TAP CHI HOA HOC
DOI. W.15625/0866-7I44.2014-0069
T. 52(6) 760-764 THANG 12 NAM 2014
NGHIEN CLTU A N H HU-aNG C O A H Y D R O T A L X I T BIEN T I N H HlPU CQ DEN TINH CHAT NHIET CUA MANG SON EPOXY
To Thi Xuan Hing*, Nguyen Thiiy Duong, Nguyen Anh Son, Trinh Anh Triic, Pham Gia VQ, Vu K I Oanh, Biii Van Triroc, Nguyen Thi Thu Trang, Do Quang Tham, Thai Hoang
Vien Ky thugt nhiet dai, Vien Hdn lam Khoa hgc vd Cong nghi Viet Nam Den Tda soan 20-5-2014; Chap nhan dang 4-12-2014
Abstract
Zn/Al and Mg/Al hydrotalcite intercalated with stearate (ZnAl-HT-SA, MgAl-HT-SA) were prepared using the coprecipitation method. The obtained hydrotalcites were characterized by infrared spectroscopy, X-ray diffraction. The thermal properties of epoxy coatings containing 3 % ZnAl-HT-SA and 3 % MgAl-HT-SA were evaluated. The obtained results showed that stearate was intercalated in hydrotalcites The presence of ZnAl-HT-SA, MgAl-HT-SA improved the thermal resistance of epoxy coatings. The limited oxygen index of epoxy coating was increased by 16 % and 31 % with the presence of MgAl-HT-SA and ZnAI-HT- SA, respectively.
Keywords. Hydrotalcite, epoxy coatings, thermal properties.
1. MO DAU
Hydrotalxit (HT) dugc biet den nhu clay anion.
Chung cau tao bdi cac Idp hydroxit tich dien duong tuong tu nhu cau true brucit vdi anion xen giiia va cac phan tir nudc gitJa cac Idp. Cdng thuc chung cua hydrotalxit la M„^^M^70H)2^2n(A'""i/,^).xH20, trong do M^"^ va M"'"* la cation hda tn II va hda tri III chiem cac vi tri bat dien trong Idp hydroxit, n la ty le nguyen tu ciia cation hda trj II va cation hda tri III va gia trj n ndi chung thudng nam giira 2 va 4. Cac lop hydroxit dugc tich dien duong va A'"" la mgt anion CO kha nang trao ddi xen giiJa can bing dien tich duong cLia cac Idp. Khoang each giifa cac lop hydroxit cho phep cac anion (ca hiJu co va vo co) cd kich thudc khac nhau cd the chen vao [1-3]. Cac anion xen giiJa cac Idp hydroxit cd thi dugc giai phdng ra va thay the bing cac anion khac tir moi trudng. Cac li-ng dung cua hydrotalxit dugc dua tren sir hap thu, kha nang trao dii anion va su di chuyin ciia cac anion giiJa cac Idp. Hydrotalxit da dugc sir dung rgng rai lam chat hip phu, trao ddi ion, chit xiic tac, phu gia cho polyme va phu gia uc ehe an mdn, do dd thu hut su chii y rgng rai trong cac thap ky gin day [4, 5].
Hydrotalxit (HT) la phu gia rit dugc quan tam trong viec dua vao polyme nham cai thien tinh chong chay cua vat lieu. De tang kha nang tuong hgp trong nen polyme, hydrotalxit thudng dugc biln tinh hiru co trudc khi dua vao mang son [1, 2].
Frache va cdng su [3] da biln tinh hydrotalxit bing stearat trudc khi dua vao epoxy de khao sat kha nang chdng chay. Tir ket qua cua thd nghiem nhiSt lirgng cho thay epoxy chiia HT bien tinh cd thdi gian bat dau chay eham hon, lugng chit rin cdn lai sau khi chay hoan toan Idn hon so vdi epoxy khdng co mat hydrotalxit.
Trong cac cdng trinh tnrdc chiing tdi da nghien cuu bien tinh hydrotalxit bang BTSA, sir cd mat cua hydrotalxit bien tinh bing BTSA da cd tac dung tang dang ke kbit nang bao ve ciia mang epoxy [5], Kha nang ire ehe an mon cua ZnAl-HT bien tinh cao hon MgAl-HT bien tinh. ZnAl-HT bien tinh bing axit steraric da cd tac dung tang do bam dinh va kha nang chdng chay ciia mang epoxy. Trong cdng trinh nay chiing tdi nghien ciru tdng hgp 2 loai hydrotalxit bien tinh bing axit stearic (ZnAl-HT-SA va MgAl- HT-SA) va nghien ciru tinh chat nhiet ciia Idp phu epoxy chira hydrotalxit biln tinh. Hydrotalxit dugc tdng hgp bang phuong phap ddng kit tua va dugc dac trung bdi phd hdng ngoai va phd nhieu xg tia X, Mang epoxy chira 3 % hydrotalxit dugc chi tgo va danh gia kha nang chdng chay va each nhiet.
2. THU'C NGHIEM 2.1. Nguyen lieu
- Zn(N03)2.6H20, Merck.
- A1(N03)3.9H20, Merck.
TCHH.T 52(6). 2014 - Axit stearic, Merck.
- Epoxy loai X75 va chit ddng rin la PA66 cua Thai Lan
- Dung mdi sii dyng la hdn hgp cua toluen, xylen va butanol.
2.2. Ting hfjrp hydrotalxit
Hydrotalxit ZnAI dugc tdng hgp bang phuong phap ddng kit tiia trong mdi trudng nito dk loai bd CO2. 125ml dung dich chiira 0,03 mol Zn(N03)2 va 0,015 mol AI(N03)3 da loai bd CO2 bang each dun sdi dugc nhd dan dan vao 145 ml dung dich chira 0,0313 mol NaOH. Hdh hgp dung djch dugc giir d pH ^ 8-10 bing each bo sung dung dich NaOH 1 M va phan img dugc duy tri d 65 °C trong 24 gid; sau dd hdn hgp dugc li 12 gid d nhiet do phdng. San pham hydrotalxit dugc Igc, rira nhieu lan bang nudc cit, say d 50 °C trong chan khdng.
Hydrotalxit MgAl dugc tdng hgp theo quy trinh nhu hydrotalxit ZnAI va Mg(N03)2.9H20 dugc su dung thay Zn{N03)2.6H20.
2.3. Tong hgp hydrotalxit bien ti'nh bang axit stearic
Hydrotalxit ZnAI bien tinh bang axit stearic (ZnAl-HT-SA) dugc tong hgp bang phuong phap ddng ket tiia trong mdi trudng nito de loai bd CO2 cd thi din din chen C03^" vao hydrotalxit. 125 ml dung djch chira 0,03 mol Zn(N03)2 va 0,015 mol A1(N03)3 da loai bd CO2 bing each dun sdi dugc nho dan din vao 145 ml dung dich chira 0,0313 mol axit stearic va 0,0313 mol NaOH. Hdn hgp dung dich dugc giir d pH = 8-10 bang each nhd bd sung dung djch NaOH IM va phan img dugc duy tri d 65°C trong 24 h; sau dd hdn hgp dugc ii 12 gid d nhiet dd phdng. San phim hydrotalxit bien tinh dugc Igc, rda nhilu ISn bing nudc cat, say d 50 "C trong chan khdng.
Hydrotalxit MgAl biln ti'nh bing axit stearic (MgAI-HT-SA) dugc tong hgp theo quy trinh nhu ZnAl-HT-SA, nhung Mg(N03)2.9H20 dugc sir dung thay Zn(N03)2.6H20.
2.2. Che tao mang epoxy chira hydrotalxit tren nen thep
Hydrotalxit dugc phan tan trong dung mdi, sau dd dugc phoi trdn vdi epoxy va nghien bi tao thanh son epoxy/hydrotalxit. Chit ddng ran dugc trdn vao hdn hgp epoxy/hydrotalxit trudc khi son. Ham lugng hydrotalxit trong mang epoxy la 3 %. Miu thep dugc sij dung la thep CT3 cd kich thudc 100x150x2 mm.
Miu thep dugc rua sgch dau bing xa phdng, lau va
Td Thi Xudn Hdng vd cdng su siy khd, sau dd tien hanh lay gi bing dung dich axit HCI rdi bang kilm, rira sach bing nudc, danh bdng bang giay glap cd do mjn 400, rua sach bing nudc cat, cdn tuyet ddi va say khd. Mang son dugc tao tren mau thep bang may tao mang li tam. Do day mang son sau khi khd la 30 [xm,
2.4. Pho hdng ngoai
Cau tnic ciia hydrotalxit dugc phan tich bang phd hdng ngoai tren may Nicolet Nexus 760 d viing budc sdng tir 4000 cm"' din 400 cm' ciia Vien Ky thuat nhiet ddi, Vien Han lam Khoa hgc va Cdng nghe Viet Nam. Phd hdng ngoai ciia hydrotalxit dugc do d dang ep vien vdi KBr.
2.5. Pho nhieu xa tia X
Pho nhilu xa tia X ciia hydrotalxit dugc do tren may Siemen D5000, sir dung tia nhieu xa CuKjCd budc sdngX= 1,5416 A tgi Vien Khoa hgc Vat lieu, Vien Han lam Khoa hgc va Cdng nghe Viet Nam.
2.6. Xac dinh kha nang each nhiet
Kha nang each nhiet ciia mang son dugc xac djnh bing phuong phap do nhiet do be mat mau khdng tiep xiic vdi ngudn nhiet. Mat thep dugc phii Idp son epoxy khdng chira va chiia hydrotalxit dugc ddt dudi nggn lira den cdn trong vdng 60 phiit.
Trong qua trinh ddt mau thep, nhiet do ciia be mat sau cita mau thep phii son dugc xac dinh bang may do nhiet do laze (EXTECH model 42512) tir dd thilt lap ddthj tang nhiet do theo thdi gian ciia cac mau.
2.7. Xac dinh kha nang chong chay
Kha nang chdng chay ciia cac mang son dugc xac djnh bdi tieu chuan danh gia cip do chay UL94.
Mau dugc dd khudn, sau dd de khd va gia nhiet rdi dugc cat thanh cac thanh cd kich thudc 1x13 cm.
Sau do cac mau dugc thir nghiem chay ngang.
3. KET QUA VA THAO LUAN
3.L Dac trirng tinh chat cua hydrotalxit bien tinh bang axit stearic
+ Phd hong ngogi
Phd hdng ngoai cua hydrotalxit ZnAI (ZnAl-HT), hydrotalxit MgAl (MgAl-HT) va hydrotalxit bien tinh bing axit stearic (ZnAl-HT-SA, MgAl-HT-SA) dugc trinh bay tren hinh 1.
TCHH, T. 52(6), 2014
Nhan thiy, ZnAl-HT cd cac pic dac trung tai 1383 cm"' va 3441 cm"' tuong img vdi lien ket cua -NO3 va -OH. Vdi phd hdng ngoai cua axit stearic thi cd cac pic dac trung cho nhdm -COOH va nhdm -CH2, tuong img tai 1702 cm"' va 1465 cm"'. Phd hdng ngoai ciia ZnAlHT-SA cd cac pic dac trung cho hydrotalxit tgi 421 cm"' va 3458 cm'. Ben cgnh do xuat hien pic tai 1539 cm"' dac trung cho nhdm -COO. Dieu do cho thay stearat da dugc chen vao trong cau triic ciia hydrotalxit ZnAI. Tuong tu, phd hdng ngogi ciia MgAIHT-SA cd cac pic dac trung cho cac lien ket ciia Mg-0 va -OH tai 436 cm"' va 3448 cm '. Ben canh dd, pic tai 1559 dac trung cho nhdm cacboxylat, cac pic tgi 2920 cm"' va 2851 cm"' dac trung cho nhdm cacbuahydro. Cac ket qua phan tich hdng ngogi da khing djnh sir cd mat ciia sterat trong cau true ciia hydrotalxit MgAl-HT-SA va ZnAl-HT-SA.
4000 3500 3000 2500 2000 1500 1000 500
Hinh I: Phd hdng ngogi cua axit stearic, ZnAl-HT, ZnAl-HT-SA, MgAl-HT va MgAl-HT-SA + Phd nhieu xg tiaX
Khoang each gitra cac Idp hydroxit trong hydrotalxit dugc xac dinh bing phd nhilu xa tia X.
Phd nhieu xa tia X ctia hydrotalxit va hydrotalxit biln tinh bang axit stearic dugc trinh bay tren hinh 2.
Nhgn thay ZnAl-HT cd pic tuong irng vdi khoang each Idp la 0,76 nm. Pho XRD ciia ZnAl- HT-SA cd pic tuong iing vdi khoang each Idp la 1,56 nm va 2,83 nm. Dieu nay chiing td su chen stearat vao giira cac Idp ctia ZnAl-HT va tang dang ke khoang each Idp cita hydrotalxit.
Tuong tu vdi MgAl-HT, cd cac pic tuong u-ng vdi khoang each Idp la 0,81 nm va 0,38 nm, cac kit
Nghien ciru dnh hudng cita hydrotalxit...
quanay cung phii hgp vdi cac qua dS cdng bo. Ph6 nhilu xa tia X cua MgAl-HT-SA cd cac pic tuong irng vol khoang each Idp la 1,64 nm va 2,94 nm. Cac ket qua tren cho thiy khoang each giOa cac Idp trong MgAl-HT-SA cao hon khoang each giua cac Idp ctia HT, dieu nay chijng td stearat da chen vao hydrotalxit MgAl-HT va Iam tSng khoang each Idp ctia hydrotalxit Cac kit qua phan tich bing pho nhilu xg tia X phii hgp vdi cac kit qua phan tich hong ngogi.
Hinh 2: Phd nhilu xa tia X cua ZnAl-HT, ZnAI-HT- SA, MgAl-HT va MgAl-HT-SA 3.2. Tinh chat nhiet ciia mang epoxy chira hydrotalxit
Anh hudng cita hydrotalxit biln tinh bing axit stearic den kha nang each nhi?t cua mang epoxy dugc danh gia. Hinh 3 trinh bay sir thay doi nhi?t do tai mat sau ctia mau thep phu son theo thdi gian tilp xiic vdi ngudn nhiet Nhan thay nhiet dg ctia cac mau tang rat nhanh trong 10 phiit dau tien sau do thay ddi khdng dang kl. Sau 60 phtJt tilp xiic vdi ngudn nhiet, nhiet do ciia mau th6p phii epoxy cao nhat dat den 310 °C, miu thep phii epoxy chua ZnAl-HT-SA cd nhiet dg la 276 °C va miu thep phii epoxy chira MgAl-HT-SA cd nhi?t do la 300 °C.
Nhu vay s\r cd mat ciia hydrotalxit biln tinh da co tac dung tang kha nang each nhi^t cua mang epoxy.
Kha nang each nhiet ciia mang epoxy chiia ZnAl- HT-SA cao hem mang epoxy chiia MgAl-HT-SA. Sir cd mat ciia ZnAl-HT-SA d 3 % dS lam giam nhiet do bl mat hon 30 °C.
Kha nang chdng chay ciia mang epoxy khdng chira va chiia hydrotabcit dugc xac djnh theo tieu chuin UL94 (xem bang I). Kit qua cho thiy tdc dg chay ctia mang epoxy la 16,1 mm/phiit, trong khi toe
T C H l i T . 52(6), 2014
do chay ciia mang epoxy chira MgAl-HT-SA va ZnAl-HT-SA tuong iing la 11,3 mm/phiit va 12,5 mm/phut. Nhu vay sir cd mat ciia hydrotalxit bien tinh bang axit stearic d ndng dg 3 % da lam giam dang ke tdc do chay cua mang epoxy, giam 22,5 % vdi ZnAl-HT-SA va giam 30 % vdi MgAl-HT-SA.
Su giam tdc chay phy thudc vao loai hydrotalxit, hydrotalxit MgAl-HT-SA cd tac dung giam toe do chay cao hon hydrotalxit ZnAl-HT-SA.
Td Thi Xudn Hdng vd cgng sir Bdng 2: Ket qua danh gia chi sd LOI bang phuong phap phan tich nhiet ciia cac mang son
Miu Epoxy Epoxy + 3 % MgAl HT-SA Epoxy + 3 % ZnAI HT-SA
Lugng ran con lai CT 800 °C (%)
3,40 10,91 18,06
Chi so oxi gioi h^n, LOI
(%)
18,86 21,86 24,72
•E •
g 0 10 20 30 40 so EO 70
Thdi gian dit (phiit) Hinh 3: Sir bien ddi nhiet dd ctia mat sau mau thep
phii son theo thdi gian tilp xiic vdi ngudn nhi^t Bdng I: Kit qua danh gia kha nang chdng chay
cua cac mang son theo tieu chuan UL94 Mau
Epoxy
Epoxy + 3 % MgAl HT-SA Epoxy + 3 % ZnAI HT-SA
T6c dp chay (mm/phiit)
16,1 11,3 12,5 Ben cgnh do kha nang chdng chay theo phuong phap UL94, chi sd gidi ban oxi (LOI) ctia cac mau son cDng dugc xac dinh bang phuong phap phan ti'ch nhiet. Chi sd LOI dugc xac dinh theo cdng thirc sau:
Loi = 17,5 + 0,4CR [12]. Trong dd CR la % khoi lugng cdn lai ciia mau tai 800 **C xac djnh bang phuong phap phan tich nhiet trong mdi trudng nito.
Ket qua xac dinh chi sd LOI ciia cac mau dugc trinh bay trong bang 2. Khdi lugng cdn Igi tgi 800 "C cua cac mau chiia hydrotalxit bien tinh cao hon han cua mau epoxy. Chi sd LOI ciia epoxy la 18,86 trong khi chi sd LOI cua miu epoxy chiia MgAl-HT-SA va ZnAl-HT-SA tuong img la 21,86 va 24,72. Nhu vay su cd mgt cua MgAl-HT-SA va ZnAl-HT-SA da lam tang chi so LOI ciia epoxy tuong irng la 16 % va 31 %.
0 100 200 300 400 500 600 700 800 Nhifi ao C O
Hmh 4: Gian do phan tich nhiet ciia cac mau epoxy (a) epoxy chiia 3 % MgAl-HT-SA (b) va epoxy chiia
3 % ZnAl-HT-SA (c) 4. KET LUAN
Da tdng hgp va nghien ciru anh hudng ctia hydrotalxit MgAl va hydrotalxit ZnAI biln tinh bang axit stearic (MgAl-HT-SA va ZnAI-HT-SA) din tinh chat nhiet va kha nang chdng chay ciia mang epoxy. Ket qua phan tich da chiing td stearat dugc chen vao cau true ciia hydrotalxit lam tang khoang each Idp ciia hydrotalxit. Sir cd mat cita hydrotalxit da lam tang dang ke kha nang chdng chay ciia mang epoxy. Tdc do chay cita mang epoxy giam 22,5 % va 30 % vdi sir cd mat tuong iing 3 % ZnAl-HT-SA va MgAl-HT-SA. Chi sd oxi gidi ban cung tang vdi su cd mat cita ZnAl-HT-SA va MgAl-HT-SA tuong ung la 31 %va 16%.
Loi cam om. Cdc tdc gid xin chdn thdnh cdm on So Khoa hgc Cdng nghe Hd Ndi dd tdi trg cho cdng trinh ndy. de tdi mdso 0IC-03/02-20I3-2.
TAI LIEU THAM KHAO
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T C H H . T . 52(6), 2 0 1 4
double hydroxide: a new emerging class of nanocomposites, Chem Mater., 13,3507-3515 (2001) 3. A. I. Khan, D. O'Hare. Intercalation chemistry of
layered double hydroxides: recent developments and applications, J. Mater. Chem., 12, 3191-3198 (2002).
4. B. F. Sels, D. E. De Vos, P. A. Jacobs. Hydrotalcite- like anionic clays in catalytic organic reactions.
Catalysis Reviews, 43,443-488 (2001).
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Heinrich. Layered double hydroxide based polymer nanocomposites. Adv. Polymer Sci., 210, 101-168 (2008).
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Amico. Mechanical and flame-retardant properties of epoxy/Mg-Al LDH composites. Composites: Part A, 42, 196-202(2011).
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Nghien ciru dnh hudng cua hydrotalxit...
Schrekker, S. C. Amico. Energetic effect of LDH and glass fiber on the properties of two- and three- component epoxy composites. Polymer Testing, 31, 741-47(2012).
7. A. Frache, O. Monticelli, M. Nocchetti, G.
Tartaglione, U. Costantino. Thermal properties of epoxy resin nanocomposites based on hydrotalcites, Polymer Degradation and Stability, 96, 164-169 (2011).
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Layered double hydroxides as containers of inhibitors in organic coatings for corrosion protection of carbon steel. Progress in Organic Coatings, 74, 343-348 (2012).
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Liin h?: T o Thi X u a n H i n g Vien Ky thuat nhiet ddi
Vien Han lam K h o a hgc va C d n g nghe Viet N a m Sd 18, H o a n g Q u d c Viet, Cau Giay, Ha Ngi E-mail: [email protected].
