polyme phân hủy sinh học, biocompozit sợi tre với chất gắn kết sinh học

8/3/2019 Polyme phn hy sinh hc, biocompozit si tre vi cht gn kt sinh hc

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Nhm 1

Polyme phn h y sinh h c / biocompozit s i trev i cht gn k t sinh h c

Tennessee S n phm Trung tm Lm nghi p, 2506 Jacob Drive, i hc Tennessee, Knoxville, TN37996-4563, USA nh n 9 thng 12 nm 2004; sa i ngy 28 thng 3 nm 2005; chp nhn 20 thng 4

nm 2005 Tm t t

nh h ng ca lyzin trn c s diizocyanat (LDI) nhmt cht gn k t trn ccthuc tnh c a biocompozit t poly (lactic acid) (PLA), poly (Butylene succinate)(PBS) v ch t s i tre (BF) c iu tra. Tnh b n ko, kh nngchu n c, vbm dnh bmt phn pha c a ccompozit PLA / BF v PBS / BF cci thin bng vi c bsung cc LDI, trong khi s chy ra nhi t tr nn hi khkhndo lin k t ngang gi a mch nn polymer v BF. Nhi t k t tinh ventanpy trong c hai compozit tngv gim theo l ng LDI , tng ng. Nhi tca phn ng tng h p trong c hai compozit b gim do b sung LDI, trong khikhng c s thay i ngk trong nhi t nng ch y. Nhi t phn h y ca chaicompozit th p hn sov i nhng mng chu i polymer tinh khi t, nhngcc h pv i LDI cho th y nhit phn h y cao hn so v i tr ng h p khng c LDI. Ccchphm enzym c kh nng phn hy compozit c a PLA / BF v PBS / BF

c iu tra b i proteinaza K v Lipaza PS, tng ng. C hai compozit ny cth c nhanh chng b phn h y b i enzyme v vi c thm vo LDI nh m trhon s phn h y .

2005 Elsevier Ltd- tr quyn tc gi .

Tkha: Biocompozit ; Poly (lactic acid), Poly (Butylene succinate), s i tre,diizocyanat Lyzin, ch t gn k t sinh h c.

1. Gi i thi uTrong nh ng nmgn y, spht tri n ca biocompozits t polyme phn h ysinh h c v cc lo i s i tnhin thu ht c l i squan tm l n trong khoahc tng h p, b i v c th cho phn h y hon ton trong t hoc bng cch phn qu trnh v khng pht ra b t k thnh ph n c hi, c hi.


2/20

Nhm 1

Trong s cc polyme phn h y sinh h c (acid lactic) c bit poly (PLA) v poly(Butylene succinate) (PBS) c quan tm thng mi ngy cng tng. PLA c th c tng h p bng cch trng h p ngng tca cc dimer lactide theo chu k .Cng ngh tin ti n trong cng nghi p trng h p c pht tri n c thtngh p PLA tr ng l ng phn t l n dn n mt tim nngcho v t liu cu trc vithi gian sng duy tr cc c tnh c hc m khng c s thy phn nhanhchng ngay c trong mi trng m t, cng nh c kh nng lm phn bn tPLA trong sut v tinh th polymer vi im nng chy tng i cao v c tnh d v, vi cng cao v ko di chm s t.

PBS l nh a nhit do v i tinh th mu tr ng c im nng ch y kho ng 90-120 0C(tng t nhLDPE), nhi t thy tinh ha kho ng -45 t i -10 0C (gia PE vPP), ch u lc ko gi a PE v PP, v cng gia LDPE v HDPE. PBS c kh nngx l tuy t v i v c th c x l trn cc my ch bin polyolefin nhitca 160-200 0C, thnh cc s n phm khc nhau, ch ng hn nh p nv thi.Hn na, nguyn li u ca n, butanediol v succinec acid, c th sm c tmthy tcc ngu n ti nguyn ti t o sinh h c.

S i tnhin c th c ti t o v r hnthay th cho s i tng h p, chng hn nhthy tinh v carbon v c r t nhiu l i th, chng hn nhchi ph th p, t trngthp, do dai cao, c kh nng chu sc mnh theo t trng , d dng tch v c

kh nng phn husinh h c. V v y, c r t nhiu nghin c u vcompozit c t s itnhin. Tuy nhin, nhc im chnh ca cht si t nhin c th l bn cht anc can , lm gim kh nng tng thch vi mng li (nn) polymer knc. Trong nhng lnh vc tng hp, do , hu ht cc nghin cu tp truvo vic ci thin cc thuc tnh trn mt phn pha gia nn polymer v cht t nhin tng cng cc tnh cht c l ca sn phm cui cng.

Mc ch ca nghin cu ny c pht trin biocompozits vi vic c th spt cc thuc tnh bn trong b mt t polyme phn hy sinh hc, PLA v PBS,v

cht si tre bng cch s dngLDI nh mt cht gn kt sinh hc.

Cho n nay,cc lo i izocyanat ch ng hn nhmethylene diizocyanat (MDI),toluene diizocyanat (hydro ha MDI), v diizocyanat hexamethylene c s dng nhmt cht gn k t [34-38].V d , Wang et al. bo co v nh h ng MDI


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Nhm 1

ln thu c tnh c a blend PLA/tinh b t. Vi c bsung c a MDI em li k t qul s tng c ng ca c tnh c hc v kh nng chng n c.

Tuy nhin, nh ng izocyanat tm thy c h n chsdng nh mt vt liu

tng h p sinh h c b i v chng l nh ng sn phm cui ca qu trnh th y phn,tc l cc diamin tng ng ca chng, ch ng hn nh4,4 '-methylenedianiline v2,4-diaminotoluene c tm th y v nghi ng nh mt tc nhn gy ung th,gy ra b nh vim gan ng i. V v y, vi c sdng vt liu khng c hi nhmt tc nhn gho n i, tng h p y cc biocompozits phn h y sinh h c mkhng pht th i cc thnh ph n c hi.

Lyzin-diizocyanat (LDI) c da trn lysine vi hai nhm amin v mt nhmcacboxyl, l mt trong cc axit amin t nhin. LDI c th phn ng vi cc

nhm hydroxyl hoc carboxyl trong PLA hoc PBS, sinh ra cc lin kturethanemt cch d dng vhon ton c th thy phn thnh nguyn liu [41-45]. V d ,polyurethane t ng h p tLDI, glycerol v acid ascorbic (vitamin C) c th chon ton b r ra trong dung d ch n c v s n l ng ch t khng c hi cphn ra c a lysine, glycerol v acid ascorbic [46]. Trong th c t, squan tm c achng ta t i LDI nhmt cht gn k t sinh h c xut pht t nhng thc tny, b isnhim c sinh thi hi n angl mt im quan tr ng trong biocompozits.2. Th nghim

2. 1 Ha cht PLA (LACEA H-100J0 v PBS (Enpol G5300) c mua t MitsuiChemical, Inc (Tokyo, Nh t Bn) v Ire Ha ch t Ltd (Wonju, Hn Qu c).

Th i gian trung bnh v ng knh c a s i tre (BF ) c sdng trongnghin c u ny c khong 500 v 70 m.

L-lysine diisocyanate (LDI) c cung c p b i Kyowa Hakko Co, Ltd(Tokyo, Nh t Bn).

BF c sy kh trong l 105 0C trong 6 gi , trong khi PLA v PBS

c sy kh trong chn khng 400

C 24 gi tr c khi s dng. Proteinaza K v Lipaza PS c mua t Nacalai Tesque, INC (Kyoto, Nh tBn).

Tt ccc ha ch t khc c mua t cc ngu n thng mi.

2.2 S tng hp v nn p c


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Nhm 1

Cc polyme v BF tr c tin c trn d i dng cht rn kh. H n h p ny c t vo m t my tr n hng lo t (Labo Prostomill, Tokyo Seiki, Nh t Bn)quay v i tc ca 30vng/pht. Sau tc quay c tng ln n 70vng/pht v qu trnh nho tr n c thc hin trong 5 pht. Sau ,LDI

c thm vo h n h p v qu trnh nho trn ti p tc thc hin trong 10 pht.L ng LDI thm vo c thhin bng l ng NCO n h phng trnh di y:

NCO =

x100 (%)

Cc nhi t nho tr n l 180 0C v 140 0C trong cc tr ng h p ca PLA v PBS.Cc m u nho tr n c nn c thnh cctm d i p su t 150 kgf cm -2 mc180 0C (PLA / BF compozit) v 140 0C (PBS / BF compozit).2.3 Thu c tnh ko gin v th nghi m ht n c.Mt mu hnh xng ch(5x0.4x 50 mm ) c ct tcc tm cnn v o bn ko c thc hin v i mt my Shimadzu Autograpg AG-1 (5kN) Kyoto,Nht Bn) v i tc u v t qua m c 5 mm pht -1.Cc mu vi kch thc 50x50x0, 5mm c s dng kim tra trng thi hpthu nc sau khilm kh chn khng ti 450 trong 24h. Cc mu cngm honton trong nc kh Ion ha (250C) v ln lt a ra khi nc. Sau , ccnc d tha trn b mt c loi b bng cch thm vi khn giy v cc

mu vt c cn. Lng nc b hp th Mt c tnh nh sau:M t = (W t - W 0)/ W 0 x100 (%)

Vi Wt , W0 l trng lng ca mu trc v sau khi ngm trong nc tng ng. 2.4 Vi sai qut nhi t l ng k (DSC) v phn tch l c hp dn nhi t (TGA)DSC o l ng c thc hin trn d ng cgi l dPerkin-Elmer Diamond DSC.Cc m u (kho ng 7 mg) c unnng n 200 v 150 0C 200C pht -1 trongPLA v PBS/BF v t liu tng h p, tng ng, v gi trong 5 pht loi bccqu trnh nhi t. Sau ,cc mu c lm l nh n 40 0C v i tc 2 v 10 0Cpht

-1trong PLA v PBS/BF t ng h p, tng ng, v un nngmt ln na 200

v 150 0C v i tc 200C.pht -1 trong PLA v PBS/BF t ng h p, tng ng. Vi cthu nhi t v ta nhit c thhin trong b ng 1:

Nng l ng kch ho t cho s tan ch y ca compozit PLA v PBS/BF(70/30)


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Nhm 1

Lng NCO (%) Nng lng kch hot cho s tan chy PLA/BF tng hp

0 193,9 63,40,11 195,1 76,50,33 195,3 91,50,65 197,0 114,11,30 211,9 -

im cc i c gi l nhi t k t tinh (T c) v nhi t nng ch y (T m), tngng. Entanpy k t tinh ( Hc) v nhi t ca phn ng tng h p ( Hm) cng c xcnh tcc cc i ca s k t tinh v s tan ch y, tng ng. Nh ng gi tr nytrong cc h p c chia theo t ltrng l ng ca polymer v cc gi tr thu c trong B ng 1. gim phm cht do nhi t c ob i mt Perkin-ElmerPyris 1 TGA. M u kho ng 7 mg c unnng t 50 t i 600 0C v i tc 10 0C.pht -1 d i dng nit (20mL/pht).2.5 c tnh tan ch y do hi u ng nhi tHin nhin nh t tan ch y ca compozit c o nhit khc nhau v i mtthnghim dng ch y (Shimadzu CFT-500D). Nh ng bi n dng nh n mnh cp dng l 2,452x10 4 Pa v cc mi ng bnh v i ng knh v chi u di ch t 1 v10mm, tng ng.

2.6 Cc ch phm enzym th y phnMu c sy kh chn khng (10x10x0.4mm 3) c cn v nhng vo m tng nghi m 5 ml c a dung d ch proteinaza K (50 mM ch t m Tris-HCL, pH 8,6)v dung d ch Lipaza PS (0,1 M ch t m photphat, pH 6,0) trong tr ng h p caPLA v PBS / BF t ng h p, tng ng. ng nghi m c nim phong v gi mc 38 0C trong m t th i gian nh tr c v c thay th mi 48 gi (proteinazaK) v 1 tu n (Lipaza PS ), do hot ng ca enzyme v n mt mc mongmun trong su t th i gian th nghim. Mu sau c bra khi dung d ch, ra

k bng n c ct v ethanol, v sau sy kh trong chn khng mc 380

C.Th i gian qu trnh gi m khi l ng c nh giv cc m u cn l i c quanst b i SEM2.7 Hi n vi in t quyt Hnh thi h c ca cc m u b gy sau khi th nghim bn ko c kim trabng cch s dng mt knh hi n vi qut JEOL 5900LV JSM.


6/20

Nhm 1

3 Kt qu v th o lun3.1 M t phn gi i hnh thi h c Nhiu thuc tnh ca vt liu conpozit s b nh hng bi hnh thi hchng. Hnh 1 cho thy SEM

Hnh 1 SEM giao di n ca hin vi gi a mng l i v BF trong compozit PLA / BF (70/30)khng c (A), ho c c LDI ( l ng NCO, 0,65%) (B), v compozit PBS / BF (70/30) m khng

cn (C), ho c c LDI ( l ng NCO, 0,65%) (D).

nh hin vi c a bmt ko b gy ca PLA v PBS / BF t ng h p c ho c khngc LDI. T ng h p PLA/BF m khng c LDI, hai giai on c th c thy r vnhiu BFs c ko ra kh i mng l i trong qu trnh n t gy, vi khongtrng ln do c to ra. Ngoi ra, khong cch gia PBS v BF trocompozit PBS/BF m khng c LDI c nhn thy.Nhng tm kim cho thyrng s tng tc gia mng liv cht in y rt yu, bm dnh t b mt

chung . Nhng tnh nng ny l in hnh ca cc vt liu tng hp polymer khtng thch.Mt khc, nh hin vi ca chai vt liu compozit sau khi ha h pv i LDI 0,65% cho th y rng BF xu t hin c ph v i mng l i polymer.Ci thin bm dnh gia hai bmt ny c th l do tc d ng tngthchcopolymer ghp v i cc trung gian LDI, m c th c sn xut thng qua m tphn ng ha h c gia cc nhm hydroxyl c a polymer v BF nho tr n trong iu


7/20

Nhm 1

kin nhit cao hnv p l c [39,40]. Trong bi bo trc y ca chng ti,iu c xc nhn rng nhm isocyanate phn ng vi cc nhm thiu cui hydroxyl hoc carboxyl ca PLA v cc nhm hydroxyl ca tinh bt,xut copolymer ghp ca PLA v CS urethane lin kt c xc nhn bi NM

lng [15].Kt quhnh thi h tr vic ci thin tnh b n ko v kh nng chngn c bng cch thm LDI, m s ctho lun di y.3.2 Thu c tnh b n ko

Hnh 2: nh h ng ca l ng NCO n cc thu c tnh cngca compozit PLA ho c PBS / BF(70/30). #, Ko s c mnh; m unYoung; , gin di ph v .

Hnh2 cho th y nh h ng ca nhm isocyanate (NCO) ch a trn cc thu c tnhcngca PLA v PBS/BF (70/30 b i wt) compozit. Trong tr ng h p ca PLA/BFcompozit, l ng NCO tng0,33%, bn ko v m unYoung tngnhanh chngt29 n 42 MPa v t 2666 n 2964 MPa , tng ng, v sau san bng-ofF.Tuy nhin, khng c tc d ng ng kLDI ngoi ra s ko di t, hin th gi trdi 5%. Tng t, bn ko ca vt liu tng hp PBS / BF tng nhanh bin t 21 n 34 MPa vi lng NCO cha 0,33%, tng ng, v sau san bng . Tuy nhin, m un Young khng c nhiu thay i bng vic b sung ccLDI. gin di t tng nh nu b sung LDI, nhng vn cho thy gi tr t h10%. Lng nhm NCO ti gi tr ca bn ko gi nguyn c th c xemxt tp trung ti b mt phn pha, l gi tr ti thiu ca bo ha ti b mphn pha cho mt cht gn kt trong giai on phn tn, v kch thc trung bnca phn tn BF s khng c thay i vivic b sung cc cht gn kt 15,-49].


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Nhm 1

Hnh 3 Hnh 4

Hnh 3 v 4 th hin cc tc d ng ca ni dung BF trn cc thu c tnh cngcaPLA v PBS / BF compozit c ho c khng c LDI. L ng NCO c t mc0,65%. Trong c hai compozit m khng c LDI, bn ko gi m dn v i sgia


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Nhm 1

tngca l ng BF. iu ny c th l do k t dnh km bmt phn pha gi amng l i polymer v BF ph . y l mt hin t ng chung trong compozitkhng tng thchv i cc c im khc nhau, ch ng hn nh tnh k n c camng l i polymer v tnh a n c ca cht ph[50-53]. Tuy nhin, bn koca cc h p PLA / BF v i LDI gi gi tr ca kho ng 45 MPa b ng cch tng l ng BF ln n 30% v sau gim. Nhng gi tr ny cao hn so vi nhng cchp khng c LDI. Hn na, bn ko ca PBS / BF compozit vi LDI tnglng BF ngy cng tng v s ci thin r rt khi lng BF cao hn. iu ny cth l do tng cng bm dnh b mt phn pha gia mng lipolymer v ph BF bng cch thm LDI.

Tt ccc compozit cho th y s gia tngca m unYoung cng v i l ng BFtngln. iu ny l ph bin trong v t liu compozit c gia c bng mt chtn cng. M t khc, cc v t liu compozit v i LDI cho th y gi tr cao hn compozit khng c, ch ra rng tng h p c tip tc lm c ng bng vic b sung cc LDI.

gin di t gim vi vic tng lng BF trong tt c cc vt liucompozit.iu ny c th l do s gia tng trong gin on ca mng li polymer vi sgia tng trong giai on phn tn (BF). Tuy nhin, cccompozit vi LDI cho thy bn ko di t hi cao hn so vi compozit m khng LDI.3.3. thm nc BF l cht a nc bi v n c cha mt lng ln cc nhm hydroxyl, nhnPLA v PBS l polyme k nc. Hiu qu ca vic b sung cc lng chtLDI vBF vo hnh vi hp th nc cacccompozit c nghin cu v ch ra tronghnh. 5. S hp thu n c cho t t ccc v t liu compozit tng ng ktrong 20h u tin v sau t cnb ng. Khi so snh v i cc h n h p c v khng c LDI,shp ths l ng v th i gian t n s n nh nh hn v lu hn, tngng, cho t t ccc vt liu compozit v i LDI hnkhng c, ch ra rng vic bsung ca LDI lm cho s hp thu nc kh khn. iu ny c th c gii thch

bi s ci thin trong bm dnh b mt phn pha gia mng lipolymer vcht ph BF do s ghp ni ca LDI v phn ng ca LDI vi cc nhm hydroxylca polyme v BF kt qu l t a nc hn.

Ng i ta cng c tm ra r ng s l ng hp th tng ln trongtt ccc vt liucompozit v i l ng BF tngln. B i v PLA v PBS c th hp th n c kho ng1%, l ng BF l y u tchyu nh h ng n shp thu n c ca vt liu


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Nhm 1

compozit.S gia tngca l ng BF lm tng tc hp th, b i v tnh a n cmnh mca n.

Hnh 5 : nh h ng ca BF l ng v b sung c a LDI h p th n c ca cc v t liu compozitPLA ho c PBS / BF. 0,90 / 10; , 80/20; A, 70/30; , 60/40, 50/50; tr ng v * (r n dng)

LDI ( l ng NCO, 0,65% ) , mu en+, (dugch ngang dng) m khng c n LDI

3.4. Nhi t tan ch y thu c tnh

Hnh 6 Mi quan h ca logarit nh t tan

chy hon ton(Ln) v nhi t i ng (07/01)PLA / BF compozit. L ng NCO: , 0%; ,0,11%, 0,33%; , 0,65%, 1,30%.


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Nhm 1

Hnh 6 v 7 cho th y mi quan h gia logaritca nh t tan ch y hon ton(Ln ) v nhi t i ng (l / T) trong PLA v PBS / BF v tliu compozit , tng ng. D i s cng thngct (4.9X104Pa), nh t biu kin ca tt c cc vt liu compozit gi m khi nhi t tng..Mi quan h gia Ln v l / T l tuy n tnh,ch ra rng sphthuc ca vo nhi t tun theo phng trnhArrhenius:

= A x (3)Hnh 7 Mi quan h ca logarit nh t tan ch y hon ton(Ln tj) v nhi t i ng

(l/T) trong PBS / BF compozit. L ng NCO: 9, 0%; . 0,11%; A, 0,33%; , 0,65%.

V i: A l m t hng s c lin quan n c tnh v t liu

E nng l ng kch ho t cho lu l ng

R hng skh l t ng

T nhit tuyt i.

Theo phng trnhArrhenius, nng l ng kch ho t cho lu l ng c tnh ton

v cc gi tr c tm t t trong B ng 1. Cc v t liu tng h p v i LDI trong c hai vt liu tng h p yu c u nng l ng kch ho t cho lu l ng cao hnso v icc h p khng c LDI, bi u th cc gi tr ln hn so v i cc h p khng c LDI.N cng c tm th y v i nng l ng kch ho t tng khi l ng LDI tngln.iu ny cho th y rng vic bsung c a LDI d n n s gia tngtr ngi v chuyn ng ca phn t ca mng l i polymer do cc lin k t ngang v i BF, lmcho snng ch y kh khn.

3.5 K t tinh v tr ng thi tan ch y

Tnh ch t nhit c nghin c u b i DSC v cc k t qu thu c tm t t trongbng 2 di y:


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Nhm 1

( ) Values divided by the weight proportion of polymers

C bn PLA v PBS c mt nhit k t tinh (Tc) c a 112,8C v 68,1C,tng ng. Trong c hai PLA v PBS / BF compozit, Tc chuy n sang nhi t caobng cch thm ho c BF ho c LDI, v ti p tc tngt lni LDI. Nh ng gi tr

TQ ny cao hnca compozit hn so v i cc polyme tinh khi t ch ra rng t lk ttinh hn so v i cc v t liu compozit tr nn nhanh hntrong cc qu trnhnonisothermal. S gia tngtrong T c c th c coi l do hi u ng to mm caBF v LDI. c bit, mi lin k t urethane gi a mng l i polymer v BF vi c b sung cc LDI c th tng c ng hnna mm ca ma tr n polymer. Trong c haivt liu tng h p, tuy nhin, k t tinh entanpy ( Hc) gim bng cch tng l ngLDI. Cc chuy n ng phn t ca mng l i polymer c th b hn chb i vicbsung cc LDI, k t qul gim entanpy k t tinh. Vi c bsung cc LDI c th tng c ng hnna s to mm ca mng polymer. Trong c hai compozit, tuynhin, k t tinh entanpy ( Hc) gim bng cch tng l ng LDI. Cc chuy n ngphn t ca mng polymer c th b hn chb i vic bsung cc LDI, k t qulgim entanpy k t tinh. Nhit nng chy (Tm) tinh khit PLA v PBS l 165,3 v112,1C, tng ng. Nhng TMS khng b nh hng bi vic b sung ca mtrong hai BF hoc LDI. Tuy nhin, nhit nng chy (A // c) trong c hai vt liucompozit c gim b sung ca BF v LDI. y c thl do s tng tcmnhmgia mng l i polymer v BF bmt phn pha, giam gi nh h ng chu ipolymer.

3.6 Nhi t phn h yHnh 8 v 9 hi n th cc ng cong TGA v bi u nhit phi sinh (DTG) choPLA, PBS, BF, v PLA v PBS / BF h p v i l ng LDI khc nhau.

Nhit phn h y ca PLA v PBS cho th y trong m t giai on hon ton duy nh tv xy ra t i 376 v 405C , tng ng. Trong tr ng h p ca BF, m t ba giai on

Effect of LDI on crystallization and melting behavior of the PLA and PBS/BF (70/30) compozitsSample NCO

content (%)

T c CC) AH C (J/g) 7- m(C) (J/g)

PLA - 112.8 33.2 165.3 41.1 PLA/BF 0 115.2 23.5 (33.6) 162.3 27.4 (39.1) compozit 0.11 118.4 21.5 (30.7) 162.7 23.5 (33.6)

0.33 118.7 20.2(28.9) 161.8 23.6 (33.7) 0.65 119.4 16.4(23.4) 162.2 23.1 (33.0) 1.30 120.2 14.5(20.7) 161.6 22.8 (32.6)

PBS - 68.1 60.1 112.1 65.3 PBS/BF 0 74.6 40.8(58.2) 112.0 42.3 (60.4) compozit 0.11 78.0 37.8(54.0) 112.1 35.8 (51.1)

0.33 80.2 38.1 (54.4) 112.3 29.4 (42.0) 0.65 82.2 37.3 (53.3) 112.9 24.5 (35.0) 1.30 82.6 31.2 (44.6) 112.1 21.7 (31.0)


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Nhm 1

chnh c a khi l ng c quan st. Giai on u tin v imt khong nh trong ph m vi nhi t t250 n 300C l c trngca cc thnh ph n trngl ng phn t thp, chng hn nhhemixenluloza v m t trong giai on thhai,xut hin nhit cao trong kho ng 300 v 400C, tng ng v i phn h y nhitca cellulose. V 1/3 g n 420C l do lignin phn h y.

Trong trng hp caPLA / BF compozit, s kt hp caBF trong m ng li PLA b nh hng ng k nhit phn hy nhit. Cc vt liucompozit chothy nhit gim cp thp hn(trn 50C) so vi ca PLA v mt mthai giaion ca i chng ch yu lquan st cho tt c cc vt liucompozit. l, sgim cptrong phm vi280 - 340C l do phn h y PLA g n kho ng nh gn350 0C l do BF phn h y. Nh ng nhi t gim cp thp hnc thl do gi mtrng l ng phn t ca PLA b i nhit cao nho (180C). Tuy nhin, v i cccompozit nhi t gim cp nhit l ng LDI. N c th c ni r ng s gia tng trng l ng phn t bng ccn i ngang t phn ng gia mng v BF, s m rngmng phn t ca ma tr n ring c a n, c th lm tngnhit phn h y nhi t54-56].PBS / BF t ng h p cho th y mt s n nh nhi t trung gian gi a nhng ng i caPBS v BF, b sung c a LDI cng c ci thin s n nh nhi t ca hn h p,nhit cao hnphn h y nhi t trong compozit v i LDI.


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Hnh 8

Hnh 9


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Nhm 1

3.7 Cc ch phm enzim phn h y Cc hi u ng ca vic bsung c a LDI trn kh nng phn husinh h c ca vtliu tng h p c iu tra b i phn h y enzyme b ng cch s dng proteinazaK v Lipaza PS, cng c bit n lm suy gi m mt cch d dng PLA vPBS, tng ng [57-59]. Hnh 10 v 11 cho thy trng lng cn li ca PLA v /hoc vt liu tng hp PBS / BF c v khng c LDI cng vi tinh khit PLA vPBS nh mt chc nng ca thi giantri qua , tng ng. N c quan st thyrng trng lng cn li ca tt c cc mu gim gn nh tuyn tnh vi thi giantri qua. Phn hy tinh khit PLA v PBS l chm hn so vi tt c cc vt liucompozit, ch ra rng BF ci thin s xung cp ca c hai polyme. Khi so snhgia cc vtcompozit c v khng c LDI, tt c cc vt liu compozit c LDI skh phn hy hn so vi nhngcompozit khng c. Bng cch tng lng LDI tc

phn hy tr nn chm hn nhiu. Ci thin bm dnh b mt gia mngpolymer v BF bng kh nng kt ni ca LDI s lm cho khu vc tip xc vi e Hnh12 cho th y hin vi SEM c a PLA ho c compozit PBS / BF (70/30) v i LDIgim cp trong th i gian phn h y khc nhau. N c th c nhn th y r rngrng ma tr n ca chai vt liu tng h p tr thnh gi m nhenzyme phn h ytip tc.Hnh 13 cho th y nh h ng ca l ng LDI vo phn h y ti cng m tth i gian. Trong tr ng h p ca cc h p khng c LDI (A v D) zyme nh hn,dn n gimtc phn hy. a scc m ng l i b phn h y mc d phn h yth i gian ng n. Tuy nhin, s mt mt c a mng xy ra ch m hntrong cccompozit c LDI hn khng cn LDI v r t nhiu cc b phn trong cc compozitc l ng LDI nhi u hn. Nh cp trn, bmt phn pha s k t dnhmnh m hnsgim din tch ti p xc c th y phn enzyme v iu ny s chok t qutrong m t th i gian phn h y di hn.


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Hnh 12 SEM hi n vi ca PLA ho c compozit PBS / BF v i LDI ( l ng NCO 0,65%) sau khith i gian phn h y enzyme khc nhau. (A) ki m sot c a compozit PLA / BF, (B) sau 7 ngy,

(C) 9 ngy, (D) ki m sot c a compozit PBS / BF, (E) sau 2 ngy, (F) 4 ngy.


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Hnh 13 SEM hi n vi c a compozit PLA / BF (sau 7 ngy) v PBS / BF (sau 7 ngy) c ho ckhng c LDI sau khi phn h y enzyme. (A) compozit PLA / BF m khng c LDI, (B) v i LDI

(L ng NCO, 0,33%), (C) (0,65%), (D) compozit PBS / BF m khng c LDI, (E) ( L ngNCO, 0,33 %), (F) (0,65%) .

4. Kt lun Mt nng thp caLDI l cht gn kt sinh hc c b sung biocompozit thn thin vi mi trngtrong qu trnh nho trn. c bit, tnhcht cngko v kh nng chng nc ng ci thin bng cch ch bin ny phnng c hc-ha hc, ci m c gi tr cao trong cc ng dngcng nghip. Nhngci thin ny l do tng c ng bm dnh bmt phn pha gi a mng chu ipolymer v BF. Hn na, cc k t quca phn h y enzyme cho th y kh nngphn hu sinh h c c th c iu ch nh bng cch ki m sot m c bm dnhtrn b mt sdng LDI. T i cc khu v c, nim tnh tng h p sinh h c v yucu thit k xy dng ph hp vi phng din mi trng c yu cu, nhbiocompozit s c tim nng cho s tng trng n tng vi mt khi nim muxanh l cy. ng dng chnh cho biocompozit s bao gm chi cho tr em, ni


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tht, phn cng, vn sn cho cc sn phm in t, c bit l mt sn phmmt ln

L i cm n

Cng trnh ny c htr b i USDA Wood Utilization Research Grant and theTennessee Agricultural Experiment Station, Project #83.

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polyme phân hủy sinh học, biocompozit sợi tre với chất gắn kết sinh học

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