Polyamide Materials Research Articles

Laboratory Investigation of the Strength Degradation against Ultraviolet Radiation of Geonets for Slope Protection.

Sufficient light and high UV intensity pose significant challenges to the long-term performance of polymeric geonet materials for slope-protection structures. This study investigates strength degradation under the effect of UV radiation; five different types of geonets were selected, which can be categorized as polyamide (PA), polypropylene (PP), and polyethylene (PE) materials. A comprehensive experimental investigation was performed, including tension strength, peer strength, artificially accelerated aging, and SEM tests, to further establish a service life prediction method used for slope-protection design. The results showed that the tension strength, percentage of breaking elongation, and peer strength all depict a descending trend with aging-elapsed time, especially in the early 600 h. The decreasing tendency of these mechanical properties' magnitude differed in the diversity of direction and material type. Significant changes have been generated on the geonet surface after aging; materials with smooth surfaces exhibit a strong ability against strength degradation. Fitting results affirmed the predictive technique as a useful engineering tool for tension strength assessments, offering guidelines for using and designing of geonets for slope-protection structures.

Thermomechanical and Structural Analysis of Manufactured Composite Based on Polyamide and Aluminum Recycled Material.

The paper presents an analysis of the filler's effect on the machining process and on changes in the thermomechanical properties of polymer composites based on aluminum chips. Composite research samples with a polymer matrix in the form of polyamide 6 were made by the pressing method. Comparative studies were carried out on the changes in thermomechanical properties and structure of the obtained molders with different filler contents and different fractions after the machining process. In order to determine the changes in thermal and mechanical properties, analysis was carried out using the differential scanning calorimetry (DSC) method, thermal analysis of dynamic mechanical properties (DMTA) and a detailed stereometric analysis of the surface. After mechanical processing, roughness amplitude parameters and volumetric functional parameters were determined. In order to analyze the structure, tomographic examinations of the manufactured composite were conducted. In relation to the polymer matrix, a significant increase in the storage modulus of the composites was noted in the entire temperature range of the study. An increase in the enthalpy of melting of the matrix was noted in composites with a lower filler content and a shift in the melting range of the crystalline phase. Significant differences were noted in the study of the composite surfaces in the case of using fillers obtained after machining with different fractions. The dependencies of the functional and amplitude parameters of the surfaces after machining of composite samples prove the change in the functional properties of the surface. The use of aluminum chips in the composite significantly changed the surface geometry.

Pyrolysis kinetics and flame retardant enhancement of bio-based polyamide 56/6

The development of polyamide materials with fire safety is of great importance at this stage. A novel nitrogen-phosphorus bisystem flame retardant (MC) with a multi-branched structure was synthesized and applied to a new bio-based polyamide 56/6 (PA56/6). Notably, at 8 wt% MC content, flame-retardant PA56/6@MC8% (FRPA56/6@MC8%) achieved an Limiting Oxygen Index (LOI) of 26.6% and a V-0 rating in UL-94 tests. Cone calorimetry results indicated that FRPA56/6@MC8% exhibited a 22.9% reduction in total heat release (THR) and a 41.0% decrease in peak heat release rate (PHRR), underscoring the flame retardancy promotion by MC in PA56/6. The study further explored the pyrolysis kinetics and mechanisms of polyamide materials, offering insights crucial for flame-retardant modifications. Overall, the findings present an innovative strategy for enhancing the flame retardant properties of PA56/6, potentially applicable in automotive components and other pertinent fields.

Recent Advances in the Biosynthesis of Mid- and Long-Chain Dicarboxylic Acids Using Terminally Oxidizing Unconventional Yeasts.

As high-performance monomers for the manufacture of polyamide materials, mid- and long-chain dicarboxylic acids (DCAi, i ≥ 6) have received extensive attention from researchers. Biosynthesis is gradually replacing chemical synthesis due to its outstanding advantages in the industrial production of mid- and long-chain dicarboxylic acids, which is mostly achieved by using the strong terminal oxidation ability of nonmodel microorganisms such as Candida tropicalis to oxidize hydrophobic substrates such as alkanes. Here, we first summarize the metabolic pathways of oxidative alkane conversion into dicarboxylic acid by terminally oxidizing unconventional yeasts and the corresponding metabolic engineering strategies. Then, we summarize the research progress on new dicarboxylic acid production processes. Finally, the future development directions in the biosynthesis of mid- and long-chain dicarboxylic acids are prospected from synthetic biology and bioprocess engineering, which can also provide a reference for the synthesis of other biobased chemicals and biomaterials.

Effects of hydrogen cycling on the performance of 70 MPa high-pressure hydrogen storage tank liners formed by different processes

Current research on the compatibility between plastic liners utilized in Type IV high-pressure hydrogen storage containers and hydrogen remains insufficiently comprehensive. Therefore, further exploration into how the high-pressure hydrogen storage process influences the crystalline phase transition of polymers is essential to improve the applicability and safety of plastic lining materials. This study primarily investigated the preparation of polyamide 1012 (PA1012) and polyamide 11 (PA11) through rotational molding and injection molding, denoted as Roto-PA1012/Roto-PA11 and In-PA1012/In-PA11, respectively. Considering the operational parameters of the 70 MPa Type IV hydrogen storage tank, we conducted hydrogen cycling experiment using the long carbon chain polyamide (LCPA) liner materials and comprehensively analyzed the morphology, crystal structure, grain size, mechanical properties and hydrogen barrier properties of polyamide materials before and after hydrogen cycling. The results showed that after hydrogen cycling, no significant changes were observed in Roto-PA1012/Roto-PA11, while In-PA1012/In-PA11 demonstrated severe foaming. Rotational molding of LCPA maintained stable mechanical and hydrogen barrier properties throughout the hydrogen cycle, which can be attributed to the favorable thermodynamic stability of the α' form achieved during rotational molding, leading to uniform and stable crystal sizes. In conclusion, this study provides a theoretical foundation for future investigations into the molding process and material selection of high-barrier polymer liners, as well as the actual production and utilization of Type IV hydrogen storage tanks.

Investigation of Dual Network Construction for Toughening in Bio-Based Polyamide Composites.

This study investigated the role of constructing a dual network in toughening bio-based long-chain polyamide 610 (PA610) composites. Rheological studies were conducted to reveal the effects of toughening agent type and content on the material properties. According to the variation trend of mechanical properties and the appearance of a rheological low-frequency plateau of the materials, the percolation network concentration ϕc of the toughening agent in the PA610 matrix was determined to be 13.5 vol.%. The interfacial interaction of the composite was evaluated through the percolation theory, and the scaling value v = 1.36 for both indicated the good affinity between PA610 and the toughening agent. Rheology results found that the combination of ethylene terpolymer (PTW) and maleic anhydride-g-styrene-b-(ethylene-butylene)-b-styrene (MAH-SEBS) could achieve an optimal balance between the mechanical properties and fluidity of the composites. Furthermore, the addition of ultra-high-molecular-weight polytetrafluoroethylene (PTFE), in conjunction with the toughening agent, facilitated the construction of a dual semi-interpenetrating network. The strengthened intermolecular interactions restricted the relative slippage and mobility of the polymer chains and therefore enhanced the strength and toughness of the material. This study provides new possibilities and approaches for optimizing the comprehensive properties of bio-based polyamide materials.

Influence of Layer Thickness of 3D Printed Polyamide Against Temperature

Polyamide is one of the materials in 3D printing that can produce valuable products to meet the needs of the industry. Previous studies have proven that the layer thickness of the 3D printed material and the increase in temperature affect the mechanical and physical properties. However, only a few studies involve polyamide material as a test material, especially in analyzing the influence of the layer thickness of the printed material and the increase in temperature on the mechanical and physical properties of polyamide. Therefore, the bending properties of polyamide with different layer thicknesses at 0.1 mm, 0.2 mm and 0.3 mm and the tensile properties of the material at different temperatures at room temperature, 75˚C and 110˚C will be studied. This study will involve polyamide (PA) materials printed at three different layer heights using the Fused Deposition Modelling (FDM) process. Bending and tensile tests at different temperatures from 27˚C to 110˚C are conducted using the Instron Universal Testing Machine. The study results show that the layer height of 0.3 mm exhibits the highest flexural strength at an average rate of 11.05 MPa compared to 0.1 mm (6.7 MPa) and 0.2 mm (9.6 MPa). The tensile strength decreases when the temperature elevates, making the temperature of 110˚C have the lowest tensile value (1.591 MPa) compared to the temperature of 75˚C (1.6MPa) and 27˚C (2.1MPa). Several material characterizations such as SEM, TGA, DMA, DSC and density have been performed to study the microstructure and influence of tensile test temperature on the mechanical properties of polyamide.

Decreasing the electrostatic discharge generated from friction of polyester and polyamide sing carbon fiber

AbstractThe present work discusses the voltage difference as a measure for electrostatic charge generated from the contact‐separation and sliding of polymeric textiles on polyamide textile. It is proposed to blend polyester by carbon fiber to decrease the electrostatic charge generated on the contact surfaces. Because polyester acquires a negative charge and polyamide gains a positive one, carbon fiber is proposed to conduct the negative electrostatic charge from polyester to polyamide and conducts the positive one from polyamide to polyester, so that the resultant electrostatic charge decreased. The effect of carbon fiber to decrease the electrostatic charge depends on its area of contact, interaction, and distribution with polyester. Polyester double weaved by carbon fiber showed the lowest voltage. Based on those observations, it can be recommended to use double weaves of carbon fiber with polyester. The reduction in voltage was relatively lower for braided polyester by carbon fiber than that detected for double‐weaved polyester by carbon fiber.

MERANCANG JARING INSANG PERMUKAAN UNTUK MENANGKAP IKAN DI TELUK AMBON DALAM

The use of gill nets in fishing is a well-established practice among fishermen due to several factors including ease of material acquisition, simple operational techniques, relatively affordable costs, and high selectivity in catching fish of specific sizes. This study aims to describe the design of fishing gill nets in Inner Ambon Bay. The research was conducted at the Ambon Fisheries Training and Extension Center (BP) in April and May of 2024. The design and construction of surface gillnets for mackerel scad consist of mesh size (inches), fish body circumference, net length, hanging ratio, weights, and distance between floats and weights. The design of the surface gill net with a 2-inch mesh size and a 45% hanging ratio has proven to be effective in catching mackerel scad (Decapterus sp) ranging from 17 cm to 26 cm in length. The use of polyamide (PA) material for the net body provides the necessary strength and flexibility, while the float made of polyvinyl chloride (PVC) and lead weights ensures balanced distribution for optimal functioning in the water. A 45% hanging ratio provides an ideal balance between net length and fish trapping ability, avoiding nets that are too curved or stiff, which can reduce fishing effectiveness.

Technological optimization and fatigue evaluation of carbon reinforced polyamide 3D printed gears

Nowadays, this is even more challenging while additive manufacturing technology is used for prototyping, as well as the production of gearing systems. Presented is an optimization and characterization of the additively manufactured (AM) gears made of carbon-reinforced polyamide material in correlation to conventional polymer gearings. Based on the obtained results, the fatigue life data for AM carbon-reinforced Polyamide gears is calculated and compared to traditionally produced Polyamide 66-based gears. Results show that the durability of AM-produced carbon-reinforced Polyamide gears can be compared to conventional-produced Polyamide 66-based gears. Furthermore, deduced that wear of the AM-reinforced Polyamide teeth, can be closely connected with the meshing temperature in correlation with fatigue.

Comparison of mechanical properties polyamide materials produced by different additive technologies

Comparison of mechanical properties polyamide materials produced by different additive technologies

Synthesis and characterizations of random copolyamide PA(56-co-66): Excellent toughness and transparency

Random copolyamides PA(56-co-66) (coPA-n) with various comonomer compositions were synthesized by a one-pot polycondensation reaction of pentamethyleneammonium adipate (PMA) salt and hexamethyleneammonium adipate (HMA) salt in aqueous solution. All copolymers have high Mn (≥15000 g/mol). The molecular segment composition can be regulated by controlling the feed ratio of PMA salt and HMA salt. Tc and Tm of copolymers obtained by nonisothermal crystallization depend on the composition, showing a clear pseudo-eutectic behavior. Copolyamide coPA-50 exhibits a eutectic phenomenon with the melting point decreasing to a minimum of 218.9 °C. WAXD and SAXS results confirm that the crystalline structure of the copolyamides follows that of the rich component, exhibiting a typical isodimorphic characteristic. Mechanical properties of the copolyamides indicate that the elongation at break could be improved significantly with slight sacrifice of strength, which provides a promising approach for fabricating polyamide materials with desired properties. The tensile strength, tensile modulus, and elongation at break of coPA-50 was 65.2 MPa, 1.0 GPa, and 758.1 %, respectively. These copolymers can be melt-spun into fibers with excellent mechanical properties. Especially, the transmittance of coPA-60 reaches a high value of 88.01 % due to its low crystallinity and small crystal size.

Antimicrobial activity of cleanser tablets against S. mutans and C. albicans on different denture base materials

BackgroundIn this study, the antimicrobial activity of three different cleanser tablets on S. mutans and C. albicans adhesion to PMMA, polyamide and 3D printed resin was investigated.Methods40 samples were prepared for PMMA (SR Triplex Hot), polyamide (Deflex) and 3D printed resin (PowerResins Denture) materials and divided into four subgroups for cleansers (Aktident™, Protefix™, Corega™ tablets and distilled water) (n = 5). After the surface preparations were completed, the samples were immersed separately in tubes containing the prepared microorganism suspension and incubated at 37˚C for 24 h. After the incubation, the samples were kept in the cleanser solutions. The samples were then transferred to sterile saline tubes. All the tubes were vortexed and 10 µl was taken from each of them. Sheep blood agar was inoculated for colony counting. The inoculated plates were incubated for 48 h for S. mutans and 24 h for C. albicans. After incubation, colonies observed on all plates were counted. Statistical analyses were done with three-way ANOVA and Tukey’s multiple comparison test.ResultsPolyamide material registered the highest colony count of S. mutans, whereas PMMA registered the lowest. Significant differences in S. mutans adherence (p = 0.002) were found between the three denture base materials, but no such difference in C. albicans adherence (p = 0.221) was identified between the specimens. All three cleanser tablets eliminated 98% of S. mutans from all the material groups. In all these groups, as well, the antifungal effect of Corega™ on C. albicans was significantly higher than those of the other two cleanser tablets.ConclusionsAccording to the study’s results, it may be better to pay attention to surface smoothness when using polyamide material to prevent microorganism retention. Cleanser tablets are clinically recommended to help maintain hygiene in removable denture users, especially Corega tablets that are more effective on C. albicans.

Decarbonizing polyamide textile production in China: Footprints and mitigation pathways from life cycle perspective

Escalating demand for textiles has led to the entire supply chain contributing 8 % of global GHGs emissions. However, the carbon footprint (CF) and low carbon pathways of polyamide textile production remain ambiguous. Herein the CF of polyamide textile in China is evaluated using a "cradle to gate" life cycle system boundary allowing for comparison with other textile categories. To explore low carbon pathways of polyamide textile production, we introduce four groups of measures resulting in 12 scenarios. The CF of 1 kg polyamide textile is 35.37 kg CO2-eq, 1.38 and 3.91 times that of polyester and cotton textiles, respectively. Direct emissions from energy combustion, and indirect emissions from raw materials and energy production contribute 43.87 % and 56.13 % of the total CF. Emission reduction potentials vary from 51.37 % to 88.52 % across scenarios. These explored low carbon pathways should serve as references for achieving low and net zero emissions in the textile sector.

Engineering polyamide materials: s-triazine framework with specialized bulky side chains for advanced applications

The focus of this study is on the synthesis of organic fluorescent and thermally stable polyamides using an s-triazine frame. Coumarin and n-phenyl anthranilic acid have been utilized as bulky pendent groups in the synthesis of the monomer, resulting in polyamides with two groups that enhance stability and fluorescence. The synthesized polyamides have been characterized using a variety of techniques. The thermal stability of the polyamides has been studied using thermogravimetric analysis. These polyamides offer appealing features such as fluorescence and enhanced thermal stability, making them significant for a wide range of applications, including biosensors, clean energy technologies, and explosive sensing.

Numerical and experimental investigation of direct rapid tooling for sheet metal forming using selective laser sintering

The rapid tooling approaches were most sought after for the low-volume production of sheet metal parts within a short duration. This study presents an investigation of direct rapid tools produced with Selective Laser Sintering (SLS) for sheet metal forming. SLS is one of the widely used additive manufacturing techniques to produce polymer parts. The ability to form the sheet metal components using SLS direct rapid tools was assessed through cup drawing from aluminium blanks. A full factorial experiment was formulated to design the tools by varying the punch radius, die radius and draw ratio. The tools were fabricated with SLS using glass bead - filled polyamide material (PAGF) and finite element analysis was employed to study the stress distribution. The stress concentrations were observed at the tool edge radius, yet the PAGF tools sustained the load from the cup drawing process. The inspection of the PAGF tools and drawn cups shows that they are sensitive to the edge radius and draw ratio. Wear at the edge radius was evaluated in terms of percentage deviation from the initial radius. While the designed dimension of the edge radius is a significant factor affecting respective tool edges, the die edge wear was also influenced by the draw ratio. Both the formed parts and the tools exhibit geometrical variations localised to the forming edges and demonstrate good repeatability even up to 200 draw cycles.

Effect of using time in small pelagic purse seine with two vessels (slerek) on breaking strength and mesh size change in Pengambengan Archipelago Fishing Port (PPN), Bali, Indonesia

The bunt net of a small pelagic purse seine with two vessels (slerek) serves as a place for captured fish before being loaded onto the boat. Seine nets that are operated within a certain of long time can be weathering and deterioration of the material caused by aging and environmental factors. This study aims to analyze the effect and relationship of the use time of a bunt net with Multifilament polyamide (PA) material 210 D/12 mesh size ¾ inch on breaking strength and changes in mesh size. The methods used are observation, interview, literature study and documentation to be further analyzed using descriptive analysis and MANOVA. The results showed a decrease in the breaking strength value of the net by 38% while on the contrary, a 5% increase occurred in the change in mesh size. The analysis conducted shows the influence of usage time on breaking strength by 95.9% with a very strong not unidirectional relationship level of -0.977 and the influence of usage time on changes in mesh size by 99% with a correlation coefficient value of 0.985 which means the level of relationship is very strong and unidirectional.

Analysis of the machining process of short carbon fiber-reinforced polyamide additive manufactured parts

In recent years, additive manufacturing technologies have revolutionized the production of parts, particularly in the aeronautical sector. This new manufacturing paradigm has created significant challenges and opportunities for researchers in materials and manufacturing processes. One important aspect is the development of optimal strategies for finishing-oriented machining of parts produced through additive manufacturing.This article focuses on the analysis of reinforced polyamide materials and the integration of large-scale additive manufacturing using Big Area Additive Manufacturing (BAAM) technology, along with robotic systems for subtractive machining. The aim is to explore the potential of integrating additive and subtractive processes to produce high-quality, large-scale components.The study examines the production and subsequent machining of reinforced polyamide parts using BAAM technology, showcasing the advantages and promising results observed. By combining additive manufacturing with subtractive machining, this research contributes to the ongoing advancements in the field of manufacturing, particularly in relation to reinforced polyamide materials. The findings presented in this article shed light on the potential of integrating additive and subtractive processes in the manufacturing industry, paving the way for more efficient and high-quality production methods.

Process Cascade for the Production of Green Polymers from CO2 and Electric Energy

AbstractProduction processes based on CO2 as raw material offer high scalability and sustainability. Here, a novel process cascade is introduced, combining the advantages of electrochemical CO2 conversion with the synthetic potential of industrial biotechnology: CO2 is electrocatalytically reduced to formic acid as substrate for the metabolically engineered bacterium Methylorubrum extorquens that produces l‐lysine as precursor of the polymer building block 1,5‐diaminopentane (cadaverine). Cadaverine is purified through targeted downstream processing and finally used in a polycondensation process to produce polyamide materials.

Safety assessment of mixtures of 1,9-nonanediamine (NMDA) and 2-methyl-1,8-octanediamine (MODA), for use in food contact materials.

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP) assessed the safety of mixtures of 1,9-nonanediamine (NMDA) and 2-methyl-1,8-octanediamine (MODA) when used to produce polyamide food contact materials for contact with all food types for long-term storage at room temperature and below, including heating up to 121°C for up to 2 h. The polyamide material is also intended to be used for repeated use up to 121°C with short contact (up to 30 min). The polymer typically contains ■■■■■ of a low molecular weight fraction (LMWF, < 1000 Da). The specific migration was measured with polyamide samples in a set of migration tests with 3% acetic acid and 10% ethanol. NMDA and MODA were not detected at ■■■■■, respectively. The specific migration of the LMWF consisting of NMDA/MODA-related species was up to ■■■■■. The overall migration in olive oil was below the detection limit (3 mg/dm2). The most abundant migrating LMWF oligomers were identified. Toxicological studies were performed with NMDA, MODA and with polyamide formulations enriched in the LMWF. The results of genotoxicity assays did not raise a concern. From a repeated-dose oral 90-day toxicity study in rats, the Panel identified a no observed adverse effect level (NOAEL) of 1000 mg/kg body weight per day for the migrating LMWF. The CEP Panel concluded that NMDA/MODA mixtures do not raise a safety concern for the consumer when used as comonomer with terephthalic acid to manufacture polyamide articles intended for contact with all food types, except for infant formula and human milk, if the migration of NMDA and MODA does not exceed 0.05 mg/kg food (as a sum of the two substances) and if the migration of the LMWF consisting of NMDA/MODA-related species does not exceed 5 mg/kg food.