Mechanical Properties Of Polyamide Research Articles

Morphological, Rheological, and Mechanical Properties of Polyamide 6/Polypropylene Blends Compatibilized by Electron-Beam Irradiation in the Presence of a Reactive Agent.

An immiscible polyamide 6 (PA6)/polypropylene (PP) blend was compatibilized by electron-beam irradiation in the presence of reactive agent. Glycidyl methacrylate (GMA) was chosen as a reactive agent for interfacial cross-copolymerization between dispersed PP and continuous PA6 phases initiated by electron-beam irradiation. The PA6/PP (80/20) mixture containing GMA was prepared using a twin-screw extruder, and then exposed to an electron-beam at various doses at room temperature to produce compatibilized PA6/PP blends. The morphological, rheological, and mechanical properties of blends produced were investigated. Morphology analysis revealed that the diameter of PP particles dispersed in PA6 matrix was decreased with increased irradiation dose and interfacial adhesion increased due to high surface area of treated PP particles. Complex viscosities (η*) and storage moduli (G’) of blends increased with increasing irradiation dose and were higher than those of PA6 and PP. The complex viscosity of the blend irradiated at 200 kGy was 64 and 8 times higher than PA6 and PP, respectively. The elongation at break of blend irradiated less than 100 kGy was about twice that of PA6. Electron beam treatment improved the compatibility at the interface between PA6 and PP matrix in the presence of GMA.

Correlation of viscosity ratio, morphology, and mechanical properties of polyamide 12/natural rubber blends via reactive compatibilization

Natural rubber (NR)-modified polyamide 12 (Nylon12/NR) was produced by melt blending Nylon12 and NR in the presence of polystyrene/maleated natural rubber (PS/MNR) copolymer as a reactive compatibilizer. The influence of compatibilizer loading on viscosity ratio, morphology, and mechanical properties of the blends was investigated. As a consequence of the reactive blend between Nylon12 and maleated NR in PS/MNR, the formation of amide and succinimide linkages was set at rubber-Nylon12 interfaces. Thus the dispersion of rubber particles was improved, and the particle coalescence was prevented so that the fine morphology with good interfacial adhesion was stabilized. This also resulted to enhance the blend viscosity and to lower viscosity ratio. The data revealed strong correlation between low viscosity ratio and fine spherical morphology of the compatibilized blends. An optimum PS/MNR compatibilizer content was at 7 phr to produce good dispersion of small rubber domains (size ≤0.3 μm) in Nylon12 matrix. Thermal properties by DSC revealed that crystallization temperature of Nylon12 was lowered by the presence of NR and crystallinity of Nylon12 was slightly affected by the PS/MNR content. An enhancement of mechanical properties, especially the impact energy was observed without suffering the tensile and flexural properties. Compared to the neat Nylon12, the compatibilized blends showed an increase in impact energy by a factor of 5. This large enhancement is successfully interpreted in term of the toughening effect by rubber phase of suitable dispersed size and the interparticle distance.

Investigation on Mechanical and Tribological Behaviors of PA6 and Graphite-Reinforced PA6 Polymer Composites

In this paper, the effects of adding graphite on the mechanical and tribological properties of polyamide 6 (PA6)-based composites were investigated. PA6 was reinforced with graphite by varying the weight proportions. The test specimens for mechanical and tribological experiments were molded in an injection molding machine. The mechanical properties of PA6 and graphite-reinforced PA6 polymer composites were investigated in terms of tensile strength, impact and hardness tests. The PA6 composite containing 20 wt% graphite revealed the better mechanical behaviors. The wear test was observed by using a pin-on-disk machine under dry sliding conditions at 5, 10, 20 and 30 N applied load values and sliding speed of 1000, 1500 and 2000 rpm. Scanning electron microscopy was utilized to examine the worn surfaces microstructure and wear mechanisms before and after the tribological test. The results showed that the reinforced PA6 polymer composites with 20 wt% graphite enhanced the best tribological behavior. The addition of graphite enhances the life condition of normal PA6 to a greater extent. Also, this composite exhibits stronger interfacial bonding characteristics with improved wear resistance.

Влияние температурного режима экструзионного компаундирования на структуру и механические свойства композита полиамида 6 и терморасширенного графита

Влияние температурного режима экструзионного компаундирования на структуру и механические свойства композита полиамида 6 и терморасширенного графита

Effects of anhydrites before and after modification as well as their contents on the thermal and mechanical properties of polyamide 6/anhydrite composites

The anhydrite (AII) is treated with different methods: calcination (c-AII) and surface modification (c-AIIg, AIIg) by γ-glycidoxy-propyltrimethoxysilane (GPS), and the polyamide 6 (PA6)/anhydrite composites are prepared by a twin-screw extruder. The effects of different anhydrites as well as their contents on the thermal and mechanical properties of PA6 composites are studied in the present work. Fourier transform-infrared spectroscopy and X-ray photoelectron spectroscopy demonstrate that the active GPS chains are chemically tethered onto the surface of the anhydrite. The differential scanning calorimetry measurements indicate that different anhydrites act as a heterogeneous nucleation agent in PA6 matrix and lead to the appearance of new γ-PA6 crystalline form. Thermogravimetric analysis suggests that the addition of anhydrite after calcination or surface modification has little effect on the thermal stability of the composites. Moreover, it is found that the impact strength of the composites is decreased with the increasing content of different anhydrites, while the tensile strength is increased with the increase of c-AIIg and AIIg content and the most significant improvement of the tensile strength of PA6/c-AIIg and PA6/AIIg composites is obtained when the content of c-AIIg and AIIg is 15 wt%, respectively. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

Effect of dynamic crosslinking on phase morphology and mechanical properties of polyamide 6,12/ethylene vinyl acetate copolymer blends

The dynamic crosslinking of polyamide 6,12 and ethylene vinyl acetate (PA6,12/EVA) blends in the mixing chamber of a torque rheometer was investigated. EVA was selectively crosslinked within the PA6,12 phase through free radical reactions using dycumil peroxide. The degree of EVA crosslinking in the PA12,6/EVA materials was estimated based on the gel content (insoluble EVA fraction). The PA6,12/EVA phase morphology was investigated by scanning electron microscopy. The mechanical properties were investigated by determining the tensile strength and hardness. The half-life time (t1/2) for homolytic scission of the dcumil peroxide (DCP) was ~6s, and this time is longer than the dispersion time of the DCP in the blends. The addition of DCP resulted in increased torque values due to specific crosslinking in the EVA phase. For the pure EVA and its blends with PA6,12 the stabilized torque values increased proportionally with the amount of DCP in the system, due to a higher degree of crosslinking of the elastomeric phase. The gel content of the dynamically crosslinked blends increased with the amount of DCP incorporated until 4 phr. At 1 phr the gel content value was 2.6wt.%, while at 4 phr it was 17wt.%. For the polymer blend with 8 phr of DCP a lubricating effect contributed to reducing the gel content. The dynamically crosslinked blends, regardless of the amount of DCP added, showed a reduction in the mechanical properties, which is related to the morphological features of the system due to the low mechanical fragmentation during melt processing. http://dx.doi.org/10.18226/23185279.v3iss1p23

Rheological and mechanical properties of polyamide 6 modified by electron-beam initiated mediation process

Abstract Polyamide (PA6) has been modified by electron-beam initiated mediator process to improve drawbacks of PA6. Glycidyl methacrylate (GMA) was chosen as a reactive mediator for modification process of PA6. The mixture of the PA6 and GMA was prepared by using a twin-screw extruder, and then the mixture was exposed to electron-beam irradiation at various doses at room temperature. The modified PA6 were characterized by observing rheological and mechanical properties and compared virgin PA6. Thermal properties, water absorption, and gel fraction were also investigated. Tight gel was not found even when PA6 was irradiated at 200 kGy. Complex viscosity and storage modulus of PA6 were remarkably increased by electron-beam irradiation with medium of GMA. Maximum increase in complex viscosity was 75 times higher than virgin PA6 at 0.1 rad/s when it was irradiated at 200 kGy with the GMA. Mechanical properties were also improved without scarifying of processability. The reaction mechanisms for the mediation process with the reactive mediator of GMA were estimated to elucidate the cause of significantly enhanced rheological and mechanical properties without loss of thermoplasticity.

Influence of a synthetic ureido nucleating agent on crystallization behavior and mechanical properties of polyamide 6

A synthetic ureido mixture prepared from the reaction of 4,4′-diphenylmethane disocynanate (MDI) and cyclohexylamine without using any harmful organic solvents, has been used as a nucleating agent (PNA) for polyamide 6 (PA6). The effect of PNA on the crystallization and mechanical properties of PA6 has been studied by means of differential scanning calorimetry (DSC), polarized optical microscopy (POM), tensile test, melt flow index (MFI), and X-ray diffraction (XRD). The results show that PNA is an effective nucleation agent for PA6. PNA affects the nucleation mechanism of PA6, and substantially accelerates the crystallization rate of PA6 and gives rise to smaller crystal size. In comparison with PA6, the crystallization temperature (Tc) of PA6/PNA (100/0.5) increases 21.3°C and the degree of sub-cooling (ΔTc) decreases 23.7°C. Furthermore, because of the heterogeneous nucleation induced by PNA, the spherulites of PA6 become even and tiny based on POM observation. Polymorph transform has been obtained from XRD analysis. The virgin PA6 is free of γ-phase crystals, presented as α-phase crystals in this study, but γ-phase crystal appears after the introduction of PNA. The mechanical and thermal properties of PA6 are obviously improved by the addition of PNA. POLYM. ENG. SCI., 55:2011–2017, 2015. © 2015 Society of Plastics Engineers

Graphene and carbon nanotubes for the synergistic reinforcement of polyamide 6 fibers

Poly(styrene-maleic anhydride) functionalized graphene (FG) and functionalized carbon nanotubes (FCNTs) were fabricated using in situ polymerization. The FG and FCNTs were used in the in situ ring-opening polymerization of e-caprolactam to form polyamide 6 (PA6)/FG/FCNTs composites. Both PA6 and the composite fibers were melt-spun in a piston spinning machine. The structure and properties of the composites and the fibers were characterized. The experimental results demonstrate that the mixture of graphene and carbon nanotubes exhibits good dispersion in a PA6 matrix. No obvious aggregation of graphene or CNTs was observed inside the composite fibers. The mechanical properties of PA6 are improved by inserting FG/FCNTs into the composite fibers, in particular, the tensile strength of composite fiber containing FG (0.2 wt%)/FCNTs (0.3 wt%) is 2.4 times that of pure PA6, and Young’s modulus is 132 % higher than that of the control. The crystallinity of the composite fibers is also enhanced. With the improvement of the tensile strength and Young’s modulus of PA6, its application will be expanded.

Lower purity dimer acid based polyamides used as hot melt adhesives: synthesis and properties

Hot melt polyamides exhibit high adhesive strength. The polyamides synthesized from dimer fatty acids and diamines can present low crystallinity and a broad range of melting temperatures. In this work, polyamides with different compositions of dimer fatty acids, piperazine, ethylenediamine, sebacic acid and stearic acid and different content of secondary diamine (piperazine) and primary diamine (ethylenediamine) were synthesized. Polyamides with higher purity of dimer acids showed greater molecular weight, adhesion performance and a better mechanical resistance evaluated in stress/strain test. Softening point increased with increase in monomers content. By differential scanning calorimetry analysis, it was observed that polyamides with low percentage of monomer content show only one narrow melting peak in 100 °C. The increase in the acids monomer content leads to a larger temperature range of melting peak. The use of dimer fatty acid with a low content of monomers (up to 6%) in the polyamides synthesis promotes the formation of hot melt adhesives with good adhesion performances. The lowest monomer content leads to an increase in molecular weight, viscosity and mechanical properties of polyamide. Increase in the content of primary amines in polyamides increases crystallinity, viscosity and mechanical properties due to the higher number of hydrogen bonds formed by amide groups.

Investigation of the alumina nanoparticle role in the enhancement of the mechanical properties of polyamide/polycarbonate blends

In this work, we have investigated the effect of the incorporation of alumina nanoparticles on the mechanical properties of polyamide 6/polycarbonate (PA6/PC) blends. Nanocomposites were prepared through melt processing using both unreactive and reactive surface-treated alumina nanoparticles. Simple PA6/PC blend comprising 20 wt% of PA6 showed ductile mechanical behaviour with an ultimate elongation close to 50%. Contrarily, the incorporation of 20 wt% of PC into PA6 led to a drastic decrease of the strain at break (3%). A thorough study of the morphology, thermal and rheological properties pointed out that these poor mechanical properties were due to an autocatalytic thermal degradation of both PA6 and PC phases. Advantageously, the incorporation of 5 wt% of alumina nanoparticles, whatever their surface nature, significatively improved the tensile properties of the blends inducing an important increase in the elongation at break up to 88% when 5 wt% of hydrophilic alumina is used. Alumina nanoparticles proved to behave as protective agents for both PA6 and PC phases within the nanocomposite materials.

The effect of conditioning upon the mechanical properties of polyamide

The effect of conditioning upon the mechanical properties of polyamide

Application of bis(glycidyloxy)phenylphosphine oxide as a chain extender for polyamide-6

Figure melt torque of PA6 mixed with different contents of chain extender BGPPO. The addition of small molecule diepoxide (BGPPO) greatly enhanced the melt torque, rheological and mechanical properties of polyamide-6 through chain extension reaction.

Predicting mechanical properties of elastomeric modified nylon blend using adaptive neuro-fuzzy interference system and neural network

Artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) are employed to predict the final mechanical properties of Polyamide 6 (PA6)/ ethylene-propylene-rubber (EPR)-grafted blend at different compositions. An individual ANFIS model is developed to predict the mechanical property at different processing condition. The results of this study are suggestive that both ANFIS and ANN could be employed quite effectively for this aim in such a polymer blend system. Therefore, the mechanical properties such as yield strength, modulus, and Izod impact strength are well predicted employing this method including an acceptable range of errors.

Effect of Maleated Styrene/Ethylene-co-Butylene/Styrene on the Dispersed Particles Size and Mechanical Properties of Polyamide 6/Poly(styrene-co-acrylonitrile)/Poly(styrene-b-(ethylene-co-butylene)-b-styrene) Ternary Blends

In this study, the effect of several parameters, including composition, order of mixing, viscosity, and interfacial tension, on the phase structure and size of dispersed particles of polyamide 6 (PA6)/poly(styrene-co-acrylonitrile) SAN/poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) ternary blends was investigated. Moreover, the effect of addition of different ratios of reactive SEBS (maleic anhydride grafted-SEBS) and non-reactive SEBS at a fixed order of mixing and composition of 70/15/15 (PA6/SAN/SEBS + SEBS-g-MAH) on the mechanical properties of ternary blends was examined. Scanning electron microscopy (SEM) micrographs showed that among the studied parameters, interfacial tension and viscosity of dispersed phases were the leading factors in the formation of morphology and size of dispersed droplets. Mechanical results revealed that in contrast to the expectation, formation of core/shell structure of PA6/SAN/SEBS ternary blends did not result in a significant increasing of impact strength. The highest impact strength was achieved when a 50/50 weight ratio of SEBS/SEBS-g-MAH was used.

Effect of uniaxial stretching on thermal, oxygen barrier, and mechanical properties of polyamide 6 and poly(m‐xylene adipamide) nanocomposite films

In this study, the effect of uniaxial stretching on the thermal, oxygen barrier and mechanical properties of aliphatic polyamide 6 (PA6) and aromatic Poly(m‐xylene adipamide) (MXD6) nylon films as well as their in‐situ polymerized nanocomposites with 4 wt% clay were studied. Cast films were prepared by extrusion process and rapidly cooled using an air knife. The precursor films were uniaxially stretched at 110°C with draw ratios varying from 1.5 to 5. DSC results showed that the cold crystallization temperature (Tcc) of the uniaxially stretched MXD6 and MXD6/clay films drastically shifted to the lower temperatures when draw ratio increased. The aromatic nylon films had lower oxygen permeability than those of the aliphatic films, due to more rigidity and chain packing. However, the oxygen permeability of the stretched films increased with draw ratio (DR) up to a critical value for each sample, while further stretching resulted in a reduction in the oxygen permeation. This phenomenon was related to the changes in free volume upon uniaxial stretching. The ability of different geometrical models to describe the experimental relative permeability data was investigated. The Bharadwaj model that took into account clay orientation was the most successful one to predict the oxygen barrier characteristics of the stretched nanocomposites at high draw ratios. The Young's modulus and tensile strength of the aliphatic and aromatic nylons increased with uniaxial deformation, while the flexibility and elongation at break of the former decreased with increasing DR. A larger increase in the Young's modulus of the uniaxially stretched nanocomposite films compared with the neat samples was observed and could be related to the improvement in the clay orientation as well as a better alignment of the crystalline phase due to incorporating the clay platelets in the polymer matrix. In contrast, the flexibility of the stretched MXD6 improved remarkably (ca., 25 times) compared with the precursor film (DR = 1) when the draw ratio increased to 1.5. This could be related to the effect of hot stretching on the enhancement of polymer chains relaxation and mobility at low draw ratios. POLYM. ENG. SCI., 55:1113–1127, 2015. © 2014 Society of Plastics Engineers

Mechanical Properties of Polyamide 6 (Pa6) / Ethylene Vinyl Acetate (Eva) / Sepiolite Composite

The objective of this study is to investigate the effect of sepiolite concentration (2-10 phr) on the mechanical properties of polyamide 6 (PA6) / ethylene vinyl acetate (EVA) blend at the ratio 80/20. Twin screw extruder and injection moulding machine were used to prepare the samples. The strength and modulus of flexural was increased until 6 phr of sepiolite content. On the other hand, the impact strength of PA6/EVA/sepiolite composite was decreased gradually as sepiolite content increased.

Structure, electrical and mechanical properties of polyamide 66/acid-treated MWCNT composite films prepared by solution mixing in the presence of nonionic surfactant

Two different sets of polyamide 66(PA66)-based composite films containing 2.0-10.0 wt% acid-treated multiwalled carbon nanotubes (MWCNT) were manufactured by solution mixing and casting method in the presence or absence of a nonionic surfactant. For the improved dispersion and interfacial interaction of MWCNTs in the PA66 matrix, carboxylic acid-functionalized MWCNTs were prepared by the acid-treatment of pristine MWCNTs. The uniform dispersion of the acidtreated MWCNTs in the PA66 matrix was confirmed from FE-SEM images of the fractured composite film surfaces. DSC thermograms supported that the acid-treated MWCNTs served as nucleating agents for the melt-crystallization of PA66 in both composite films prepared with/without the addition of the surfactant. The electrical and tensile mechanical properties of the composite films prepared with the surfactant were ~20 % higher than those of the composite films manufactured without the surfactant. For both composite films, sheet resistivity and tensile mechanical properties were found to be highly decreased and increased, respectively, with the increment of the acid-treated MWCNT content.

Influence of the Processing Conditions on the Morphology and the Mechanical Properties of Polyamide 6‐Carbon Fibre‐Carbon Nano Tube‐Compounds

SummaryPolyamide 6‐compounds containing carbon nano tubes and carbon fibres are prepared by melt compounding. To investigate the influence of the processing conditions on the mechanical properties and the morphology of carbon fibre reinforced polyamide 6‐nanocomposites the process parameters are varied while preparing the compounds. The processing conditions affect the mechanical properties and the morphology. The investigations reveal, that a micro‐nano‐compound with a PA6‐matrix should be compounded at a maximum barrel temperature of 260 °C, a throughput of 15 kg/h at a screw speed of 500 min−1 and a screw configuration, which introduces a low amount of shear energy into the compound. These processing conditions lead to a comparatively high specific mechanical energy input of 334 Wh/kg and to the best set of mechanical properties of the investigated materials. However, the morphology of the investigated carbon fibre reinforced nanocomposites does not show significant differences and has to be further investigated.

Flame retardancy and mechanical properties of polyamide 6 with melamine polyphosphate and ionic liquid surfactant‐treated montmorillonite

ABSTRACTThe mechanical properties and inflammability of polyamide 6 (PA6) nanocomposites incorporated with Montmorillonite organoclay (MMT) modified with thermal stable ionic liquid surfactants were investigated. The compatibility between ionic liquid‐treated MMT and PA6 matrix was improved and the intercalation morphology was achieved, which resulted in the increaseof tensile modulus. However, the addition of organo‐MMTs alone did not improve the inflammability of the PA6 nanocomposite, because of strong melt‐dripping behavior of PA6 matrix. Addition of auxiliary melamine polyphosphate (MPP) intumescent flame retardant to the nanocomposite prevented the melt dripping and enhanced inflammability performance. The enhanced inflammability of PA6/organoclay/MPP nanocomposites was attributed to the synergistic effect between imidazolium or phosphonium organo‐MMTs and intumescent flame retardant MPP. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40648.