Tap chi Hoa hgc,
T. 48(4), Tr. 463 - 468, 2010
NGHIEN CLfU CHE TAO VI SOI XENLULO TLf SOI LUONG LfNG DUNG LAM VAT LIEU EP
• • •
De'nTda sogn 17-9-2009
NGUYfiN C H A U GIANG, TA THI PHUONG HOA, N G U Y I N HUY TUNG Trung tdm Nghien cicu Vgt lieu Polyme, Dgi hgc Bach khoa Hd Ndi
ABSTRACT
Application of microfibrillated cellulose (MFC) in molding materials are broaden rapidly as it possesses very high strength, stiffness and biodegradable. Generally cellulose microfibrils were obtained from homogenization process of plant cell walls however a homogenizer costs a lot of money. The aim of our study was to develop an effective mean to extract microfibrillated cellulose from bamboo fiber and made it refined to each nano-level at laboratory scale. Long bamboo fibers were firstly applied with chemical treatment by using NaOH solution 1 N and HCl solution 1 N at 80''C. The treated and untreated bamboo fibers were then chemically analyzed for pentosan, lignin and cellulose contents to study the effect of chemical treatment process. After chemical treatment, the microfibrills were still associated within the cell walls however the cell wall structure has become loose because of removal of lignin and hemicelluloses. A mechanical treatment was applied to defibrillate them. A stone milling which often was used in traditional cake and noodle production was done for this purpose. This stone milling has successfully provided shear force that created the liberation of microfibrills from the cell walls. SEM micrographs of mechanical treated fiber showed improvement of degree of defibrillation with increasing in number of circles of stone milling and size of fiber has started to reduce submi iron level. A novel polymer composite from received MFC was also fabricated.
• . Key words: Microfibrillated cellulose (MFC), cellulose microfibrils, bamboo fiber, stone milling, chemical treatment.
1 - D A T \AH D E cdng su dua ra mdt hinh thai ciu tnic mdi cua xenlulo la vi sgi xenlulo (microfibrillated Viec s£t dijng sgi thuc vat cd ngudn gdc tit cellulose - MFC). Ben trong cac ldp thanh te bao cac ngudn nguyen lieu cd the tai sinh dugc trong cua sgi thuc vat cac vi sgi tap hgp lai thanh timg mdt thdi gian tuang ddi ngln nhu gd, tre, niia... bd trong nin lignin. Tuy thudc vao miic do be lam vat lieu gia cudng cho polyme compozit da gay ciia qua trtnh xit ly m l vi sgi thu dugc se cd va dang trd nen ngay mdt phd biin va thu hiit kfeh thudc tut vai pm tdi vii run. Vi sgi la mdt dugc nhiiu su quan tam cua cic nha khoa hgc tap hgp cac mach phin tit xenlulo slp xip song bdi chiing cd kha nang phan buy sinh hgc sau song vdi true ciia vi sgi, ciu tnic nay tao cho vi khi hit thdi gian sit dung vl vd hai ddi vdi mdi sgi cd tfnh chat co hgc dat gin tdi gidi ban ly tradng sinh thii cua chiing ta. Mat khac, chiing thuyit cua cic tinh thi xenlulo hoan thien, md cd cic tfnh chit ca hgc tuong ddi cao va re tiin dun dan hdi udc tfnh len tdi 150 GPa va do bin hon so vdi cic loai sgi tdng hgp thdng thudng. khoang 10 GPa [1]. Nhu vay, v i ly thuyet vat Vao diu nhirng nam 1980 Tubark va cac ^^^"^ nanocompozit tren co sd vi sgi xenlulo se cd
tinh chit cao ban rat nhiiu so vdi sgi thuc vat thdng thudng. Viec dua vi sgi xenlulo vao mdt sd loai vat lieu ep se tang cudng do ben, do ciing vl do bin nhiet cua vat lieu din tdi viec chiing dugc ling dung ngay mdt rdng rai ban trong ddi sdng nhu lam chat tang do bin cho cdng nghe san xuit gia'y, lam chat tang do min trong cdng nghiep thuc pham, my pham.... Trong linh vue dugc phim vi sgi xenlulo dugc sit dung lam chat mang thudc nhd cd be mat rieng Idn va cd nhiiu nhdm chiic boat ddng. Mac diu cd nhiiu cdng trinh nghien cun ve qua ttinh tich vi sgi xenlulo tii cac ngudn sgi thuc vat khac nhau nhung viec ling dung chiing lam chit gia cudng cho polymer compozit va cac vat lieu chiu luc cdn kha khiem ton do vap phai mdt so khd khan nhu viec phan tin vi sgi xenlulo trong nhua nin, dac biet la cic nhua nen ky nude.
Bai bao nay trinh bay kit qua nghien ciiu chi tao vi sgi xenlulo tit sgi luong ky thuat bing phuang phap boa hgc kit hgp ca hgc vl khao sit anh hudng cua qui trinh xit ly hoa hgc tdi thanh phin hoa hgc cua sgi cung nhu anh hudng cua qua trtnh nghiin co hgc tdi kha nang tach vi sgi.
Thit nghiem chi tao vat lieu ep khdng cd nhua nin tren co sd vi sgi che tao dugc.
II - PHUONG P H A P T H U C NGHIEM 1. Nguyen lieu
Luong Hoa Binh 3 nam tudi dugc sit dung di che tao vi sgi xenlulo. Cay ludng dugc loai bd mau va che thanh 4 - 6 thanh nhd.
Vi sgi xenlulo cua Nhat Ban, cung clp bdi Dai hgc Doshisha, Kyoto dugc diing di so sinh.
2. Phuong phap xac dinh do ben keo cua sgi Miu do do ben keo cua sgi dugc chuan bi nhu hinh 1.
Tambia Vitri cat Keo dan
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30 '
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^ Sai luong 30 50
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Dd bin keo cua sgi dugc xac dinh tren may Lloyd Instrament 500 kN.
3. Phuong phap che tao vi sgi
Giai doan 1: Tich sgi ky thuat tit cay ludng
Thanh luong Can dap (May can 2
Sgi ky thuat Cao tach sgi (May cao tach)
— •
')^\i ly kiim (NaOH IN, 80°C/4 gid)
ir Can dap (May can 2
Hinh 1: Miu do dd ben cua soi
Giai doan 2: Tich vi sgi xenlulo tit sm ky thuat.
Sgi ky thuat dugc tiep tue xit ly kiim vdi dung dich NaOH IN d 80°C trong 4 gid sau dd rita sach bang nude tdi khi dat pH = 7. Sau xii ly kiem sgi dugc dua vao may clt (Restch) cd mit sang cd 25 pm trade khi dua vao mIy nghien dl. Qua trtnh nghiin dugc lap di lap lai nhiiu chu ky di thu dugc vi sgi, ky hieu la MFC-K40.
Mdt phin sgi sau khi xit ly kiim d tren dugc tiip tue xvf ly vdi dung dich HCl 1 N trong 2 gid d 80°C. Sau khi xii ly axit sgi dugc tiep tue xii ly ca hgc gidng nhu tren vdi mIy clt va may nghiin di thu vi scri, ky hieu la MFC-A40.
May nghiin dl su dung d day la loai thudng diing di xay bdt lam biin, banh cudn ... dugc san xuit tai lang nghe tinh Ha Tay.
4. Phuong phap xac dinh thanh phan hoa hgc cika sgi luong trudc va sau xut ly hoa hgc
Ham lugng cic chat tan trong axeton va him lugng tro cua bdt ludng nguyen lieu dugc xac dinh theo tieu chuin TAPPI tuong img la T 280 pm-99 va T 211 om-93. Ham lugng lignin, va pentozan trong bdt ludng trade va sau khi xii ly hoi hgc dugc xic dinh theo tieu chuin TAPPI tuong ling la T 222 "om-98, T223 cm-84. Ham lugng xenlulo dugc xic dinh theo phuong phap Kiursber- Hofft.
5. Hinh thai ca'u true sgi
Su thay ddi hinh thai cl'u tnic, klch thudc sgi trong qua trtnh nghiin dugc xic dinh bing each chup M l SEM cac miu sgi sau mdt sd chu ky nghien nhit dinh tren mIy JEOL 6360-LV (Nhat Ban) vdi dien thi tang tdc 15 kV.
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6. Phuong phap che tao vat lieu ep
Vat lieu ep dugc c h i tao tit vi sgi xenlulo khdng cd nhua nin. Vi sgi c h i tao dugc d dang dung dich 8 - 9% dugc Igc chan khdng, nit hit nude, sau dd la'y ra khdi phiu loc va say d nhiet do 60 - 80°C tdi khi khd. Miu dugc clt vita vdi kfeh thudc cua khudn va ep ndng tren may ep thuy luc vdi Ip luc 200 kG/cm^ d nhiet do 160°C trong thdi gian 7 phiit.
7. Phuong phap xac djnh do ben co hgc cua vat lieu ep
Do bin udn dugc xac dinh tren may Lloyd Instrament 500 kN vdi khoang each giiia 2 gdi dd II 30 mm. Miu do ed kfeh thudc 50 x 5 x 2 mm.
Do bin keo dugc xac dinh tren may Lloyd Instrament 500 kN vdi tdc do keo Imm/phiit.
Miu do cd kich thudc 50 x 5 x 2 mm dugc dan them cic miing thep mong d 2 diu d i tao dang cd eo.
Ill - KET QUA VA THAo LUAN 1. Anh hudng cua qua trinh xu ly hda hgc tdi
thanh phan va tinh chat sgi luong
Vi sgi xenlulo dugc hinh thanh trong thanh te bao sgi thuc vat d kich thudc cd vai chuc nm trong qui trinh sinh tradng cua cay. Chiing lien kit vdi nhau rit chic chin bdi nin lignin, pectin vl hemixenlulo, bdi vay de cd t h i tach vi sgi can CO su hoa tan va thuy phin cac chit lien kit nay.
Da tiin hanh xii ly boa hgc sgi ludng ky thuat bang dung dich NaOH IN d 8d°C trong 4 gid va xii ly kiim kit hgp xii ly bing axit HCl IN trong 2 gid d 80°C. Kit qua phan tich thanh phin hoa hgc cua sgi ludng ky thuat trade va sau khi xir ly hda hgc dugc trinh bay d bang 1.
Kit qua tren bing 1 cho thay qua trinh xir ly kiim da loai bd dugc mdt phan lignin trong sgi, ham lugng Hgnin giam tit 29,2% xudng 21,7%
sau hai lin xii ly kiim, nhung khdng lam thay ddi ham lugng pentozan. Diiu nay chiing td xu ly kiim khdng cd tac dung loai bd pentozan ma chi cd qua trtnh xii ly axit mdi lam duge diiu nay. Sau khi xii ly vdi axit HCl 1 N ham lugng pentozan trong sgi da giam tit 17% xudng 13%.
Tuong ling vdi su boa tan ciia lignin va pentozan
trong qui trinh xir ly, ham lugng xenlulo trong sgi ludng tang tir 52% len 62,6% sau khi xir ly kiim va 68,2% sau khi xii ly kiem kit hgp axit.
Mac diu vay cd thi thiy ring qua trinh xu: ly boa hgc nay chua dat hieu qua tdi da vi ham lugng lignin vin cdn kha Idn.
Bang 1: Thanh phin hda hgc cua sgi ludng trade va sau khi xir ly boa hgc
Ham luong,
% ' Xenlulo Lignin Pentozan Tro
Chit trich ly trong axeton
cay ludng
52,2 29,2 17 1,2 1,7
Sgiky thuat
57,7 24,1 17 1,2 -
Sgi kt xir ly kiim
62,6 21,7 17 1,2 -
Sgi kt xii ly kiim/
axit 68,2 20,0 13 0,9 - Trong qui trinh xii ly hoa hgc, dac biet la xii ly kiim, xenlulo cd the bi phan huy mdt phin din tdi viec suy giam do bin cua sgi, do vay qua trinh xit ly kiim cin dugc kiem solt chat che.
Da tiin hanh xac dinh do bin keo cua sgi ky thuat sau khi xii ly boa hgc, kit qua trtnh bay d bang 2.
Qua trinh xir ly kiem da lam giam do bin keo cua sgi, tii 481,2 MPa xudng cdn 450,8 MPa. Them vao dd dudng kinh sgi cung giam.
Tuy nhien cac miic do thay ddi nay khdng nhiiu.
Bang 2: Anh hudng cua xii ly kiem tdi do bin keo cua sgi ludng
Loai sgi Sgi ky thuat Sgi ky thuat xir ly kiim
Dudng kfnh sgi,
pm 137,7 134,8
Do ben keo, MPa 481,2 450,8
Modun dan hdi keo,
GPa 33,7 32,5 2. Su thay doi hinh thai ca'u triic sgi trong
qua trinh che tao vi sgi
Da tiin hanh chup anh SEM cac miu sgi d i
tim hieu su thay ddi ciu tnic sgi trong qua trinh xir ly ca hgc.
Hinh 2: Anh SEM sgi ky thuat sau khi xii ly kiim (a) va xh ly kiim/axit (b)
Tit hinh 2 thiy ring, sau qua trtnh xu ly hda hgc ca hai loai sgi diu cd dudng kinh khoang tii 1 0 - 1 5 pm. Ddi vdi sgi cd xir ly axit b i mat sgi xuat hien nhiiu ranh, khdng nhin nhu ddi vdi sgi chi xir ly kiim, chiing td su hda tan cac chit nin (lignin, pentozan) lien kit cac vi sgi ben trong nhiiu hon.
Sau qua trinh xir ly hda hgc, cac vi sgi vin cdn tap hgp thanh timg bd ben trong cac ldp thanh te bao, tuy nhien ciu tnic nay da trd nen long leo ban do su tich ra cua cac thanh phin lignin va hemixenlulo. Do vay cin ap dung them mdt qua trinh xii ly ca hgc niia vdi luc clt xe cao mdi cd the tach dugc cac vi sgi. D i tai da thit nghiem sir dung mIy nghiin da d i thuc hien qua trinh xir ly nay trong diiu kien chua cd thiet bi ddng nhit boa (homoginizer) dit tiin nhu cua nude ngoai. May nghiin da nay la mdt thiet bi tuong ddi don gian va re tien thudng dugc diing d i xay cac loai bgt banh trayin thdng gdm cd hai khdi da mai dat Ip sat vao nhau va quay ngugc chiiu nhau. Khi quay vdi tdc do cao chiing se tao ra mgt luc ma sit, luc xe tuang ddi Idn lam cac vi sgi tragi len nhau va din din tich ra khdi bd sgd. Qua trtnh nghiin dugc lap lai tdi 40 lan nhim dam bao su tach vi sgi d miic do cao. Sau mdi 10 lin nghiin, miu sgi dugc dem di chup SEM de danh gia hieu qua tach sgi cua qua trinh xic ly ca hgc.
Anh SEM cua sgi xit ly kiim sau 20, 30 lan nghiin tuong ling la K20, K30 va cua sgi xii ly kiim kit hgp axit sau 20, 30 lan nghiin tuong ling la A20, A30 dugc trmh bay d hinh 3.
Cac anh SEM cho thay mire do tach sgi tang din theo sd lin nghiin. Sau 20 lin nghiin, tir
mdt sgi to dudng kfnh khoang 10 pm da bi xe tude thanh 2 hay 3 sgi nhd ban vdi dudng kinh khoang tii 2 - 5 pm (hinh 3a, 3c). Tiep tue nghiin tdi 30 lan thi bit diu xuit hien cac vi sgi cd kfeh thudc cd 1 pm va nhd hon 1 pm (hinh 3bva3d). , . ,
Hinh 3: Anh SEM (x 4.500) ciia sai ludng sau khi xit ly hoa hoc kit hgrp co hoc.
a): K20, b): K30,'c): A20 va d): A30 Anh SEM tren hinh 4 cho thiy, sau 40 lan nghien cac vi sgi duagc tich ra nhiiu hon tif ca hai loai sgi xu ly kiim va kiim kit hgp axit, kha nhiiu sgi cd kich thudc nhd ban 1 pm (hinh 4a va 4b).
Tir hinh 3 va 4 cung nhan thiy rang miic do tach vi sgi sau khi nghiin cua sgi da qua xit ly kiim/axit va sgi chi xir ly kiim la tuong duong nhau.
So sinh anh tren hinh 4a va 4b vdi hinh 4c tha'y ring, vi sgi c h i tao dugc cd nhiiu sgi co dudng kinh tuong duong vdi vi sgi cua Nhat Ban, tuy nhien vi sgi cua Nhat cd miic do ddng deu vi kich thudc Idn hon khi nhiiu.
3. Tinh chat co hgc cua vat lieu ep tii vi sgi xenlulo
Da tiin hinh che tao vat lieu ep tit cac loai vi sgi c h i tao dugc (K40 vl A40), va vat lieu ep tif vi sgi cua Nhat Ban (N) de so sanh. Kit qua xac dinh do bin keo va udn cua vat lieu dugc trtnh bay tren hinh 5 va 6.
(a)Soi xir ly kiem(K40) (b)Sgi xir ly kiem/axit(A40)
(c) vi sgi cua Nhat Ban(N)
Hinh 4: Anh SEM (x 10000) ciia sgi ludng sau 40 chu ky nghiin
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Hinh 5: Dd thi dd bin keo va modul keo eiia cac loai vat lieu ep
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N-K40 N-A40
Hinh 6: Dd thi dd bin udn va modul udn cua cac loai vat lieu ep
Hmh 5 vl 6 cho thiy, ddi vdi vat lieu ep K40 cd do bin keo cao hon so vdi vat lieu ep loai A40, tuy vay vin thap ban so vdi vat lieu ep tif vi sgi ciia Nhat Ban. Do bin keo va bin udn cua vat lieu ep K40 bing 6 1 % va 8 1 % so vdi dd bin keo va bin udn ciia vat lieu ep tit vi sgi Nhat Ban. Vat lieu ep tit vi sgi loai A40 cd do bin keo bing 44% va do bin udn bing 55% so vdi vat lieu ep loai N.
Da tiin hanh c h i tao vat lieu tit hdn hgp vi sgi c h i tao dugc vdi vi sgi Nhat Ban theo ty le 90:10 phin khdi lugng. Vat lieu ep loai N-K40 cd do bin kio tang 40%, nhung do bin udn lai giam 10% so vdi vat lieu ep loai K40. Tuong tu, vat lieu ep loai N-A40 cd do bin keo tang 8%, cdn do bin udn giam 30% so vdi vat lieu ep loai A40.
I V - KET LUAN
1. Da nghien ciiu anh hudng cua viec xii ly hda hgc sgi ludng din thanh phin cua sgi.
- Xii ly kiem giiip tiip tue nang cao ham lugng xenlulo va lam giam ham lugng lignin, nhung khdng giam ham lugng pentozan va ham lugng tro.
- Xir ly kiem kit bctp vdi axit clobycJ'-ic giiip nang ham lugng xenlulo len 68,2%, ddig thdi giam dugc ham lugng pentozan ciing nhu ham lugng tro ciia sgi.
2. Da khao sat qui trinh nghien sgi da xii ly hda hgc bing may nghiin da. Cac nghien ciiu SEM vi hinh thai hgc cho tha'y cd su tich sgi din din trong qua trinh nghiin. Sau 40 lin nghiin, da tach dugc khi nhieu sgi vdi dudng kfnh dudi 1 pm. Tuy nhien, do ddng diu cua sgi chua cao.
3. Da c h i tao dugc vat lieu ep tir cac san phim vi sgi che tao dugc. Vat lieu ep tut san phim K4Q cd tfnh chit ca hgc tuong ddi tdt vdi do ben keo va bin udn tuong ung bing 61 % va 81% so vdi vat heu ep tir vi sgi cua Nhat Ban.
4. Cin tiip tue nghien ciin bien phap de giam tiep ham lugng petoza cung nhu nang cao do ddng diu cua vi sgi c h i tao dugc.
T A I LIEU THAM K H A O 3. Mohamed El-Sakhawy, Mohammad L.
Hassan, Carbohydrate Polymers, 67, 1-10 1. A. N. Nakagaito, H. Yano, Appl. Phys A (2007).
(2003), DOI: 10.1007/s00339-003-2225-2. 4. Mohamed E. Malainine, Mostafa Mabrouz, 2. Tanja Zimmermann, Evelyn Pohler and ^^^i" Dufresne, Composites Science and
Thomas Geiger, Advanced Engineering Technology, Vol. 65, 1520 - 1526 (2005).
Materials, 6(9), 754 - 761 (2004). 5. E. Dinand, H. Chanzy, M. R. Vignon, Food Hydrocolloids, Vol. 13, 275 - 283 (1999).
Lien he: Ta Thj Phuong Hoa
Trang tam Nghien ciiu Vat lieu Polyme Tradng Dai hgc Bleb khoa Ha Ndi Sd 1 Dai Cd Viet, Ha Ndi
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