NGHIAN ClJU-TRflOD6l

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NGHIAN ClJU-TRflOD6l

DIEU CHE VAT LIEU HON HOP POLYMER THAN THIEN MOI TRUtUG

THEN NEN POLYETHYLENEVATINHBOTSANIhlGDUNGTRONGLiNHVUC BAO Bl

NGUYIN OANG MAO, HA THUC CHI NHAN, TRAN DUY THANH Khoa Khoa hqc V$t ll#u, Trudng Oî hgc Khoa hpc T^r nhiin Pî hQC Quflc gia TP H.^ Oif Mhh L£ VAN KHANH, HA THUC HUY Khoa H6a, Trudng Pî hpc Wwa hpc T^f nhifin D4ii hpc Qudc gia TF H^ Oif Minh

KL.NnOD.M'ION o r MATI'X^IM. MW)

ON&TADCIIANDPOI.YKTIIYLKNI';

APPLICATION rOD PACKACINC, PDODDCT

When ttie environmental pollution recently caused Irom fossil pacliaging waste becomes more seriously, tlie biocfegradable materials wbicb can be used in pacliaging liled. are the attracted subject tor the research around the world. The use ol renewable source from corn starch in the elaboration of friendly environmental material based on HDPE/slarch which is capable to replace Ihe traditional pacltaging material. Having some advanlages such as: low cost, self-dlsinlegrated In soil and diminution the use ol fossil polymer, Ihe material slill has some drawbacl(S in mechanical properties and resistance to water which are decreased as compared to Ihe neal ffDPE.

In this research, the HDPE/corn starch blend has been studied with the maleic anhydrid additive used to improve Ihe interface interaction between the HDPE and starch molecules, and used as the plasficizer for Ihermoplastic starch (TPS). The miilures ol HDPE and TPS composition from 10 to 60% wt are mell blended using a Hakee inlernal mixer al 170°C in 5 minutes. The morphology ol miilure sample characterized by X-ray dilfraclion (XRD) and Scanning Eleclronic Microscopy (SEIVI) showed that the components in materials are well compatible, even at 60%

wt of starch in the mixture. However, the material is only applied In lilm pacliaging field at 20-30% wt of slarch, with nearly 25%

reduction of Ihe efongation at breali of material as compared to Ihe neat HDPE.

1.Gldlilil9u

Hi$n nay, nhya nhidt dip dang dgpc sii dgng rdng rai trdn thi gidi trong nhilu ITnh vgc, dac bi^t la bao bl thyc phim vl nhilu Ipi thi, nhu: d l gia cdng, tai chl, khi nang chju nhiet cad va ching hda chit, tia cgc tim,:. nhgng cung cdn mdt s i dilm ylu, nhu: gia thanh cao, tinh chit co lj> thip, qua trlnh phan tiiiy lit Cham, gay I nhilm mli trudng... VI vay, nghlSn ciiu v l v$t iiau ting hop dya Irdn cac clilt ddn va nhya nhi$t dlo khdng chl giup cai thidn tfnh chit da vat liau ma cdn lam gikm dang ke ham luong nhya sii dyng. vat lidu phan hiiy sinh hoc da dupc nghiin ciiu ting hpp va dupc ling dyng trong cdng nghl$p nhung chi phi cac va hgn chl finh vgc sCr dyng cDa Chung. Trong khi dd, chit ddn tU ty nhidn rIt phong phg va da dgng, tyong dii r l tiln va cd sin nhy: b|t gl, trig..., d^c bi|t la tinh b|t. Dilu dd hUa hgn vi|c chl tgo nhiing v$t li$u mdi cd gia thanh giim va than thi$n vdi mdi trydng.

Chiing tdi da nghidn ciiu san xult bao bl ty hiiy trdn nln nhya nhi^t ddo Polyethylene (PE) vdi ham luong tinh b|t nhi^t dIo khac nhau. Ciu tnic va tinh chit ciia bao bl ty hDy duoc xac djnh bdi mdt s i thilt bj ky thuat nhu kinh hiln vi didn tCl qudt (SEM), phj nhieu xg tia X (XRD), phdn tich nhidt vi sai (DSC), may kilm tra d | bin kdo va phan tfcti nhidt trpng lyc (TGA).

2. Thire nghISm

2.1. H6a chit

Tinh bpt sin (Vidt Nam) cd trpng lypng phan tii.

Mn = 46.000 g/mol, ham lupng amylose kholng 20%; HDPE cd Tg = -100°C, tjr trpng d = 0,941-0,965 g/cm', trong luong phan tii Mn - 200.000-500.000 g/mol. MAH (Anhydrid Maleic), Glycerol 99,4% dUOc

K H O A H O C ^'"•'^"8 10.2012

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NGHI6NClJU-TRfiOe6l

cung cap b6i CQng ty Tianjin Camel Imp & Exp (Trung Qu6c).

2.2. Thi nghi$m

2.2.1. Quy tr)nh chi tao composite PE/TPS Mau daoc thi/c hi$n tr§n m^y tr6n kfn 2 tryc vft Haake. Dau ti§n, hon h0p tinh bdt nhiet d^o, PE vd IVIAH daoc tr6n so b6 trong becher theo nhUng tjf l§

can ithSo sAt [l]. H6n hop daoc cho v^o mdy trdn k(n, t5c d6 tr6n 80 v6ng/phut, nhi^t do bu6ng tr^n 6 1BCC, sau 5 phOt l^y h6n hop ra, cho v^o khuSn c6 b^ d&y 2 mm ep bing miy 6p thuy li/c 6 nhi§t 06 leo^C, vdi ap su&'t 50 kg/cm^ trong 3 phut d^ tgo ra mSu h6n hop PEn"PS cho qu^ trinh kilm tra tfnh ch^t v$t lieu.

Mang bao bi ta hCiy dyoc t?o ra ti/ TPS/PE daoc thac hien nha sau: cho h6n hop cCia cdc logi PE, tinh bpt va cac chS't phg gia sau khi t6i au hoa cdc ham luong bing mdy Haake, di qua mdy tron vat li§u d l daoc phoi tron d6ng diu. H6n hop daoc daa vao may dun, sau khi daoc daa vao cdc chSt phg gia va chat phdn tan, se cho ra slin phim dang hgt (compound).

Hat ndy daoc si-f dung de thli bao bi th6ng qua cdc thiet bj thli bao bi tiisng thadng danh cho PE.

Hlnh 1: quy trlnh chg t^o hBn hdp PE/TPS tis miy trdn kin Haake

2.2.2. Toi du hdm iddng tdc ehit

D l CO the tao dUdc mang bao bi d&m bSo tinh chat CO ly va mot so tinh chd't khdc tii cdc tac ch^t ban diu, traOc tien phdi toi au hoa ham laong cdc chat:

hdm laong ch^t hoa dSo (Glycerol), tinh bot, phy gia va naOc trong qua trinh gia cong, dac bi§t la thdng so giacdng cua h6n hOP-

2.2.3. Cdc phddng phdp phan tich vat lieu De khdo sat tfnh ch^t co Iv- cOa vdt lieu tgo thanh, tat cS cac mau duoc c i t theo tieu chuln ASTM D638,

daoc do tr6n mdy kilm tra d6 bin kdo Cometech (Dai Loan). Tic d6 k6o 10 mm/phut. Mac dp phdn tdn ciia tinh b6t nhi$t d^o (TPS) vdo nhya nln rd't quan trpng vi no inh hadng nhilu din khd ndng taong hop gii^a cdc tdc chit vd khd ndng thli mang cOa v$t lieu. Chung t6i si!f dyng kfnh hiln vi di6n ti!f qudt (SEM) d l khdo sdt so phdn tdn cda tinh bOt 6 cdc ty le khdc nhau cung vdi sO phdn huy cCia vdt lidu sau khi sCf dgng. D l xac djnh khd ndng taOng hop cung nha 06 kit tinh cua vdt lieu thay dii nha t h i nao khi thay doi hdm laong TPS trong hon hop, chiJng t6l si!f dyng pho nhieu xg tia X (XRD). Ngoai ra con nhilu thilt bi ky thudt khdc h6 tro phdn tfch dac tfnh cua mau ciJng nhU mang bao bi tao thdnh.

Ddc bidt, vdi thilt bj phan tfch nhidt trong luOng (TGA) CO i h l xde djnh daoc khd nang chju nhiet nha do Im cua vdt lieu.

2.2.4. Khd nang hip thij nUdc cua mdu Mau sau khi t i i au ham laong, dem ngam vdo nOOc d nhiet dp phong, m6i ngdy lay mau ra lau sgch, dem can va ghi Igi so lidu, lap lgi cho den khi khoi lUdng cua mdu khong doi, sau do lay mdu ra lau sgch va de mpt thOi gian cho on djnh roi tien hdnh do cO ly so sanh vdi mlu ban dau.

2.2.5. St/phan hOy cOa mdng bao bi Khd nang phdn hdy cija mdng TPS/PE dadc khdo sdt trong moi trOdng dlt, tien hdnh chdn mdng bao bi can kilm tra trong dd't, sau thdi gian 7, 20, 35, 50, 51 ngdy vd 9 thang, quan sat mang, ghi nhdn sa khac biet ve hinh thdi va khoi lUdng so vdi mdng ban dau theo thdi gian.

3. Ket qua va thao luan

3.1. Anh hddng cua ham Iddng chat hoa deo len tinh chat hon hdp PE/TPS

Tinh bpt thong thaOng ton tai d dang hgt co mdng phCi ben ngoai amylose tan dope trong node va amylosepectin ben trong khdng tan. Chat hoa deo co t h i xuyen qua Idp mang Idm tinh bdt traong nd va hap thy node. Sy tradng n6 ndy se tgo ra sa trdp ldn mat trdt to ciJa cdc mgch polymer. Hinh 2 cho thay, dp dan ddi h hdm laong chat hoa deo 0% vd 20% so vdi tinh bpt, vl hdm tapng nh6 ndn chua the hda d^o hit tinh bdt. Do dd Idm cho TPS vd PE khdng cd sa tUOng hOp.

ddn din tinh bpt phdn tdn trong PE khdng diu, mlu cd tinh chat cO thip (dp dan ddi kem). 6 ham iaong 40% chd't hda deo, tinh bdt bj hda deo hoan todn, lam cho modul cung nhu ufng suat giam r6 ret. Dieu ndy cho thay, chat hda deo da dUdc sCf dung 6 ham luong

So thang 102012 i n J ? ? ? * * ? ? " I

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NGHIAN ClJU-TRI^0e6i

khiln va kilm soat dupc sy phan tan cOng nhu hlnh thai cOa TPS theo ham luong chit hda ddo (vdi nhOng ciu tnic khac nhau s§ Inh hudng d i n Unh chit co ciia v$t ll|u).

3.2. inh hudng cia trif tirang hpp [5]

Hlnh 4 chd thiy, tinh chit cO ciia v l t ll|u (iing suit, biln dgng) tang khi tang ham luong MAH, dilu nay chiing td d ham luong trO tuong hop cac thi khi nang tyong hop giOa TPS va PE cang tang. Tinh chit cOa vat ll|u nay dgt cyc dgi tgi ham lupng MAH la 7%, tuy nhiln khi tang ham luong trO tUOng hop. Unh chit CO igi giam dc xiy ra hi$n tUOng tach pha.

Hinh 2 dd Itv unh chAI co ciia vSI l:^u PETPS vdi su [hay ddi h.tm ludng Glycerol

cao, vin cdn du trong hin hop ndn tinh chit cO bj giam xulng. Trong khi dd, d tjr id 30% chit hda dIo so vdi Unh bdt, tinh chit co dgt duoc dd b i n cao nhit. va day cung la ty Id ma tinh bdt duOc hda ddo tit nhit, tgo ra sy phdn tan ciia Unh bit vdo PE t i t hon tit c l cac mau khac.

H6n hop PE/TPS t h i hi$n cac hlnh thai khac nhau theo sy thay dii ham luong chit hda did. Hin hop duoc chuan bj vdi 30 vd 40% chit hda ddo so vdi Unh bdt (hlnh 3a vd 3b). 6 ham luong 40% chit hda ddo cho thiy, hgt tinh bdt bj biln dgng, mdc md rIt cgc.

Vdi hdm luong 30% chit hda die cho thiy It biln dgng hon. Mdt s i kit qua tinh todn v l tinh luu biln va Unh chit CO ly cua hIn hop cho thiy, vdi ham tuOng chit hda ddo 30% id cin thilt d l cho hi^u q u i ddo tinh bdt cao nhit [2]. Ngoai ra, khi hda d i d tinh b$t vdi ham luong 30% chit hda dIo cdc hgt tinh b|t phdn tan d i u trong nhya nln va cd dgng hlnh c i u . NhOng kit q u i ndy chiing minh ring chiing ta cd t h i dilu

Hinh 4 anh hudng cua ham tudng MAH len tinh chai cd

Giln d l DSC ciia HDPE khi khdng phli trfn Unh b|t cd mdt peak nhi|t dd ndng chly tgi 132°C, khi hIn hop cd tinh b|t thi nhidt d | chly ciia hSn hpp giSm xulng va cung cd m|t pegk chly duy nhit. Oilu ndy duoc gill thfch khi tr^n Unh b|t vao hdn hop PE cd sA dyng tro tuong hop thi Unh bQt tOOng hop va phdn tdn tit vao nhga n l n , lam nhl|t dd chly ciia hin hop glim xulng cdn 130°C vd chl xult hi|n 1 peak Ouy nhit (hinh 5)

Hinh 3: ^nh hudng cua ham luong Glycerol len hlnh Ihdi cua hon hgp PE/TPS 70/30: (a) 40% chgt hda ddo.

lb) 30% chSl hda dSo Hlnh 5: DSC cua HDPE vdi cua hdn hgp PE/TPS/MAH 70/30/7

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NGHieNCOfU-TRflOOdl

3.3. Anh hddng cia hdm Iddng TPS [3,5]

Dua vdo kit qud cO 1^ (hinh 6) h5n hop PE/TPS 70/30 cho tfnh chd't tit nhd't v l Ung suit vd d | dan ddi. Trong khi dd, 6 ty 1$ PE/TPS 60/40 vdt li$u cdn giO daoc tfnh chd't nhUng vin khdng bing t? 1$ 70/30.

Cdn 6 t? Id 50/50 thi v§t lieu da khdng cdn giO daoc tinh chit, dieu ndy Id do tinh b$t c6 cd'u tnic kit tinh cao, bdn chd't cUng, gidn vd khd gia cdng. Khi dUa vdo hdn hop vOi hdm laong Idn se t h i hidn rd ddc tfnh khd tOdng hop vdi nhoa nln, Idm cho dd dan ddi gidm mgnh. Vdy d ham lUOng tinh b|t 30, 40% cd t h i dem thoi mdng duoc.

• Do d i n dai ("o)

Hlnh 6 inh hddng cOa him lUdng tinh bdt len tinh chSt cd cOa vit lieu

Ciu true be mat cOa hon hop PE/TPS 70/30 cho thay tinh bot phan tan tot trong nhOa nen va kich thudc hgt rat nhd vdi dang hinh cau (hinh 7). Khi tdng hdm laong TPS, kich thudc hgt ldn din do so kit hOp giiJfa cac hgt vdi nhau. Kfch thudc hgt cdng Idn thi hdm lUOng TPS cdng tang, ddn den hidn taong keo ddi sOi TPS khi quan sat true tilp bang kfnh hien vi dien tii quet.

Khi hdm luong TPS cao (60%), rIt khd d l phdn biet giffa PE hay TPS vi cd hai thanh phin nay diu xuat hien day dD lidn tuc gan giong nhau. Kfch thudc hgt cung nha dp phan tdn cCia TPS trong nhaa nln dnh hadng rat ldn den qud trlnh phd'i tron vd thli mdng.

Hlnh 7: inh hddng cOa him lugng TPS lin hinh thii cua hdn hdp PE/TPS. (a) 30% TPS. (b) 40% TPS,

(c) 50% TPS, (d) 60% TPS

3.4. Tinh Chat nhl$t

Hdm laOng HDPE dUOc xde djnh bang cdeh sii dyng thilt bi phdn tfch nhiet TGA. Nhiet dp thay doi tii 35 den 700°C, too dp gia nhiet 107phut. SU thay dii khii luong cCia thanh phan theo nhiet dp daoc quan sdt trong dadng cong TGA (hinh 8). SU thay doi diu tien, khoang lOO^C do nudc boc hoi. Su thay doi thU hai 6 180°C do sa bay hoi cCia chat hda deo. Khi nhidt dp tang dan den 300*'C xdy ra sU phdn hiiy cCia tinh bdt. Su thay dot cuoi cung khoang 400°C xay ra sa phan huy nhiet cua PE. Cd the tfnh dUOe ham luong PE dem trdn tii sU khdc biet v l khoi laOng 6 mUc tU 400 din 5800C.

-

I=- 3sr ! V ,

v.„_ \

" " " ™ ~ "

Hinh a- dd bSn nhidt cCia PE, tinh bdt, PE/TPS 70/30 vd PE/TPS 40/60

SSthano 10.2012 K H O A H O C I "

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NGHIAN Cl)U-TRflOD6l

3.5. Khio sit si/phkn huy [4]

6 hlnh 9, mlu bao bl ban diu c6 b l m^t lang bdng, trdng suit, sau 7 ngdy chdn vao dlt cd sy ngi mau, cd hidn tuong phdn hiiy xiy ra, idm cho b l mat ciia mang dye hon va xult hi|n nhilu IS nhd. Budc diu cho thiy sy phan hDy cua mang xiy ra khd nhanh.

Mao dii bdn chit cCia PE rIt cham bi phan hiiy, nhung khi phli trdn vdi tinh bdt, tinh b|l phdn ldn r l l l i t vao nhya nln PE, chia PE ra lam nhOng thdnh phin rIt nhd. Vdi d | I m cao cOng vdi sg hogt d|ng ciia vi sinh vat trong dlt se nhanh chdng phan hiiy tinh bdt Irudc, ldm tang d | xIp tgo khoang trIng idm mit Ilnh nguydn vgn cDa mdng. Mat khac, sau khi Nnh bdt bj phdn huy se lam cho c i u true mgch ciig polymer ting hop r5 ra, c i u true trd nSn ldng Ido, se d l ddng bj tdc kfch va phan huy nhanh hon so vdi binh thudng dudi dilu kidn mdi truflng. va sau thdi gian 9 thang khdo sat, vat lidu hiu nhu bj phdn ra tiing mdnh nhd dgng bdt. Dilu nay cho thiy, hdm luong tinh bdt hiu nhy da cd t h i bj phan huy hoan toan va phin vat fidu phdn ra dgng bdt cd t h i la cac phan mdnh polyethylene dang trong qua trinh bj gikm cap.

PE thdng thudng, od t h i Ung dgng r|ng rai trong cdng nghidp d l s i n xult bao bl gia thanh thip, thdn thi|n vdi mdi trudng. Tuy nhidn, s i n phim khi cd sy hi^n dl$n thdnh phin ciia tinh b|t thi dac tinh hip thy nudc cung tang Idn, dilu nay se dnh hudng Irgc Ulp din Unh chit CO 19 va khd ndng Ung dgng cua s i n phim.

VI thi, s i n phim tgo thanh c i n phli dUOc nghiin cilu va Ulp tgc cdi tiln ning cao ham fgong tinh b|t bing each biln tinh tinh b|t d l Unh b|t giim Unh Ua nUdc hon, din d i n gidm hdm luong PE hoac thay t h i hodn todn PE trong tuong lal khdng xa. mat khdc cd t h i thay t h i PE bing cdc logi polymer cd khd nang phan hiiy sinh hpc nhu PVA, PLA_ d l tgo ra bap bl cd t h i phan hiiy sinh hpc hpdn toan •

Tai ll$u tham khao

[1] W a n g S h u j u n , Y u J I u g a o . Y u J i n g l i n . Preparation and characterization ol compatible thermoplas6c starch/pofyettiylene blends. P o l y m e r D e g r a d a t i o n a n d S t a b i l i t y V o l 8 7 , 2 0 0 5 , p. 395- 4 0 1 .

[2] F J R o d r i g u e z - G o n z a l e z , B A R a m s a y , B 0 . F a v i s , High pertormancB L O P C I h e r m o p t a s t k : starch Intends: a sustainable alternative to Pure poiyettiytene. P o l y m e r V o 4 4 . 2 0 0 3 , p. 1517- 1526

f3] I s m a e l E R i v e r o , V i t t o n a B a l s a m o , A t e | a n d r o J . Muller, A^fcrowara-asslsted modilication ot starch for compabbilaing LLDPE/starch Blends. C a r b o f i y d r a t e P o l y m e r s V o ) 7 5 , 2 0 0 9 , p.

3 4 3 - 3 5 0

[4] D a n u t a l u c h o w s k a , R y s z a r d S t e l l e r , W a n d a M e l s s n e r , Structure and properties of degradable potyoleftn-starch blends.

P o l y m e r D e g r a d a t i o n a n d S t a b i l i t y V o l 6 0 , 1 9 9 8 , p. 4 7 1 - 4 8 0 .

|5] D . B i k i a r i s , J . P r i n o s , K K o u t s o p o u l o s , N . V o u r o u t z i s , E, P a v l i d o u , LDPBpiastiazed starch blends containing PE-g-MA copolymer as compalibilaer P o l y m e r D e g r a d a t i o n a n d Stability V o l 5 9 , 1 9 9 8 , p. 2 8 7 - 2 9 1 .

Sauasngdy SauSOngdv Sau91hang i Hlnh 9: miu ban dSu chda chdn vdo dSt vd mSu chdn vio dit

sau 7, 20, 35, 50 ngdy vd 9 thdng

4. Ket luan

Nghidn cUu nay da tgo ra vat li$u ty hiiy vdi 30 din 40% wt ham lupng Unh bpt trong h6n hpp, vdt lieu ndy cd cac tinh chit co ly kdo v i n cd t h i so sanh duoc vdi

" K H ' O A H O C S ^ " ^ * " 9 " ' 2 0 1 2