نشریه پژوهش های کاربردی مهندسی شیمی - پلیمر
سال سوم شماره 4 (پیاپی 10، زمستان 1398)

Research subject: 

Due to the public's attention on the environmental issues as well as strict environmental regulations, the eco-friendly methods for nanoparticles have received considerable attention in the recent years.
Research approach: In the present study, a mixed oxide nanoparticles containing cerium and zirconium (Cex-Zr1-xO2) was fabricated the in supercritical water (SCW) medium. The synthesized nanoparticles were characterized by various analyses, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

The results of the analyses demonstrated that fine nanoparticles with mean size of 13±3 nm, with high crystallinity, and with appropriate size distribution and surface area were synthesized by SCW. Moreover, an oxygen storage capacity (OSC) as high as 1.25 mmol O2/g was estimated for Cex-Zr1-xO2 nanoparticles through temperature programmed reduction in hydrogen (H2-TPR). According to the obtained results, the Cex-Zr1-xO2 nanoparticles could be a suitable candidate for catalysts of oxidation processes as well as three-way catalyst for control of automotive exhaust gases.

Research subject:

 The use of scrap tires to recover energy and their compounds is an effective way to protect the environment and recover energy and materials.
Research approach: In this research, the aim is to investigate the process of tire pyrolysis as well as the simultaneous pyrolysis (co-pyrolysis) process of tire and fuel oil. Here, the effect of different operating conditions such as temperature, volumetric nitrogen gas, heating rate and tire parts size on the physical quantities and physical properties of the products manufactured by these processes have been investigated.

The optimal operating conditions for these experiments are 420C, the volumetric gas flow rate is 100 ml / min and the heating rate is  3 C / min. The volume of the reactor used is 500 ml and the amount of mazut in the coprolysis process is 30 wt%. The highest amount of liquid produced in the process of pyrolysis of used tire was achieved using feed with a particle size of 4×2×0.5cm3, which is 43.3% by weight. In contrast, the largest liquid product produced in the simultaneous pyrolysis process of the tire and mazut was obtained using tire parts with a size of 4×4×0.5cm3, which is 52.3% by weight. In this study, the physical properties of liquid products produced by two processes of pyrolysis of tire and co-pyrolysis of tire and mazut, such as kinematic viscosity, density and refractive index, have been investigated.

Regarding new researches on chemorheology of energetic composites,it is determined that HTPB slurry should have convenient viscosity for ease of casting. In the other word, available time for appropriate casting of energetic composite after curative addition called pot-life. Long pot-life of HTPB binder system is necessarily for good processability and non-defect production of energetic composite grains. In addition to long pot-life, the physical-mechanical properties of HTPB energetic composite are of at most important. In this research, effect of  curative type (structure), casting temperature and the amount of DBTDL as a curing catalyst on chemorheological behavior of HTPB binder system and physical-mechanical  properties of energetic composite were investigated. Toluene diisocyanate (TDI), Isophorone diisocyanate (IPDI) and Hexamethylene diisocyanate (HDI) were selected in order to investigate the role of molecular structure of curing agent on Chemorheology of binder system and its slurry and also on physical-mechanical  properties of energetic composite. Moreover, temperatures of 40, 50 and 60 ˚C, were selected to study the effect of casting temperature on chemorheology. By decreasing each 10˚C of casting temperature, pot-life of binder system (IPDI and TDI) was increased about 10 min. Pot-life of binder system and energetic composite slurry based on IPDI in the presence of 0.005% DBTDL (the optimum content) at similar temperatures, showed the longest pot-life. The elastomer and energetic composite based on IPDI showed the most crosslinking density (CLD) and modulus in comparison to other curing agents with retain of tensile strength and adequate elongation.

Research subject: 

In recent years, there are so many attractions in the field of effective detection and discrimination of volatile organic compounds (VOCs). Detection of VOCs compounds, are very important in many applications and industries such as air pollution control, air quality control, food packaging, food quality control, disease diagnostic, agriculture etc. The sensitivity and selectivity of the prepared sensors to detect of VOCs needs to improve.   

 Research approach:

 A conductive polymer composite sensitive layer based on poly (lactic acid) as polymer matrix and multiwall carbon nanotubes as conductive filler was prepared to detect of volatile organic compounds (VOCs). For this purpose the porous sensitive layer was prepared by non-solvent induced phase separation (NIPS) method. In this structure, chloroform (low boiling point temperature) was used as the solvent and ethanol (high boiling point temperature) was used as a non-solvent. The sensitive layer was used to detect of toluene, methanol, and chloroform. The structure and morphology of synthesized layer was investigated by means of scanning electron microscopy (SEM) and BET test.

The investigation indicated that the phase separation method induced the open cell morphology into the conductive composite. The BET results showed that the specific surface area of composite increased to 22.3 m2/gr. The experimental results showed that the response properties of porous layers was improved dramatically in comparison with dense layers. It was related to the increase of specific surface area of polymer composite and therefore the increase of diffusion coefficient of analyte molecules into the polymer matrix. Finally the sensitivity and selectivity of porous sensitive layers was investigated based on Flory-Huggins interaction parameter.

Research subject: 

Selectivity and permeability are the major parameters of polymeric membranes in gas separation process. Hence, nowadays in order to improve aforementioned parameters, modification and enhancement issues for such membrane have been highly noticed.

Research approach: 

In this study, in order to improve the performance of polymeric membranes, the two-component blend membranes containing Pebax®1657 and PVA were synthesized for CO2 separation. The effect of different PVA concentrations within the Pebax matrix on structure, morphology and gas separation properties of resultant membranes was investigated. The chemical bonds, crystallinity and cross-sectional morphology studied through, Fourier transform infrared (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), and were utilized.

The results of the thermal analysis indicated an increase in crystallinity and also glass transition temperature in presence of 5 – 15 wt.% PVA, while the membrane crystallinity decreased by increasing the PVA content up to 20 wt.%. FESEM images demonstrated a uniform cross-section without any cracks and defects for neat Pebax membrane but by adding PVA to Pebax matrix, appeared cracks and cave structures on the cross- section of blend membranes. The CO2/CH4 separation performance of membranes was measured using a constant volume set up at 30°C and feed pressure of 2, 6 and 10 bar. The obtained results revealed that the CO2 permeability in blend membranes improved as the PVA content increased within the membrane. The best obtained CO2 permeability was 204.64 Barrer which gained by Pebax/PVA (20wt.%) at feed pressure of 10 bar. Moreover, the highest selectivity of CO2/N2 for blend membrane with 15 wt.% of PVA was about 100.21 at 10 bar and 30°C.

Research subject: 

Parkinson’s disease is a neurodegnerative disorder with no treatment due to the blood brain barrier (BBB) existence. The cure for this disease is Dopamine a chemical molecule.

Research approach: 

This study investigates biodegradable naoparticles (NPs) carrying dopamine (DA) across the blood-brain barrier. Ion polymerization and solvent methods were used to achieve this goal. Particle size, zeta potential, entrapment efficiency and in vitro drug release behavior, at pH 7 were examined.

The empty nanoparticles and drug-loaded nanoparticles were found to be spherical in shape and fluffy exterior, with mono-modal size distribution and negative zeta-potentials of increasing average sizes 90 to 120 nm simultaneously. Fourier transform infrared (FTIR) spectra demonstrated the polymerization of nBCA monomers and encapsulation of DA inside poly (butylcyanoacrylate) (PBCA).Thermal characteristics of the copolymer were investigated by Fourier-transform infrared spectroscopy (FTIR). Drug loading efficiency was around 25%.The in-vitro drug release profile of DA -loaded PBCA nanoparticles prepared from ion polymerization following solution techniques exhibited a gradual release; more than 20 ٪w/w of the drug was released after 51 h. The results showed that the DA-PBCA nanocapsules could be an effective carrier for hydrophilic agents. In this study, PBCA-NSPs were successfully generated as a delivery system for DA, providing a promising approach to improve the therapy of PDs.