Vd836-2011S002009043.pdf

Nghien cim. Phdt triin va (%? dung Cone nehe Vdt lieu (KC.02/06-10)- Ha Noi 27/11/2009 TONG HOP VA DAC TRUNG COPOLYME T I N H BOT GHEP POLY(AXIT

ACRYLIC) Slf DUNG CHAT K H O I M A O CERI A M O N I NITRAT Nguyln Van Khoi, Nguyen Thanh Tung, Tran Vu Thang, Do Cong Hoan

Vien Hoa hoc- Vien Khoa hoc va Cong nghe Viet Nam (VAST), 18 Hoang Quoc Viet Ha Noi Email: vlpolyme vhh@vnn.vn

Tom tit. Qua trinh ghep axit acrylic (AA) len tinh bot trong moi truang nude khai mdo bang ceri amoni nitrat (CAN) duac nghien cuu trong khi quyen N2. Dieu kien tdi uu ddi vdi ndng do monome, ndng dd chdt khai mao, nhiet do, thdi gian phan irng va ndng dd tinh bot duac nghien ciru theo hieu suat ghep (%GY) va chuyen hod tong sd (%TC). Dieu Men tdi uu thu duac ddi vdi qua trinh ghep AA len Wg tinh bot Id: [AA] = 1.25M; [CAN] = 0.012M; [Tinh bot] = 125gA; nhiet do 40°C vd thai gian 60 phut. Copolyme tinh bot ghep axit acrylic duac dac trung bai phan tich nhiet trong luong (TGA), nhieu xa tia X (XRD) va anh chup kinh hien vi dien tir quet (SEM). Nhanh ghep PAA thu duac sau khi thuy phan tinh bot duac dac trung bai pho hong ngoai bien ddi Fourier (FTIR) chirng minh sir ton tai san phdm ghep.

I. GIOITHIEU

Khi trung hop mot loai monome de tao mach nhanh dinh vao mot polyme cd san, qua

trinh dugc goi la trung hop ghep, san pham phan ung dugc goi la copolyme ghep. Cac mach nhanh nay cd dac diem thanh phan hay cau hinh khac vdi mach chinh. Tinh bot la mot polyme tu nhien trong lugng phan tir cao dugc tao thanh tir nhieu mat xich anhydroglucoza (AGU) va thudng la hon hop ciia 2 thanh phan mach thang va mach nhanh la amyloza va amylopectin.

Tinh bdt thudng dugc sir dung nhu mot chat nen dien hinh de nghien cuu qua trinh ghep do cac vinyl monome rat de ghep len tinh bot [1].

Cac copolyme ghep tinh bdt thudng dugc sir dung lam chat keo tu [2], chat lam dac [4], tac nhan gia keo be mat [3] trong cong nghiep giay va det va tac nhan lam ben cau true dat [5].

Hau het qua trinh trung hop ghep deu dugc thuc hien nhd cac phuong phap hoa hoc. Qua trinh ghep tinh bdt vdi cac vinyl monome khac nhau dugc thuc hien nhd cac he khoi mao nhu K2S2O8 [6], KMn04 [7], Fe^{2 +}- H2O2 [8]...Qua trinh ghep len cac polyme tu nhien sir dung he khoi mao ceri amoni nitrat (CAN) dugc nghien cuu kha pho bien do co che don gian, nang luong hoat hoa thap va de tao goc tu do tren tinh bdt. Bai bao nay nham muc dich tdi uu hoa qua trinh trung hgp ghep axit acrylic len tinh bdt san sir dung he khoi mao CAN trong moi trudng nude.

H. THUC NGHIEM Hoa chat

Tinh bdt san (Cong ty Luong thuc Ha Tay, cd trong lugng phan tir trung binh - 860.000), dung dich natri hypoclorit (Cong ty Hoa chat Viet Tri, cd ham lugng clo hoat dong ~80g/l).

Axit acrylic (Merck) dugc cat lai dudi ap suat giam va bao quan trong tu lanh trudc khi sir dung. Ceri amoni nitrat (CAN) (Merck) dugc sir dung trong dung dich H N 03 0,01M.

Metanol, axeton, hydroquinon (hoa chat thi nghiem) dugc sir dung ngay khong qua tinh chi.

Oxi hoa tinh bot san bang natri hypoclorit [11]

Qua trinh oxy hoa tinh bdt san dugc tien hanh d 35°C, pH = 7, ndng dd tinh bot 700g/l va ty le khdi lugng hypoclorit so vdi tinh bot la 1%. Trong lugng phan tir trung binh ciia tinh bdt oxy hoa nhan dugc la ~1,36.10⁴.

Nghien cim. Phdt trien va Ung dims Cons nshe Vdt lien (KC.02/06-10). Ha Noi 27/11/2009

Trung hop ghep

lOg tinh bot dugc khuay voi nuac cat trong binh cau 3 c6 dung tich 250ml sau dd them chat khoi mao, sue khf N2 de dudi oxy va khuay deu. Sau 10 phiit, dung dich monome dugc them vao binh phan ung va bo sung nude cat de thu dugc ty le pha ldng/tinh bot mong mudn.

Qua trinh trung hgp ghep dugc tiln hanh trong khi quyen nita va dugc dilu chinh nhiet dd bang be dilu nhiet. Sau nhung khoang thai gian nhat dinh, dirng phan ung bang each them lml hydroquinon vao hdn hop phan img. San pham phan ung dugc tach khdi hdn hop bang each ly tam. D l loai bd homopolyme, san pham dugc chiet Soxhlet bang metanol trong 24 gid va say chan khong d 60°C din k h l i luong khong ddi thu dugc copolyme ghep.

Hieu suit ghep (%GY) va chuyln hoa ting s i (%TC) dugc xac dinh theo phuong trinh sau:

%GY= ^m2~^m' xlOO

%JC=ahzaiL xl0o

trong dd mi, m2, m3, nu lan lugt la khdi lugng ciia tinh bdt oxy hoa, copolyme ghep tinh che, san pham ghep thd va monome.

Tach nhanh ghep

0,5g copolyme ghep dugc dua vao 100ml dung dich HC1 I N va dun hoi luu trong 2 gid de thuy phan hoan toan mach chinh tinh bdt. San pham dugc ket tiia lai trong axeton va lam khong trong tii say chan khong d 60°C den khdi lugng khong ddi.

Pho hong ngoai (FTIR) dugc ghi tren Quang pho ke hong ngoai biln ddi Fourier FTIR IMPACT Nicolet 410 trong viing 4000-400cm"'. Mau dugc siy kho 2 ngay trong tu siy chan khong d 60°C va sir dung ky thuat ep vien vdi KBr.

Nhilu xa tia X (XRD) dugc ghi tren thilt bj nhilu xa Ronghen SIEMENS D5000 vdi dilu kien do: t l bao CuKc (X = 0,15406nm), U = 35kV, I = 35mA, gdc quet 29 tir 5° din 50°.

Phan tich nhiet trong luong TGA (Thermal Gravimetric Analysis) dugc ghi tren thilt bi phan tich nhiet TA-50 Shimadzu. Cac mau deu dugc phan tich trong khi quyln nita vdi toe dd gia nhiet 10°/phut tir nhiet do phong den 700°C.

Chup anh kinh hien vi dien t u quet SEM (Scanning Electronic Microscopy) dugc thuc hien tren may JEOL- 5300 (Nhat).

ffi. KET QUA VA THAO LUAN 1. Anh huong cua thoi gian

Anh hudng ciia thai gian phan ung trung hop ghep tdi cac thong sd ghep dugc trinh bay

tren hinh 1. K i t qua cho thiy cac thong sd ghep tang deu dan theo thdi gian phan ung, do chuyen hoa dat cue dai sau khoang 60 phiit. Qua trinh trung hgp ghep cd xu hudng tang cham dan va khong ddi d giai doan sau. Sau khoang 60 phiit, hieu suit ghep gin nhu khong doi khi keo dai thdi gian phan img. Dieu nay la do ndng do monome cung nhu chit khai mao giam khi keo dai thai gian phan img, lam cham qua trinh khuech tan do tao polyme tren b l mat tinh bdt. Mot nguyen nhan nua cd the la do dd nhdt ciia moi trucmg phan ung tang khi keo dai thoi gian trung hgp lam giam sd vi tri hoat dong tiep xiic vdi monome lam cho monome khd phan img vdi cac vi tri nay.

2. Anh huong cua nhiet do

Anh hudng ciia nhiet do phan ung dong trung hgp ghep tdi cac thong si ghep duac trinh

bay tren hinh 2. Co the thay rang hieu suit ghep tang va dat cue dai khi nhiet do tang tdi 40°C

Nghien cim. Phdt triin va Ung duns Cons nshe Vdt lieu (KC.02/06-10)- Ha Noi 27/11/2009 tich cue tdi qua trinh ghep nhu: kha nang truang ciia tinh bot cao hon, tang do tan ciia monome, tang tdc do khulch tan ciia monome va chit khoi mao len cac vi tri ghep, tang tdc do phan huy ciia chit khoi mao do dd lam tang tdc do ghep trong giai doan dau ciia phan ung.

Tuy nhien, hieu suit ghep giam khi tiep tuc tang nhiet do cd the la do cd su tao phirc ben giura mudi ceri vdi tinh bdt va tang tdc do phan ung ngat mach cung nhu tdc do phan ung tu trung hop tao homopolyme.

40 60 Thdi gian (phiit) Hinh 1. Anh hudng cua thdi gian (Nhi?t dp 40°C, [CAN] 0.012M, [AA] 1.25M,

ndng dp tinh bdt 125 gA)

too 80 60 40 20 0

-%GY -%TC

35 40 45 Nhiet dr) (do C)

Hinh 2. Anh hudng cua nhiet dp phan ung (Thdi gian 60phut, [CAN] 0,012M, [AA] 1.25M,

ndng dp tinh bdt 125'gA) 3. Anh hudng cua nong do monome

Ket qua tren hinh 3 cho thay khi tang ndng dd monome thi hieu suat ghep tang va dat tdi mot gia tri tdi uu sau dd giam dan. Dieu nay cd the giai thich la do tang ndng dd monome lam tang ndng dd AA cue bd trong hoac xung quanh cac hat tinh bdt truang. Dieu nay thuan loi cho qua trinh khuech tan ciia cac phan tir monome len vi tri ghep tren mach chinh tinh bot, tang kha nang ket hop ciia cac phan fur monome d vitng lan can vdi goc dai phan tir tinh bdt.

Tang ndng dd monome cung gdp phan tao phuc cho nhan giua tinh bdt va monome, cd loi cho su di chuyen dinh hudng ciia monome.

§ 60

-%GY

%TC

1 1.5 2 Nong dr} AA (M)

Hinh 3. Anh hudng cua ndng dp monome (Thai gian 60 phut, nhiet dp 4(fC, [CAN]

0,012M, ndng dp tinh bdt 125gA)

oo 40

- %GY -%TC

0.005 0.01 0.015 Nong d6 CAN (M)

Hinh 4. Anh hudng cua ndng dp CAN (Thdi gian 60 phut, nhiet dp 4(fC, [AA] 1,25M,

ndng dp tinh bdt 125gA)

Tuy nhien, ndng do monome tiep tuc tang cung khong lam tang them hieu suat ghep do tang van tdc ciia phan ung chuyen mach sang monome tao homopolyme. Dieu nay d l nhan thiy do tang dd nhdt ciia moi trucmg phan ung trong dd homopolyme ciia AA tan va cung do ban chit dinh ciia san pham ghep khong gidng nhu san phim dang hat khi ndng do AA thip.

Homopolyme vdn cue gay can trd tdc dd khuech tan ciia cac phan tir monome len dai phan tir tinh bdt lam giam hieu qua ghep.

Nshien a'cu. Phdt trien vd Ung duns Cons nshe Vdt lieu (KC.07./D6-J0)- Ha Ndi 27/11/2009

4. Anh huong ciia nong do CAN

Anh hudng ciia ndng do chat khoi mao tdi cac thong sd ghep dugc trinh bay tren hinh 4.

K i t qua cho thay hieu suit ghep tang deu dan khi tang ndng do Ce⁴* tdi 0,012M va hieu suit ghep giam khi nong do Ce⁴* tiep tuc tang. Xu hudng nay cung gidng nhu ddi vdi hieu qua ghep va phin tram chuyen hoa tong sd. Hieu suat ghep tang khi tang ndng do chit khoi mao cd thi la do du chit khoi mao hay tang tdc do ghep d ndng do thap. Tuy nhien hieu suat ghep va hieu qua ghep giam khi tiep tuc tang ndng do chat khoi mao la do giam tdc dd trung, hop.

Vdi ndng dd Ce^ cao, viec tang tdc dd cac giai doan phan ung lien quan den ion Ce ⁺ lam tang sd gdc dai phan tir tinh bot bj ngat mach trudc khi them monome. Mot yeu to khac gdp phin lam giam hieu suit ghep khi ndng do chat khoi mao cao la tang su hinh thanh homopolyme canh tranh vdi phan ung ghep ddi vdi monome san cd.

5. Anh hudng cua nong do tinh bot

Anh hudng ciia ndng dd tinh bdt tdi cac thong sd ghep dugc trinh bay tren hinh 5. Co the thay rang hieu suat ghep tang khi ndng do tinh bdt tang tir 80 den 125g/l va giam dan neu tiep tuc tang ndng do tinh bdt. Phan tram chuyen hoa tong sd tang khi tang ndng do tinh bdt. Dieu nay cd the giai thich la do khi ndng dd tinh bot tang, sd trung tam hoat ddng tren mach chinh tinh bot tang, xac suat va cham ddng hoc giua cac phan tir monome va gdc dai phan tu tang, thuan lgi cho qua trinh ghep, ddng thoi tang phan tram chuyen hoa tong sd. Tuy nhien neu ndng dd tinh bot tiep tuc tang, hieu suat ghep lai giam. Dieu nay chung to vugt qua mot gia tri ndng do tdi uu hieu ung gel ddng vai trd dang ke. Su tao thanh mot lugng ldn gel lam tang dp nhdt ciia moi trucmg phan img va chuyen ddng ciia nhanh ghep polyme dang phat triin bi nan che, do dd su tan cong len cac trung tam hoat ddng tren mach chinh tinh bdt giam, din ddn tao thanh homopolyme.

0 A , 1 , ——, , 50 100 150 200 250 300 Nong do tinh bot (g/T)

Hinh 5. Anh hudng cua ndng do tinh bdt

(Thdi gian 60phiit, nhiet do 40°C, [CAN] 0.012M, [AA] 1.25M)

6. Pho hong ngoai

Tren phd hong ngoai ciia nhanh ghep PAA (khong dua ra d day) quan sat thiy dai hip thu rpng d vi tri 3423cm"¹ dac trung cho lien kit O-H trong nhom -COOH. Lien k i t C=0 ciia axit dugc quan sat d 1747cm"¹. Pic 1242cm"¹ dac trung cho dao ddng keo ciia lien k i t C-0 Ngoai ra cac pic d vi tri 2924 va 2839cm'¹ dac trung cho dao ddng hoa tri bit ddi xung ciia nhom - CH2 va dao ddng hoa tri ciia lien ket C-H. Nhu vay phd hong ngoai ciia nhanh ghep la mot bang chung gian tiep chung minh su ton tai ciia san pham ghep.

Nghien cim. Phdt triin vd L^rne dung Cone nshe Vdt lieu (KC.02/06-10)- Ha Noi 27/11/2009

7. Phan tich nhiet trong lugng (TGA)

Gian do phan tich nhiet trong lugng (TGA) cua tinh bdt va copolyme ghep cho thay su khac biet ro ret chung to qua trinh ghep ciia PAA len tinh bdt (du lieu khong dua ra d day). Sd lieu phan huy nhiet dugc thd hien trong bang 1.

Tinh bdt oxy hoa cho gian do TGA dac trung gdm 3 budc, trong do ton hao trong lugng chii yeu diln ra d budc thu 2, nhiet do phan huy cue dai d giai doan nay la 305°C. Qua trinh phan huy gan nhu hoan toan d 500°C vdi 2,84% tinh bdt con lai khong bi phan huy. Do ben nhiet ciia tinh bdt va copolyme ghep cd the dugc so sanh tren ca sd nhiet do bat dau phan huy,

% khdi lugng bi mat d cac giai doan khac nhau va % khdi lugng con lai d nhiet do phan huy cue dai. Duong cong TGA ciia copolyme tinh bdt ghep PAA, tru giai doan bay hoi am ban dau, cd the quan sat thay 3 giai doan phan huy tiep theo vdi ton hao trong lugng tuong ddi on dinh trong dd hai giai doan dau van la qua trinh bay hoi am va nude cung vdi cac qua trinh ete hoa, este hoa noi phan tir, qua trinh tao anhydrit. Giai doan thu 3 cd su phan huy tao ra monome, CO2 va hydrocacbon de bay hoi ciing vdi qua trinh dut mach.

Bdng 1. Du lieu phan huy nhiet cua tinh bdt oxy hod vd copolyme tinh bdt ghep PAA

7

Hgp chat Giai doan phan Khoang nhiet do Tmax Ton hao trong luong

huy (°C) ' (°C) (%)

Starch 1 25-218 11,89

2 218-350 305 51,91

3 350-500 33,36

Starch-g-PAA 1 25-175 8,51

(GY = 14,7%) 2 175-250 206 21,08

3 250-350 286 16,91

4 350-450 398 18,24

8. Nhilu xa tia X (XRD)

Gian do nhieu xa tia X ciia tinh bdt oxy hoa va copolyme ghep PAA dugc trinh bay tren hinh 6. Gian dd nhieu xa tia X ciia tinh bdt cho 4 pic chung to muc dd ket tinh thap. Hon nixa, khi tien hanh trung hgp ghep, 4 pic nay gan nhu sat nhap lai va chi con 1 pic vdi cudng dd rat thap chung to pha ket tinh ciing lien quan ciing vdi pha vd dinh hinh trong phan ung ghep.

, (a)_ (b) Hinh 6. Gian do nhieu xa tia X cua tinh bdt oxy hod (a)va copolyme tinh bdt ghep PAA (b)

9. Anh chup kinh hien vi dien tu quet (SEM)

Anh chup kinh hien vi dien tir quet (SEM) ciia tinh bdt va copolyme ghep dugc trinh bay tren hinh 7.

Nghien cim. Phdt trien va tins duns Cons nshe Vdt lieu (KC.02/06-1Q)- Ha Noi 27/11/2009

(a) w (b)

Hinh 7. Anh SEM ciia tinh bdt san (a)vd copolyme tinh bdt ghep PAA (b) Cac ket qua cho thay co sir khac biet trong hinh thai hoc ciia tinh bot ghep so voi tinh bot ban dau. Tren cac anh SEM ciia copolyme ghep quan sat thay pha vd dinh hinh ciia polyacrylic axit bam tren be mat hat tinh bdt chiing to qua trinh ghep da xay ra.

IV. KET LUAN

Dieu kien tdi uu ciia qua trinh ghep axit acrylic len tinh bdt la: [AA] = 1,25M, [CAN] = 0,012M trong H N 03 0,0TM, ndng do tinh bdt 125g/l, nhiet dd 30°C va thdi gian 60 phiit. Gian dd nhieu xa tia X cho thay qua trinh ghep PAA len tinh bdt khong chi dien ra trong vilng vd djnh hinh ma con lien quan den ca vung ket tinh trong phan tu tinh bdt. Anh SEM cung cho thay qua trinh ghep chi la mot hien tuong be mat thuan tuy.

Loi cam on

Cong trinh nay dugc thuc hien vdi sir hd trg ve kinh phi cua Bo Khoa hoc va Cong nghe, Chuong trinh KC02/06-10 trong khudn kho Du an SXTN KC02.DA01/06-10.

Tai lieu tham khao

Athawale V. D. and Rathi S. C, "Graft polymerization: Starch as a model substrate", J. M . S.- Rev. Macromol. Chem. Phys.. C39(3), 445-480 (1999).

Qudsieh I. Y., Fakhru' 1- Razi A., Kabbashi N. A.. Mirghani M. E. S., Fandi K. G., Alam M . Z., Muyibi S. A.. Nasef M. M . , "Preparation and characterization of a new coagulant based on the sago starch biopolymer and its application in water turbidity removal" J Appl. Polym. Sci.. 109, 3140-3147 (2008).

Zhang X.. L i W. L.. "Synthesis and properties of graft oxidation starch sizing agent" J Appl. Polym. Sci.. 88. 1563-1566 (2003).

Lu S.. Yao K., Lin S., Cao D.. Chen Y.. "A study on preparation and thickening efficiency of an inverse emulsion of anionic starch-graft-polyacryiamide". Starch 55 518-523

(2003). ' ^J "

Bouranis D. L.. Theodoropoulus A. G. and Drossopoulus J. B., "Designing synthetic polymers as soil conditioners". Communications in Soil Science and Plant Analysis 26

1455-1480(1995). ' ' Qudsieh I. Y.. Fakhru' 1- Razi A., Muyibi S. A., Ahmad M . B.. Rahman M. Z. A., Yunus W. M . Z. W.. "Preparation and characterization of poly(methylmethacrylate) grafted sa°o starch using potassium persulfate as redox initiator", J. Appl. Polym. Sci., 94 1891-1897 (2004).

Zhang L., Gao J., Tian R., Yu J., Wang W., "Graft mechanism of acrylonitrile onto starch by potassium permanganate", J. Appl. Polym. Sci.. 88. 146-152 (2003).

1.

2.

3.

Nghien cuu, Phdt triin va tins duns Cons nshe Vdt lieu (KC.02/06-10)- Ha Noi 27/11/2009 8. Aravindakshan P., Bhatt A.. Kumar V. G., "Matrix- induced variation in kinetics and

control of molecular weight of methacrylic acid polymers during grat copolymerization with starch", J. Appl. Polym. Sci., 66, 397-403 (1997).

9. Pourjavadi A., Zohuriaan- Mehr M . J., "Modification of carbohydrate polymers via grafting in air. 1. Ceric- induced synthesis of starch-g-polyacrylonitrile in presence and absence of oxygen", Starch, 54, 140-147 (2002).

10. Fanta G. F., Felker F. C., Shogren R. L., "Graft polymerization of acrylonitrile onto spherocrystals formed from jet cooked cornstarch". Carbohydrate Polymers. 56. 77-84 (2004).

11. Huy N. Q., Ha P. T. T., Hung H. T., Tung N . T., Khoi N. V., "Oxidation of tapioca starch by sodium hypochlorite", Vie. J. Chem., 41(2), 127-131 (2003).