Emulsion Polyvinyl Chloride Research Articles

Modified emulsion polyvinyl chloride membranes for enhanced antifouling and dye separation properties by introducing tungsten disulfide (WS2) nanosheets

In this study, the fabrication and modification of emulsion polyvinyl chloride (EPVC) membranes were studied using tungsten disulfide (WS2) nanosheets. The layered WS2 nanosheets were synthesized, characterized, and applied in the modification of EPVC membranes. The nonsolvent induced phase inversion method was utilized to fabricate new membranes by introducing the WS2 nanosheets into the polymeric solutions with different percentages. The performance of the fabricated membranes was characterized and evaluated using scanning electron microscopy, atomic force microscopy, attenuated total reflection-Fourier transform infrared, mean pore radius, porosity, contact angle analyses, pure water flux, fouling parameters, rejection tests for bovine serum albumin (BSA) and two dyes, and long-term and reusability tests. The results indicated that the use of WS2 nanosheets in the membrane structure up to the optimum value (1 wt%) increased the water flux and improved the antifouling properties. The pure water flux enhanced from 56.4 L/m2.h in the bare membrane to 191.2 L/m2.h in the 1 wt% WS2/EPVC membrane. In addition, the flux recovery ratio parameter increased from 64.7% to 83.5%. dye rejection rates of 94.7% and 97.8% were obtained for Reactive Red 195 and Reactive Green 19, respectively. Reusability tests for the 1 wt% WS2/EPVC membrane indicated a slight flux drop and negligible BSA rejection changes. Long-term tests showed very high stability in dye rejection and a negligible flux drop.

Experimental investigation of operational E-PVC drying conditions on morphological properties of particles in a pilot-scale spray dryer

A Study of the process followed by an Emulsion Polyvinyl Chloride droplet in a spray dryer is necessary to understand the morphology of produced dry powder. For the Production of E-PVC, vinyl chloride monomer turns into liquid under pressure and high temperature. This liquid is extracted into the water in the form of emulsion with the help of an emulsifier, and polymerization is performed using water-soluble catalysts. Investigating the operational parameters of the latex drying process can provide helpful information for the design process. In the present study, a pilot plant of Arvand petrochemical spray dryer with a scale of 1:10 is constructed and studied. The purpose of this study is to experimentally analyze the drying of E-PVC in a pilot-scale spray dryer with a particular focus on determining the effects of drying conditions on the powder properties including morphology. For this purpose, the pilot-scale dryer is constructed, and the impact of various parameters such as inlet air temperature, atomization ratio, and latex concentration on outlet temperature and powder moisture content are investigated. A scanning electron microscope is employed to observe the particle morphology parameters mentioned above. The results showed that the outlet temperature decreased dramatically by increasing the atomization ratio and latex concentration. The results showed that more than 90% of the E-PVC particles are solid spheres. About 6% of donut-like particles, about 3% of particles with pore, less than 1% of broken hollow particles. The SEM image of latex used in experiments with a concentration of 40% and a Class D was taken to determine the shape of the latex particles. The picture showed that the particles were spherical before the drying, so the particles' final deformation is due to spray parameters changes during the drying process. From the morphological viewpoint, the number of agglomerates increased at higher inlet temperatures. More than 84% of particles maintained their spherical shape and have a diameter of 15-20 microns.

Modification of EPVC membranes by incorporating tungsten trioxide (WO3) nanosheets to improve antifouling and dye separation properties

In this research, the modification of emulsion polyvinyl chloride (EPVC) filtration membranes was evaluated by incorporating tungsten trioxide (WO3) nanosheets. The WO3 nanosheets at five different percentages were blended with the polymeric casting solution to prepare flat sheet membranes via the phase separation method. The prepared nanocomposite membranes were characterized by SEM, AFM, ATR, mean pore radius, porosity, and contact angle measurements. The investigated parameters were water flux, rejecting protein and three dyes, antifouling ability, long-term test and reuse ability. The obtained results showed that adding an optimal amount of WO3 (1 wt%) enhanced water flux and dye rejection. The nanocomposite membranes presented a lower contact angle due to the hydrophilicity of inserted WO3 nanosheets. The water permeability increased from 191 L/m2h.bar for the bare membrane to 238.8 L/m2h.bar for 1 wt% WO3 EPVC membrane with 96.6, 95.4 and 57.5% rejection rates for Reactive Green 19, Reactive Red 195 and Reactive Yellow 39 solutions with molecular weights of 1419, 1136.31 and 699.2 g/mole, respectively. The long-term test and reuse ability performance showed that the dye rejection did not change sensibly and good resistance was observed against the flux reduction. In conclusion, WO3 can be applied as a suitable nanosheet to modify PVC membranes.

Influence of solvent type on the ability and properties of the boehmite nanoparticles embedded emulsion polyvinyl chloride nanocomposite ultrafiltration membranes

The effects of two different solvents of dimethylacetamide (DMAc) and N-methyl-2-pyrrolidone (NMP) were investigated on the properties and performance of the neat and EPVC/nano-boehmite nanocomposite membranes. Boehmite nanoparticles were embedded into the membranes structure to improve their performance. Water contact angle, EDX, SEM, and AFM analyses were used to inspect the hydrophilicity, surface roughness, membrane morphology, and boehmite nanoparticles dispersion in the membranes structures, respectively. The optimum amounts of 1 wt% and 0.75 wt% of the boehmite nanoparticles were obtained for the EPVC-based nanocomposite membranes prepared in different solvents of DMAc and NMP, respectively. It indicated that the optimum amount of nano-boehmite that promoting the properties of the membranes was depended on the type of solvent. In comparison with the neat membranes, the modified ones fabricated in DMAc and NMP solvents, using optimum concentrations of boehmite nanoparticles showed growth of 61.7% and 66% in the fluxes of pure water, correspondingly and exhibited a significant improvement in the permeability. The value of BSA protein rejection for all of the EPVC-based membranes was higher than 98% which showed that the prepared membranes had excellent separation performance. The membranes fabricated in NMP solvent in the presence of the optimum amount of boehmite nanoparticles demonstrated the higher improvement in anti-fouling property and fouling resistance. Finally, it can be concluded that NMP solvent showed better performance in comparison with DMAc solvent for the improvement of the EPVC/nano-boehmite nanocomposite ultrafiltration membranes properties.

Designing and Fabricating Nano-Structured and Micro-Structured Radiation Shields for Protection against CBCT Exposure

Researchers have always been interested in finding new and effective materials for protection against radiation. This experimental study aimed to design and fabricate new types of nano-material and micro-material based shields against the ionizing effect of cone beam computed tomography (CBCT) X-rays. To fabricate a flexible prototype, we added dioctyl phthalate (DOP) oil to emulsion polyvinyl chloride (PVC) powder. The paste was mixed and dispersed. Then, nano- and micro-powders of WO3 and Bi2O3 were added to the paste, with the weight ratio of 20% PVC, 20% DOP, and 60% nano- and micro-metals. Using an ultrasonic mixer, the polymer matrix and metals were mixed and a paste with a thick texture was developed. The resultant paste was poured into glass molds and the molds were then heated in an oven. After cooling, the resultant sheets were selected for further experiments. A CBCT unit and dosimeter were used to evaluate the characterization and X-ray shielding properties of the fabricated prototypes. The half-value layers (HVL) for nano-WO3, micro-WO3, nano-Bi2O3, and micro-Bi2O3 were 0.0390, 0.0524, 0.0351, and 0.0374 cm, respectively. In addition, the linear attenuation coefficient (µ) for these materials were 17.77, 13.20, 19.71, and 18.5 cm−1, respectively. The findings indicate that nano-structured samples are more effective in the attenuation of X-ray energy. The nano-structured WO3 prototype was nearly 34% more efficient in attenuating radiation compared to the micro-structured WO3 prototype. This difference in nano- and micro-structured Bi2O3 prototypes was 6.5%.

Fabrication of a new emulsion polyvinyl chloride (EPVC) nanocomposite ultrafiltration membrane modified by para-hydroxybenzoate alumoxane (PHBA) additive to improve permeability and antifouling performance

New emulsion polyvinyl chloride (EPVC) microporous nanocomposite ultrafiltration membranes were fabricated by doping them using various amounts of para-hydroxybenzoate alumoxane (PHBA) via the phase inversion technique. High hydrophilicity of PHBA particles made it an outstanding selection for improving the membranes performance. The prepared membranes were characterized with scanning electron microscopy (SEM), energy dispersive X-ray (EDX), atomic force microscopy (AFM) techniques along with water contact angle, permeation, rejection and fouling tests. The modified EPVC membranes indicated an improvement in hydrophilicity and pure water flux because of the attendance of hydrophilic PHBA additive. All of the fabricated membranes demonstrated higher flux recovery ratio (FRR (%)) in comparison with the pristine EPVC membrane. The modified membrane with 0.5wt.% of PHBA showed the highest water flux growth (47.1%) and the best antifouling performance (FRR=65.3%). In addition, the rejection of the bovine serum albumin (BSA) was more than 98% for all of the prepared membranes. The performance of the neat and optimum membranes was evaluated for reusability and concentrating the whey protein and the obtained results showed that the modified nanocomposite membrane had higher fouling resistance and permeability.

USE OF MECHANICAL ACTIVATION OF POLYVINYL CHLORIDE IN THE PRODUCTION OF TENT MATERIALS

Physical and mechanical characteristics of tent materials depend on the quality of raw materials, which varies depending on its mechanical processing. A mathematical model of the process of dispersed materials activation is proposed, which describes the kinetics of change both during processing and dur-ing the further storage of the product of one or a number of factors characterizing physicochemical prop-erties of the material. The process of mechanical activation and verification of the adequacy of mathe-matical model proposed was carried out on emulsion polyvinyl chloride in a disintegrator unit. When processing PVC-E in a disintegrator, physicochemical processes take place, leading both to an increase and to a decrease in the viscosity of PVC-E solutions. The processes of dehydrochlorination breaking molecules, lead to a decrease in viscosity, and the formation of organic acids and copolymers - to in-crease. And these processes are irreversible. Conformational transformations of macromolecules con-tribute to the growth of viscosity of PVC-E solutions and are reversible. The adequacy of the proposed mathematical model describing the process of mechanical activation of dispersed materials is shown on the example of viscosity change of PVC-E solutions. Calculations show that increasing the loading speed, it is possible to maximize viscosity of PVC-E solutions in the minimum number of treatment cycles. If the number of processing cycles is more than one, then the rate of each subsequent loading should increase. The use of PVC-E, treated once in a disintegrator at a speed of 140 m / s, allows increasing physical and mechanical parameters of tent materials.

Preparation and characterization of a novel high-flux emulsion polyvinyl chloride (EPVC) ultrafiltration membrane incorporated with boehmite nanoparticles

A novel high-flux emulsion polyvinyl chloride (EPVC) ultrafiltration membrane incorporated with different concentrations of boehmite nanoparticles was prepared. The modified EPVC membranes demonstrated enhanced hydrophilicity property and higher pure water flux and lower water contact angle because of the presence of hydrophilic boehmite in membrane matrix. The results showed that water flux was enhanced from 422.6Lm−2h−1 for neat membrane to 7014Lm−2h−1 for 0.75wt.% boehmite incorporated membrane at 2bar. In addition, BSA flux growth of the optimum nanocomposite membrane in comparison with the neat one was 37.2%. BSA rejection for all nanocomposite membranes was above 98%.

Design of electrically conducting polymer hybrid composites based on polyvinyl chloride and polyethylene

Interest to electrically conducting polymer composite materials in recent times has grown considerably, which is associated with the design of new branches of science and technology. The existing analogues are different in the complexity of production and high cost. One of the ways of solving the problem may be designing polymer composite materials with a combined filler. The research was carried out on creating electrically conducting hybrid polymer composites, based on emulsion polyvinyl chloride and polyethylene, using fillers of varying nature and dimensions. We studied the dependence of electrical conductivity of mono­ and binary­filled polymer composites on the type and content of fillers. It was found that the binary filling allows designing electrically conducting polymer composites, which are more promising economically compared to mono­filled ones. We defined physical and mechanical characteristics: tensile strength and relative elongation at break of obtained polymer composites. A method to improve them was proposed by introduction of a compatibilizer – graft­polymer of polyethylene with maleic anhydride. Depending on the value of the electrical conductivity, polymer hybrid composites can be used for: at a value of of elecrical conductivity 10 –4 –10 –7 Cm/cm as anti­static materials; at 10 1 –10 –4 Cm/cm – as scattering anti­static materials, at 10 1 – 10 4 Cm/cm as current­conducting materials.

Fouling reduction of emulsion polyvinylchloride ultrafiltration membranes blended by PEG: the effect of additive concentration and coagulation bath temperature

In the present work, ultrafiltration membranes were prepared using emulsion polyvinyl chloride (EPVC) with the addition of various concentrations of polyethylene glycol (PEG) to investigate the morphological structure and separation properties. The effects of polymer concentration, coagulation bath temperature (CBT), and PEG (6 kDa) concentrations—a pore former hydrophilic additive—were studied. Through the phase inversion, the membranes—which were induced by immersion precipitation in a water coagulation bath—were fabricated through dissolving EPVC in N-methyl-pyrrolidinone, a polymer solvent. Morphological features of the membranes were characterized through scanning electron microscopy, pore size and porosity, and contact angle measurements. Water and bovine serum albumin (BSA) were used in order to study the separation and permeation performance of the fabricated membranes at 3 bar, which is operating pressure. The results which were obtained from contact angle test indicated an increment in the membranes hydrophilicity with an increase in PEG concentrations, and then it decreased again. Increasing the CBT led to macrovoid formation in the membrane structure and the appreciation of both membrane permeability and BSA rejection. The addition of PEG resulted in a more porous structure and a higher water flux for those membranes, which were prepared with 13 wt.% EPVC; while, for those which were fabricated with 15 wt.% polymer, an opposite trend was observed.

Investigation of the Effects of Titanate as Coupling Agent and Some Inorganic Nanoparticles as Fillers on Mechanical Properties and Morphology of Soft PVC

The effects of titanate as a coupling agent and some particulate nanoscale particles such as TiO2, CaCO3, and ZnO on thermal and mechanical properties of emulsion polyvinylchloride (E-PVC) were investigated by thermogravimetric analysis (TGA), and mechanical tests. In this research, it was found that, in the presence of nanoparticles of CaCO3, TiO2, and ZnO, the peak temperature of dehydrochlorination of E-PVC was shifted to higher temperatures, and the rate of mass loss was decreased. Also results of differential scanning calorimetry showed that the addition of nanoparticle of CaCO3, TiO2, and ZnO led to an increase in glass transition temperature. The impact strength, elastic modulus and toughness of the samples were enhanced after addition of 0–10 part of filer in hundred parts of resin (phr) nano-CaCO3, nano-TiO2, and nano-ZnO due to improvement of compatibility of the polymer and the nano-particles. Also UV and thermal stability of the samples were enhanced by means of the nanoparticles. It was found that, in the presence of titanate as coupling agent, content of additives that could be used in the composite of PVC shifts to higher amounts.

Pulmonary toxicity of polyvinyl chloride particles after a single intratracheal instillation in rats. Time course and comparison with silica

Our previous in vitro studies indicated that emulsion polyvinyl chloride (PVC) particles (PVC-E3), with a mean diameter of 2 μm, exhibited a moderate toxicity in different pulmonary cell cultures. The in vitro cytotoxicity and pro-inflammatory potential of PVC-E3 particles were reduced when the additives had been “washed off” (PVC-W3), indicating that PVC-particle associated toxicity is probably related to the residual additives. In the present study, male Wistar rats (230 ± 18 g) received a single intratracheal instillation of vehicle, crystalline silica particles [Min-U-Sil, 10 mg/kg body weight (BW)], PVC-E3 (10 or 50 mg/kg BW), or PVC-W3 (10 or 50 mg/kg BW). After 2, 7, 28, or 90 days, the rats were sacrificed ( n = 6) and pulmonary injury and inflammation were determined by measuring lung weight, lactate dehydrogenase (LDH) activity and protein concentrations in bronchoalveolar lavage fluid (BALF), differential BALF cell count, and histopathology. Silica exposure resulted in pulmonary inflammation and damage at all time points with a progressive deterioration. Exposure to high concentrations of PVC particles caused pulmonary inflammation and damage, which were similar to the silica-exposed group at 2 days, but at 90 days, most parameters had returned to the control level, except for minor histopathological lesions. PVC-E3 did not induce more damage than PVC-W3. Two days after exposure, PVC-W3 caused less neutrophil but more eosinophil influx than PVC-E3. Although the pulmonary toxicity of both PVC-E3 and PVC-W3 appeared limited, this in vivo study has not confirmed the conclusion from the in vitro toxicity tests that removal of residual additives reduces the toxicity of PVC-E3 particles.

Pulmonary toxicity of polyvinyl chloride particles after repeated intratracheal instillations in rats. Elevated CD4/CD8 lymphocyte ratio in bronchoalveolar lavage

Occupational exposure to polyvinyl chloride (PVC) particles has been associated with interstitial lung disease. Our previous study showed that a single intratracheal instillation of emulsion PVC particles, with or without residual additives, induces acute but transient alveolitis in a dose-dependent manner in rats. The aim of the present study was to investigate the pulmonary response after the administration of the same PVC particles (PVC-E3 and PVC-W3) given in the same cumulative doses (10 and 50 mg/kg BW), but fractionated as seven intratracheal instillations (7 × 1.4 and 7 × 7.1 mg/kg BW) in the course of 3 weeks (day 0 to day 21). Pulmonary response was characterized by analysis of lung weight, bronchoalveolar lavage (BAL) fluid for lactate dehydrogenase (LDH), total protein, and cell cytology, and a microscopic evaluation of lung tissue. BAL T lymphocyte phenotypes (CD3+CD4+, CD3+CD8+) were analyzed by flow cytometry. On day 28, lung weights, BAL-LDH, cell numbers in BAL, and CD4/CD8 ratios in BAL T lymphocytes were higher in rats that had received the high dose of PVC-E3 or PVC-W3 than in rats that had received the low dose of PVC particles and control rats. On day 90, the pulmonary response had partially regressed towards control values, but there were still microscopically evident lesions in the lungs and greater CD4/CD8 ratio in the high dose groups. There were significant positive correlations between the CD4/CD8 ratio and a histopathology score of the lung ( r = 0.36, P = 0.038 on day 28, and r = 0.46, P = 0.006 on day 90). In conclusion, repeated intratracheal instillations of PVC particles yielded similar results as single instillations. The examined PVC particles have the potential of inducing a limited and transient acute inflammatory reaction in the lung, and possibly a more persistent alteration of pulmonary T lymphocyte subsets towards a high CD4/CD8 ratio.

Role of residual additives in the cytotoxicity and cytokine release caused by polyvinyl chloride particles in pulmonary cell cultures.

Occupational exposure to polyvinyl chloride (PVC) dust has been linked to pulmonary disease. The aim of the present study was to investigate, in vitro, the role of additives in the cytotoxicity and the release of inflammatory mediators caused by PVC particles in different cells. We compared two types of emulsion PVC particles (E3 and E8) with their washed (hence, "additive-free") counterparts (W3 and W8). A positive control (crystalline SiO2, Min-U-Sil) and the pure additives, sodium lauryl sulfate (A3) and sodium alkylbenzenesulfonate (A8), were tested concurrently. Cytotoxicity (MTT assay) was assessed in primary cultures of rat alveolar macrophages, rat type II pneumocytes, and human alveolar macrophages (h-AM), and cultures of the A549 cell line (type II cell-derived) and the differentiated THP-1 cell line (macrophage-like). Hemolytic potential was assessed after a 2-h incubation with human erythrocytes. Cytokine release (IL-8, IL-6, and TNF-alpha) by A549 cells, THP-1 cells, and h-AM, was measured by ELISA after 4, 16, 24 and/or 48 h of exposure. Cytotoxicity and hemolytic activity of the washed particles were abolished or markedly decreased compared with their nonwashed forms. In A549 cells, E3 and E8 (2.5 mg/ml) caused a 3-fold increase in IL-8 release and a more than 10-fold increase in IL-6 release, whereas W3 and W8 did not elicit any significant response at similar concentrations. Compared with Min-U-Sil (0.1, 0.5, and 2.5 mg/ml), the response to E3 and E8 occurred later and was slightly lower (IL-8) or much more pronounced (IL-6). A3 and A8 exhibited similar responses to E3 and E8, at concentrations corresponding to those present in the particles. In conclusion, the in vitro cytotoxicity and inflammatory potential of some PVC particles appear to be mostly due to their residual additives.

Study of the classification of emulsion polyvinyl chloride in air-centrifuge equipment

The properties derived from Miplast emulsion polyvinyl chloride (E-PVC) separators for accumulators (strength, porosity, etc.) are known to be mainly governed by the granulometric composition of the powder available for processing [i]. The results of experimental studies [2] have been used to formulate the E-PVC dispersity requirements that guarantee the production of microporous sheets with a specified set of properties (in particular, the median particle size of the powder should be within the range 14-22 ~m and the content of particles with a size greater than 63 ~m should not exceed 1.5-2%).

Air-transfer separator for classifying emulsion polyvinyl chloride

Air-transfer separator for classifying emulsion polyvinyl chloride