The Optimization of Dispersion and Application Techniques for Nanocarbon-Doped Mixed Matrix Gas Separation Membranes

In this work, supported cellulose acetate (CA) mixed matrix membranes (MMMs) were prepared and studied concerning their gas separation behaviors. The dispersion of carbon nanotube fillers were studied as a factor of polymer and filler concentrations using the mixing methods of the rotor–stator system (RS) and the three-roll-mill system (TRM). Compared to the dispersion quality achieved by RS, samples prepared using the TRM seem to have slightly bigger, but fewer and more homogenously distributed, agglomerates. The green γ-butyrolactone (GBL) was chosen as a polyimide (PI) polymer-solvent, whereas diacetone alcohol (DAA) was used for preparing the CA solutions. The coating of the thin CA separation layer was applied using a spin coater. For coating on the PP carriers, a short parameter study was conducted regarding the plasma treatment to affect the wettability, the coating speed, and the volume of dispersion that was applied to the carrier. As predicted by the parameter study, the amount of dispersion that remained on the carriers decreased with an increasing rotational speed during the spin coating process. The dry separation layer thickness was varied between about 1.4 and 4.7 μm. Electrically conductive additives in a non-conductive matrix showed a steeply increasing electrical conductivity after passing the so-called percolation threshold. This was used to evaluate the agglomeration behavior in suspension and in the applied layer. Gas permeation tests were performed using a constant volume apparatus at feed pressures of 5, 10, and 15 bar. The highest calculated CO2/N2 selectivity (ideal), 21, was achieved for the CA membrane and corresponded to a CO2 permeability of 49.6 Barrer.

Lab-Scale Twin-Screw Micro-Compounders as a New Rubber-Mixing Tool: ‘A Comparison on EPDM/Carbon Black and EPDM/Silica Composites’

The research and development (R&D) in rubber formulation development require reproducible, repeatable, fast, accurate, and efficient sample preparation. The lab-scale formulation development is conventionally carried out using small-scale internal mixers and two-roll mills. However, high torque laboratory twin-screw micro-compounder, which have been serving the plastic industry for more than 30 years, can be used to formulate new rubber compounds for fast and accurate sample preparation that on top can contribute to the economics of R&D. In this study, we investigated the possibility of using lab-scale 15 mL high torque twin-screw micro-compounder as a tool for new rubber compound development. For this purpose, we formulated EPDM/carbon black and EPDM/silica recipes through conventional way using a Banbury mixer followed by a two-roll mill, and through the possible way using a lab-scale 15 mL twin-screw micro-compounder. We crosslinked both systems via hot press at a predefined temperature and time. The rheological and mechanical properties of the compounds were investigated. Moreover, the dispersion of carbon black and silica in the EPDM matrix was judged by DisperGrader and scanning electron microscope (SEM). The conventional way of sample preparation was compared with a possible sample preparation method based on materials’ parameters and ease of operation.

Effect of Short Banana Fiber on Hardness and Tensile Properties of Natural Rubber Composites

Banana fiber (BF) was utilized as a reinforcing filler for natural rubber (NR). BF/NR composites containing banana fiber contents of 5, 10, and 15 parts per hundred parts of rubber (phr) were mixed on a two-roll mill machine. The hardness, tensile properties of BF/NR composites were studied. It was found that the hardness and moduli of BF/NR composites are higher than that of NR. Despite tensile strength and strain at break of BF/NR composite lower than NR. Moreover, hardness and moduli of BF/NR composites increased, while tensile strength and strain at break decreased with the increase in banana fiber content. Thus, banana fiber exhibited improvement in the stiffness significantly of NR composites

ANALYSIS OF THE WAYS OF GRINDING OF BEAN CULTURES SEEDS

Рассмотрены способы измельчения семян люпина и эспарцета на существующем в кондитерском производстве оборудовании – дезинтеграторе, валковой дробилке и трехвалковой мельнице с целью повышения эффективности дробления семян бобовых культур и, как следствие, их биологической ценности после дезинтегральной обработки. Установлено, что с увеличением зазора между валками возрастает среднее значение размеров дробленых частиц, т. е. доля крупных фракций увеличивается, мелких – снижается, при этом дисперсия существенно не меняется. При использовании валковой дробилки, варьируя величину зазора между валками и частоту вращения, можно оптимизировать режим дробления. Доказано, что применение для дробления семян вертикальной трехвалковой мельницы с засыпанными в нее вместе с семенами бобовых культур металлическими твердосплавными шарами за счет комбинаций ударных и истирающих воздействий на частицы семян интенсифицирует процесс, снижает время помола и способствует получению равномерного гранулометрического состава, обеспечивая высокий эффект измельчения сырья с сохранением его качественных показателей. The ways of grinding of seeds lupine and cock's head on the existing in the confectionery industry equipment, disintegrator, roller crusher and three-roll mill with the purpose of increase of efficiency of the grinding bean cultures seeds and, consequently, their biological value after disintegrating treatment were considered. It is established that with increase in gap between the rolls, the average value of the sizes of crushed particles increase, i.e. the share of large fractions increases, small – decreases, this variance does not change significantly. When using roll crusher, by varying the size of the gap between the rolls and the rotational speed can optimize the crushing mode. It is proved that use for crushing seeds vertical three-roll mill with filled in it along with the seeds of legumes metal carbide balls due to the combinations of impact and abrasive effects on the particles of seed intensifies process reduces grind time and helps to ensure a uniform particle size distribution, providing a high effect grinding of raw materials while maintaining its quality.

On the Multi-Functional Behavior of Graphene-Based Nano-Reinforced Polymers

The objective of the present study is the assessment of the impact performance and the concluded thermal conductivity of epoxy resin reinforced by layered Graphene Nano-Platelets (GNPs). The two types of used GNPs have different average thicknesses, <4 nm for Type 1 and 9–12 nm for Type 2. Graphene-based polymers containing different GNP loading contents (0.5, 1, 5, 10, 15 wt.%) were developed by using the three-roll mill technique. Thermo-mechanical (Tg), impact tests and thermal conductivity measurements were performed to evaluate the effect of GNPs content and type on the final properties of nano-reinforced polymers. According to the results, thinner GNPs were proven to be more promising in all studied properties when compared to thicker GNPs of the same weight content. More specifically, the glass transition temperature of nano-reinforced polymers remained almost unaffected by the GNPs inclusion. Regarding the impact tests, it was found that the impact resistance of the doped materials increased up to 50% when 0.5 wt.% Type 1 GNPs were incorporated within the polymer. Finally, the thermal conductivity of doped polymers with 15 wt.% GNPs showed a 130% enhancement over the reference material.

Development of Graphite- and Graphene Reinforced Styrene-Butadiene Rubber

The environmental impact of rubber waste can be reduced by extending the lifetime of rubber products. It can be achieved by developing graphene/rubber nanocomposites with good abrasion resistance. In this paper, we investigated how rubber mixing technologies influence the mechanical properties of rubber. We added various amounts (0, 1, 5 and 10 phr) of graphite and graphene to rubber mixtures using a two-roll mill, an internal mixer, a single- and a twin-screw extruder. We performed tensile, tear strength and Shore A hardness tests on the vulcanisates and analysed their fracture surfaces with a scanning electron microscope. Our results show that graphene had a better reinforcing effect than graphite. Rubber mixing via extrusion may contribute to more severe polymer degradation, though their reproducibility is better than that achieved on a two-roll mill or in an internal mixer.

Effects of nanocrystalline calcium oxide particles on mechanical, thermal, and electrical properties of EPDM rubber

In this research, the effect of calcium oxide (CaO) nanocrystalline particles filled ethylene propylene diene monomer (EPDM) rubber composites is investigated, at different weight percentages (1.0, 2.0, 4.0, and 8 wt%) of CaO nanocrystalline particles using two methods of mixing. In one case conventional mixing on twin roll-mill was used, in the other case ultrasonic mixing as a pre-mixing was applied. CaO particles are synthesized by the precipitation method. The average crystallite size of CaO is 100 ± 20 nm. Adding CaO nanocrystalline particles increases the thermal stability of EPDM and the glass transition temperature. The hardness of EPDM rubber gradually increases with increasing the amount of CaO particles, the maximum hardness 64.2 observed in 8 wt% of CaO particles for both cases almost 26% higher than neat EPDM. Tensile strength decreases, while the maximum % modulus of the ultrasonic mixed sample was 1.48 MPa which is 24% higher than EPDM.