bg polyme ch5 amorphous polymer

Tran Hai Ninh - Polymer Center- HUTS *Chng 5: Polyme v nh hnh(Amorphous polymer) trng thi tp hp rn (bulk state, condensend or solid state) polyme c th tn ti trng thi pha v nh hnh v pha tinh th.Tran Hai Ninh - Polymer Center- HUTS Tinh th(crystalline phase)V nh hnh (amorphous phase)M hnh Fringed-Micelle ca polyme bn tinh th (Bunn-1953)

Tran Hai Ninh - Polymer Center- HUTS

Tran Hai Ninh - Polymer Center- HUTS *Mt s m hnh m t cu trc ca polyme v nh hnh


Tran Hai Ninh - Polymer Center- HUTS *V d 1: nhit phng (25o C), PMMA v PS l cht do cng v dn. Trong khi polybutadien, poly(etyl acrylat) v polyisopren l vt liu mm, do, n hi ging nh cao su. Tuy nhin khi PMMA v PS c gia nhit n 125oC chng th hin tnh cht ging nh cao su.V d 2: Qu bng bng cao su khi c lm lnh trong Nit lng chng tr nn cng, gin v d v vn khi c gng tc dng lc c hc (p bng)5.1. Nhit ha thy tinh, Tg, v cc phng php xc nh Tg


Tran Hai Ninh - Polymer Center- HUTS *Nh vy, tn ti mt nhit no , Tg (khong hp nhit ): T < Tg polyme v inh hnh tn ti trng thi thy tinh (glassy state) T >Tg polyme v inh hnh tn ti trng thi mm cao (rubbery state)Tg Nhit ho thu tinh


Tran Hai Ninh - Polymer Center- HUTS *12345Cn Carghin-Sokolova6Cni trngThanh nng hnh trMu polymen nh nhitH thng quang o dch chuynI Trng thi thy tinhII Trng thi mm caoIII Trng thi chy nhtTg - nhit ha thy tinhTf - nhit chy nhta. Phng php c nhit (thermomechanical method)


Tran Hai Ninh - Polymer Center- HUTS * S chuyn ng ca phn t trong polyme v nh hnhChuyn ng tnh tin ca ton b phn t hin tng chy ca polymeS dch chuyn ca on mch (segment c khong 40 50 nguyn t C) (s dch chuyn ring r ca mt s on phn t mm do m khng lm thay i v tr tng i ca cc on khc xa hn) mm do ca mch v kh nng cun trn.Chuyn ng ca mt s nguyn t trn mch chnh hoc nhm th gn vo mch chnh.Dao ng ca cc nguyn t quanh v tr cn bng.


Tran Hai Ninh - Polymer Center- HUTS *Chuyn ng 1 4 c sp xp theo chiu gim nng lng hot ha (cn mt lng nh hn nng lng nhit (kT) to ra s chuyn ng ). Nhit ha thy tinh l nhit m ti chuyn ng 1 v 2 khng xy ra v nng lng ch cho chuyn ng loi 3 v 4Nng lng ca tng phn t tun theo quy lut phn b Boltzman (ngha l khng phi tt c phn t u c cng nng lng nhit nht nh), do khi nhit nh hn Tg chuyn ng loi 1 v 2 vn c th xy ra (cn thi gian rt lu c th quan st c).


Tran Hai Ninh - Polymer Center- HUTS * on I (Trng thi thy tinh): ch c dao ng nhit ca cc nguyn t hoc nhm nguyn t xung quanh v tr cn bng (chuyn ng loi 3 v 4) bin dng xy ra do thay i gc ha tr v di lin kt di tc dng ca ngoi lc (bin dng n hi). bin dng b khi ng sut khng ln


Tran Hai Ninh - Polymer Center- HUTS *Trng thi mm cao: khi nhit tng, kh nng quay quanh trc lin kt ca mch phn t tng ln lm thay i hnh thi sp xp ca mch phn t. Dao ng ca cc on (dch chuyn) bin dng chy ca polyme. Bin dng chy tng khi nhit tng. Bin dng thun nghch ln


Tran Hai Ninh - Polymer Center- HUTS * Trng thi chy nht: bin dng gy ra do s dch chuyn khng thun nghch ca cc mch polyme xut hin bn cnh bin dng n hi v mm cao.


Tran Hai Ninh - Polymer Center- HUTS * Polyme v nh hnh c th nm trong 3 trng thi vt l: Rn (thy tinh) polyme dng thy tinh polyme v nh hnh rn Mm cao (rubber-like) Chy nht Mt s loi polyme v nh hnh ch c th hai, thm ch mt trng thi.Ch Tg v Tf l nhit trung bnh ca khong nhit xy ra qu trnh chuyn t trng thi thy tinh sang trng thi mm cao v t trng thi mm cao sang trng thi chy nht.


Tran Hai Ninh - Polymer Center- HUTS *b. Phng php xc nh th tch ring (Measuring Specific Volume or Dilatometric Method)Mercury-based dilatomterA mu polyme (1g)B mao qun B o thay i th tch ca Hg + polymeG Mao qun dng hiu chnh c hn kn u F


Tran Hai Ninh - Polymer Center- HUTS *nh hng ca nhit ln th tch ring ca polyme v nh hnh


Tran Hai Ninh - Polymer Center- HUTS *b. Phng php nhit(Thermal Method)DTA differential thermal analysisDSC differential scanning calorimetry


Tran Hai Ninh - Polymer Center- HUTS *5.1. Cc yu t nh hng n nhit ha thy tinhKt b rng ca polyme (free volume) vf Kt b rng ca polyme l phn th tch khng b chim gi bi cc phn t polymevf = v - vsV th tch ca mu polymeVs - th tch ring ca phn t polyme trng thi xp chtvf /v = 0.025 khi T = Tg


Tran Hai Ninh - Polymer Center- HUTS *


Tran Hai Ninh - Polymer Center- HUTS *2. Lc tng tc gia cc phn tLc hp dn lin kt gia cc phn t cng ln th cng cn nhiu nng lng nhit to ra s dch chuyn, dao ng ca cc phn t polyme.Tg t l thun vi ha tan, (o mc tng tc gia cc phn t.


Tran Hai Ninh - Polymer Center- HUTS *nh hng ca cu to ho hc


Tran Hai Ninh - Polymer Center- HUTS *nh hng ca phn cc


Tran Hai Ninh - Polymer Center- HUTS *Lc hp dn gia cc phn t ko cc phn t li gn nhau hn, do ngn cn chuyn ng ca on mch. Polyme phn cc v polyme c cha lin kt H u c Tg cao.


Tran Hai Ninh - Polymer Center- HUTS *nh hng ca kch thc nhm th


Tran Hai Ninh - Polymer Center- HUTS * nh hng ca cu to mch chnhKh nng quay t do xung quanh trc lin kt


Tran Hai Ninh - Polymer Center- HUTS *3. nh hng ca khi lng phn t polymeTg - nhit ho thu tinh ca polyme c khi lng phn t l Mn - nhit ho thu tinh ca polyme c khi lng phn t rt ln c - hng s V du: polystyren S lng u mch phn t (chain ends) to ra khong trng cho cc chuyn ng xy ra


Tran Hai Ninh - Polymer Center- HUTS *4. nh hng ca cht ho doCht ho do: ph gia c khi lng phn t thp lm mch phn t dui ra hot ng nh l cht bi trn iu chnh lc tng tc gia cc phn t to ra cc khong trng (free volume) gia cc phn tVD: thm ph gia DOP bis(2-etylhexyl) phtalat lm gim ng k Tg ca hn hp PVC v DOP


Tran Hai Ninh - Polymer Center- HUTS *Chng 6: Polyme bn tinh th(Semicrystalline polymer)


Tran Hai Ninh - Polymer Center- HUTS *Trng thi nng chyKhi lm lnh polyme t trng thi nng chy (liquid), cu trc ca polyme c th thay i theo 2 hng: (a) kt tinh - crystallisation hoc (b) hnh thnh cu trc thu tinh v nh hnh


Tran Hai Ninh - Polymer Center- HUTS *6.1. Hnh thi hc ca polyme bn tinh thM hnh Fringed-Micelle (m hnh n gin u tin) M hnh c xy dng da trn tnh cht c hc v kt qu nhiu x tia Rnghen ca polyme bn tinh th M hnh m t s phn b ngu nhin ca vng tinh th v vng v nh hnh Mch phn t polyme c th i qua vng tinh th v vng v nh hnh nhiu ln


Tran Hai Ninh - Polymer Center- HUTS * M hnh Fringed-Micelle khng cn thch hp khi cu trc hnh cu c pht hin ra vo nhng nm 1960. Cu trc hnh cu: s phn b i xng hnh cu ca lp tinh th (crystalline lamellae) thay cho s phn b ngu nhin ca tinh th nh (small crystals)Cu trc hnh cu (Spherulite 1960s)


Tran Hai Ninh - Polymer Center- HUTS *n tinh th - Cu trc dng tm (Single Crystal, Keller 1957) n tinh th ca PE (c to thnh bng phng php kt tinh t dung dch) rt mng v mch chnh song song vi chiu dy ca tinh th. Chiu di mch phn t polyme ln hn rt nhiu so vi chiu dy tinh th mch phn t phi gp li (folded) !!!


Tran Hai Ninh - Polymer Center- HUTS * Tm tinh th pht trin theo c ch gp mch(chain folding mechanism) Chiu dy tinh th c iu khin bng hiu s lm qu lnh (chm ng) T = Tm - Tc


Tran Hai Ninh - Polymer Center- HUTS *Cu trc tm tinh th c mch gp li khi polyme kt tinh t trng thi nng chy(Chain Folded Lamellar Structure, Fisher, 1959)PPVL Poly(pivalolactone)


Tran Hai Ninh - Polymer Center- HUTS *6.2. Nhit ng hc qu trnh nng chy v kt tinh ca polyme tinh th Kt tinh l qu trnh chuyn t trng thi c th t gn sang trng thi c th t xa. Nng chy l qu trnh chuyn t trng thi c th t xa sang trng thi c th t gn (trng thi nng chy liquid melt).c im chungL qu trnh to pha mi Chuyn pha bc mt Xy ra nhit xc nh


Tran Hai Ninh - Polymer Center- HUTS * C ch ca qu trnh kt tinhGiai on 1: to mm Cc mm tinh th c to ra trong pha v nh hnh, v dn dn pht trin ln ln L qu trnh thun nghch nn nhit nh hng rt ln n bn vng, s lng v kch thc ca mm tinh th


Tran Hai Ninh - Polymer Center- HUTS *Giai on 2: pht trin tinh th dng tm Trng thi ban u S hnh thnh v pht trin ca tinh th hnh cu t n tinh th ban u Cu trc a lp c to thnh bi c ch chuyn v tr do xon (screw dislocation mechanism)n tinh thCu trc tinh th hnh cu hon thin


Tran Hai Ninh - Polymer Center- HUTS * Trng thi hon thin cu trc hnh cu Khi cu trc tr ln ln hn, cc lp tinh th pht trin, to nhnh v lan rng tch khi nhau


Tran Hai Ninh - Polymer Center- HUTS * C ch hnh thnh tinh th dng tm (lp) C nhiu gi thuyt a ra gii thch s sp xp ca mch phn t polyme vo mt ang pht trin ca tinh th dng tm


Tran Hai Ninh - Polymer Center- HUTS * Tc pht trin tinh th hnh cu (spherulites)Quan st trn knh hin vi quang hc phn cc Trong iu kin kt tinh ng nhit, tc pht trin bn knh ca tinh th hnh cu l khng i (bn knh t l tuyn tnh vi thi gian)


Tran Hai Ninh - Polymer Center- HUTS * S ph thuc vo nhit ca tc pht trin tinh th hnh cu


Tran Hai Ninh - Polymer Center- HUTS *Yu t no s nh hng n qu trnh kt tinh ca polyme? Tnh u n, cn i ca cu trc mch phn t polyme l yu t chnh nh hng n kh nng kt tinh ca phn t polymeCu to ca mch polymeV d: - actactic PS l polyme v nh hnh - Syndiotactic-PS v izotactic-PS c kh nng kt tinh


Tran Hai Ninh - Polymer Center- HUTS *b) Nng lng tc dng tng h gia cc phn tCc nhm th phn cc lm gim tc kt tinh, nhng lm tng nhit kt tinh v tng nhit nng chy ca polyme tinh thc) mm do ca mch polyme mm do lin quan n chuyn ng nhitChuyn ng nhit gy ra 2 tc dngTng tc dch chuyn cc cu trc tng tc kt tinhPh v nhng cu trc trt t c th ph v nhng tinh thPolyme c mm do thch hp th mi c kh nng kt tinh tt. mm do qu ln hoc qu b th gy ra hiu ng ngc li


*

bg polyme ch5 amorphous polymer

Documents