Chemistry Reference
In-Depth Information
particles of crystal silicon gives a share of amorphy of the sample, and crystallinity
degree turns out as a difference between unit and an amorphy fraction.
It was supposed that one technology of ¿ lm obtaining allowed an identical struc-
ture. It proved to be true by coincidence relative intensities of all peaks on diffrac-
tograms Figure 3, and samples consists only crystal and amorphous phases of the
same chemical compound. Therefore, received values of degree of crystallinity should
reÀ ect correctly a tendency of its change at modi¿ cation polyethylene by powders nc-
Si though because of a structure of ¿ lms they can quantitatively differ considerably
from the valid concentration of crystal areas in the given material. The found values of
degree of crystallinity are represented in Table 2.
TABLE 2
Characteristics of the ordered (crystal) areas in polyethylene and its composites with
nc-Si.
PE
PE + 1% nc-Si-36
PE + 0.5% nc-Si-97
Crystallinity
46%
47,5%
48%
d [ȿ]
d [ȿ]
d [ȿ]
e
2
θ
[
°
]
ε
2
θ
[
°
]
ε
2
θ
[
°
]
21.274
276
8.9
21.285
229
7.7
21.282
220
7.9
23.566
151
12.8
23.582
128
11.2
23.567
123
11.6
36.038
191
6.8
36.035
165
5.8
36.038
162
5.8
Average values
206
9.5
×
10
−3
174
8.2
×
10
−3
168
8.4
×
10
−3
One more important characteristic of crystallinity of polymer is the size
d
of the
ordered areas in it. For de¿ nition of the size of crystalline particles and their maximum
deformation
in
X-ray diffraction analysis [21] Bragg peaks width on half of maxi-
mum intensity (Bragg lines half width) is often used. In the given research the sizes
of crystalline particles in a polyethylene matrix calculated on three well expressed
diffractogram peaks Figure 3. The peaks of polyethylene located at corners 2
ε
θ
ap-
proximately equal 21.28
(peaks PE-1, PE-2 and PE-3 on Figure
4 see) were used. The ordered areas size
d
and the maximum relative deformation
°
, 23.57
°
, and 36.03
°
of their lattice were calculated by the joint decision of the equations of Sherrera and
Wilson [21] with use of half width of the peaks de¿ ned as a result of approximation
by analytical functions, and taking into account experimentally measured diffractom-
eter tool function. Calculations were spent by means of program
WinX
POW
size/strain.
Received
d
and
ε
, and also their average values for investigated ¿ lms are presented in
Table 2. The updated positions of maxima of diffraction peaks used at calculations are
speci¿ ed in the table.
The offered technology allowed the obtaining of ¿ lms LDPE and composite ¿ lms
LDPE + 1% nc-Si-36 and LDPE + 0.5% nc-Si-97 an identical thickness (85 microns).
Thus concentration of modifying additives nc-Si in composite ¿ lms corresponded to
the set structure that is con¿ rmed by the X-ray phase analysis.
ε
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