hd gi&a hai tim di nghiin cing hep thi sgi thu dugc cd kich thudc cing nhd. De thu dugc vi sgi cd ciing mpt kich thudc, nguyen lieu ban dau cd kich thudc cang nhd thi sd chu ky nghien cing giim.
2.2.2. Tach vi sgi xenlulo tir sgi ludng xic ly kiem
Thanh ludng dugc xii ly bing kiem 3N, d nhiet do 90''C, rira sgch vi tich soi ludng bang phuang phap CO hgc. Sau dd, sgi ludng dugc tich thinh vi sgi tren may nghiin di MKCA 6-2 (Masuoka Sangyo). Vi sgi thu dugc tir phuang phip niy ki hieu la M F C A L cd dudng kinh nhd han 1 pm, d dgng huyen phii trong nudc vdi him lupmg phin khd khoing 9-10%.
2.3 Phiromg phap che tao vat lieu compozit Vi sgi xenlulo che tgo dugc d dang gel trong nudc vdi him lugng vi sgi 9-10%, vi vgy cin logi bd nudc trudc kht phan tan vao nhya nen. Phuong phip thay the dung mdi dugc sii dyng de logi bd nudc: Vi sgi dugc Igc chin khdng sau dd phan tan lgi trong etanol, qua trinh nay dugc lip lgi 2 lan nham thay the nudc bang con d mire dg tdi da. MFC trong etanol vdi him lugng 0,3% khdi lugng dugc phin tin trong nhya epoxy va PEKN bing thilt bj khuiy i*tdc dp cao Ultra Turrax (11000 vdng/phut).
Nguyin Chdu Giang vd cdng su Dung dich nhya epoxy sau do dugc .siy chan khdng d dO^C tdi khdi lugng khdng ddi de loai bd cdn. Vat lipu PC tren ca sd nhua epoxy (cd vi khdng cd MFC) vdi him lugng chat ddng rin polyamine 32% khdi lugng so vdi nhya nen, sgi thiiy tinh (vdi ty le sgi/nhya = 1/1) dugc chl tgo theo phuong phap lan ep bang tay, sau do mau compozit dugc ep ndng theo 2 giai dogn 80°C trong 1 gid vi 150''C trong 3 gid d i p lyc 3MPa.
2.5. Phiro'ng phap xac dinh tinh chat cff hoc cua vat lieu compozit
Dg ben vit lipu dugc kiem tra theo cic tieu chuin sau: Dp bin keo: ISO 527-1993 tren miy INSTRON 5582 - lOOKN (My). Dp bin mdi thu keo dugc xac djnh theo tieu chuin ASTM D3479-96 miy 810 Material Test System (My), ip lyc tdi da dgt vio miu bing 70% dp ben keo ciia vat lieu, tin so 10 Hz.
3. KET QUA VA THAO LUAN
3.1. Anh hudng cua phuong p h i p tich sgi tdi thanh phan hda hpc, hinh thai va tinh chat ciia vi
Viec che tgo MFC tir thyc vat bang each phan tich sgi xenlulo tdi kich thudc cd nanomet ddi hoi qui trinh xir ly co hpc die biet. Tuy nhien nguyen lieu dau d diy Ii cay ludng cd cau triic rat cirng, thinh giong ludng diy (tren I cm) nen viec ap dung qui trinh tien xu ly li rit cin thiet nham giim thieu tdi da viec tieu hao nang lugng trong qua trinh xii ly CO hpc. Da sir dung hai phuong phap tien xii ly khac nhau la xu ly hda hgc bing dung djch kiem 3 N trong 24 gid d 90*'C va mpt phuong phap co nhiet la tich nd hai nudc. Hieu qui cua hai phucmg phip tien xii ly dugc dinh gii thdng qua phan tich thinh phan hda hpc cua sgi xenlulo, ket qui trinh bay trong bing 1.
Bdng 1: Sy thay ddi thinh phin hda hgc ciia sgi ludng sau cic qui trinh xir ly hda hpc S^i ludng
Cay luong Sgi luong tach lo hai nuoc Sgi tach no xijr ly Iciem (0,3N/90°C/20')
Sgi xO ly kiem (3N/90°C/24h)
Thanh phan, % Xenlulo
52,2 55,0 73,2
69,3 Lignin
29,2 33,0 17,7
17,3 Pentozan
17 12 9,3
11,3 Tong cpng 98,4 100,0 100,2
97,9 Him lugng lignin trong hot ludng trudc va sau khi xu ly hoi hpc dugc xic dinh theo tieu chuan
TCHH, T. 49(6), 2011
TAPPI T 222 om-98, ham lugng pentozan dirge xic dinh theo T223 cm-84. Ham lirgng xenlulo dugc xac dinh theo phuang phip Kiursher - Hofft.
Til' bing 1 thi;/ ring phirang phap xir ly ludng bing dung djch kilm dgc (3 N) trong thdi gian 24 gid da logi bd duac mgt phan khi ldn cic chat nen polyme vd dinh hinh d thanh tc bgo sgi, him lugng lignin giim tir 29% xuong cdn 17,3% vi pentozan giam tir 17% xuong cdn 11,3%. Sgi xenlulo thu dugc cd dudng kinh cd 7-10 pm, chieu dai tir vai mm den 1cm (hinh lc).
Khic vdi phuong phip xir 1> kiem, tich no hai nudc li mdt phuang phip hda ly khdng sir dyng hda chat, giiip tach cic sgi xenlulo ra khdi cic chat nen lien ket vd djnh hinh trong cic Idp thanh lc bao thyc vat nhd tic dung ciia ddng hai nudc ap lyc cao vi sy thay doi ip suit dpt ngpt trong mgt thiet bj noi hai kin. Ket qui phan tich thinh phan hda hgc tren bing 1 cho thiy sgi ludng thu dugc tir qui itinh tich no hoi nudc cd him lugng pentozan giani ding kc tir 17% xudng con 12% trong khi dd him lugng lignin lai tang len. Ket qui niy cung phii hgp vdi cic nghien ciiu ciia Shao S. [6] qui trinh tach no hoi nudc ciia mgt logi irc thupc vung ddng nam Trung Qudc va nghien ciru ciia Suzuki S ve qui trinh tach nd hoi nudc ciia ciy cp [7]. Su ting him lugng lignin trong sgi ludng tich nd hoi nudc dugc giii thich li do cd su hda tan ciia cic polysacarit trong thinh tl bio thyc vit ma d day chii ylu li him lugng pentozan. That vay, tir kit qui tren bang 1 thiy ring him lugng holoxenlulo (tdng tit ca cic phin polysacarit trong sgi thyc vat bao gdm xenlulo vi cic logi hemixenlulo) giim tir 69,2% trong cay ludng xudng cdn 67% trong sgi ludng tach nd hoi nudc.
De quan sit sy thay ddi hinh thii ciu triic sgi trudc vi sau xii ly da sii dung kinh hiln vi dien tir quet (SEM) Jeol 6360LV (Nhat Bin), kit qui dua ra tren hinh 1 vi 2.
Phuang phdp tdch vi stri .xenlulo..
Til hinh la thay ring, be mat ciia sgi ludng lai no hai nudc thd rip va bi bao plni bdi cac viy va h.
nhd. Theo cic ket qui nghien ciru ciia Shao S (200f Ihi dd chfnh li lignin bj tacli ni trong qui trinh (ac lid hai nudc vi ty tgp lgi irC-ii hO in;1l soi, Dieu na giai thich tgi sao chi vdi dii-u kiOii xir ly kicni vk nh vi llidi gian xir ly rit ngin cik cluit lien ket nay dai:
hda tan dc ding, d l 1$ ra cac vi sgi xenlulo tren b mgt sgi, hinh lb, vi dSn tdi h:im lugng xenlulo irom sgi tich no xir ly kiem tSni! Icn diing kc (73.2 %]
cao hgn so vdi him lugnji xciiluUi irong sgi xir h kiem die.
Dc tich vi sgi xenlulo lir sgi ludng. da ticn hani sir dyng phuang phip xir ly ca hpc li nghien da Dudi tic dyng ciia lyc cfit xO va trirgt rat ldn l^ori do hai phien di mii quay ngugc chieu nhau tronj Ihict bj nghien di, cau triic sgi dirge md ra vi vi soi dugc lich ra dan dan theo tirng chu ky nghien, Hinli inh cau triic ciia cic logi \ i sgi xenlulo dugc dira ra tren hinh 2. De tien hinh cluip anh SEM. cac lam MFC dugc lim khd ty nhien a nhicl dg phong, \e thinh cic minh nhd v i phu plalin trirdc khi codinh vao miy SEM. Anh dugc chup lgi mcp cua cac tam MFC khd.
Tir hinh 2a va 2c tha\ ring ci hai loai vi sgi xenlulo che tgo dugc cd kich ihudc kha dong deu, a dg phdng dgi Idn hon (" 15.000) nhu tren hinh 2b va 2d cd the udc tinh dugc kieli llurdc ciia cac loai vi sgi, dudng kich dao dgng ur vii chuc tdi vai iram nanomet va chieu dii c5 vai tram micromet. Tu;
vgy, viec xac dinh chinh xac chieu dii ciia cic vi sen xenlulo la rit khd khan do cd mgt lugng ldn cac nhdm hydroxyl tren be mat vi sgi nen Iudn co xu hudng tgo thinh cic lien ket hvdro giCra cac vi sci vdi nhau rat manh me din den sy dinh kit ciia cac vi sgi lai vdi nhau vi hiu nhu khdng xiie dinh dupe hai dau ctia mgt vi sgi.
Hmh I Anil SLM ^gi luong tich nd hoi nudc ^ 500 (a) vi sgi ludng tach no hai nudc sau xir ly kilm 0,3N X 1,5k (b), sgi ludng xir ly kilm 3N x 1,5k (c)
iriiih 2- Anil SEM eiia hai loai MFC: a) MFC__AL\
2k, b) MFC_AL x 15k, c) M FC ST x2k va d) MFC ST X 15k
TCHH, T. 49(6), 2011
Vi sgi xenlulo, thinh phan cau triic nhd nhit ciia sgi thuc vit, dugc hinh thinh tir cic mach phan tii xenlulo x§p song song vdi nhau tgo nen mgt ciu triic tinh the xen lln vdi cic viing vd dinh hinh. D I xic djnh mire do kit tinh ciia MFC chl tgo cung nhu inh hudng cua phuong phip chl tao tdi dp kit tinh ciia xenlulo da tiln hinh do nhilu xg tia X cac ming mdng MFC. Do kit tinh ciia MFC dugc xic dinh theo cdng thiic ciia Segal (1959):
''020
Trong do:
-1 020^ cudng dp pic 020 (phin xg ciia vimg vd dinh hinh vi vimg tinh the d gdc 20 bing 23") -1 am- cudng dp thap nhit ciia vimg nam giiia pic
020 vi 110 (viing vd djnh hinh d 16°) - Xcr^ him lugng tinh the xenlulo (%)
Ket qui trinh biy Ircn hinh 3 cho thay ca hai logi vi sgi MFC_ST vi MFC_A1 deu cd mgt pic hpp cd cudng dd cao d gdc 20 = 23" vi mgt pic rpng cd cudng dp thip hon d gdc 29 = 16", dgc trung cho xenlulo logi 1.
Nguyin Chdu Giang vd cpng su nen vd dinh hinh trong sgi thyc vat li pentozan, dan tdi M F C S T thu dugc tir sgi tich nd hoi nudc cung cd ham lugng tinh the cao ban MFC AL
10 20 30 40 2 theta (deg.)
Hinh 3: Dd thj X-ray ciia MFC Ket qua cho thay dg ket tinh ciia MFC_ALvi MFC_ST tuong ting li 63,65% va 64,82%. Nhu vay qui trinh xCr ly cic thanh ludng bang dung dich kiem 3N trong thdi gian 24 gid da khdng giy ra sy hda tan vi ket tinh lgi cua xenlulo ty nhien (xenlulo logi I) tgo thanh mdt dang thii hinh mdi, xenlulo loai II, nhu thudng thay ddi vdi nhilu qui trinh xii ly kiem khic. Kit qua xac djnh miic do kit tinh cua MFC cijng phii hgp vol ket qui phan tich thinh phin hda hpc cua sgi ludng, sgi ludng tich no hgi nudc sau khi dugc xu ly kilm cd him lugng xenlulo cao han sgi xii iy kilm 3N do da logi bd dugc nhilu hon chit
10 0 -10 -20 -30 -40 -50 -60 -70 -80
MFC_AL MFC ST
0 100 200 300 400 500 Nhiet dp, "C)
Hmh 4 Dd thi TGA cua MFC Dp ben nhiet ciia MFC duac dinh gii thdng qua phirong phip phin tich nhiet TGA, ket qua trinh bay tren hinh 4. Tir hinh 4 thiy rang, hai dudng dp thj cd hinh dang cQng nhu dp ddc hau nhu trung khdp nhau, dieu niy chirng td c i hai logi MFC che tgo dugc cd dp ben nhiet tuang duang nhau vi miic dp phin hiiy nhu nhau, mac dii cd sy sai khac ve mire dp kit tinh cua xenlulo. Ci MFC_AL vi MFC_ST deu bat diu phin hiiy manh d nhiet dp 295°C.
3.2. Anh hudng cua vi soi xenlulo toi tinh chat co hoc ciia vat lieu compozit tren co' sd nhua epoxy- lua thiiy tinh
Dp ben keo ciia vat lieu compozit cot sgi thiiy tinh tren ca sd nhua epoxy bien tinh vdi hai logi MFCAL vi MFC_ST dugc trinh biy tren hinh 5.
Tir hinh 5 thay rang dp ben keo ciia vat lieu compozit cd dugc cii thien khi cd mat MFC nhung miic dp khdng nhieu. Rieng vdi do ben mdi thi sy cd mat ciia MFC lgi cd tie dyng tich cue rat ro ret.
Da tien hinh khao sit dp bin mdi thii keo ciia vat lieu compozit epoxy - lua thiiy tinh vdi 0,3%
khdi lugng MFC so vdi nhya nin d hai dilu kien luc keo dat vio mau khic nhau la 147 MPa (tucmg duong 70%i gii tri do ben keo diit ciia vit lieu compozit) vi 168 MPa (tuong duong 80% gii tri do ben keo diit ciia vit lieu compozit). Miu do dugc keo d tirng gii tri luc keo cd dinh nhu tren vdi tin sd 1 OHz tdi khi man gay hoin toin, ket qui dugc dua ra tren hinh 6. Tir hinh 6 nhin thiy ring dp ben mdi thir keo ciia vat lieu da dugc cii thien ro ret khi cd mat MFC, vimg phan bd gii tri dp ben mdi cua vgt lieu compozit vdi 0,3 phan khdi lugng MFC tren do thj hinh 6 da cd sy dich chuyin sang ben phii, theo
TCHH, T. 49(6), 2011
chieu ting ciia sd chu ky keo. C\\ the d lyc k^o 147MPa tuong duang 70% dg bin keo khi dirt, vgt lieu vdi 0,3% khdi lugng MFC cd dp ben mdi bing 6,3><10'' chu ky tang 2,1 lin so vdi khi khdng cd MFC (SxlC chu ky). Doi vdi vgt lipu PC vii Ihiiy tinh nen nhya polyeste khong no cung cd ket qua tuong ty, dp ben mdi ciia vgt lipu PC cung ting 2,2 lan so vdi khi khong cd MFC. Cac kel qua tren ciing phii hgp vdi mgt so cdng bo vc cic logi MFC khic [2, 4]. Dieu niy cd the dugc giii thich li do sy cd mat ciia vi sgi xenlulo d kich ihudc nanomet di cd tic dung han che sy phit trien cac vet mit trong vgt lipu d dieu kien phii chju tic dyng lyc ldn. din tdi lim ting dd ben mdi ciia vgt lipu.
260 200 150 100 50 0
rir
210
1
225 T
1
253
0% MFC MFC_ST MFC AL
Hinh 5: Dp ben keo vat lieu compozit epoxy cot sgi thiiy tinh vdi 0,3% khdi lugng MFC
• 0,3% MFC o 0% MFC
2.Et04 4.E+04 So chu ky
Hinh 6: Dp ben mdi thii keo vgt lipu compozit epoxy cdt sgi thuy tinh vdi 0,3% khoi lugng MFC 4. KET LUAN
1. Da che tgo dugc hai logi vi sgi xenlulo tir cay Liin he: Nguyen Chau Giang
Trung tarn NCVL POLYME, Trudng Dgi hgc Bach khoa Ha Ngi So 1 Dai Co Viet, Hai Bi Trung, Ha Ngi.
714
Phuong phdp tach vi sgi xemuiu..
ludng bing phuang phip xii ly kiem die vi tach i hoi nudc kit hgp vdi xii ly co hgc. Phuong phip ti<
xir ly bing tich no hoi nudc cho kit qui logi I lignin vi pentozan tot hon, tuy nhien ddi hdi thilt chuyen dyng dit ticn han. X6t vl m$t than than thi^
mdi trudng thi phuang phip tich no hoi nudc c nhilu lgi thi han do sir dyng hda chit khdng dang V so vdi phuang phip xur ly kilm dgm die.
2. M F C s t tich dugc tir sgi luong tach no h(
nudc vi M F C a l thu dugc tir sgi luong xir iy kier dgc cd miic dp kit tinh vi dp bin nhipt tuang diron nhau. Ca hai logi vi sgi xenlulo deu la xenlulo loai I khdng cd sy biln doi thinh xenlulo logi H d ca lo^
MFC sau qua trinh xir Iy kilm.
3. Vi sgi xenlulo tir sgi luong chl tgo dugc ci khi ning cii thipn dp ben k^o ciia vgt lipu compozr nin nhya epoxy cot sgi thiiy tinh, die bipt dp ber mdi tim keo ciia vat lipu tang 2,1 lan so vdi khi khdng cd m$t MFC.
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