STUDY OF THE KINETICS AND MECHANISM OF THE BROMINATION REACTION OF ULTRA-HIGH MOLECULAR WEIGHT POLYETHYLENE
Rubrics: 1. CHEMISTRY
Authors:
1.
North-Eastern Federal University (NEFU)
(Chemical department, Starshiy prepodavatel')
North-Eastern Federal University (NEFU) (Chemical department, Starshiy prepodavatel')
Yakutsk, Yakutsk, Russian Federation
North-Eastern Federal University (NEFU) (Chemical department, Starshiy prepodavatel')
Yakutsk, Yakutsk, Russian Federation
2.
North-Eastern Federal University (NEFU)
(Chemical department, veduschiy nauchnyy sotrudnik)
M. K. Ammosov North-Eastern Federal University (Chemical department, Veduschiy nauchnyy sotrudnik)
Yakutsk, Yakutsk, Russian Federation
M. K. Ammosov North-Eastern Federal University (Chemical department, Veduschiy nauchnyy sotrudnik)
Yakutsk, Yakutsk, Russian Federation
3.
North-Eastern Federal University (NEFU)
(Chemical department, Docent)
M. K. Ammosov North-Eastern Federal University (Chemical department, Docent)
Yakutsk, Yakutsk, Russian Federation
M. K. Ammosov North-Eastern Federal University (Chemical department, Docent)
Yakutsk, Yakutsk, Russian Federation
4.
North-Eastern Federal University (NEFU)
(Chemical department, Docent)
M. K. Ammosov North-Eastern Federal University (Himicheskoe otdelenie, Docent)
Yakutsk, Yakutsk, Russian Federation
M. K. Ammosov North-Eastern Federal University (Himicheskoe otdelenie, Docent)
Yakutsk, Yakutsk, Russian Federation
5.
Severo-Vostochnyy federal'nyy universitet im. M.K. Ammosova
(Institute of Natural Science, senior research)
from 01.01.2016 until now
Yakutsk, Yakutsk, Russian Federation
from 01.01.2016 until now
Yakutsk, Yakutsk, Russian Federation
6.
M. K. Ammosov North-Eastern Federal University
(Chemical department)
Yakutsk, Yakutsk, Russian Federation
Yakutsk, Yakutsk, Russian Federation
7.
M. K. Ammosov North-Eastern Federal University
(Prikladnaya mehanika i stroitel'noe materialovedenie)
M. K. Ammosov North-Eastern Federal University (Prikladnaya mehanika i stroitel'noe materialovedenie)
Yakutsk, Yakutsk, Russian Federation
M. K. Ammosov North-Eastern Federal University (Prikladnaya mehanika i stroitel'noe materialovedenie)
Yakutsk, Yakutsk, Russian Federation
8.
North-Eastern Federal University (NEFU)
(Chemical department, Professor)
North-Eastern Federal University (NEFU) (Chemical department, Professor)
Yakutsk, Yakutsk, Russian Federation
North-Eastern Federal University (NEFU) (Chemical department, Professor)
Yakutsk, Yakutsk, Russian Federation
Type:
Article
Pages:
from 12
to 17
Status:
In work
Language:
Russian
Keywords:
ULTRA-HIGH MOLECULAR WEIGHT POLYETHYLENE, BROMINATION, POLYMER MATERIAL, REACTION MECHANISM
Abstract (English):
The physicochemical regularities of the technology of bromination of ultra-high molecular weight polyethylene (UHMWPE) are investigated, the conditions and modes of the process are substantiated, and some kinetic aspects of the process are studied. Possible mechanisms of the reaction of bromination of UHMWPE are considered. Experimental data of the modification process are characterized by some common kinetic models. Kinetic constants of the equations describing the bromination process are calculated. It was found that the Elovich model most adequately describes the process under study. It was assumed that UHMWPE bromination is a three-stage process. At the first stage, molecular bromine migrates from the solvent medium to accessible adsorption centers, and the second stage is chemisorption. At the final stage, free-radical bromination occurs directly. It was found that the modification conditions make it possible to obtain brominated UHMWPE (B-UHMWPE) containing from 10 to 46 wt.% bromine. It is shown that during the process, partial destruction of the polymer chain occurs, as a result of which the initial molecular weight of the polymer decreases by ~ 2.54 times. The IR spectra of the modified UHMWPE, in addition to the absorption bands of vibrations of the methyl and methylene fragments, contain absorption bands of vibrations of the C-Br bond (absorption maxima 540; 614 cm-1). Scanning electron microscopy revealed that the supramolecular structure of B-UHMWPE differs from that of UHMWPE, and some compaction is observed. Structural elements merge with each other, and their size distribution is wider. Energy dispersive analysis confirmed the presence of bromine and its uniform distribution in the volume of UHMWPE. XPS showed that in the spectrum of the B-UHMWPE sample, in addition to the carbon line, peaks appear at 286.9 and 288.4 eV, related to the (C-Br) bond, and a doublet with the Br3d component binding energy of 70.5 eV is also observed in Br3d, which is typical of bromine atoms covalently bonded to carbon atoms (Br-C). The mechanical characteristics of B-UHMWPE and polymer composite material (PCM) based on UHMWPE and B-UHMWPE were studied. It was found that the strength characteristics of B-UHMWPE are naturally inferior to those of the original UHMWPE. However, the introduction of up to 9.5 wt. % B-UHMWPE into the polymer matrix of UHMWPE allows increasing the elastic modulus of PCM up to 1.4 times, but does not lead to a statistically significant change in the relative elongation and tensile strength. Thus, B-UHMWPE can be used as a promising modifier for improving the deformation and strength parameters of polymeric materials
The physicochemical regularities of the technology of bromination of ultra-high molecular weight polyethylene (UHMWPE) are investigated, the conditions and modes of the process are substantiated, and some kinetic aspects of the process are studied. Possible mechanisms of the reaction of bromination of UHMWPE are considered. Experimental data of the modification process are characterized by some common kinetic models. Kinetic constants of the equations describing the bromination process are calculated. It was found that the Elovich model most adequately describes the process under study. It was assumed that UHMWPE bromination is a three-stage process. At the first stage, molecular bromine migrates from the solvent medium to accessible adsorption centers, and the second stage is chemisorption. At the final stage, free-radical bromination occurs directly. It was found that the modification conditions make it possible to obtain brominated UHMWPE (B-UHMWPE) containing from 10 to 46 wt.% bromine. It is shown that during the process, partial destruction of the polymer chain occurs, as a result of which the initial molecular weight of the polymer decreases by ~ 2.54 times. The IR spectra of the modified UHMWPE, in addition to the absorption bands of vibrations of the methyl and methylene fragments, contain absorption bands of vibrations of the C-Br bond (absorption maxima 540; 614 cm-1). Scanning electron microscopy revealed that the supramolecular structure of B-UHMWPE differs from that of UHMWPE, and some compaction is observed. Structural elements merge with each other, and their size distribution is wider. Energy dispersive analysis confirmed the presence of bromine and its uniform distribution in the volume of UHMWPE. XPS showed that in the spectrum of the B-UHMWPE sample, in addition to the carbon line, peaks appear at 286.9 and 288.4 eV, related to the (C-Br) bond, and a doublet with the Br3d component binding energy of 70.5 eV is also observed in Br3d, which is typical of bromine atoms covalently bonded to carbon atoms (Br-C). The mechanical characteristics of B-UHMWPE and polymer composite material (PCM) based on UHMWPE and B-UHMWPE were studied. It was found that the strength characteristics of B-UHMWPE are naturally inferior to those of the original UHMWPE. However, the introduction of up to 9.5 wt. % B-UHMWPE into the polymer matrix of UHMWPE allows increasing the elastic modulus of PCM up to 1.4 times, but does not lead to a statistically significant change in the relative elongation and tensile strength. Thus, B-UHMWPE can be used as a promising modifier for improving the deformation and strength parameters of polymeric materials
Keywords:
ULTRA-HIGH MOLECULAR WEIGHT POLYETHYLENE, BROMINATION, POLYMER MATERIAL, REACTION MECHANISM
ULTRA-HIGH MOLECULAR WEIGHT POLYETHYLENE, BROMINATION, POLYMER MATERIAL, REACTION MECHANISM
