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Tran Hai Ninh - Polymer Center- HUTS *Chng 3: Tnh mm do ca mch
polyme (Polymer Chain Flexibility)Nguyn nhn chnh lm cho mch polyme
mm do: kch thc khng cn i ca mch polyme kh nng quay quanh trc cc lin
kt to thnh mch chnh ca polyme
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS *Chiu di ca mch polyme
Polyethylene (PE)Nu n = 10,000 th chiu di mch phn t PE khi dui thng
l bao nhiu?(zigzag planar)
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*3.1. S quay ni ti trong phn t3.1.1. Hin tng quay ca phn t
thpetan CH3 CH3 HC
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Tran Hai Ninh - Polymer Center- HUTS *S ph thuc th nng phn t
etan vo gc quay nhm metyl
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS *n-butan CH3 CH2 CH2
CH3
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS *Trng thi nng lng caoTrng
thi nng lng thp(quan st dc theo trc C2-C3)
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS *EoEEo - Thm th nng quay
(thm th nng hot ha)Eoetan = 15 kJ.mol-1Eetan = 2,1 kJ.mol-1
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS *3.1.2. Hin tng quay ni ti
trong phn t polymeXt mt mch polyme c lp (isolated polyme chain), cc
nguyn t C ch lin kt vi nhau bng lin kt n (lin kt )Alkan CnH2n+2 n 1
lin kt (lin kt n)C bao nhiu hnh thi sp xp ca mch phn t
alkan?3n-3
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS *Trong thc t, s quay ni ti
ca phn t polyme b cn tr do: Lc tc dng gia cc phn t (intramolecular
interation): lc lin kt hydro, lc Vandevan, lc phn tc, lc nh hng Lc
tc dng gia cc nguyn t (intermolecular interation) trong cng mt mch
(lc ni phn t): Tc dng tng h khong cch gn gia cc nguyn t ca cc mt
xch ln cn cn tr quay t do. Tc dng tng h khong cch xa l lc tc dng
tng h gia cc nguyn t hoc nhm nguyn t ca cc mt xch cch xa nhau.
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS *
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS *3.1.3. mm nhit ng v mm ng
hc E c trng cho mm nhit ng (thermodynamic flexibility) ca polyme
khi c cn bng nhit ng. mm nhit ng cho bit kh nng bin i hnh thi sp xp
ca mch v kh nng xy ra s thay i . gc quay (angle of rotation)
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS * mm ca mch c xc nh bng i
lng Eo gi l mm ng hc (kinetic flexibility). Eo: (thm th nng quay
potential rotation barrier or hindrance potential) nh hng n vn tc
bin i hnh thi sp xp. Eo cng ln th cc mt xch quay cng chm v tnh mm
do ca mch cng b.E: Nng lng tc ng t bn ngoi (chuyn ng nhit, lc c hc
hoc cc lc khc)
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS * mm do ng hc v mm do nhit
ng c th khng trng nhau.Khi mm nhit ng ln (E nh) nhng vn tc quay ca
cc mt xch c th b (Eo ln) th mch vn c th cng S quay quanh cc lin kt
v thay i hnh thi sp xp (t v tr c nng lng cc tiu ny n mt v tr c nng
lng cc tiu khc) ch c th xy ra khi c nng lng d tr cn thit.
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS * Nu khng c nng lng d tr cn
thit (ln hn Eo) th cc mt xch ch c th chuyn ng nhit c trng ring (v
d: dao ng xung quanh cc v tr c nng lng cc tiu). Dao ng ny cng nh th
mch phn t cng cng.
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS * phn cc ca phn t Phn t
khng phn cc Phn t phn cc
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Tran Hai Ninh - Polymer Center- HUTS *3.1.4. Cc yu t nh hng n
tnh mm do ca mch Thm th nng quay Khi lng phn t Kch thc mch nhnh Mt
mng li khng gian Nhit
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Tran Hai Ninh - Polymer Center- HUTS * Thm th nng quay Eo Thm th
nng quay ph thuc vo lc tc dng tng h bn trong phn t v gia cc phn t v
do ph thuc vo phn cc ca cc nhm th.(cc gi tr c tnh khi hp cht trng
thi kh l tng)
Eo (kcal/mol)H3C CH32,80H3C C2H53,40H3C CH(CH3)23,90H3C
C(CH3)34,40H3C CH=CH21,95
Eo (kcal/mol)H3C CF33,700,45H3C OH1,07H3C SH1,06H3C NH21,90H3C
SiH31,70F3C CF34,35
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS * Mch polyme c thm th nng
quay thp th c mm do cao Polyme mch hydrocacbon: PE, PP,
Polyisobutylen, Polybutadien, Polyisopren Polyme d mch c cha cc nhm
C O C, - CO O , - NH COO v c phn tch bi s lng lng ln nhm CH2 Mch
polyme c cha nhm th phn cc vi hm lng thp (v d cao su polyclopren v
cao su nitril) Mch polyme c cha nhm th kch thc nh ( - CH3) hoc thm
ch ln hn nhng sp xp tha tht trn mch chnh. (v d polyisobutylen,
poly(butadien co- styren)
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS *b. Khi lng phn t Khi lng
phn t ca mch tng khng lm thay i Eo , nhng kh nng bin i hnh thi sp
xp tng ln.c. Mt mng li khng gian Khi s lng lin kt ngang tng ln th
di mch trn th hin s mm do s gim xung. Khi mt lin kt ngang rt ln th
mm do s bin mt hon ton.V d cao su thin nhin lu ho vi 30% lu
hunh
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS *d. Kch thc nhm th Kch thc
ln ca nhm th lm cn tr s quay ca mt xchPolystyren
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Tran Hai Ninh - Polymer Center- HUTS *d. Nhit Khi nhit tng th mm
do ca mch polyme tng ln nh tng mm ng hc.
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS *Monte Carlo Simulation
Tran Hai Ninh - Polymer Center- HUTS
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Tran Hai Ninh - Polymer Center- HUTS *
Tran Hai Ninh - Polymer Center- HUTS
