Chemistry Reference
In-Depth Information
temperature treatment of compositions, so the second stage of the com-
position processing was carried out in plunger extruder at the temperature
of 185 °C.
Average molecular weight of the elastomer was characterized by vis-
cometry method. Average molecular weight of PIB was calculated accord-
ing to the equation Mark-Houwink:
[ ]
h=×
Mm
α
(1)
K
,
where [η] - the intrinsic viscosity, mL/g; Mm - average molecular weight
of the polymer; К, α - constants for a given system “polymer-solvent.”
Heptane was used as solvent, the constants К=1.58´10
-4
, α=0.69 [8].
For each sample, a series of solutions were prepared with different con-
centrations (0.2, 0.4, 0.6, 0.8 and 1.0 g/100 mL), and then determines the
relative, specific and intrinsic viscosity. The calculated molecular weights
presented in Table 4.1.
Investigation of the structure of the compositions by atomic force mi-
croscopy was performed on the tunnel atomic force microscope brands
Ntegra Prima (company “NT-MDT”) (cantilever NSG-01 with a frequen-
cy of 0.5-1 Hz). Investigations were carried out by semi contact mode.
Microtome cuts were made on the brand Microm HM-525 (company
“Thermo scientific,” Germany).
Investigation of the structure of the compositions was carried out by
differential scanning calorimetry on differential scanning calorimeter
DSC-60 (company “Shimadzu,” Japan). Samples of PHB-PIB blends
weighing several mg were placed in open aluminum crucibles with a di-
ameter of 5.8 mm and a height of 1.5 mm and weighing 13 mg upper
temperature limit of 600 °C. Temperature range from minus 100 to plus
250 °C, heating rate of 10 deg/min. Liquid nitrogen is used to generate low
temperature. Instrument calibration was performed according to indium,
tin and lead.
The rheological curves of pure polymer melts and their mixtures were
obtained with the multifunction rheometer “Stress Tech” (company “REO-
LOGICA Instruments AB,” Sweden). The measuring cell consisted of two
parallel planes (the lower plane was fixed, the upper plane being a rotating
rotor); the shear rate was 0.1 s
-1
, the temperature range was 443-513K
(170-240 °C). The lower limit of the temperature range was chosen by the
melting temperature of PHB (174.4 °C the data obtained for DSC), the up-
per limit is the beginning of irreversible degradation in polymers.
