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第 4 章 分子量与分子量分布 PowerPoint PPT Presentation


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第 4 章 分子量与分子量分布. Molecular Weight Molecular Weight Distribution. 聚合物分子量的特点. 聚合物分子量比低分子大几个数量级,一般在 10 3 ~10 7 之间 除了有限的几种蛋白质高分子外,聚合物分子量是不均一的,具有多分散性。 聚合物的分子量描述需给出分子量的统计平均值和试样的分子量分布. 高聚物分子量的多分散性 Polydispersity. n i. M i. 高聚物性质与分子量及其分布的关系. 拉伸强度和冲击强度 (Tensile and impact strength)

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第 4 章 分子量与分子量分布

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4

Molecular Weight

Molecular Weight Distribution


  • 103~107


Polydispersity

ni

Mi


  • (Tensile and impact strength)

  • (Solution viscosity and low shear melt flow)


M(W)

5

10

15

M10-4

(Mw)

c1520

c

a

b

a

b


4.1

  • Number average molecular weight

  • Weight average molecular weight

  • Z

    z-average molecular weight

  • Viscosity-average molecular weight


m, n, i

i Mi , ni , mi , xi , wi , :


Number average molecular weight

Weight average molecular weight


z-average molecular weight

Viscosity-average molecular weight



Example1:

ni 10 10 10

Mi(10-4)30 20 10


W(M)

M


:

Polydispersity index

: Polydispersity coefficient

Monodispersity


  • : , , ,

    • Schulz-Flory , Schulz, Poisson

  • : , ,

    • Gaussian , Wesslau , Schulz-Zimm , Tung


4.2

  • Chemical method

  • Thermodynamics method

  • Optical method

  • Dynamic method

  • Other method


4.2.1

  • :

    • ,

    • : 102 ~ 3104 g/mol

    • : , ,

    • :

    • :


4.2.2Colligative properties

  • , ,


(1)

Boiling-point elevation

Freezing-point depression

c: ( g/kg g/ml ), Kb Kf ,


DT/c c , c = 0, K1/Mn



(2) (VPO)

DT


, DG, DT

M2, Why?

:


(3) ()

h


4.2.3

r

q

:

(1) ; (2) ; (3) ; (4) ; (5) ; (6) .


  • : (1/20)

    • , ,

  • :

    • , , ,

    • 105,


, q r :


, K

-, ,


(), :

90o, :


c

?


B

A

D

q

q

C

D:

, P(q )


:

:

, , , sinq .


Zimm

Y


q7

q6

q5

q4

q3

q2

q1

Y

(1)

(2)

(3)

(4)

Slope =

Rq

c4

q = 0

c3

Slope = 2A2

c2

c1

c = 0

qc4


4.2.4

hsp

[h]

hr


(1)

Mark-Houwink:

K, , . a , a 0.5~1

-, , Ka


(2)

c



(3) Flory

Vh, ,

Einstein


:

Flory,

A

q , :


Kq

~

, Kq

, :


4.3

  • , , , ,

  • , ,

  • , , ,


i


I=0.050.15 0.95()


(GPC)Gel Permeation Chromatography

  • 1964J. C. Moore


solution

solvent


(1)

  • Ve


(2)

  • , . , , , GPC(SEC Size Exclusion Chromatography)


W(M)

M

GPC

--M

--W(M)

GPC


(3)

  • -----


-

:

logM

Ve

Ve

M4

M3

M5

M2

M1

C

V1

V2

V3

V4

V5

Ma, ?

A

logMa

Mb, ?

B

logMb

:

Mb~Ma

D

V0


(GPC)

Mw: 3,400,000 1,800,000

MDW: 2.8 12.8


PE

PE

Ve

Ve

, , ?

GPC,


Ve

Ve

Flory

Ve ~ Vh ~ [h]M

log([h]M ) ~ Ve


Mark-Houwink

, ,

K1, K2, a1, a2, (M1)--


    • , , , , , ,


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