Mechanical Properties Of Polyamide Research Articles

Effect of service temperature on structure and mechanical properties of polyamide 6 & 66 tyre cords

The effect of service temperature on chemical structure and mechanical properties of polyamide 6 & 66 tyre cords was studied over the broad range of 50–200 °C and for a period of 16 h. The heat treatment of cords at below 100 °C and above 120 °C was found to reduce their tensile properties considerably. The changes in properties above 120 °C were caused by increase in width of the molecular weight distribution curve as ascertained by gel permeation chromatography (GPC) studies and increase in irregularity of the polymeric chains as ascertained by birefringence studies; this appears to be due to the fact that, by raising the temperature, both chain folding and chain scission occur. Since there was deformation of the amorphous regions as ascertained by FTIR spectroscopy and birefringence studies, the changes in properties below 100 °C were attributed mainly to the effectiveness of thermal oxidation and annealing in the amorphous phase. In other words, the degree of crystallinity increased, the tyre cord became brittle, and breaking load and elongation at break were decreased. The lower reduction of tensile properties at an intermediate temperatures of 100–120 °C was caused by the lower polydispersity and irregularity in the polymeric chains, in comparison with higher temperatures and less crystallinity than lower temperature treatments.

The effect of random branching on the balance between flow and mechanical properties of polyamide-6

The rheological and mechanical properties of a series of linear and randomly branched polyamide 6 samples, with varying molar mass and varying degree of moderate branching, have been investigated.As expected, it was found that random long-chain branching has a pronounced effect on the rheological behaviour of the materials in both shear and extensional flow. The zero shear viscosity increases with branching while the flow curve becomes more shear thinning. Randomly branched materials have an enhanced melt strength in elongational flow. Although branched, the materials show perfect melt stability in their rheology.The mechanical properties show minor differences between the linear and the moderately branched samples and are mainly dependent on the weight average molar mass. A small increase in modulus, yield stress and failure stress and a decrease in the strain at break are found, which is probably due to increased molecular orientation in the plane of injection moulding. The IZOD impact strength is similar to what is normally found for linear polyamide-6, and independent of branching. Also the fracture toughness KIC is not affected by the incorporation of random branching. However, it is clearly dependent on the weight average molar mass.By using random branched polyamide-6, molecular weights and related mechanical properties can be obtained that are out of reach for linear polyamide-6.

Influence of reactive compatibilizers on the rheometrical and mechanical properties of PA6/LDPE and PA6/HDPE blends

In this work, the influence of reactive compatibilizers on the rheometrical and mechanical properties of polyamide 6/low density polyethylene (PA6/LDPE) and polyamide 6/high density polyethylene (PA6/HDPE) blends was investigated. Polyethylene grafted with maleic anhydride (PEgMA), polyethylene grafted with acrylic acid (PEgAA), and ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA) were used as compatibilizers. The blends were characterized by torque rheometry, mechanical properties, and morphology. Rheometrical properties results show that PEgMA and PEgAA compatibilizers are more reactive with PA6 than EMA-GMA. Mechanical properties and scanning electron microscopy analysis results show that EMA-GMA compatibilizer is as effective as PEgMA and PEgAA for PA6/LDPE blend. For PA6/HDPE blend, PEgAA and EMA-GMA compatibilizers proved to be as effective as PEgMA. For PA6/HDPE blend compatibilized with PEgAA, an intriguing “web” or “bridge” like structure was observed.

Effect of POSS on morphology and mechanical properties of polyamide 12/montmorillonite nanocomposites

Sodium-montmorillonite (MMT) was modified with two types of AP-POSS and OA-POSS and dual-surfactants (POSS with a ditallow-based second surfactant: 04AP-POSS/08DTDMA and 04OA-POSS/08DTDMA), respectively, via ion-exchange reaction. The interlayer space, interlamellar structure, thermal and surface properties of these organo-montmorillonites were investigated by X-ray diffraction, thermogravimetric analysis, and contact angle measurement. The interlayer space of POSS modified clay was strongly dependent on the arrangement of POSS surfactants, but less on the POSS concentration. The POSS modified montmorillonites have partially exchanged silicate surfaces and good thermal stabilities due to steric hindering and thermal stability of the POSS molecules. Dual-surfactant modified montmorillonites showed higher exchange ratio and possessed better compatibility with PA12 due to the lower interfacial free energy. Polyamide 12-montmorillonite nanocomposites were prepared by conventional melt compounding with the four POSS based organo-montmorillonites. The best dispersion of modified montmorillonite was observed for 3 mass% 04AP-POSS/08DTDMA/MMT filled PA12 nanocomposites, which resulted in the best mechanical performance with an increase of 60% in tensile modulus and 10% in yield strength, respectively, compared to that of pure PA12. Compatibility between montmorillonites and polymer was not the only key factor affecting dispersion, thermal stability and interlayer space were also crucial for good dispersion of montmorillonites in polymer matrix.

Structure and mechanical properties of polyamide 6/Brazilian clay nanocomposites

Recent interest in polymer/organoclays nanocomposites systems is motivated by the possibility of achieving enhanced properties and added functionality at lower clay loading as compared to conventional micron size fillers. By adding montmorillonite clay to polyamide 6 increases the Young modulus, yield strength and also improves barrier properties. In this work, nanocomposites of polyamide 6 with montmorillonite clay were obtained. The clay was chemically modified with three different quaternary ammonium salts such as: Dodigen, Genamin and Cetremide. In this case, a dispersion of Na-MMT was stirred and a salt equivalent to 1:1 of cation exchange capacity (CEC) of Na-MMT was added to the dispersion. The montmorillonite clay (untreated and treated by ammonium salts) and nanocomposites were characterized by X ray diffractions. Also the nanocomposites were characterized by transmission electron microscopy and mechanical properties. The results indicated that all the quaternary ammonium salts were intercalated between the layers of clay, leading to an expansion of the interlayer spacing. The obtained nanocomposites showed better mechanical properties when compared to polyamide 6. The clay acted as reinforcing filler, increasing the rigidity of nanocomposites and decreasing its ductility.

Environment-friendly synthesis of long chain semiaromatic polyamides

Long chain semiaromatic polyamides were synthesized by the reactions of p-phenylenediacetic acid with long chain aliphatic diamines, and characterized by Fourier transform infrared spectroscopy (FTIR) and by proton nuclear mag- netic resonance ( 1 H NMR). The thermal behaviors were determined by differential scanning calorimetry (DSC) and ther- mogravimetric analysis (TGA). The solubility, dynamic mechanical, physical and mechanical properties of the polyamides were also investigated. The resultant polyamides have intrinsic viscosity ranging from 1.8 to 2.1 dl·g -1 , their melting tem- peratures range from 254 to 290°C, and their glass transition temperatures obtained from dynamic mechanical analysis are in the range 87-113°C. The physical and mechanical properties of long chain semiaromatic polyamides were compared with those the PA9T. The results show that the heat resistance and the mechanical properties of poly(decamethylene-p- phenylenediacetamide) (PA10P) are near to those of PA9T, so PA10P is a promising heat resistant engineering plastic.

Parameters of Dilaton and Limit Assessments of the Mechanical Properties of Polyamides during Highspeed Deformation

Parameters of Dilaton and Limit Assessments of the Mechanical Properties of Polyamides during Highspeed Deformation

Morphology and mechanical properties of polyamide-6/K resin blends

Mechanical properties and morphological studies of compatibilized blends of polyamide-6 (PA-6)/K resin grafted with maleic anhydride (K-g-MAH) and PA-6/K resin/K-g-MAH were investigated as functions of K resin/K-g-MAH and dispersed phase K resin concentrations, and all the blends were prepared using twin screw extruder followed by injection molding. Scanning electron microscopy (SEM) were used to assess the fracture surface morphology and the dispersion of the K resin in PA-6 continuous phase, the results showing extensive deformation in presence of K-g-MAH, whereas, uncompatibilized PA-6/K resin blends show dislodging of K resin domains from the PA-6 matrix. Dynamic mechanical thermal analysis (DMTA) test reveals the partially miscibility of PA-6 with K-g-MAH, and differential scanning calorimetry (DSC) results further identified that the introduction of K-g-MAH greatly improved the miscibility between PA-6 and K resin. The mechanical properties of PA-6/K resin blends and K-g-MAH were studied through bending, tensile, and impact properties. The Izod notch impact strength of PA-6/K-g-MAH blends increase with the addition of K-g-MAH, when the K-g-MAH content adds up to 20 wt %, the impact strength is as more than 6.2 times as pure PA-6, and accompanied with small decrease in the tensile and bending strength less than 12.9% and 17.5%, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Morphology, thermal, and mechanical properties of polyamide 66/clay nanocomposites with epoxy‐modified organoclay

AbstractA new kind of organophilic clay, cotreated by methyl tallow bis‐2‐hydroxyethyl quaternary ammonium and epoxy resin into sodium montmorillonite (to form a strong interaction with polyamide 66 matrix), was prepared and used in preparing PA66/clay nanocomposites (PA66CN) via melt‐compounding method. Three different types of organic clays, CL30B–E00, CL30B–E12, and CL30B–E23, were used to study the effect of epoxy resin in PA66CN. The morphological, mechanical, and thermal properties have been studied using X‐ray diffraction, transmission electron microscopy (TEM), mechanical, and thermal analysis, respectively. TEM analysis of the nanocomposites shows that most of the silicate layers were exfoliated to individual layers and to some thin stacks containing a few layers. PA66CX–E00 and PA66CX–E12 had nearly exfoliated structures in agreement with the SAXS results, while PA66CX–E23 shows a coexistence of intercalated and exfoliated structures. The storage modulus of PA66 nanocomposites was higher than that of the neat PA66 in the whole range of tested temperature. On the other hand, the magnitude of the loss tangent peak in α‐ or β‐transition region decreased gradually with the increase in the clay loading. Multiple melting behavior in PA66 was also observed. Thermal stability more or less decreased with an increasing inorganic content. Young's modulus and tensile strength were enhanced by introducing organoclay. Among the three types of nanocomposites prepared, PA66CX–E12 showed the highest improvement in properties, while PA66CX–E23 showed properties inferior to that of PA66CX–E00 without epoxy resin. In conclusion, an optimum amount of epoxy resin is required to form the strong interaction with the amide group of PA66. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1711–1722, 2006

Morphology and mechanical properties of polyamide 12/polypropylene blends in presence and absence of reactive compatibiliser

Blends of polyamide 12 (PA12) and isotactic polypropylene (PP) were prepared by melt mixing in an internal mixer in presence and absence of compatibilisers. The compatibiliser used was maleic anhydride functionalised polypropylene (PP- g-MA). Effect of compatibilisation on the blends has been evaluated from the morphological parameters derived from scanning electron micrographs (SEM) of cryogenically fractured and extracted surfaces of the specimens. The uncompatibilised blends showed two-phase unstable morphology due to high interfacial tension and coalescence effects in the absence of favourable interactions at interface between the individual phases. Incompatibility increased as the concentration of dispersed phase in the blend increased. Compatibilisation stabilised the morphology by reducing the particle size as well as interparticle distance and enhancing the interfacial area and interface adhesion. A critical concentration of compatibiliser required for effective compatibilisation (CMC) was observed beyond which there was no net improvement in interfacial properties and was considered as the point of interfacial saturation. Experimental results were compared with the compatibilisation theories of Noolandi and Hong and Leibler and based on the calculated average interfacial area occupied per compatibiliser molecule it was concluded that the molecular state of compatibiliser at interface changed with concentration. It was supported by the rate constant for change in interfacial tension ( K) values which experienced a maximum at CMC followed by drastic reduction. Mechanical properties of the uncompatibilised blends showed inferior properties. It was found that compatibilisation significantly improved the mechanical properties. A good correlation has been observed between the mechanical properties and morphological parameters.

The Effect of Polyethylene-Octene Elastomer on the Morphological and Mechanical Properties of Polyamide 6/Polypropylene Nanocomposites

Rubber-toughened nanocomposites (RTNC) consisting of ternary blends of polyamide 6 (PA6), polypropylene (PP) and polyethylene-octene elastomer (POE) containing 4 wt% of organophilic modified montmorillonite were produced by melt compounding followed by injection moulding. The blend composition was kept constant (PA6/PP=70/30 parts by weight) while the POE content was varied between 5 and 20 wt%. Maleated PP (PP-g-MA) was used as compatibilizer. The morphology of the RTNC was studied by scanning electron microscopy and X-ray diffraction (XRD). The mechanical properties of RTNC were studied through tensile, flexural, Izod impact and fracture toughness properties. While the tensile and flexural properties were found to decrease with the increasing concentration of POE, the toughness was significantly enhanced as compared to the neat PA6/PP blends. In general, the blends containing 10-15 wt% of POE had the best balance of stiffness, strength and toughness. The addition of 30 wt% of PP in the PA6 matrix improved the compatibility between PA6 and the rubber phase. XRD established that the organoclay was well dispersed (exfoliated) and preferentially embedded in the PA6 phase.

Wplyw metylomaleinianu rycynolo-2-oksazoliny na strukture oraz wlasciwosci mieszanin poliamidu 6 i polietylenu malej gestosci

Effect of PE-LD grafting with ricinol-2-oxazoline methylmaleate (MRO) on phase structure as well as thermal and mechanical properties of polyamide 6 and low-density polyethylene blends (PA 6/PE-LD-g-MRO), differing in composition, obtained in reactive extrusion process, has been studied. This effect was studied using the following methods: infrared spectroscopy (FT-IR, Fig. 1 and 2), differential scanning calorimetry (DSC, Fig. 3 and 4, Table 1 and 2), scanning electron microscopy (SEM, Fig. 5) and dynamic mechanical/thermal analysis (DMTA, Figs. 6-10). The blends show heterogenic structure which, as a result of chemical reactions going during the extrusion, stabilizes at microphase level [probably of functional groups of PA 6 with oxazoline groups grafted onto PE according to equation (2)]. It advantageously influences mechanical properties (Tables 3-5, Fig. 11). Results of investigations show the compatibilizing effect of MRO.

Study of injection molded microcellular polyamide‐6 nanocomposites

AbstractThis study aims to explore the processing benefits and property improvements of combining nanocomposites with microcellular injection molding. The microcellular nanocomposite processing was performed on an injection‐molding machine equipped with a commercially available supercritical fluid (SCF) system. The molded samples produced based on the Design of Experiments (DOE) matrices were subjected to tensile testing, impact testing, Dynamic Mechanical Analysis (DMA), and Scanning Electron Microscope (SEM) analyses. Molding conditions and nano‐clays have been found to have profound effects on the cell structures and mechanical properties of polyamide‐6 (PA‐6) base resin and nanocomposite samples. The results show that microcellular nanocomposite samples exhibit smaller cell size and uniform cell distribution as well as higher tensile strength compared to the corresponding base PA‐6 microcellular samples. Among the molding parameters studied, shot size has the most significant effect on cell size, cell density, and tensile strength. Fractographic study reveals evidence of different modes of failure and different regions of fractured structure depending on the molding conditions. Polym. Eng. Sci. 44:673–686, 2004. © 2004 Society of Plastics Engineers.

A processing‐induced clay dispersion and its effect on the structure and properties of polyamide 6

AbstractThe nanostructures and morphologies of polyamide 6 (PA6)/organoclay nanocomposites prepared by melt compounding have been studied by using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). A combination of XRD and TEM indicates that an exfoliated clay morphology dominates at low clay loadings (≤5 wt%) and a mixture of intercalated and exfoliated structures exists at high clay concentrations. It is worth noting, however, that optical microscopy (OM) even shows the presence of large clay agglomerates in samples with higher clay contents. OM images further present an overview of an uneven clay distribution due to the effect of injection molding. The crystalline structure of PA6 is greatly affected by this unevenness in the processing‐induced clay dispersion, as evidenced by differential scanning calorimetry (DSC). The thermal dynamic and mechanical properties of PA6 and the nanocomposites have been investigated as a function of clay concentration. The tensile tests show that the degree of dispersion of the nanoclay within the polymer matrix plays a vital role in property improvement. Copyright © 2004 Society of Chemical Industry

Effects of swelling agents on the crystallization behavior and mechanical properties of polyamide 6/clay nanocomposites

AbstractMontomorillonite was organically modified with three different swelling agents: n‐dodecylamine, 12‐aminolauric acid, and 1,12‐diaminodecane. These organoclays and polyamide 6 (PA6) were blended in a formic acid solution. X‐ray diffraction analysis showed that the clay still retained its layer structure in the PA6/clay nanocomposite. Consequently, these materials were intercalated nanocomposites. The effects of the swelling agent and organoclay content on the crystallization behavior of the PA6/clay nanocomposites were studied with differential scanning calorimetry. The results showed that the position and width of the exothermic peak of the PA6/clay nanocomposites were changed during the nonisothermal crystallization process. The clay behaved as a nucleating agent and enhanced the crystallization rate of PA6.The crystallinity of PA6 decreased with an increasing clay content. Different swelling agents also affected the crystallization behavior of PA6. The effects of the type and content of the swelling agent on the tensile and flexural properties of PA6/clay nanocomposites were also investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1686–1693, 2003

Determination of moisture content in nylon 6,6 by near‐infrared spectroscopy and chemometrics

AbstractThe effects of moisture on the morphology and mechanical properties of polyamides have been extensively studied by a number of researchers. However, the assessment of water content in the resins has been carried out by thermal or thermogravimetric methods, which are destructive. In the present work partial least‐squares (PLS) calibration models based on near‐infrared (NIR) spectroscopy were produced in order to predict the moisture content of nylon 6,6. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and the loss‐on‐drying (LOD) method were used as reference methods. TGA, LOD, DSC, and NIR analysis were performed in parallel, and the obtained data were used for multivariate calibration purposes. Data pretreatment techniques such as derivation and multiplicative scattering correction (MSC) successfully eliminated the baseline offset present in the raw spectra and compensated for differences in thickness and light scattering of the analyzed samples. Calibration models were validated by full cross validation with the help of a test set. A comparison of the prediction ability of PLS models based on pretreated data was also done. NIR spectroscopy is a rapid and nondestructive method for the determination of moisture in recycled nylon. The moisture content can be predicted with a RMSEP = 0.05 wt %. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2165–2170, 2003

Morphology, thermal and mechanical behavior of polyamide 6/layered-silicate nanocomposites

The microstructure, morphology, thermal and mechanical properties of polyamide 6/layered-silicate nanocomposites (PLSN) have been studied using X-ray diffraction (XRD), tapping-mode atomic force microscopy (AFM), differential scanning calorimetry (DSC) and tensile tests. The XRD and AFM results indicate that the organically-modified layered silicates are intercalated in the polyamide 6 (PA6) matrix. Also, the crystallization and thermal behavior of PA6 are influenced by the addition of layered silicates into polymer matrix. A silicate-induced crystal transformation from the α-form to the γ-form of PA6 is confirmed by XRD and DSC, i.e., the formation of γ crystal is enhanced by the presence of silicates. In comparison to PA6, the thermal property of PLSN has been investigated using DSC. The possible origins of a new silicate-induced endothermic peak are discussed. Tensile tests show that the tensile modulus and yield strength increase while the strain-at-yield decreases with increasing clay loading.

Recycling of dry and wet polyamide 6

AbstractRecycling of polycondensation polymers can give rise to secondary materials with good mechanical properties only if a careful drying is carried out before the melt reprocessing operations. The presence of humidity provokes the hydrolytic chain scission of the macromolecules and the consequent decrease of molecular weight and properties. In this work, the drying step was substituted by the addition of an antioxidant that is able to protect the macromolecules because it is the autioxidant is more prone to hydrolysis, thus removing the water from the melt. The mechanical properties of polyamide 6 reprocessed more times in wet conditions and in the presence of this stabilizer are even better than those obtained reprocessing the dry polyamide. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1899–1903, 2002

Compatibility and mechanical properties of polyamide-6/ polystyrene/diblock poly(styrene-b-ethylene oxide) copolymer blends

Dynamic mechanical studies indicate that poly(styrene-b-ethylene oxide) (SbEO) diblock copolymer can be utilized to achieve compatibility in blends of incompatible polymer pairs, polyamide-6/polystyrene (PA6/PS). It has been found that both the compatibility and the mechanical properties of the blends PA6/PS (80/20 wt/wt) can be improved by the addition of small amounts (2 phr) of SbEO copolymers.

Struktura fazowa i wlasciwosci mieszanin poliamidu 6 z poli(tereftalanem butylenu)

Struktura fazowa i wlasciwosci mieszanin poliamidu 6 z poli(tereftalanem butylenu)