Papers by Keyword: Polyamide

Abstract: Today, the solid waste problem is expanding at an alarming rate, and considering the scale of production and consumption, the textile industry contributes significantly to this waste. An indispensable component of fast fashion, polyamide-containing pantyhose are included in the disposable product group and cause irreversible loss of a very valuable raw material. The waste of this product group constitutes a hidden waste group that does not decompose in nature and has not yet been recycled. This study focuses on recycling polyamide-containing pantyhose waste and evaluating them in thermal insulation panel production. In this context, the process of opening the fibers of the pantyhose is carried out in a carding machine, and a hot press technique is utilized with the addition of low melting temperature polypropylene fibers as a binder, for panel production. Rice husk, which is a commonly known agricultural waste, is also introduced into the panels in different forms (granule and powder) for better air encapsulation. The effect of ply number (two and four) and the form of rice husk added as an additive on thermal and air permeability properties is examined within the framework of a full factorial experimental design plan. The findings obtained reveal that the variables affect both thermal insulation and air permeability properties both individually and in binary interactions. The lowest thermal insulation coefficient is obtained in the two plied, granule form rice husk added sample group (0.02117 W/mK), which also has the highest air permeability values (442.57 l/m²/s) and the results are found to be competitive with commercial products. This suggests that it is possible to use this waste group in sustainable panels for construction, and the findings reveal that it may create value in terms of both solid waste management and exploring new resources for polyamide-based fibrous products.

Abstract: This study examines the feasibility of utilizing the press forming method on multi-layer, multi-orientation continuous CFRP preform produced by the additive manufacturing (AM) technique. The 5-layer preforms with fiber orientations of 45° and -45° impregnated in Nylon-6 resin layers were made by a 3D printer, and press-formed in varying temperatures and pressures. Optimal forming outcomes were determined by qualitative evaluations of the surface finish, fiber impregnation, resin flow, and quantitative observations on shape variations by comparison with the mold dimensions. Experimental results showed that the molding temperature of 220°C and pressure between 0.5MPa - 1MPa could produce preforms with optimal surface conditions. There was almost no void of bubble defects, no excess resin flow, and a smooth transition was established between the carbon fiber and the matrix resin layers while allowing the full mechanical strength properties to be realized. The formed preform evaluations confirmed that the press molding method is feasible on multi-layer, multi-orientation continuous CFRP with optimal surface conditions.

Abstract: In response to the escalating global water crisis, this study introduces the development of polyamide-modified membranes (PA-PES, PA-PP, and PA-PTFE) through interfacial polymerization to enhance the efficiency of a passive solar desalination system. FTIR analysis and morphological characterization showed that a thin polyamide film formed above the modified membranes using m-phenylene diamine (MPD) and trimesoyl chloride (TMC). Notable improvements were observed in its productivity and distillate salinity by integrating these modified membranes into the membrane distiller of the system. Mainly, the PA-PES membrane achieved productivity of 764.56 ml/m²-h and reduced salinity to as low as 2 g NaCl/L. Despite challenges in salinity reduction, possibly due to residual chlorides, this study demonstrates the potential of polyamide-modified membranes in advancing solar-driven desalination, offering a promising solution to mitigate global water scarcity. This research paves the way for further advancements in sustainable desalination technology, emphasizing the need for continued optimization and exploration of membrane-based systems.

Abstract: In this article, a regulatory processes study and technological properties of polyamide waste agglomerate modification is carried out. The legal support issues for polymer waste management in Ukraine are considered, ways to improve the most problematic aspects in this area are proposed. The technological properties of polyamide-6 waste agglomerate modification processes were studied in order to improve its technological and strength characteristics. MW-PA CB10 masterbatch modifier impact on the polyamide-6 waste agglomerate technological and strength characteristics complex was studied. It was established that the best is polyamide-6 waste agglomerate with 2 % wt. of masterbatch MW-PA CB10. For this composition the impact strength is 43.5 MPa, breaking stress during bending is 126.4 MPa, tensile strength is 342 N and elongation at break is 117 %. It can be recommended for reuse in traditional fields of primary polyamide-6 to obtain engineering and technical products.

Abstract: A vast amount of agricultural waste, such as dried leaves, stems, pits, seeds, etc., are produced by date palm trees in Saudi Arabia each year. This waste is an excellent source of degradable biomass suitable for many uses. Crystalline nanocellulose (CNC) is one of the most important nanomaterials that can be used in various applications. Due to its unique properties, which include biorenewability, optical transparency, high mechanical strengths, and sustainability, nanocrystalline cellulose has become a significant nanomaterial in recent years. In this study, CNC was isolated from the waste date palm leaves and used for the production of PA-modified membranes for water treatment by reverse osmosis membrane technology. The membranes were prepared by surface polymerization with the polyamide as a selective layer on the polysulfone support film. Three membranes were produced, two with 0.01% and 0.02% (w/v) CNC and the third with PA-free CNC for comparison. Each membrane produced was tested using different characterization techniques. The polyamide membrane with 0.01% w/v CNC had a higher water permeability of 43.25 L/m² h bar than the membranes with 0% w/v CNC (36.25 L/m² h) and 0.02% w/v CNC (42.85 L/m² h bar). Under the same conditions, salt retention was also found to be above 98% for both NaCl and MgSO4 for the two modified membranes. The contact angle was found to be 68.04±3.7, 72.83±0.8, and 63.76±5.5 for PA(0%CNC), PA-CNC (0.01% w/v), and PA-CNC (0.02% w/v), respectively. The 0.01% PA-CNC membrane exhibited a higher water contact angle, greater hydrophobicity and lower surface roughness. As a result, the isolated CNC might be appropriate for use as a modifier agent for membrane fabrication and water treatment.

Abstract: Socks, being a necessary item of clothing, must be comfortable and maintain their quality throughout their life. Therefore, it is very important to select the yarns for their production. Usually, casual socks are made from a high percentage of cotton to ensure softness and comfort, and blended with polyamide to improve fit, durability and shrink resistance. The objective of this study is to compare five groups of black colored cotton calf-length men's socks produced under the same conditions in full plating with different textured polyamide 6.6 multifilament yarns, designated as: 22 dtex f7 × 2, 33 dtex f10 × 2, 44 dtex f13 × 2, 78 dtex f23 × 2, 110 dtex f34 × 2. The influence of the linear density of the polyamide plating yarn on the usage properties of the socks was evaluated by testing abrasion resistance and propensity to surface pilling with the Martindale abrasion and pilling tester, dimensional stability and color fastness to washing, perspiration and rubbing, as well as on comfort-related properties by testing moisture absorption, air permeability and thermal resistance with the Thermal foot manikin system. In addition, the basic physical properties of the socks, consisting of density parameters, mass and thickness were measured, all according to the standardized test methods. The results show that increasing the linear density of polyamide 6.6 yarns (i.e., increasing the amount of polyamide in the socks) has the following effects: increase in mass, thickness and structural change of sock plain knits, increase in abrasion resistance and change in dimensional stability of socks, decrease in moisture absorption, air permeability and thermal comfort of socks. From the obtained results, it can be concluded that when selecting the plating yarn for the production of cotton socks, it is necessary to take into account their linear density and structure, as well as the intended purpose of the socks, their specified comfort and the expected usage quality.

Abstract: Achieving a strong bond between carbon fiber (CF) and recyclable thermoplastic polymer (TP) has always been highly sought after. So far, applying electron beam (EB) irradiation with optimal dose and cathode potential (V_c) has shown success in increasing mechanical properties of interlayered CFRTPs. However, with concern for durability and safety, higher strength is desired. Therefore, EB setting applying electron beam (EB) irradiation with cathode potential (V_c) to 170, 210, 225 or 250 kV was applied to CFRTPA (carbon fiber reinforced thermoplastic polyamide) articles just before shipping. Specimens were 9 CF plies alternating between 10 PA (polyamide) sheets, designated [TPA]₁₀[CF]₉. When optimal EB dose of 43.2 kGy is applied to both finished specimen surfaces after fabrication, experimental results show higher V_c setting of 250 kV can increase impact strength of the [TPA]₁₀[CF]₉ over that at 170 kV. In summary, the 250 kV-EB (250 kV) strengthens [TPA]₁₀[CF]₉ significantly, about 25 to 27% larger than that of 170 kV and zero (untreated). Based on Christenhusz and Reimer equation to calculate penetration depth, D_th of EBI into polymers, increasing V_c to 250 kV increased D_th to more than 2 times that at 170 kV.

Abstract: Synthetic polymers have become essential in our life, nevertheless, the high production and the low recycling around the world have caused serious problems of contamination in soil and water. In addition, its fragmentation into microplastics in environmental conditions has exacerbated the ecological problems due to its possible ingestion by organisms and its high capacity to transport and release a wide variety of organic pollutants. Photo-Fenton process was used to evaluated its capacity to degrade PA6.6 microplastic under simulated solar irradiation and natural solar irradiation plus LED visible light in order to get a best knowledge about its behavior in environmental conditions. PA6.6 was degraded for 7 h through photo-Fenton process under simulated solar irradiation. Superficial defects were observed along the PA6.6 microplastic after degradation experiments. However, FT-IR analysis did not show the formation of additional bands which indicated the formation of new products. DSC analysis showed changes in the melting point of the PA6.6 after the photo-Fenton treatment at different times. The assays carried out under natural solar irradiation showed lower degradation of the PA6.6 under the same experimental conditions, nevertheless, it was observed an increase of the specific surface area 90 times higher in the PA6.6 treated for 10 h.

Abstract: The urgency of improving the performance properties of concrete, as the most common building materials, is noted. The reasons for the increased demand for products made of high-strength gas-filled concrete are stated. It is shown that the current volume of polymer fibers production makes it possible to predict the possibility of their widespread use in construction. The information on the physical and mechanical properties of synthetic fiber, which is important for its successful use as dispersed reinforcement of foam concrete mixtures, is presented. The technology of manufacturing experimental samples and methods of their testing are described. It has been established that the introduction of any synthetic fiber into the foam mixture formulation improves the structural properties of foam concrete, however, the measure of efficiency depends on the ratio between the concrete moduli of elasticity and fiber. The greater the value of the elastic modulus of the fiber used, the higher the technical effect of its use in fiber-reinforced concrete for structural purposes can be.

Abstract: The aim of this research is to investigate the removal behavior of iron and manganese that naturally exist as divalent ions in groundwater by using nanofiltration membranes. The main focus of this study is to better understand the effect of applied pressures during the rejection of these metallic ions from synthetic groundwater in order to achieve drinking water standard. Polyamide and polypiperazine amide nanofiltration membranes denoted as PA-NF and PPA-NF were selected to investigate the iron and manganese rejection at low applied pressures (1-5 bar). In single solute solution with feed concentration at 10 mg/L and initial pH of 6.8 ± 0.5, the rejection of iron was ≥96% by PA-NF membrane at applied pressure of 2 bar. However, the rejection percentage by PPA-NF was 86.6% whereby this membrane unable to remove iron to the allowable drinking water standard. The rejection of manganese with single solute at concentration of 1 mg/L with initial pH of 6.8 ± 0.5 by using the PA-NF membrane was ≥98% and almost all of dissolved manganese were rejected at 5 bar. However, manganese removal by PPA-NF membrane was found less than 70% for all of the applied pressures. Findings from this work showed that the removal of iron and manganese were dependent on the applied pressures. PA-NF membrane able to remove both metallic ions that comply with the drinking water standard. The increased of applied pressure contributed to concentration polarization effect on the membrane surfaces leading to a decrease in solute rejection by decreasing the charge effect mainly for the iron removal from synthetic groundwater.