In recent years, bio-reinforced composite materials have occupied an important class among the materials of mass use in our daily lives thanks to their potential advantages such as lightness, low ...cost, ease of implementation, and in particular biodegradation. The latter has been the objective of several studies focusing particularly on poorly biodegradable polymers, among these polymers we find polyamide 6 (PA6). It is a semi-crystalline polymer, distinguished by its good mechanical properties, excellent chemical and thermal stability, and low price compared to other polyamides. In this research, we investigated the impact of reinforcing PA6 with peanut shell powder (PSP), olive pomace powder (OPP), and plaster (PL) on its biodegradation process. Our objective was to determine whether the incorporation of these reinforcements accelerates, delays, or has no effect on PA6 biodegradation. To achieve this, we conducted degradation experiments using the bacterium Alcaligenes faecalis (AF), isolated from the public landfill of Meknes, Morocco. Our findings revealed intriguing insights into the biodegradation behavior of the PA6 composites. Specifically, the incorporation of PSP significantly enhanced PA6 biodegradation, resulting in a notable 38 % weight loss. Conversely, the inclusion of OPP led to a delay in biodegradation, with only a 19 % weight loss observed. Interestingly, the addition of plaster exhibited a biodegradation pattern similar to that of raw PA6. Furthermore, we utilized FTIR and SEM coupled with EDS elemental analysis to confirm the biodegradation of the composites. These techniques provided valuable insights into the structural, morphological, and elemental changes undergone by the composites during the biodegradation process. Overall, our study contributes novel insights into the biodegradation dynamics of PA6 composites reinforced with natural materials. By elucidating the effects of reinforcement on biodegradation, our research paves the way for the development of sustainable and eco-friendly composite materials.
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•An ENHM was produced by a combination of 3D printing and electrospinning technology.•The surface area was extended more than 2.5 the area of a planar hemodialysis membrane.•A ...negatively charge hydrophilicity modification was generated by the esterification.•Hemodialysis ability and fouling resistance were enhanced by chemical modifications.
A three-dimensional (3D) pattern was fabricated using a 3D printer to develop a hemodialysis nanofiber membrane with an embossed structure for portable or wearable hemodialyzers. The membrane of the embossed structure had a much larger surface area than that of the planar membrane structure. The high-flux hemodialysis membrane was prepared using a poly(methyl methacrylate)-graft-poly(dimethylsiloxane) (PMMA-g-PDMS) copolymer and polyamide 6 (PA6). The PMMA-g-PDMS copolymer is an organic-inorganic hybrid material in which the nanofiber diameter was controlled under 0.437 μm with a surface layer thickness of 50 (±20) μm. The polyamide 6 (PA6) nanofiber membranes were made with fibers 0.072 μm in diameter with a 0.14 μm pore size. This PMMA-g-PDMS/PA6 nanofiber hemodialysis membrane was modified for enhanced dialysis efficacy, and the modified membranes were evaluated based on clearance of saline and small molecules. Esterification and crosslinking reactions resulted in anionic hydrophilic hemodialysis membranes, and the fouling resistance is due to esterification of carboxylic acid groups (COOH) of sodium alginate with hydroxyl groups (OH) of polyethylene glycol, which generated a negatively charge surface. Thereby, repulsive electrostatic forces might be generated between the negatively charged blood cells and negative surface membrane. The water contact angle showed that the membrane hydrophilicity increased from 129 and 90° to 50°, and the total fouling parameter decreased to 0.112. The fouling resistance was enhanced due to the negatively charged membrane surface. Membrane contamination was measured by protein adhesion using a surface potential difference based on fluorescent whitening with zeta potential analysis, and the efficiency of creatinine removal was increased using a beta (β-cage) zeolite.
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•An adhesive and hydrotropic nanoparticle with a core–shell structure (Car@DOPO) was synthesized.•Car@DOPO nanoparticle endows polyamide 6 with excellent UV shielding and outstanding ...flame retardancy.•Carbohydrate Caramel shows promise as a biomaterial for improving the washing durability of functional textiles.•This work demonstrates the successful and sustainable treatment of Polyamide 6 fabrics using a carbohydrate polymer.
The destruction of polyamide 6 (PA6) fabrics due to fire and prolonged UV radiation is an urgent issue that needs to be addressed. Inspired by the adhesion and inclusiveness of the sugar-coated haws, this study developed an adhesive nanoparticle with a core–shell structure (Car@DOPO) by encapsulating DOPO with carbohydrate caramel. The Car@DOPO nanoparticles exhibited excellent UV shielding property on PA6 fabrics, as indicated by a maximum UPF of 41.7, which can be attributed to the π-bonds and dark brown color of caramel shell. Additionally, the coated PA6 fabric demonstrated good flame retardancy, with a flame retardancy index (FRI) of 1.2. The LOI of coated PA6 fabric improved from 22.1% to 30.5%. Moreover, the fire growth rate (FGR) and flame inhibition effect (FIE) decreased by 13.3% and 22.0%, respectively. These improvements can be attributed to the efficient quenching effect of the DOPO core. Notably, the strong adhesion of the caramel shell allowed the Car@DOPO nanoparticles to firmly adhere to the fabric surface, providing coated PA6 fabric with durable flame retardancy. This study demonstrates the successful and sustainable treatment of PA6 fabrics using a carbohydrate nano-polymer.
Nitrogenous base tailors the network of melamine cyanurate and improves the flame retardant efficiency of polyamide 6 composites.
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•The network of melamine cyanurate was tailored by ...bases;•The modified MCA improves the flame retardancy of polyamide 6 composites.•The Polyamide 6 composites with 9 wt% C-MCA achieve the UL-94 V-0.
In this paper, nitrogenous bases adenine (A), guanine (G), cytosine (C), and uracil (U), were used to tailor the hydrogen-bonded network of melamine cyanurate (MCA) and were noted as A-MCA, G-MCA, C-MCA, U-MCA, respectively. The results showed that the size, morphology and thermal behavior of MCA are regulated by base due to the formation of hydrogen bonds between them. These modified MCAs were used to improve the flame retardancy of polyamide 6 (PA6) which was evaluated by using the limiting oxygen index (LOI) and the vertical burning (UL-94) test, etc. The results showed that the PA6 sample containing 9 wt% C-MCA achieves the UL-94 V-0 rating and has a LOI value of 30.7%, while the other samples with equal amounts of MCA only pass the UL-94 V-2 rating. The flame retardant mechanism was studied, and the results reveal that C-MCA with smaller size has greater contact area with PA6 which helps to catalyze the decomposition of PA6; Thus the PA6/C-MCA releases more NH3, CO2 etc., and produces more droplets than others, which dilutes combustible gas and takes away heat to make the samples extinguish.
This paper investigates the water absorption of polyamide 6. The high amount of absorbed water in the polymer and the large resulting decrease in the glass transition temperature (Tg) leads to a non ...Fickian water diffusion when samples are immersed, which is a significant difficulty when trying to model the water profile in thick specimens. The aim of this study is to be able to model this particular behaviour based on physical considerations. First, it is shown that the non Fickian water diffusion is caused by an increase in the diffusivity during water absorption. Two cases are then identified; one below Tg where the diffusivity is described using an Arrhenius law and one above Tg based on the free volume theory. Then, these two laws are implemented in a specific model that is able to describe the non Fickian water diffusion over a wide range of temperatures.
The antimicrobial efficacy of polyamide 6/silver-nano- and microcomposites against
Escherichia coli was studied as a function of the filler content. Polyamide 6 filled with 0.06
wt.% silver ...nanoparticles is able to eliminate the bacteria completely within 24
h. A polyamide 6/silver-microcomposite containing 1.9
wt.% of silver kills only about 80% of the bacteria during the same time.
Silver ion release tests were performed to find out the reason for the much higher antimicrobial efficacy of the nanocomposite materials. The silver ion release from the polyamide 6/silver-composites obeys a zero-order rate law. The silver ion release rate increases with growing filler content. For a fixed filler content the rate of the silver ion release from the nanocomposites is about one order of magnitude higher in comparison to the microcomposites, because of the much larger specific surface area of the nanoparticles.
A correlation between the silver ion release rate and the antimicrobial efficacy against
E. coli was found. If the rate of the silver ion release is at least 9.5
×
10
−4
mg
l
−1
cm
−2
day
−1 the silver-filled materials are able to eliminate
E. coli completely within 24
h. This value is reached for polyamide 6 filled with 0.06
wt.% of silver nanoparticles. The rate of silver ion release from the microcomposites is below this threshold value even if the filler content is 1.9
wt.%.
•The polymer-type flame retardant was synthesized by copolymerization method using DOPO derivative, decamethylene diamine and caprolactam as raw materials.•The PA6 exhibited good flame retardancy ...with the addition of polymer-type flame retardant.•The flame-retardant mode of action of polymer-type flame retardant is mainly through the quenching effect of phosphorus containing radicals in the gas phase.
A polymer-type flame retardant (PFR) based on a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative was synthesised here to improve the flame retardancy of polyamide 6 (PA6). The chemical structure and thermal property of the PFR were characterised by Fourier-transform infrared (FTIR) spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The PFR and PA6 were melt-blended to obtain a flame-retardant polyamide 6 (FRPA6). Its thermal property, mechanical property and flame retardancy were characterised via TGA, DSC and tensile, impact, vertical burning and limiting oxygen index (LOI) tests. Its flame-retardant mode of action was analysed by scanning electron microscopy, FTIR spectroscopy, cone calorimetry and pyrolysis-gas chromatography-mass spectrometry. The FRPA6 with a phosphorus content of 3000 ppm passed the UL-94 V-0 rating, and the LOI of the FRPA6 with a phosphorous content of 5000 ppm reached 28.8 %. Compared with pure PA6, the peak heat release rate, total heat release and effective heat of FRPA6–5000 were reduced by 35.4 %, 21.9 % and 26.5 %, respectively. These results indicate that the flame-retardant mode of action of PFR mainly involved the quenching effect of phosphorus-containing radicals in the gas phase.
Fused filament fabrication allows for the additive manufacturing of complex geometries without requiring moulds. The cooldown during the printing process causes the bonding between the layers to be ...weak. As a result, the mechanical properties are behind those of parts manufactured using conventional techniques. This study investigates the influence of an annealing process on the mechanical performance of continuous and chopped fibre reinforced polyamide 6 in the build-up direction. A correlation between the annealing temperature and the mechanical performance was found. The Young's modulus increased by a factor of three, while the ultimate tensile strength (UTS) increased by 50% for the chopped carbon fibre reinforced material and by 186% for the continuous glass fibre reinforced material. A temperature dependent transition from the gamma to the alpha phase was observed while the crystallinity only slightly changed. Air voids within the parts were found to be the main cause of embrittlement.
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•Annealing of additively manufactured Polyamide 6•Use of continuous glass and chopped carbon fibre reinforcement•Temperature dependent increase of the material strength•Transition from the gamma to the alpha phase was observed•Air void ratio increased for the continuous fibre reinforcements
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•Graphene oxide (GO) was successfully grafted onto carbon fiber (CF) surface using hexamethylene diisocyanate (HDI) tripolymer as the coupling agent, obtaining GO modified CF ...(CF-g-GO).•The interfacial shear strength (IFSS) of CF-g-GO/PA6 composites increased by 40.2% compared with that of unmodified CF/PA6 composites.•The improvement of the interfacial properties of the CF-g-GO/PA6 composites is mainly attributed to the combined effects of the better wettability and the mechanical locking.
Graphene oxide (GO) was grafted onto the surface of carbon fiber (CF) by two synthetic routes with hexamethylene diisocyanate (HDI) tripolymer as the coupling agent. The first one was to use HDI tripolymer to modify the surface of GO, named GO-NCO, and then graft GO-NCO onto the oxidized carbon fiber surface. The other route was to use HDI tripolymer to modify the oxidized carbon fiber surface, named CFO-NCO, and then graft GO onto the CFO-NCO surface. The chemical compositions of the CF surface were confirmed by infrared spectroscopy (FTIR) and X-ray photoelectron spectra (XPS). The surface morphologies of CF after modification and debonding from matrix were examined by scanning electron microscopy (SEM). The interfacial shear strength (IFSS) of CF/PA6 composites was also investigated by microbond test. It is found that the interfacial properties of GO modified carbon fiber reinforced polyamide 6 (CF-g-GO/PA6) composites are better by using the first route. The IFSS of CF-g-GO/PA6 composites reaches 61.4 MPa, is an increase of 40.2% compared with that of unmodified CF/PA6 composites. Moreover, the interfacial enhancement mechanism was further analyzed in detail.
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