Chemistry Reference
In-Depth Information
in the scales of the cluster structure characteristic sizes amorphous polymer
(or semicrystalline polymer amorphous phase) may be considered as inho-
mogeneous system [6].
Katsnelson [9] has given the following definition of the matter phases:
they are “…states of the matter able, being in touch, to exist simultaneously
in equilibrium with one another. Obviously different properties correspond
to different phases. In addition, it should be taken into account that by dif-
ferent phases… parts of a body are meant, related to the solid phase, but
possessing different structure and properties.” Clusters and loosely packed
matrix which in accordance with the cluster model [10] are the main struc-
tural elements of the polymer amorphous state meet the above definition,
at least, partly. It is known that these elements possess different mechani-
cal properties [11] and different glass transition temperatures [12]. All these
facts together allow to consider the polymer amorphous state to be a quasi-
two-phase state, disclaiming full strength of line definition [6].
TABLE 9.1
The Comparison of Characteristic Sizes of the Fluctuation Theory L
0
and the
Cluster Model R
cl
For Amorphous Glassy Polymers [6]
Polymer
L
0
, Ǻ
R
cl
, Ǻ
Polystyrene
76.4
36.1
Poly(methyl methacrylate)
31.7
31.6
Poly(vinyl chloride
54.0
27.1
Polycarbonate
39.7
31.1
Polysulfone
36.4
25.0
As it has been noted in chapter five, the local plasticity zone type de-
fines the fracture type: if a craze forms at critical defect tip, then polymer
failed quasibrittle and if deformation zone (ZD) or local shear yielding zone
(“shear lips”) - then quasiductile [13]. The inelastic deformation mechanism
change is considered as brittle-ductile transition [14]. The treatment of the
indicated transition will be considered below within the frameworks of both
cluster model and solid body synergetics.
