چكيده به لاتين
The phenomenon of membrane fouling is considered as the most important challenge
and the main obstacle in the development of membrane processes such as
microfiltration, ultrafiltration and so on. Improving the membrane hydrophilicity has
been accepted as an effective way to solve membrane fouling problem. In order to
increase the hydrophilicity of PVDF membranes, PVDF blend with PMMA is one of
the most efficient method because of its economic efficiency and long - term stability.
In recent years, in order to overcome membrane fouling problem, the use of modified
polymers with zwitterion due to high hydrophilicity and excellent resistance against
fouling has attracted the attention of researchers and industries. In this project, by using
all - atom simulation, a blend model of PVDF with PMMA random copolymer and
SBMA was made to investigate and evaluate the hydrophilicity and permeability
behavior. In order to evaluate the miscibility of PVDF blend model with random
copolymer PMMA and SBMA, the distribution of PMMA atoms in three directions x
,y,z was investigated. According to the obtained results, a same distribution of atoms
was obtained in three directions. Also, the glass transition temperature, which was
considered a challenge in experimental research similar to the current research, was
calculated and the value was -34/24 degrees celsius. The results of the pore size
distribution showed that in the blend model of PVDF with random copolymer PMMA
and SBMA, the pore diameter is to 8/625 angstroms and the largest pore was 3/62
angstroms in diameter. This shows that the distribution has occurred in a wider range
than the other two models. Also, free volume and free volume fraction of polymer
blend models were calculated. The obtained results showed that PVDF blend model
with PMMA random copolymer and SBMA has the highest free volume and free
volume fraction. The hydrophilicity of the blend was calculated using the contact angle
of water molecules. For the PVDF model, the value is 89 degrees, for the model
PVDF/PMMA, the value is 72 degrees, and for the model PVDF/PMMA-ran-SBMA
was 44 degrees, which shows a good agreement between the simulation results and the
reported experimental data. X- ray diffraction analysis showed that in the blend model
of PVDF with PMMA random copolymer and SBMA, amorphous regions has
increased compared to the other two models. Also, the distance between the two crystal
plates of PVDF blend model with random copolymer PMMA and SBMA wascalculated to be 6/01 angstroms, which is more than the other two models.
