TAP CHi HOA HOC
DOL 10.15625/0866-7144.2015-0095
T. 53(1)95-100 THANG 2 NAM 2015
U'NG DUNG NANOSILICA BI^N TJNH PHENYL TRIETOXYSILAN LAM CHAT PHU GIA CHO Lap PHCI BAO VE CHONG AN MON
Nguyen Thiiy Duong', Nguyen Anh Sffn, Tnnh Anh True, To Thi Xnan King Vien Ky thugt nhi^t ddi, Viin Hdn ldm Khoa hgc vd Cdng nghe Vi$t Nam
Din Tda sogn 10-01-2014; Chip nhan dang 13-2-2015 Abstract
Nanosilica was prepared by hydrolysis of tetraethyl orthosilicate (TEOS) at low pH and then Ueated with phenyl triethoxysilane (PTES). Nanosilica and PTES treated nanosilica were characterized by Field Emission Scanning Electron Microscope (FESEM), infrared specuoscopy (IR) and thermal gravimetric analysis (TGA). The obtained results showed that the size of nanosilica and treated nanosilica is about 20 nm and PTES treated nanosilica more homogeneous and separated. The TGA analysis results showed that the organic matter on the surface nanosilica is about 8 wt.%. Epoxy coatings and epoxy coatings containing 3 wt % of nanosilica and 3 wt % of PTES Ueated nanosilica were prepared and applied on carbon steel. Protective property of coatings was evaluated by electrochemical impedance spectroscopy (EIS). The results showed that the presence of PTES Ueated nanosilica significantly improved barrier property and conosion protection of epoxy coating.
Keywords. Treated nanosilica, PTES, epoxy coating, EIS.
1. MdDAU
Ldp phli hiiu eg dugc sir dung rpng rai de bao ve chdng an mdn cho cac cdng trinh kim logi. Trong nhung nam gan day, viec sii dyng cac hgt nano (TiOi, ZnO, FejOs, SiOz-..) di gia cudng cac tinh nang ciia ldp phii hiiu ca ngay cang thu hiit dugc nhieu sy quan tam [1-8]. Nanosilica dugc su dugc sii dung nhiiu trong Idp phii hOn ca [9-13] vdi nhieu dgc tinh nhu dp ciing cao, chi sd khiic xa thip va gia thanh hpp ly so vdi cac hgt nano khac. Tuy nhien, be mat ciJa nanosilica cd chiia cac nhdm OH, diiu nay khiin cho cac hgt nanosilica de bj ket ty va khd phan tan trong mang. Di hat nanosilica tuong hpp vdi mang polyme thi ngudi ta xu ly be mat cua hat vdi cac chit hiJU ca [1-4, 14, 15].
Bai bao nay nghien ciiu tdng hgp va bien tinh nanosilica sii dung phenyl trietoxysilan. Dgc trung cau tnic ciia nanosilica va nanosilica bien tinh dugc phan tfch bing phd hdng ngoai, kinh hiin vi trudng di?n tu quet. Ham lugng silan cd mat tren nanosilica dugc xac djnh bing phucmg phap phan tich nhiet.
Kha nang bao ve chdng an mdn cua Idp phCi epoxy chiia nanosilica bi^n ti'nh dugc danh gia bang phuang phap tdng trd dien hda.
2. THirC NGHIEM 2.L Vat lieu
Tetraethyl orthosilicat (TEOS) va Phenyl trietoxysilan (PTES) cd dp tinh khiet 98 %, do hang Merck cung cap.
Chat tao mang la nhya epoxy X75 va chat ddng ran polyamin polyamit PA66, loai thucmg pham cua Thai Lan.
Nen kim loai nghien cihi la thep cacbon, kich thude 15 X 10x0,2 cm.
Nanosilica dugc tdng hgp bang phuang phap thiiy phan TEOS trong mdi trudng axit, tiin hanh nhu sau: TEOS hoa tan vao cdn v^ nhd tir tir dung dich vao hdn hgp H2O va HCl, khuiy tu lien tyc trong 12 gid d nhi?t do phdng. San pham sau khi ly tam dupe riia sach ve mdi trudng trung tinh va say chan khdng d 60 °C. San pham cuoi cung cd mau trang min, vdi kich thude hgt khoang 20 nm.
Bien tinh nanosilica bang phan iing vdi phenyl trietoxysilan trong dung mdi toiuen d nhiet dp thudng trong 24 gid. San pham dugc ly tam, dugc riia sach 3 lan bang cdn va siy chan khdng 24 gid d 80''C. San phim thu dugc cd mau trang va kich thude hgt khoang 20 nm.
Chuan bi mau: Mau thep dugc lam sgch dau md bing xa phdng, riia sach bang nude cat, etanol, say khd, mai bing giay nham SiC den dp min 400, nia sgch, say khd. Mang epoxy va epoxy chiia silica dugc tgo thanh tren nen thep bang may tao mang ly tam Filmftige 111 ON (Sheen) tai Vien Ky thuat nhi?t ddi. Nanosilica va nanosilica bien tinh dugc dua vao
TCHH, T. 53(1), 2015
mang epoxy vdi ham lugng 3 %. Chieu day mang sau khi khd khoang 20 |im.
2.2. Phuffng phap
Phan tich hinh thai ciu triic' phuang phap hiin vi trudng dien tii quet (FESEM) dimg de phan tich hinh thai ciia nanosilica, nanosilica bien tinh va mang epoxy chiia nanosilica va nanosilica bien tinh.
Anh FESEM dugc chyp tii may FE SEM S480D- Hitachi ciia Nhat Ban tai Vien Ve sinh Dich tl Trung uang.
Phd hdng ngogi: ciu tnic cCia nanosilica va nanosilica biin tinh dugc phan tich bing phd hdng ngoai tren may IMPACT 410-NICOLET-FTIR d viing budc sdng tur 4000 cm"' din 400 cm"' tgi Vi$n Ky thugt nhiet ddi. Nanosilica va nanosilica bien tinh dugc do d dang ep vien vdi KBr.
Phan tich nhiet: phuang phap phan tich nhiet trpng lugng (TGA) dugc su dyng dk khao sat ham lugng chat hun ca tren bi mat silica. Cac phep do TGA thyc hien tren may DTG-60H-Shimadzu ciia Nhgt Ban tai Khoa Hda hpc, Trudng Dgi hgc Su pham Ha Ndi.
Kha nang bao ve chong an mdn kim logi cua Idp phli epoxy chiia nanosilica biin tinh dugc theo ddi bang phuang phap tdng trd dien hda theo thdi gian thu nghiem trong dung dich NaCI 3 %. Phuang phap tong trd: sii dung he 3 di?n cue, dien eye lam viec la tam thep phii mang son, di?n eye so sanh la dien eye calomel, difn eye ddi la ludi platin. Cac phep do dugc thyc hien tren may Autolab PG30 (Ha Lan) tgi Vi?n KJ thuat nhi?t ddi. Mdi trudng xam thyc la dung dich NaCl 3 %. Mdi phep do dugc tiin hanh tren 3 mau de khang djnh kha nang lap lai.
3. KET QUA v A THAO LUAN 3.1. D^c tinh cua nanosilicabien tinh
Hinh 1 trinh bay anh FESEM cua nanosilica va nanosilica biin tinh silan PTES. Anh FESEM cho thay cac hat nanosilica tdng hpp va nanosilica biin . tinh silan cd kich thude kha ddng nhit khoang 10-20 nm va nanosilica bien tinh cd kich thude dong diu va phan tach han. Ket qua tren cho thiy viec biin tfnh hiru ca hda da lam giam kit ty cua cac hat.
Nguyin Thity Duang vd cgng su Phd hdng ngogi ciia nanosilica va nanosilica bien tinh silan PTES dugc trinh bay tren binh 2 va cac pic dac trung duge trinh bay trong bang 1.
Hinh 1: Anh FESEM ciia nanosilica (a) va nanosilica-PTES (b)
Hinh 2: Phd hdng ngoai ciia nanosilica (a) va nanosilica-PTES (b)
?C=Hs
96
TCHH, T. 53(1), 2015
100 200 300 400 500 600 Nhiet do (°C)
Hinh 4: Gian dd phan tich nhi$t ciia nanosilica (o) va nanosilica bien tinh silan PTES (•) Bdng 1: Cac pic dac trung va lien kit tuong ung ciia
nanosilica va nanosilica bien tinh silan PTES Lien ket
-OH Si-O-Si Si-OH
Si-0 C-H vong
0-Si-O
Si02, cm"' 3451 1090 963 798 464
Si02-PTES, cm"' 3459 1093 793 740-699
468 So sanh phd hdng ngoai cua nanosilica bien tinh PTES vdi phd hdng ngoai ciia nanosilica deu thay cd cac pic dac trung ciia Si02tai khoang 1090 cm"', 798 cm"', 464 cm"' tuong iing vdi lien ket Si-O-Si, Si-0 va 0-Si-O. Mdt dinh hap phy mgnh tai khoang 3451 cm"' dac trung cho lien kit O-H cCia H20 diu xuat hi6n tren phd eua nanosilica va nanosilica bien tinh.
Tren phd hong ngogi cua SiOi bien tinh PTES cdn cd xuit hien pic tai 699-740 cm'' dac trung cho lien kit C-H ciia vdng tham [16]. Ngoai ra tren phd ciia SiOi biin tinh khdng cdn pic 963 cm"' ciia nhdm Si- OH. Diiu dd cho thiy PTES da dugc ghep ndi vdi Si-OH tren be mat SiO; (hinh 3).
Hinh 4 trinh bay gian do phan tfch nhiet (TGA) Clia nanosilica va nanosilica bien tinh silan PTES.Gian dd TGA ciia Si02 cd I nic giam khoi lugng mgnh d khoang 100 "C vdi miic tdn hao khdi lugng khoang 17 %, dgc trung cho qua trinh mit nude hip phu tren be mgt silica. Khoang 400-500
°C, cd giam nhe khdi lugng, khoang 2 %, dac trung cho sy mit nude ket tinh. O gian dd TGA ciia silica biin tinh silan PTES, cd 1 nac giam khdi lugng
ilhg dimg nanosilica bien tinh phenyl...
khoang 12 % d khoang 100 °C, dgc trung cho qua trinh mat nude be mat. Khoang 500-600 °C, cd nac giam khdi lupng khoang 8 % tuong iing vdi su phan hiiy chat hiru co tren be mat nanosilica.Ket qua phan tich TGA cho thay cac chit hiiu ca da phii len be mat hat nanosilica, hgt nanosilica trd nen ky nude, lam giam hap phu nude tren be mgt.
3.2.Nghien eun kha nang bao ve chong an mda cua Idp phii epoxy chira nanosilica va nanosilica bien tinh PTES
Hinh 5 va 6 trinh bay phd tdng trd dgng Bode sau 2 ngay va 35 ngay thii nghiem trong dung dich NaCI 3 % Clia cac mau thep phii epoxy va epoxy chiia 3 % nanosilica va nanosilica bien tinh. Theo cac ket qua tren ta thay, phd tdng trd ciia cac ldp phii epoxy, epoxy chiia Si02 va epoxy chiia Si02-PTES cd su khac biet nhau vdi cac thdi gian thii nghiem mau khae nhau (2 ngay va 35 ngay). Trong thdi gian bit diu ngam trong dung djch NaCl 3 % (hinh 5), gia tri tdng trd cua cac mau deu cao. Gia trj tdng trd Clia mau epoxy la thip nhit so vdi eac mau epoxy chiia Si02 va Si02-PTES. Mau epoxy chiia Si02- PTES cd gia tri tdng trd cao hem so vdi mau epoxy chiia Si02. Sau 35 ngay thii nghiem trong dung dich NaCI 3 % (hinh 6), gia trj tdng trd ciia cac mau deu giam. Tuy nhien, gia tri tdng trd ciia mau epoxy chiia Si02-PTES giam it va gia trj tdng trd van cao ban so vdi cac mau epoxy va epoxy chiia Si02.
Hinh 7 trinh bay bien thien cua modul tdng trd tai tan sd I Hz theo thdi gian thii nghiem trong mdi trudng NaCI 3 % ciia cac mau thep phii epoxy va epoxy chua 3 % nanosilica va nanosilica bien tinh.
Modul tdng trd ciia Idp phu epoxy va Idp phCi epoxy chiia Si02, Si02 bien tinh deu giam dan theo thdi gian thii nghiem, do sy xam thyc cua nude va ion qua mang. Tuy nhien miic dg suy giam cua cac mau khac nhau va Idp phii epoxy chiia nanosilica bien tinh PTES cd miic dp suy giam it nhat va giii dn djnh trong thdi gian sau dd. Mau epoxy chiia nanosilica bien tinh PTES cd gia tri tdng trd cao hon so vdi mau epoxy va mau epoxy chiia Si02. Dieu nay cd the giai thich do su huu ca hda Si02 da lam tang kha nang tucmg hgp va phan tan ctia Si02 trong ldp phli, dan den tang miic do ngan each cua mang.
Hinh thai cau tnic ciia Idp phii epoxy va Idp phCi epoxy chiia Si02, Si02 bien tinh dugc quan sat qua anh chup FESEM mat cat ciia Idp phii. Hinh 8 trinh bay anh FESEM mat cat cua mang epoxy va mang epoxy chiia Si02, 8102 bien tinh. Anh FESEM mat cit cho thay mang epoxy cd cau triic nhan min do khdng chiia phy gia.
TCHH, T. 53(1), 2015 8
Nguyin Thiiy Duang vd cfng si/
Log f (Hz)
Htnh 5 Ph6 tang trcr ciia thep phii mang epoxy (x), epoxy chiia SiOz (o) va epoxy chiia SiOz-PTES (•) sau 2 ngay thii nghiem trong dung dich NaCI 3 %
0 1 2 Log f (Hz)
Hmh 6: Pho tong trcr cCia thep phii mang epoxy (x), epoxy chiia SiOz (o) va epoxy chiia SiOi-PTES (•) sau 35 ngay t h i nghiem trong dung djch NaCI 3 %
Doi voi m^ng epoxy chiia nanosilica co the quan sat thay cac 16 ro va cac hat nanosilica trong cdu true mang, dilu nay chiing to do sir kem tuofng ht;rp ciia nanosilica voi mang gay nen. Mat khac, d6i v6i mang chiia nanosilica biin tinh PTES quan sat thay cau true mang g6 ghe horn do bi6n dang xe cua mang va cac h^t nanosilica biin tinh co kich thuac to hon va deu dugc bao bcri lop mang epoxy. Dilu nay cho thiy kha nang tucmg hop t6t ciia hat nanosilica bien tinh silan vii mang va cju true d}c xit nay ciia mang da lam tang kha nang bao ve chong an mon cho lop phli.
4. KET LUAN
Da tong h(?p dirge nanosilica theo phucmg phap thiiy phan trong moi tnrong axit va huu ca hoa vcri phenyl trietoxysilan. Cac kit qua phan tich FESEM, hSng ngoai va phan tich nhiet cho thjy nanosilica co 0 20 40 60 SO 100
Thoi gian (ngay)
Htnh 7: Bien thien ciia modul tdng trat^i tin so 1 Hz Clia lop phli epoxy (x), epoxy chiia SiOz (o) va
epoxy chiia SiOz-PTES (•) theo thoi gian thu nghiem trong moi truong NaCl 3 %
T C H H , T. 53(1), 2 0 1 5
kich t h u d e d d n g n h i t k h o a n g 2 0 n m v a h a m Iugng PTES cd m a t tren b i m a t nanosilica ia 8 % .
S y cd mgt ciia nanosilica bien tinh P T E S d a lam tang k h a n a n g b a o v e c h d n g an m d n cCia ldp phii epoxy.
Hmh 8: Anh F E S E M m a t c i t ciia l d p p h u epoxy (a) va e p o x y chiia S i 0 2 (b) v a e p o x y chiia
S i O j - P T E S (c)
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