Ternary Polyamide Research Articles

Fabrication of ethylene-vinyl acetate copolymer/polyamide/modified sepiolite composite with improved physical properties via e-beam irradiation

The effects of silanized sepiolite (SP) and electron beam (e-beam) irradiation on the physico-mechanical properties of ethylene-vinyl acetate copolymer (EVA)/ternary polyamide (tPA) composites were studied. SP was silanized with vinyltriethoxysilane (VTES) to enhance the dispersion and compatibility of the inorganic filler into the EVA/tPA matrix. The crosslinking of EVA/tPA by e-beam irradiation was carried out ranging from 50 to 250 kGy. The prepared composite films were characterized for change in morphology, mechanical properties, crosslinking effect on crystallinity and swelling using various established analytical techniques. Experimental results indicated that tensile strength of irradiated composite EVA/tPA/m-SP5 (70/30/5) was 3 times higher than that of virgin composite film at an absorbed dose of 250 kGy. The storage modulus of EVA/tPA/m-SP5 (70/30/5) composite film was significantly increased with the increase of absorbed dose. However, melting and crystallization temperature of EVA/tPA composites slightly decreased with the increase of absorbed dose. Moreover, the modification of SP with VTES and irradiated composite films were subjected to oil swelling studies.

Effect of Electron Beam Irradiation on Thermal and Mechanical Properties of Polyamide Copolymer/Multiwall Carbon Nanotube Composites

Ternary polyamide (tPA) copolymer is susceptible to degradation when it is irradiated by electron beam (e-beam), and effective methods to avoid degradation and increase gel content are highly desirable for crosslinking. Carboxylated multiwall carbon nanotube (MWCNT) is modified by hydroxyethyl acrylate (HEA) in this paper and used as a co-agent for the e-beam irradiation crosslinking of tPA copolymer. HEA modified MWCNT can function as an effective co-agent for the e-beam irradiation crosslinking of tPA copolymer to increase the gel content and improve the mechanical properties of tPA copolymer. Under an irradiation of 160 kGy, addition of 2 parts per hundred (phr) HEA modified MWCNT into tPA copolymer can increase the gel content of tPA copolymer from about 20% to 40% (mass ratio) and increase the tensile strength from 45 to 59MPa. The irradiation also affects the glass transition temperature of tPA copolymer by increasing the gel content. The results show that HEA modified MWCNT can act as a nucleating agent to increase the crystallization temperature, melting temperature and crystallinity of tPA copolymer.

Effect of Electron Beam Irradiation on the Mechanical and Thermal Properties of Ternary Polyamide Copolymer

In this study, the effect of electron beam irradiation on the thermal and mechanical properties of ternary polyamide copolymer (tPA) was investigated. The crosslinking of tPA induced by e-beam irradiation was carried out over a range of dose from 50 to 300 kGy with triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), and N,N′-m-phenylene dismaleimide (HVA-2) as crosslinking co-agents. With increasing dose, the gel contents of tPA containing the co-agents increased more significantly than neat tPA. After the addition of 2.5 phr HVA-2 into tPA and the electron beam irradiation of 150 kGy, the gel content of tPA increased from 11% to 77%, which has a profound influence on the tensile strength, glass transition temperature, and thermal stability of tPA.

Reactive processing of ethylene-vinyl acetate rubber/polyamide blends via a dynamic transesterification reaction

Dynamic vulcanization process of ethylene-vinyl acetate rubber (EVM) and ternary polyamide copolymer (tPA) blends in the presence of tetraethyloxysilane (TEOS) was investigated. The morphology, crosslink density and mechanical properties of the resultant EVM/tPA thermoplastic elastomers (TPEs) were characterized. The dynamically crosslinked EVM phase was distributed homogeneously in the continuous tPA phase for the EVM/tPA (70/30) TPE, and the phase size of EVM decreased further as the TEOS content increased. The crosslink density reached 3.17 × 10−5 mol cm−3, and the tensile strength and the elongation at break were up to 10.6 MPa and 296 %, respectively, when the TEOS content was increased to 8 phr, and the heat oil resistance was accordingly enhanced. As compared to dicumyl peroxide-initiated crosslinking reaction of EVM, the crosslinking reaction of EVM through the transesterification reaction between EVM and TEOS presented lower crosslinking rate constant and activation energy, indicating that the transesterification reaction is more suitable for high temperature dynamic vulcanization processing. The optimized dynamic vulcanization process of EVM/tPA TPEs is useful for developing high-performance TPEs for automotive applications.

Mechanical and morphological properties of a ternary polyamide 6 nanocomposite with optimized stiffness/toughness performance

While developing new polymers, a high level of stiff and simultaneously tough material behavior is an important goal. This study shows a new approach to optimize the stiffness/toughness behavior of polyamide 6 (PA 6) by incorporating both stiff and elastomeric nanofillers during melt compounding. For stiffness enhancement of PA 6, an organic-modified layered silicate (organoclay) was used, whereas to compensate for the toughness properties, a nanostructured PA 6/polyether block copolymer (PA 6-copo) was applied. In the first step, binary nanocomposites have been investigated whereby correlations between morphological and mechanical properties have been derived. Subsequently, these results have been used to adapt the processing conditions for the ternary nanocomposites. Despite a considerable interaction of both nanofillers the stiffness/toughness balance of the PA 6 nanocomposite has been optimized significantly. At a filler content of only 8 mass% organoclay and 8.3 mass% PA 6-copo, Young's modulus and tensile strength of PA 6 could be increased by 55% and 18%, respectively. In addition, the notched impact strength of PA 6 was enhanced substantially by 58%. POLYM. ENG. SCI., 54:247–254, 2014. © 2013 Society of Plastics Engineers

Morphology and mechanical properties of ethylene‐vinyl acetate rubber/polyamide thermoplastic elastomers

AbstractHigh performance thermoplastic elastomers based on ethylene‐vinyl acetate rubber (EVM) and ternary polyamide copolymer (tPA) were prepared through a dynamic vulcanization process in the presence of dicumyl peroxide (DCP). The morphology, crystallization, and mechanical properties of the EVM/tPA blends were studied. A phase transition of EVM/tPA blend was observed at a weight ratio of 60/40. The presence of EVM increased the melting enthalpy at the high temperature of tPA, ascribing to the heterogeneous nucleating effect of EVM. The tensile strength of EVM/tPA (70/30) blends was increased up to 20.5 MPa as the DCP concentration increased to 3.5 phr, whereas the elongation at break of the blends kept decreasing as the DCP concentration increased. The addition of ethylene‐acrylic acid copolymer (EAA) or maleic anhydride‐grafted EVM (EVM‐g‐MAH) to the EVM/tPA blends both induced finer dispersion of the EVM particles in the tPA phase and improvement in the tensile strength and elongation at break of the blends, which were ascribed to the compatibilization of EAA or EVM‐g‐MAH. Finally, a high performance EVM/tPA (70/30) thermoplastic elastomer with Shore A hardness of 75, tensile strength of 24 MPa, elongation at break of 361%, and set at break of 20% was obtained by adding 5 wt % of EVM‐g‐MAH and 3.5 phr DCP. It has great potential in automotive and oil pipeline applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Processing and properties of modified polyamide 66‐organoclay nanocomposites

AbstractBinary polyamide 66 nanocomposites containing 2 wt % organoclay, polyamide 66 blend containing 5 wt % impact modifier, and ternary polyamide 66 nanocomposites containing 2 wt % organoclay and 5 wt % impact modifier were prepared by melt compounding method. The effects of E‐GMA and the types of the organoclays on the interaction between the organoclay and the polymer, dispersion of the organoclay, morphology, mechanical, flow, and thermal properties of the nanocomposites were investigated. Partial exfoliation and improved mechanical properties are observed for Cloisite® 15A and Cloisite® 25A nanocomposites. On the other hand, the organoclay was intercalated or in the form of tactoids in Cloisite® 30B nanocomposites. Components of the nanocomposites containing Cloisite® 15A and Cloisite® 25A were compounded in different addition orders. Mixing sequence of the components affected both the dispersion of the organoclay and the mechanical properties drastically. SEM analyses revealed that homogeneous dispersion of the organoclay results in a decrease in the domain sizes and promotes the improvements in the toughness of the materials. Melt viscosity was also found to have a profound effect on the dispersion of the organoclay according to MFI and XRD results. Crystallinity of the nanocomposites did not change significantly. It is only the type of the constituents and their addition order what dramatically influence the nanocomposite properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008

Polyamide nanocomposites with improved toughness

AbstractPolymer nanocomposites containing several percent of exfoliated layered silicates are materials with a unique weight/performance ratio. The only parameter that is not enhanced, but even decreased, is toughness. This work focused on the toughness enhancement of these advanced systems with polyamide matrix prepared via melt‐mixing (i.e., by a conventional method of polymer processing having an advantage of easy simultaneous addition of other components). Analogously to ternary polyamide blends with improved mechanical behavior, containing finely and separately dispersed elastomer and rigid polymer, elastomer particles with an average size of 60 nm were incorporated in the nanocomposite. The very low particle size was achieved by in situ reactive compatibilization by using suitably functionalized elastomers. The simultaneously increasing viscosity of the system enhanced exfoliation of the silicate. Melt exfoliated nanocomposites containing 3 wt % of clay and 5 wt % of elastomer particles exhibit increased toughness without significant loss of other properties. Elastomer particles increase toughness by both acting as stress concentrators (by initiating energy absorbing microdeformations) and influencing the clay‐induced matrix crystalline structure. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 288–293, 2005

Morphology and properties of ternary polyamide 6/polyamide 66/elastomer blends

AbstractThe aim of the work presented is to evaluate the mechanisms and phase interactions in ternary blends based on different polyamides and functionalised elastomers, and to establish a correlation between the morphology controlled by the specific binary interactions, and physical and technological properties, respectively.The properties of the ternary system polyamide 6/polyamide 66/ elastomer depend on the specific blend morphology which is determined mainly by the differences of the surface tension of the components. A phase‐in‐phase structure was observed by microscopic study (AFM) in the ternary polyamide 6/polyamide 66/elastomer blends with maleic anhydride grafted ethene‐octene copolymer, and a “quasi” phase‐in‐phase structure in blends with maleic anhydride grafted ethene‐propene‐diene copolymer as the elastomer phase. An incorporation of polyamide inside of the elastomer particles was observed in the first case due to the difunctionality of polyamide 66. This type of morphology causes an increased elongation at break and toughness of these blends.In comparison to the binary polyamide based blends the ternary blends show an increased elastic modulus, elongation at break and yield stress as well as a high impact strength at low temperatures up to −20 °C. Copyright © 2003 John Wiley & Sons, Ltd.

Control of the morphology of polyamide/styrene-acrylonitrile copolymer blends via reactive compatibilizers

The effects of several different compatibilizing agents with reactive functional groups (acid and/or anhydride) on the morphology of blends of styrene-acrylonitrile copolymers (SAN) in polyamide (PA) matrices were investigated using transmission electron microscopy. The primary focus was on the use of a series of imidized acrylic polymers and how their functionality for reaction with nylon-6 and their miscibility with SAN copolymers affected the morphology of nylon-6/SAN blends. Glass transition behaviour of binary blends of the imidized acrylic polymers with SAN systems indicated that miscible blends over a restricted range of AN content in the SAN could be obtained by limiting the imide and free-acid contents of the imidized acrylic polymers. In the case of the ternary polyamide blends, the most efficient reduction in the dispersed-phase particle size was obtained via imidized acrylic polymers that are miscible with the SAN phase and can react with the polyimide to a significant degree. For nylon-6/SAN blends compatibilized with polymers containing a high level of anhydride functionality, complex morphologies consisting of at least two distinct populations of dispersed phase were observed. The factors responsible for generation of such complex morphologies were examined using different staining techniques, and it was proposed that a rheological effect is the dominant issue. The chemical functionality characteristics of the polyamide matrix were also shown to have an effect on the morphology of nylon/SAN blends compatibilized with imidized acrylic polymers.

Morphology—properties relationships in binary polyamide 6/rubber blends: Influence of the addition of a functionalized rubber

AbstractThe modification of an amorphous random ethylene‐propylene rubbery copolymer (EPM) has been accomplished by solution grafting of maleic anhydride molecules promoted by radical initiators, The resulting EPM‐g‐succinic anhydride (EPM‐g‐SA) and EPM have been used to obtain binary polyamide 6/EPM or polyamide 6/EPM‐g‐SA and ternary polyamide 6/EPM/EPM‐g‐SA blends by melt mixing. The formation of an EPM‐g‐PA6 graft copolymer during the blend preparation has been assumed. Different blend morphologies were observed by scanning electron microscopy (SEM) according to the nature and content of the rubber used. The tensile mechanical properties and the impact behavior of the prepared blends were investigated and correlated with the SEM analysis of the fracture surfaces. Binary and ternary blends containing 20 percent by weight of total rubber show a significant improvement of the impact properties at low temperature (−20°C) when the rubber is partly or entirely EPM‐g‐SA. In the case of PA6/EPM‐g‐SA (80/20) blend these results are related to the presence of rubbery domains of very small size strongly adherent to the PA6 matrix. In the case of 80/10/10 ternary blends, a much more complicated overall morphology is observed. Such morphology is characterized by the presence of large EPM domains, likely containing some EPM‐g‐PA6 graft molecules acting as an interfacial agent, and domains of EPM‐g‐PA6 of smaller size strongly adherent to the matrix as in the previous case.