Chemistry Reference
In-Depth Information
The polymeric materials structure and properties prediction is the most im-
portant polymer physics goal and the fact, that at present this goal is solved
fragmentarily only, speaks on its complexity. Both polymers structure com-
plexity and external factors (testing temperature, strain rate, defects avail-
ability, sample sizes and so on) large number, influencing on sample behavior
in testing process, are those difficulties, with which scientists are clashed at
this problem solution. Strictly speaking, the theoretically valid relationships
are necessary for all these factors appreciation, but at present the majority
of them are still not obtained. Therefore, further the empirical relationships,
having clear physical grounds, will be used. The authors of Ref. [1] offered
the methodology of mechanical behavior prediction for amorphous glassy
polyarylatesulfone (PASF) film samples, received from different solvents,
that allows to vary effectively their structure [2, 3]. For the mentioned goal
solution the authors of Ref. [1] used the fractal analysis and cluster model of
polymers amorphous state structure.
The polycondensation multiblock copolymer PASF film samples were
studied, which were prepared by the method of 5% copolymer solutions in
9 different solvents (N, N-dimethylacetamide, chlorobenzene, dichloroeth-
ane, chloroform, methylene chloride, N, N-dimethylformamide, 1,4-diox-
ane, tetrachloroethane and tetrahydrofuran) pouring of glass substratum. As
the data of Ref. [2] have shown, samples preparation by the indicated mode
allows to vary their structure, estimated within the frameworks of the clus-
ter model of polymers amorphous state structure [4, 5]. The samples were
tensile-stressed with discontinuous strain (the range 0.75%) on the special
installation, assembled on optical polarization microscope “Biolam” slide.
After each discontinuous strain change the sample region, including a notch
and local deformation zone at its tip, was photographed, that allows to deter-
mine characteristics of stable crack propagation process (see Fig. 5.2).
Polymers are often enough used as films, which were prepared from
polymer solutions. As it is known [6], a solution change results to the essen-
tial variations of film samples of the same polymer. Therefore, a film sample
structure prediction as a function of solvent characteristics, from which it
was prepared, is the goal solution first stage. It is obvious, that the solubility
parameter of solvent 8 is its characteristic the best choice [7, 8]. The fractal
dimension structure
d
f
was chosen as its characteristic [9], which can be de-
termined according to the Eqs. (1.9) and (2.20).
solvents is adduced, where the value d was accepted according to the literary
data [10].
