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This paper presents a part of development of a non-standard method for testing of cylindrical test specimens for measurement of fracture properties of pipeline materials. This method for testing of cylindrical structures working under pressure is based on determining of fracture mechanics parameters on SENT (Single Edge Notched Tension) specimens and new PRNT (Pipe Ring Notched Tension) specimens. In this work, both types of specimens required for this testing were manufactured from polyamide PA12 by using SLS (selective laser sintering) additive manufacturing method. Testing of the specimens is performed on the universal device for testing of mechanical properties of materials Shimadzu, AGS-X 100 kN. The tensile testing is accompanied by GOM Aramis 2M system, used for digital image correlation. By using these two systems, test results are obtained for ring-shaped and SENT specimens, including forces, displacements and fracture mechanics parameters CMOD (Crack Mouth Opening Displacement) and CTOD-?5 (Crack Tip Opening Displacement obtained by ?5 technique), as well as crack growth. Repeatability of this process, along with valid result consistency, represent the basis for further development of the new method, including the determining of energy-based fracture mechanics parameters: J integral and stress intensity factor.

Biopolymers often show deterministic chain folding templated by repeat unit sequences whose conformations are locked in by intramolecular interactions. In this work, we have used repeat units based on rigid anthracene or acridine scaffolds, which we refer to as "U-turn" repeat units, to template chain folding reminiscent of beta-serpentine folds in bulk synthetic polyamides. Unlike the rigid kinked repeat units present in certain commercial semiaromatic polyamides, the acridine-based U-turn repeat units did not impede crystallization in the polyamides, whose crystalline phase was shown to be stabilized by infinite arrays of intermolecular hydrogen bonds and pi-pi interactions between the acridine units. This led to a unique layered crystalline structure characterized by a well-defined lamellar thickness that depended on the length of the aliphatic spacers between the U-turn repeat units and regular adjacent re-entrant chain folding, which is not usually expected for semiaromatic polyamides crystallized at high supercooling. Our work hence provides the first example of the introduction of deterministic chain folding into a nonpeptidic polyamide in order to tailor its crystalline morphology and may consequently open up new perspectives for the molecular design of structural materials.

This study will contribute to the identification and understanding of the reinforcement mechanisms of thermoplastic matrices by nanofillers. This aspect is addressed through the investigation of the thermal and mechanical properties of nanocomposites consisting of a polyamide 12 (PA12) matrix crammed with organically modified clay nanoparticles. An efficient approach to the synthesis of polyamide 12 (PA12) nanocomposites was investigated; Maghnite may be a processed Algerian mineral clay which will act both as a catalyst and as an inorganic reinforcement. Two sorts of organic substances were used, labeled CTA-Mag (1CEC) and CTA-Mag (2CEC), modified by cetyltrimethylammonium (CTA) ions. However, PA12/CTA-Mag nanocomposites are characterized by various physico-chemical techniques, XRD, FTIR, TGA, scanning and transmission electron microscopy (SEM and TEM). Measurements of tensile modulus, yield strength, lastingness, elongation at break and toughness were done to assess the behavior of the mechanical properties. Furthermore, we have analyzed the consequences of the mass fraction of the fillers on the structural, thermal and mechanical properties of those nanocomposites. Specific attention has been paid to the study of relationships between the macroscopic properties and therefore the structure of nanocomposites. Thermomechanical tests showed a big improvement within the properties of the nanocomposites compared to neat PA12.

A new kind of bio-based polyamide 5,6 (PA56) fiber has been synthesized from adipic acid and 1,5-pentanediamine. In this report, the characterization, antistatic treatment, mechanical properties, m...

High molecular weight poly(amide-imide)s containing cardo structures were readily prepared by a supported palladium-catalyzed carbonylation polymerization of diiodo imide monomers, aromatic diamines containing cardo groups, and carbon monoxide. Polycondensation reaction proceeded effectively in N,N-dimethylacetamide (DMAc) at 100 °C in the presence of a bidentate phosphino-modified magnetic nanoparticles-anchored palladium complex [2P-Fe3O4@SiO2-PdCl2] as catalyst and 1,8-diazabicyclo[5,4,0]-7-undecene (DBU) as base under 1 atm of CO, yielding a series of new poly(amide-imide)s with inherent viscosities up to 0.95 dL/g. All the polymers obtained were easily soluble in some strong polar aprotic organic solvents and could be cast into transparent, flexible and tough films from their DMAc solutions. These cardo poly(amide-imide)s displayed high thermal stability with the glass transition temperatures ranging from 237 to 265 °C, the temperatures at 5% weight loss ranging from 433 to 475 °C in nitrogen. These PAI films also exhibited good mechanical behavior and high optical transparency. The present method provides the flexibility of incorporating different ratios of imide and amide groups in the polymer backbone in a controlled manner and eliminates the possibility of postpolymerization curing due to the imide moiety being preformed. Importantly, the supported palladium catalyst can be conveniently separated from the polymer by simply using an external magnetic field and recycled at least 8 times without apparent loss of catalytic efficiency.

The effect of filler amount and kind on the crystalline structure, thermal stability, and mechanical, rheological, and morphological properties of polyamide 6 (PA6) was studied in this research. Glass bead and glass fiber were chosen as mineral fillers. They were incorporated to PA6 solely or in mixed formulations at different proportions (hybrid composites). Tensile strain, tensile strength, impact strength, flexural strain, flexural strength, melt flow index, crystallite size, and thermal degradation parameters were determined for all composites. The addition of glass bead or glass fiber increased the brittleness of pure PA6. The incorporation of glass fiber to pure PA6 improved flexural, impact, and tensile strengths, and mixing of glass bead with pure PA6 polymer caused deterioration of both (tensile and flexural) strengths, but enhanced impact strength. Among hybrid composites, the highest flexural, tensile, and impact strength values were achieved with 15 wt% glass bead and 15 wt% glass fiber content. The addition of glass bead and/or glass fiber to PA6 polymer caused a decrement in melt flow index value. X-ray diffraction results indicated that pure PA6 polymer had α- and γ-crystalline forms, and the reinforcement of glass bead or glass fiber would induce the crystallization into γ-form. It was also found that the incorporation of glass bead or glass fiber influenced the lamellar thickness, and pure PA6 gave thicker lamellar crystal than that of glass bead/fiber-reinforced PA6 and its hybrid composites. Higher thermal stability with glass bead or glass fiber incorporation was found as compared to pure PA6 polymer.

Additive manufacturing is traditionally used to manufacture either prototypes or very small-scale demonstrators. In recent years though, it is being increasingly used to make low volume parts for the aeronautical and defence industry. One concern with laser sintered parts is that their relatively porous nature, means that they may be more susceptible to ageing than injection moulded parts. Parts were aged for 6 months in at different temperatures (18°C, 40°C, 50°C, 60°C, 80°C and 100°C) and in a humidity chamber at 60°C and 80% relative humidity. Each month samples were removed for characterisation. The testing included tensile testing, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and gas pycnometry. During ageing the samples displayed visible discolouration and embrittlement over the 6-month test period. This embrittlement was not observed in those samples aged at room temperature or an elevated humidity. The observed yellowing in the samples aged above ambient temperature is likely a result of the build-up unsaturated degradation products. No significant differences as a result of ageing were observed via DSC, TGA, SEM or gas pycnometry.

Fused Filament Fabrication is a very common additive manufacturing technology and several manufacturers have developed commercial 3D-printers that enable the use of fibre-reinforced filaments in order to improve the mechanical properties of the printed parts. The obtained material is a composite that exhibits complex mechanical properties. The aim of this study is to characterize the mechanical behaviour of 3D-printed continuous glass fibre-reinforced polyamide composites. In a first step, we focus on the reinforced filament: the heterogeneity of its microstructure is evidenced as well as its brittle elastic tensile behaviour. In a second step, parts of different fibre orientations and fibre volume contents are manufactured using a Mark Two 3D-printer (MarkForged®), their microstructure is analysed and tensile, flexural and short beam bending tests are performed. As expected, the results show a significant influence of fibre volume content and fibre orientation. Standard homogenization methods are used to compare the predicted mechanical behaviour to the experimental results. Regarding the elastic stiffness, a good correlation is observed when the material is loaded in the direction of the fibres. Regarding the tensile strength, the results show that no benefit is obtained above a fibre volume content of about 11%. These results highlight the importance of choosing an optimised stacking sequence prior to the printing process, in order to obtain composites with the desired mechanical properties. The mechanical results are analysed in the light of Scanning Electron Microscopy observations of specimen cross-sections before and after testing.

Formaldehyde-based resins are widely used in the field of wood adhesives. However, high formaldehyde emission is still a serious problem. Therefore, a low-toxic wood adhesive was successfully synth...

Due to the poor compatibility caused by the large difference in hydrophilicity and interface between polylactic acid (PLA) and cellulose acetate (CA), the blending of the two materials is difficult and the application is limited. To solve this problem, a type of polyamide amine (PAMAM) dendrimer was introduced to modify PLA/CA blends in this work. The results showed that PAMAM could improve the compatibility of PLA/CA blends, promote the distribution of CA and crystallization of PLA. At the same time, adding PAMAM could enhance the mechanical properties of the blend material, and the toughness and tear strength were increased by 551% and 141%, respectively. In addition, the incorporation of PAMAM increased hydrophobicity and oxygen permeability of PLA/CA blends, and the oxygen permeability could be increased by up to three orders of magnitude. Degradation test results showed that the blend exhibited good biodegradability. The overall performance of the PLA/CA blend film was optimal when the content of PAMAM was 3 phr. The biodegradable blend films with excellent performance provided wide application prospect in the food green packaging fields.

HIPS-g-MAH compatibilizer and the other three compatibilizers were prepared and added to the polyamide 66/polyphenylene oxide (PA66/PPO) alloy. The FT-IR spectra showed that the maleic anhydride (MAH) had successfully undergone grafting on the high impact polystyrene (HIPS). The effect of the MAH ratio in the HIPS-g-MAH compatibilizer, the HIPS-g-MAH compatibilizer weight ratio, and the PA66/PPO ratio on the mechanical properties of PA66/PPO alloy was systematically studied. The results showed that the PA66/PPO alloy possessed the optimal mechanical properties when the HIPS-g-MAH compatibilizer weight ratio was 7% and the MAH ratio in HIPS-g-MAH compatibilizer ranged 4% ~ 8%. The fracture morphologies of PA66/PPO alloy with different HIPS-g-MAH compatibilizer weight ratios were characterized by scanning electron microscope (SEM). The PA66/PPO alloy without HIPS-g-MAH compatibilizer showed a typical brittle fracture. The mechanical properties of PA66/PPO alloys with the HIPS-g-MAH compatibilizer were improved. In addition, the crystallization temperature of PA66/PPO alloy decreased with the increase in the HIPS-g-MAH compatibilizer weight ratio. The PA66/PPO ratio also played an essential role in the PA66/PPO alloy properties. The coefficient of friction and wear rate both increased with the increase in the PPO ratio.

This study investigates the addition of ground tire rubber (GTR) into virgin polyamide 6 (PA6) to produce thermoplastic elastomer (TPE) blends. In particular, a wide range of GTR concentration (0–100% wt.) was possible by using a simple dry blending technique of the materials in a powder form followed by compression molding. The molded samples were characterized in terms of morphological (scanning electron microscopy), physical (density and hardness) and mechanical (tension, flexion and impact) properties. The results showed a decrease in tensile and flexural moduli and strengths with GTR due to its elastomeric nature. However, significant increases were observed on the tensile elongation at break (up to 167%) and impact strength (up to 131%) compared to the neat PA6 matrix. Based on the results obtained, an optimum GTR content around 75% wt. was observed which represents a balance between high recycled rubber content and a sufficient amount of matrix to recover all the particles. These results represent a first step showing that a simple processing method can be used to produce low cost PA6/GTR compounds with a wide range of physical and mechanical properties.

Natural materials often consist of hierarchical architectures, which are extremely efficient in mechanical terms. Whereas the structure-function relationship is well-studied in natural hard materials, soft materials are not getting equal attention, despite their high prevalence in nature. These soft materials are usually constructed as fiber-reinforced composites consisting of diverse structural motifs that result in an overall unique mechanical behavior. In this study, as a proof-of-concept, a soft biomimetic composite was fabricated from a hierarchical electrospun polyamide fiber, reinforcing a hydrogel matrix and creating a simple synthetic analog for natural soft composites. This material system investigates the structure-function relationship between the structure and mechanical function by mimicking different structural motifs. The polyamide-hydrogel composite exhibited large deformations and nonlinear material behavior. Varying degrees of crimping enabled a controlled strain stiffening behavior and engineered transition from matrix-dominated to fiber-dominated behavior. We also observed that the individual nanofibers in our bundles created cross-bridges with the matrix and within the bundle, making the material system more resistant to failure. Our bio-inspired composite demonstrated mechanical behaviors similar to natural soft composites, which can aid in the future design and development of the next generation of soft architectural composites.

Poly(vinylidene fluoride) (PVDF)-based composites attract tremendous attention as dielectric materials. However, their development has been limited due to the raised problem in the in-homogeneous polymer composites. In this work, a novel PVDF-based film incorporated with polyamide-1, containing the highest density of dipole among all polyamides, was prepared to improve the crystallization behaviors and dielectric properties. The results showed that the optimal concentration of polyamide-1 in PVDF was 6 wt.%. The crystallization rate of PVDF was improved in the presence of polyamide-1. Interestingly, the polyamide-1 was conductive to the formation of β form crystal of PVDF, which exhibited great electric performance. The dielectric constant of PVDF increased sharply and loss tangent still kept at a low level of 0.03@100 Hz when the concentration of polyamide-1 was 6 wt.%. This work may provide a new direction to design dielectric materials for PVDF blends.

Purpose This paper aims to investigate the mechanical and thermal behavior, i.e. tensile strength, hardness, impact strength and glass transition temperatures of water-treated polyamide6/boric oxide (PA) composites. Design/methodology/approach The PA6 and PA6/boric oxide composites were exposed to an open environment and immersed in water for 15 days to analyze the effect of environmental humidity and frequent water immersion conditions on the composite’s mechanical and thermal properties. The tensile strength, elastic modulus, hardness and impact strength of materials were measured to identify the mechanical properties. The scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) characterizations were used to see the effect of humidity/water absorption on microstructure, crystallinity and glass transition temperatures. Findings The testing results revealed the loss in strength, elastic modulus and hardness, while the impact resistance was improved after exposure of materials to humidity/water. SEM images clearly show the formation of voids and XRD graphs revealed the loss in crystallinity after water immersion. The DSC plots of water immersed materials revealed the loss of glass transition temperatures up to 15°C. Originality/value The mechanical and thermal behavior of PA composites varies according to the surrounding atmosphere. Experiments were performed to investigate the influence of water treatment on the PA6/B2O3 composite’s mechanical and thermal properties. Water treatment resulted in the bonding between PA and water molecules, which generated voids in the materials. These voids generations are found the main reason for the low strength and hardness of water-treated materials.

Membrane separation has been widely used for various applications including microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF) processes in the fields of biomedicine, food, and water purification. In this work, a facile synthesis of new polyamide thin-film composite nanofiltration membranes (NF-TFC) for water purification was described. The polyamide thin film was deposed over a synthetic cellulose acetate (CA) support by interfacial polymerization method. 1,3 cyclohexane bis (methylamine) (CHMA) and trimesoyl chloride (TMC) were used as monomers. The membranes were characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared spectroscopy (FT-IR), water uptake, porosity, contact angle, water permeability and rejection towards specific salt and dye molecules. The effect of the variation of the CHMA concentration (0.2–2 wt.%) on the morphology, porosity, water permeation and rejection properties of the prepared membranes was studied. SEM results displayed the growth of the membrane thickness when the CHMA concentration increased from 0.2 to 2 wt.%. The strong adhesion between the cellulose acetate substrate and the polyamide layer explained by the formation of the polyamide film in the substrate surface and inside the pores. The water permeability varied from 36.02 to 17.09 L h−1 m−2 bar−1. The salt rejection of Na2SO4 and NaCl increased from 9 to 68% and from 38.41% to 89.4%, respectively, when the CHMA concentration was changed from 0.2 to 2 wt.%. The prepared membranes were further applied successfully for the removal of malachite green and congo red. The results indicated that the maximum rejection reached 89% and 85% for malachite green and congo red, respectively.

Polyamide 6 (PA6) is extensively used in many industrials due to its chemical and wear resistance, stiffness, excellent strength properties, low friction, and high melting points. In this study, PA6/nitrile butadiene rubber (NBR)/graphene nanocomposites were fabricated by twin-screw extruder (TSE) and friction stir process (FSP). The novelty of our present work is that the fracture mechanisms and failure analysis of PA6/NBR/graphene nanocomposites were studied by the essential work of fracture (EWF) methodology. The scanning electron microscopy and wide X-ray diffraction were used to study the morphology of TSE and FSP samples. The results illustrated that the higher shear stress in FSP compared to the TSE is the reason for better dispersion of the graphene in the PA6 matrix and smaller size of NBR particles. The smaller size of NBR particles and better distribution of graphene in PA6/NBR blend led to high total work of fracture ( $${w}_{f}$$ ) in the FSP sample compared to the TSE sample. The results of the EWF test showed that the addition of 0.5% (wt) graphene nanoparticles into the PA6/NBR blend in the TSE sample decreased the essential work of fracture ( $${\rm{w}}_{\it{e}}$$ ) from 105.6 N/mm to 87.8 N/mm and increased the non-essential work of fracture (βWp) from 2.76 N/mm2 to 3.9 N/mm2; whereas in FSP sample, $${\rm{w}}_{\it{e}}$$ and βWp increased to 115.58 N/mm and 4.66 N/mm2, respectively.

The friction stir process (FSP) method used to prepare polyamide 6 (PA6)/nitrile-butadiene rubber (NBR) nanocomposites with 1 wt% Graphene nanoparticles. Response surface methodology (RSM) and Box-Behnken design were used to study the effects of four input variables including tool rotational speed (ω), shoulder temperature (T), traverse speed (S), and the number of passes (N) on tensile strength and impact strength of PA6/NBR/Graphene nanocomposite. In order to investigate the dispersion state of Graphene and the morphology of the PA6/NBR blend in the presence of Graphene, wide x-ray patterns (WAX), scanning electron microscopy (SEM) were performed. Furthermore and differential scanning calorimetric (DSC) was used to investigate the thermal properties of PA6/NBR containing 1 wt% Graphene nanoparticles. The results confirmed that at the optimum range of input variables, PA6/NBR/Graphene nanocomposite provided good thermal stability as well as the highest tensile strength, and impact strength. This is caused by the large surface area to volume ratio of the dispersed layered Graphene in PA6/NBR blends. Under optimal conditions of the rotational speed of 1200 rpm, traverse speed of 20 mm/min, shoulder temperature of 125°C, and number pass of 3, the maximum tensile strength and impact strength are 70.4 MPa and 70.3 J/m, respectively.

The new aromatic m-catenated diamine, N-(3,5-diaminophenyl)-4-(naphthalen-7-yloxy)benzamide was synthesized from 2-naphthol and 4-fluoro benzonitrile as starting materials. A series of novel aromat...

The paper deals with the investigation results of nanocomposites based on polyamide-6 (PA6) and montmorillonite (MMT) intercalated by polyvinylpyrrolidone (PVP). Nanocomposites were obtained by mix...

Biomass bifunctional polyamide elastomers (BbPEs) were successfully prepared from dimer acid (DA), trimer acid (TA), and triethylenetetramine with shape memory and self-healing abilities. In the composition structure of BbPEs, vast hydrogen bonds formed among the amide bonds of different segments endowed the BbPEs with self-healing ability. At room temperature, the mechanical properties of BbPEs can be restored to 49% of the original condition after healing for 2 h. In addition, the physical and chemical cross-linking endowed the BbPE with preferable mechanical and shape memory properties. The tensile strength of the material is 4.4 ± 0.1 MPa, and the elongation at break reaches 1500 ± 2%. Under the recovery temperature of 60 °C, the shape memory recovery rate of 5 min can reach 95%. The recovery efficiency is 88.9%. This material can be utilized for many practical applications, such as intelligent electronic devices, bionic materials, and so on.

Unidirectional carbon fiber reinforced polyamide 6 (CF/PA6) laminates after tensile tests exhibited two different types of fracture modes, namely, splitting and step-like. In this study, the mechanical properties and fracture behavior of the unidirectional CF/PA6 laminates were simulated and analyzed by using finite element simulation of a tensile test. The simulations considered the actual deformation and damage mechanism (matrix plastic deformation, stochastic fiber fracture, and interfacial debonding between the fiber and the matrix) experimentally observed in previous research. Results of the numerical simulations were in good with the experimental stress–strain curves. Moreover, the above-mentioned two types of fracture mode were well simulated by changing the interfacial properties. The simulated results showed that the unidirectional laminates with weak interface properties exhibit the splitting fracture mode. Meanwhile, the unidirectional laminates with strong interface properties show the step-like fracture behavior.

Generally, polyamide cannot be used as film blowing material because of its unsuitable properties. In this study, polyamide 6 clay nanocomposite (cPA) and styrene maleic anhydride copolymer (SMA) were mixed in various ratios for the preparation of modified polyamide 6 clay nanocomposite SxcPAy resins by reactive extrusion. The S1cPA14 resin was blended with recycled maleic anhydride polyamide (rPA) to form the (S1cPA14)x rPAy resins. Finally, they were mixed with LDPE in 1:9 ratio to afford (SxcPAy)1LDPE9 and ((S1cPA14)x rPAy)1LDPE9 resins, respectively, followed by film blowing and the analyses of the physicochemical properties of resins. The FTIR spectrum illustrated that the C=O symmetric and asymmetric absorption fingerprint peaks in the anhydride (-OC-O-CO-) group of SMA disappeared and the new characteristic absorption peak of-CO-N-CO- of imides was observed. The anhydride functional group of SMA underwent reactive extrusion with the terminal amino group of cPA to generate the imides structure. The thermal properties showed that the glass transition temperature and crystallinity of SxcPAy and (S1cPA14)x rPAy resins increased with increasing SMA and S1cPA14 contents. The Tg (85.4.0°C) of (S1cPA14)12 rPA1 resin were enhanced significantly, with 30°C higher than cPA. In terms of tensile mechanical properties, S1cPA14 test pieces demonstrated the highest Young’s modulus and tensile strength. After mixing with LDPE, the tensile mechanical properties of (SxcPAy)1LDPE9 and ((S1cPA14)x rPAy)1LDPE9 resins and films were both higher than that of LDPE. ((S1cPA14)12 rPA1)1LDPE9 film shown the best tensile properties and barrier performance compared with other films due to the optimal rPA content could assisted SMA as a better compatibilizer to improve the dispersion and compatibility of cPA in HDPE. It was worth noting that (SxcPAy)1LDPE9 and ((S1cPA14)x rPAy)1LDPE9 resins were formed by film blowing at the processing temperature of 140°C followed by successful preparation of the film.

Biobased PA56 is an innovative type of biobased polyamide that is regarded as the most potential material to replace traditional petroleum-based polyamide. However, biobased PA56 exhibits poor notc...

To obtain aromatic polyamides with reduced dielectric constant, a series of aromatic polyamide copolymers derived from the reaction between m-phenylenediamine to trans-1,2-cyclohexanediamine and isophthaloyl chloride were synthesized using the low-temperature solution polymerization in the presence of 2-methylpyridine. The influence of the content of trans-1,2-cyclohexanediamine on the structure and properties of aromatic copolyamides was evaluated. With increasing the content of trans-1,2-cyclohexanediamine, the inherent viscosities of copolymers decrease from 1.95 to 1.14 dL/g. The copolymer with 25 mol % of trans-1,2-cyclohexanediamine has a reduced dielectric constant er of 4.61 at 1 MHz, which is 26% lower than homopolyamide. Meanwhile, as-synthesized aromatic polyamides and copolyamides show good thermal stability and mechanical properties.

Graphene and its derivatives have received considerable attention in industrial and academic research due to their unique, useful properties and applications. The use of graphene is still difficult due to its high cost of production. Hence, graphene nanoplatelets (GNPs) have been identified as a substitute for graphene, which are produced in large scale at a very low cost. Moreover, GNPs have played a significant role in various engineering thermoplastic materials [i.e., polyamides (PAs)] to enhance their properties and applications. The GNPs help in the production of low-cost multifunctional nanocomposites with notable useful properties such as high electrical conductivity, mechanical strength, and high aspect ratio. The GNPs based nanocomposites have a broad spectrum of application areas including 3D-printing, automotive materials, electrical appliances, low-cost composites films, and many more. This review summarizes different preparation techniques, properties, and applications of GNPs based PAs nanocomposites as reported in current literature.

In this work, we investigated the morphology, crystallization, and mechanical properties of the polyoxymethylene/thermoplastic polyamide elastomer (POM/TPAE) blends. It was found that POM and TPAE are partially compatible. By blending with TPAE, the toughness and low-temperature performance of POM can be improved significantly. However, there is a maximum value for the improvement of POM toughness, which is related to the amount of TPAE. We found that TPAE is dispersed in the POM matrix as spherical particles, and the particle size of these varies with the content of TPAE. Another interesting finding is that adding TPAE can change the crystalline properties of POM. For example, after adding TPAE, the crystallization particles of POM become smaller, part of the crystal area disappears, and the crystallization temperature decreases. All these results suggest that TPAE improves the toughness and low-temperature performance of POM by improving the crystallization, morphological structure, and morphology of the POM blends.

In this study, polyamide-6/chitosan blend dense membranes were prepared using solution casting technique. The membranes were then characterized by FTIR spectroscopy, TGA, SEM analysis and tensile testing. FTIR analysis confirmed hydrogen bonding between chitosan and polyamide. TGA analysis proved that all the membranes maintained thermal stability up to 370 °C. SEM analysis exhibited compact and dense structure of the membranes. The tensile properties of the membranes improved with the addition of hydrophilic chitosan. The membranes were then characterized for desalination properties using 2000 ppm NaCl solution by state-of-the-art dead-end membrane desalination equipment at 20 bar operating pressure. The effect of membrane thickness was then studied, and the best thickness of the membrane was determined for optimum water flux and salt rejection. The effect of chitosan concentration was also studied, and the best concentration was determined for optimum desalination properties. It has been found that the membrane having 200 micron thickness and 3 wt.% chitosan demonstrated optimum desalination properties that is 75% salt rejection and water flux of 1.52 kg/h.m2. It has been found that maximum salt rejection was achieved with 2 wt.% chitosan blend membrane and maximum permeate flux was achieved with 4 wt.% chitosan blend membrane.

Polyoxymethylene/thermoplastic polyamide elastomer (POM/TPAE) blends were prepared through melt extrusion in an attempt to improve the toughness and electrical properties of POM. The TPAE used in the study had the permanent antistatic effect, and its brand was MV2080. Acrylonitrile-butadiene-styrene copolymer grafted maleic anhydride (ABS-g-MAH) was added while preparing the POM/TPAE blends to improve the compatibility between TPAE and POM. The effects of TPAE and ABS-g-MAH on the morphologies, melting crystallization, dynamic mechanical analysis, surface resistivity and mechanical properties were examined in detail with various techniques. It was found that after adding 15 phr MV2080 as the modifier, the distribution of MV2080 in the blends was presented as many continuous long strips, which can be called “antistatic networks.” When using ABS-g-MAH as a compatibilizer, the surface resistivity of the samples 5#, 6#, and 7# which all containing 15 phr MV2080 with the best antistatic properties reached 107 Ω, and the impact strength of the above samples was all increased by more than 66%.

Low permeation flux and rapid flux decline are challenging membrane technology in wastewater treatment. Here we used a metal–ligand complexation protocol to construct novel forward osmosis (FO) membrane for efficient and sustainable phosphorus removal. Disodium and tetrasodium salts of ethylenediaminetetraacetic acid (EDTA-2Na, EDTA-4Na) were separately grafted onto the conventional polyamide (PA) membranes via chemical complexation using Fe3+ as a bridge. These EDTA salts substantially improved the membrane properties. Consequently, the water fluxes produced by the EDTA-2Na and EDTA-4Na modified membranes increased by 109% (11.1 LMH) and 140% (12.7 LMH), respectively, relative to that of the pristine membrane (5.3 LMH) with 0.5 M NaCl as the draw solution. Meanwhile, the EDTA-4Na modified membrane surpassed the naked PA membrane in performance with higher water recovery efficiencies and solute rejections after long-term experiments against a mixture of bovine serum albumin and HPO42−. Moreover, the water flux recovery ratio of the naked PA membrane was only 51%, while that of the EDTA-4Na modified membrane reached over 93% after three cycles of fouling experiments. This study provides a new paradigm to develop FO membrane via a metal–ligand complexation protocol for efficient and sustainable wastewater treatment. Novel FO membranes synthesized through a complexation protocol are used for phosphorus removal and fouling resistance in forward osmosis.

The super-tough bio-based nylon was prepared by melt extrusion. In order to improve the compatibility between bio-based nylon and elastomer, the elastomer POE was grafted with maleic anhydride. Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA) were used to study the compatibility and micro-distribution between super-tough bio-based nylon and toughened elastomers. The results of mechanical strength experiments show that the 20% content of POE-g-MAH has the best toughening effect. After toughening, the toughness of the super-tough nylon was significantly improved. The notched impact strength was 88 kJ/m2 increasing by 1700%, which was in line with the industrial super-tough nylon. X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC) were used to study the crystallization behavior of bio-based PA56, and the effect of bio-based PA56 with high crystallinity on mechanical properties was analyzed from the microstructure.

Extensional mixing elements (EMEs) that impose extension-dominated flow via stationary single-plane or double-plane hyperbolic converging-diverging channels were previously designed for twin-screw and single-screw extruders (TSE and SSE, respectively). In a recently published work by the authors, reactive extrusion was performed on PS/PA6 polymer blends TSE using EMEs and a crystalline phase transition of the minor phase in these droplets was observed as the size of droplet decreases from micron to submicron. Herein, we expand upon this work to SSE and study: a) The ability of the EMEs to improve dispersive mixing in the same blends; b) Assess the possibility of achieving the same crystalline phase transition in SSEs. The final blends were characterized by DSC, rheologically and morphologically via SEM, and the results show that while EME-based SSE leads to much improved mixing, better than non-EME TSE, the reduction in size of the PA6 disperse phase is not enough to induce the phase transition observed in EME-based TSE.