PA6 Content Research Articles

Construction of CO2‐based thermoplastic elastomer via combining aliphatic polycarbonate and polyamide: A multiblock copolymer PPC‐mb‐PA6

AbstractA CO2‐based thermoplastic elastomer, poly(propylene carbonate)‐multiblock‐polyamide6 (PPC‐mb‐PA6) copolymer, was constructed through coupling amorphous/soft PPC blocks with crystalline/hard PA6 blocks. The PPC‐mb‐PA6 copolymers with different block length pairs were designed and synthesized, and then fully characterized by structural, thermal, and mechanical analysis. The proton nuclear magnetic resonance (1H‐NMR), diffusion ordered spectroscopy (DOSY), heteronuclear multiple‐bond correlation (HMBC) and gel permeation chromatography (GPC) results confirm that the multiblock sequence structure of PPC‐mb‐PA6. The differential scanning calorimetry (DSC) tests show that all PPC‐mb‐PA6s possess melting points around 179–206°C. The thermal and mechanical analysis indicates improved service temperatures (T5% up to 270°C) and tensile strength ranging from 15.8 to 39.6 MPa with higher PA6 content. The dynamic mechanical analysis demonstrates excellent shape memory effect of PPC‐mb‐PA6 with thermal stimuli responsiveness derived from the micro phase separation between soft PPC and hard PA6 domains. And the characteristic strain fixity parameter (Rf) and deformation recovery rate (Rr) are 98% and 100%, respectively, which are comparable with other excellent shape memory polymers.

Research on torsional laminated extrusion for improving the permeability and mechanical properties ofHDPE/PA6composite for typeIVstorage tank liners

AbstractPolymers are advantageous in increasing hydrogen storage density of tanks due to their lightweight. Moreover, a uniform aggregate structure can enhance their advantages. However, achieving such as structure solely through screw extrusion can be challenging in liner moldings. This study reported a micro‐nano torsional laminated extrusion equipment that can be used before the die to effectively improve the composite orientation and reduce intercrystalline defects through divides, laminated thinning, and biaxial stretching of the melt with a strong drag flow field. The resulting HDPE/PA6 achieved a reduced helium permeation coefficient by up to 20.1% with a more pronounced effect on the diffusion than that on the dissolution. The mechanical property tests demonstrated an improvement in strength by up to 24.5% and modulus by up to 49.1% with the expanded range of toughness fracture. However, PA6 and HDPE exhibited limitations in terms of the moldable size and storage ability owing to their melt strength and gas barrier properties, respectively. Based on the analysis of the melt strength thresholds of HDPE/PA6, the PA6 content in the composites should be <70 wt% for blow molding and <50 wt% for welding. This study provides a novel approach for forming large‐diameter and thin‐walled liner billets through extrusion and welding.

Miscibility, crystallization and properties of bio-based polyamide 56/polyamide 6 blends

The miscibility, crystallization behaviors, and morphology of polyamide 56/polyamide 6 (PA56/PA6) blends were investigated. The blends had only one Tg, which confirmed that PA56 and PA6 are miscible in the blends. The melting point, crystallization temperature, crystallinity of the blends depressed due to the interaction of PA56 and PA6 in the blends. The crystalline structure of both PA56 and PA6 in the blends did not change and crystallized separately in both isothermal and non-isothermal crystallization process. PA56 in the blends crystallized in all blending ratio, while PA6 only crystallized with PA6 content φ6 > 0.2. The crystals of PA56 and PA6 grew in the same crystal skeleton but in different layers. Mechanical properties of the blends indicated that the elongation at break could be improved significantly without scarifying the strength in the case of adding a small amount of PA6 in PA56, which provides a promising approach for fabricating polyamide materials with desired properties.

Composition dependent miscibility in the crystalline state of polyamide 6 /polyamide 4,10 blends: From single to double crystalline blends

We studied the composition-dependent miscibility of polyamide 6 and biobased polyamide 4,10 (PA6/PA410) blends, as triggered by crystallization driven phase segregation. The blends were prepared by extrusion in a wide composition range and characterized by X-ray diffraction (both in-situ and ex-situ SAXS/WAXS), Differential Scanning Calorimetry (DSC), and Polarized Light Optical Microscopy (PLOM) during non-isothermal crystallization. The blends were miscible in the amorphous state, as demonstrated by a single Tg that follows the Fox equation as a function of composition. The blends were also considered to be miscible in the melt, as no evidence of phase segregation was found by SAXS or phase contrast microscopy in the melt. Remarkably, the blends can also be miscible in the crystalline state in a limited composition range. When only 10 or 20% PA6 was present in the blends, co-crystallization was evidenced by DSC and WAXS and the blends exhibited a single PA410 rich crystalline phase. On the other hand, as 30% or more PA6 was added to PA410, crystallization driven phase segregation occurred and progressively increased with PA6 content in the blends. Hence double crystalline blends are formed with both PA6 rich and PA410 rich crystalline phases. Clear evidence of the presence of either one or two crystalline phases was obtained by temperature-dependent measurements employing DSC, PLOM, WAXS and SAXS. Both the single and double crystalline PA6/PA410 blends exhibited good mechanical properties in view of the excellent compatibility displayed by the blends. The mechanical properties were in line with those exhibited by miscible blends following a simple rule of mixtures.

Numerical and Experimental Results on Charpy Tests for Blends Polypropylene + Polyamide + Ethylene Propylene Diene Monomer (PP + PA + EPDM).

This paper presents results from numerical and experimental investigation on Charpy tests in order to point out failure mechanisms and to evaluate new polymeric blends PP + PA6 + EPDM. Charpy tests were done for initial velocity of the impactor of 0.96 m/s and its mass of 3.219 kg and these data were also introduced in the finite element model. The proposed model takes into account the system of four balls, including support and the ring of fixing the three balls and it has a finer discretization of the impact area to highlight the mechanisms of failure and their development in time. The constitutive models for four materials (polypropylene with 1% Kritilen, two blends PP + PA6 + EPDM and a blend PA6 + EPDM) were derived from tensile tests. Running simulations for each constitutive model of material makes possible to differentiate the destruction mechanisms according to the material introduced in the simulation, including the initiation and the development of the crack(s), based on equivalent plastic strain at break (EPS) for each material. The validation of the model and the simulation results were done qualitatively, analyzing the shape of broken surfaces and comparing them to SEM images and quantitatively by comparing the impact duration, energy absorbed by the sample, the value of maximum force during impact. The duration of the destruction of the specimen is longer than the actual one, explainable by the fact that the material model does not take into account the influence of the material deformation speed in Charpy test, the model being designed with the help of tests done at 0.016 m/s (1000 mm/min) (maximum strain rate for the tensile tests). Experimental results are encouraging for recommending the blends 20% PP + 42% PA6 + 28% EPDM and 60% PA6 + 40% EPDM as materials for impact protection at low velocity (1 m/s). Simulation results are closer to the experimental ones for the more brittle tested materials (with less content of PA6 and EPDM) and more distanced for the more ductile materials (with higher content of PA6 and EPDM).

Effect of Copoly(Ester-Amide 6)(PET-PA6) on Compatibility of PET/PA6 Blended Fibers

Significant improvement of compatibility in PET/PA6 blends is essential to obtain fibers having enough mechanical strength as well as the comprehensive performance. In this article, copoly (ester-amide 6) was used as compatibilizer to improve the compatibility of PET and PA6. Three copoly (ester-amide 6) s with 5, 10% content of PA6 were prepared by co-polymerization from PTA , EG, as well as PA6 or caprolactam (A6), i.e. polyamide was incorporated both in the form of polymer and monomer, respectively. The sequence length of PET in the copoly (ester-amide 6) s is 33.4, 16.5 and 38.4 for PET-PA6-5%, PET-PA6-10% and PET-A6-5%, respectively, calculated by 13C NMR. Then PET/PA6 blend fibers were fabricated by melting spinning of PET and PA6 with 20 %wt addition of PET-PA6-5%, PET-PA6-10% and PET-A6-5%, respectively, to explore the effect of copoly (ester-amide 6) s on compatibility of PET/PA6 blend fibers, where the mass ratio of PET and PA6 is 85/15. DSC results show that the crystallization peaks of PET and PA6 during cooling from the blend melt become adjacent each other with increasing addition of copoly (ester-amide 6) s, even forming fused crystallization of them. It was found from SEM that the size of PA6 phase decreased and the phase boundary became indistinct due to the presence of copoly (ester-amide 6) s. Further more, the glass transition temperatures (Tg) of PET and PA6 closed to each other based on DMA result. Among these three copoly (ester-amide 6) s, PET-A6-5% display the best effect on the compatibility of PET and PA6 blend fiber, suggesting copoly (ester-amide 6) s could play important role in raise the compatibility of PET and PA6 blend.

Residual Monomer Content Affects the Interpretation of Plastic Degradation

Plastic degradation rates in the marine environment are essential to understand. This study demonstrates that in plastic-microbial interaction experiments, residual monomeric and oligomeric content of PA6 significantly influences the development of dissolved organic carbon. While it is well recognized that additives in plastics should be considered during the inception of plastic-exposure experiments, residual monomers have yet to be prominently considered in the same light. As such, in degradation studies where residual contents of monomers and/or oligomers are not considered, degradation of synthetic polymers could be significantly overestimated. The substantial conversion of these monomeric and oligomeric leachates also has implications for plastic-biofilm development studies and microplastic-biota-based ingestion experiments.

Prediction of barrier properties of HDPE/PA-6/nanoclay composites by response surface approach: effects of compatibilizer type and the contents of nanoclay, PA-6 and compatibilizer

This research presents study of barrier properties of the injection moulded bottles based on high-density polyethylene, polyamide-6 and nanoclay (HDPE/PA-6/NC) nanocomposites. In fact, the effects of compatibilizer type and contents of nanoclay, PA-6, and compatibilizer were assessed using response surface methodology. Investigation of individual effects showed that increase in nanoclay and PA-6 contents leads to improvement of the barrier properties, whereas compatibilizer content had an optimal level. Among three types of compatibilizers, Fusabond had the best performance. The interaction of effects of the nanoclay and PA-6 contents was very considerable. The highest barrier properties are obtained when these parameters were in high and low levels (in the range of study), respectively. Analysis of variance revealed that compatibilizer type was the most significant parameter. Eventually, using MINITAB software, a correlation for predicting the rate of mass reduction in the nanocomposites was developed.

A new high performance polyamide as an effective additive for modification of antifouling properties and morphology of asymmetric PES blend ultrafiltration membranes

Polyethersulfone (PES) ultrafiltration membrane with enhanced simultaneous permeability and fouling–resistance property was prepared using a new synthesized aromatic polyamide (PA-6) as an additive. A series of asymmetric membranes were prepared by adding different amounts of PA-6 to the casting solution using the phase inversion induced by immersion precipitation method. Attenuated total reflection-Fourier transform infrared spectra (ATR-FTIR) and water contact angle measurement confirmed the PA-6 enrichment at the membrane surface and increased the membrane hydrophilicity and wettability. The SEM images elucidated the effect of PA-6 addition on the PES membrane morphology by increasing the pore density. The results of filtration performance, which carried out by dead-end filtration of bovine serum albumin (BSA) solution showed that the permeability and fouling resistance property was improved by optimizing the PA-6 content. When the PA-6 content was 2 wt%, the permeability reached approximately 10 times over the pure PES membrane. In comparison to the blend membrane of PES and 2 wt% of polyvinyl pyrrolidone (PVP), the blend membrane of 2 wt% of PA-6 showed significant flux recovery ability. The rejection of all the blended membranes was approximately at high point over 95%. In addition, the results were compared with those obtained using PVP as a usual additive. Although the PVP blended membranes exhibited higher permeability, they showed lower antifouling properties. Finally, a membrane with 1 wt% PVP and 1 wt% PA-6 was prepared and showed the best performance regarding improved permeability and antifouling properties.

Interactions between PA6 Ratio and Tensile Properties in PVA/PA6 Hybrid Nanofiber Yarns

In this study, we fabricated poly vinyl alcohol/polyamide 6 (PVA/PA6) hybrid nanofiber yarns and examined the influence of PA6 content on tensile properties of hybrid nanofiber yarns. The surface morphology of nanofiber yarns was studied by scanning electron microscope (SEM). The average diameters of nanofibers in pure PA6 and pure PVA nanofibers yarns were 83±12 nm and 187±21 nm, respectively. The results showed that the strength of hybrid yarns was descending for PA6 contents below 16.5 % and ascending for higher contents. Also, by increasing the PA6 ratio in the hybrid yarn, the elongation at break was decreased. Three various models including: Hamburger, simple rule of mixtures (ROM) and hybrid models were applied to predict the tensile behavior of hybrid yarns. This study showed that neither ROM nor Hamburger’s models were capable of predicting the tensile properties of hybrid yarns. Whiles, hybrid model can predict properties with the lowest error (6.44 % error in strength values and 13.06 % error in elongation values prediction). Moreover, this model was modified further for higher performance. Our results demonstrate that the hybrid model can be applied in engineered tensile properties of nanofibrous yarns.

Effect of Dual Reactive Compatibilizers on the Formation of Co-Continuous Morphology of Low Density Polyethylene/Polyamide 6 Blends with Low Polyamide 6 Content

The coexistence of two kinds of reactive compatibilizers at the interface in immiscible LDPE/PA6 blends, namely, polyethylene graft maleic anhydride (PE-g-MAH) with a long backbone length and polybutadiene graft maleic anhydride (PB-g-MAH) with a short backbone length, promoted the formation of a flat interface and induced a co-continuous morphology in blends containing 30 wt % PA6. The relationships between the contents and content ratios of the dual reactive compatibilizers as well as the morphologies of the resulting LDPE/PA6 blends are examined quantitatively. The morphologies of the blends are characterized by SEM and TEM combined with a selective solvent extraction process. It is found that in these systems, when the total content of the dual compatibilizers is within 20–30 wt % and the content ratio of PE-g-MAH and PB-g-MAH is within 2:1–3:1, the minor PA6 phase can also form a co-continuous morphology in the LDPE matrix. The balance between the stability (determined by in situ formed PE-g-PA6 grafted copolymer with long backbone length) and flexibility of the flat interface (determined by in situ formed PB-g-PA6 grafted copolymer with short backbone length) in the compatibilized LDPE/PA6 blends is the key factor that controls the formation of the co-continuous morphology with low PA6 contents.

Influence of morphology on the flame retardancy of polystyrene/nylon-6/ammonium polyphosphate/clay blends

Ammonium polyphosphate (APP) and clay were utilized to flame retard polystyrene/nylon 6 (PS/PA6) blends. X-ray diffraction and transmission electron microscopy (TEM) results showed that clay formed exfoliated structures in PS/PA6/APP/clay. The results of Fourier transform infrared spectra and TEM indicated that APP and clay were exclusively dispersed in the PA6 phase. The influences of the distribution of APP and clay in PS/PA6 blends and the continuity of the (PA6 + APP) phase on flame retardancy were investigated. The flame-retardant properties were evaluated by limiting oxygen index (LOI), vertical flammability test, and cone calorimeter tests. For blends with a continuous PA6 + APP phase, the decrease of PA6 content caused an increase in LOI values from 26 to 34% and a remarkable reduction of the heat release rate. Results of thermogravimetric analysis indicated that the localization of APP and clay in the PA6 phase caused an increase in APP concentration in the PA6 phase with decreasing PA6 content, resulting in the rapid formation of intumescent charred layer, which augmented the flame retardancy. The transformation of (PA6 + APP) phase morphology from a continuous state to a discontinuous state at a PA6 content of below 40% (w/w) was observed. Meanwhile, the flame-retardant properties were decreased as the PA6 content decreases. The discontinuous intumescent charred layer thus formed and the inhibiting action of clay on the residue char from expanding could be responsible for the deterioration of flame-retardant properties, which were also confirmed by scanning electron microscopy and the aspect of intumescent charred layer.

Polymer Blends of Poly(Vinyl Chloride) and Lower-Melting Point Polyamide-6 Compatibilized by Epoxy

Lower-melting point polyamide-6 (LPA6) with the melting point of 198°C was prepared through melting extrusion. Blends of poly (Vinyl Chloride) (PVC) and LPA6 which use epoxy (EP) as compatibilizer were prepared by blending PVC and LPA6. The effects of the composition of PA6 and epoxy on the morphology and mechanical properties were investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The behavior of the blends was also determined experimentally using the dynamic mechanical analysis (DMA). Experiments revealed that, the epoxy resin F51 plays a compatibilizer. The more of the content of epoxy resin, the better of compatibility between PVC and PA6. With the increase of PA6, the degree of crystallization, crystallization rate and the regularity of crystal grain increased, the tensile strength declinged, the flexural strength and notched impact strength increase first and then decrease, both of then had an extreme value when the content of PA6 is 20wt%.

The Tribological Properties of Blending PA6 with POM Composite

The aim of this work is the evaluation of the effects of PA6 content on the friction andwear properties of POM composite system. Friction andwear properties of PA6/POM composite were determined with the help of pin-on-disc tribometer in sliding contact with a steel-ball at room temperature without lubrication. The spectroscopic investigations reveal that the increasing concentration of PA6 has a drastic influence on crosslinking efficiency due to their interference with POM in curing process. As a result, POM filled PA6 with higher concentration showed remarkably enhanced friction and wear properties.

Evolution of properties in ABS/PA6 blends compatibilized by fixed weight ratio SAGMA copolymer

Blends of acrylonitrile-butadiene-styrene (ABS) and Nylon 6 (PA6) incorporating styrene-acrylonitrile-glycidyl methacrylate (SAGMA) copolymer as compatibilizer have been studied across five different compositions by varying the PA6 ratio from 15 wt% to 55 wt%. The evolution of morphology from discrete dispersed PA6 particles to phase inversion to co-continuous phases effected due to the compatibilizer have been studied vis-a-vis preliminary melt flow analysis, viscoelastic behavior, physico-mechanical and thermal properties of the blends. Single point viscosity measurements during melt flow analyses are indicative of a significant increase in viscosity upon initial incorporation of PA6 followed by narrow increases with content. It is observed that while there are gradual positive modifications in physico-mechanical properties with increasing PA6 content, the most significant improvements are observed for room temperature izod impact strength and break elongation effected in the region of phase inversion on to the formation of a co-continuous phase. The low temperature impact strength at −40 °C essentially remains comparable to that of control ABS. DMTA analysis evidences partial dissolution of the blend components by the shifts of the damping peaks (Tg) of PB rich phase, SAN and PA6. Broadening of the damping peak of PB rich phase of ABS is attributed to increasing interfacial region due to PA6-g-SAGMA molecular layer at the interface. Thermal stability of the blends were not significantly affected in comparison to control ABS and PA6.

A facile route for preparing stable co-continuous morphology of LLDPE/PA6 blends with low PA6 content

A facile method is employed to prepare a series of LLDPE/PA6 blends with co-continuous morphology with low PA6 content via reactive extrusion. In these blends, co-continuous morphology is obtained by introducing graft copolymers with both high and low molecular weight trunk chains to the interface simultaneously. Maleic anhydride functionalized polybutadine (PB-g-MAH, Mn¯≈3000g/mol and MAH content=10 wt%) is first melt grafted onto the LLDPE backbones with dicumyl peroxide (DCP) as an initiator. Part of PB-g-MAH is grafted onto LLDPE to form LLDPE-g-PB-g-MAH copolymer. During reactive extrusion, in-situ formed Copolymer II (polybutadiene-graft-polyamide, PB-g-PA6) with a low molecular weight trunk chain (PB) is obtained from the reaction between the maleic anhydride group of free or non-grafted PB-g-MAH and the amino group on PA6 molecules; while Copolymer I (LLDPE-g-PB-g-PA6) is obtained via the reaction between the maleic anhydride group of the grafted PB-g-MAH (i.e., LLDPE-g-PB-g-MAH) and the amino group of PA6. Copolymer I with a high molecular weight trunk chain, LLDPE, should strengthen the interface and favor stress transfer, enabling the deformation of PA6; and Copolymer II (PB-g-PA6) with a low molecular weight trunk chain, PB, facilitates the formation of a flat interface between LLDPE and PA6, thus promoting an elongated PA6 phase. Therefore, co-continuous morphology of LLDPE/PA6 blend is successfully prepared with only 25 wt% PA6 by controlling suitable amounts of Copolymers I and II in the blend.

Tribological properties of PTFE composites with addition of PA6

Blending of polytetrafluoroethylene (PTFE) with PA6 at different compositions was performed in a corotating twin screw extruder, where PA6 is the dispersed phase. The effects of PA6 content on mechanical and tribological properties of the composites were investigated. The worn surface morphologies of neat PTFE and its composites were examined by scanning electron microscopy (SEM) and the wear mechanisms were discussed. The presence of PA6 particles dispersed in the PTFE continuous phase exhibited superior tribological characteristics to unfilled PTFE. The optimum wear reduction was obtained when the content of PA6 is 30 vol.-%.

RETRACTED: Effect of PA6 Content on the Mechanical and Tribological Properties of Blending PA6 with PP

Retracted

Modification of low‐density polyethylene by graft copolymerization with maleic anhydride and blends with polyamide 6

AbstractModification of low‐density polyethylene (LDPE) hyperbranched grafting with a maleic anhydride (MAH) was carried out using corotating twin screw extruder in the presence of benzoyl peroxide. The LDPE/polyamide 6 (PA6) and LDPE‐g‐MAH/PA6 blends were obtained with a corotating twin screw extruder. The melt viscosity of the grafted LDPE was measured by a capillary rheometer. The grafted copolymer was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy The effects of variations in temperature, PA6 loading, and benzoyl peroxide and MAH concentration were investigated. The results show that most MAH monomers were grafted onto the LDPE at a lower MAH concentration. With the proper selection of the reaction parameters, we obtained a grafting degree higher than 4.9%. Mechanical test results indicate that the blends had good interfacial adhesion and good stability of the phase structure during heating, which was reflected in the mechanical properties. Furthermore, the results reveal that the tensile strength of the blends increased continuously with increasing PA6 content. Moreover, the home‐synthesized maleated LDPE could be used for the compatibilization of LDPE/PA 6 blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

A study on melt grafting of maleic anhydride onto low‐density polyethylene and its blend with polyamide 6

AbstractGraft copolymerization of low‐density polyethylene (LDPE) with a maleic anhydride (MAH) was performed using intermeshing corotating twin‐screw extruder in the presence of benzoyl peroxide (BPO). The LDPE/polyamide 6 (PA6) and LDPE‐g‐MAH/PA6 blends were prepared in a corotating twin‐screw extruder. The melt viscosity of the grafted LDPE was measured by a capillary rheometer. The grafted copolymer was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microcopy (SEM). The influence of the variation in temperature, BPO and MAH concentration, and temperature on the grafting degree and on the melt viscosity was studied. The grafting degree increased appreciably up to about 0.45 phr and then decreased continuously with an increasing BPO concentration. According to the FTIR analysis, it was found that the amount of grafted MAH on the LDPE chains was ∼5.1%. Thermal analysis showed that melting temperature of the graft copolymers decreases with increasing grafting degree. In addition to this, loss modulus (E″) of the copolymers first increased little with increasing grafting and then obviously decreased with increasing grafting degree. Furthermore, the results revealed that the tensile strength of the blends increased linearly with increasing PA6 content. The results of SEM and mechanical test showed that the blends have good interfacial adhesion and good stability of the phase structure, which is reflected in the mechanical properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 267–275, 2010