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Naohide Tomita - One of the best experts on this subject based on the ideXlab platform.

  • EVALUATION OF THE BIOLOGICAL RESPONSE TO CROSSLINKED ULTRA-HIGH MOLECULAR WEIGHT POLYETHYLENE PARTICLES
    Journal of Bone and Joint Surgery-british Volume, 2016
    Co-Authors: Miho Niikura, K. Uetsuki, S. Nogi, Y. Han, A. Turner, T. Yutani, Naohide Tomita
    Abstract:

    INTRODUCTION Ultra-High Molecular Weight Polyethylene (UHMWPE) wear debris is thought to be a main factor in the development of osteolysis (1). However, the method for the evaluation of the biological response to UHMWPE particles has not yet been standardized. In this study, four different types of UHMWPE particles were generated using a mechanized pulverizing method and the biological responses of macrophages to the particles were investigated using an inverted cell culturing process (2). MATERIALS & METHODS Virgin samples were manufactured via Direct Compression Molding (DCM) technique from UHMWPE GUR1050 resin powder (Ticona, USA). For vitamin E (VE)-blended sample, the resin was mixed with VE at 0.3 wt% and the mixture was then molded using DCM. The crosslinked virgin samples were made by gamma ray irradiation to UHMWPE GUR1020 resin sheet (Meditech, USA) with doses of 95kGy ±10% and annealed. The VE-blended crosslinked samples were made by electron beam irradiation to VE-blended samples with doses of 300kGy and annealed. The material conditions were summarized in Figure 1. To pulverize the samples, the Multi-Beads Shocker (Yasui Kikai, Japan) was used. After pulverization, samples were dispersed in an ethanol solution and sequentially filtered through polycarbonate filters. Over 100 sections of the filter were selected randomly and images of the particles were analyzed using scanning electron microscope (SEM). To analyze the macrophage biological response, an inverted cell culturing process was used (2). The mouse macrophage-like cells were seeded at densities of 4×105cells per well in a 96-well culture plate and incubated for 1h. UHMWPE particles suspended in the culture medium were then added to each well in the appropriate amount. After that, fresh medium was added to fill the wells, and a sealing film was used to cover the culture plate. The culture plate was then inverted to cause the UHMWPE particles interact with the adhered macrophages. The inverted culture plate was incubated for 8h. The amount of TNF-α was measured by enzyme-linked immunosorbent assay (ELISA). RESULTS & DISCUSSION Geometric measurements showed no significant difference in the UHMWPE particles (Figure 2). The amount of TNF-α released stimulated by the crosslinked virgin particles showed significantly higher relative to the other UHMWPE particles (Figure 3). During crosslinking irradiation, the carbon free radicals are generated in the main chain (3). In the presence of oxygen, these radicals can react to form peroxy radicals and when the peroxy free radicals react with hydrogen they form hydroperoxides, which can further degrade into other oxidation products (4). It has been reported that VE hinders this cascading in UHMWPE (5). Therefore, it is possible that oxidation of the crosslinked virgin UHMWPE was involved in the cytokine response observed in this study. However resin material, Molding technique and the irradiation method were different between crosslinked virgin and VE-blended crosslinked samples. Further consideration will be needed to examine the relationship between residual radicals, hydroperoxides and biological response.

  • EFFECT OF ANNEALING TEMPERATURE ON MECHANICAL PROPERTIES OF VITAMIN-E BLENDED UHMWPE
    Journal of Bone and Joint Surgery-british Volume, 2016
    Co-Authors: Keita Uetsuki, Yuta Osaka, Naohide Tomita
    Abstract:

    Introduction Dl-α-Tocopherol (VE)-blended non-crosslinked UHMWPE has been developed as a bearing surface material for knee prostheses due to the radical scavenging capabilities of vitamin E and has demonstrated a low wear rate in knee simulator testing [1,2]. In previous our study, VE-blended, crosslinked UHMWPE has demonstrated a low wear rate in hip simulator testing [3, 4]. As the radical scavenging capabilities also reduce the crosslinking degree of the material, multiple dose crosslinking has been investigated. However, these crosslinked UHMWPE materials may have different mechanical properties, as each crosslinking process, especially the annealing condition, is different. Additionally, there is little information about VE-blended, crosslinked UHMWPE with different annealing conditions. In this study, the effect of annealing temperature was investigated with regard to tensile strength, crosslink density, and crystallinity of VE blended, crosslinked UHMWPE. Method VE blended samples were manufactured via Direct Compression Molding following the blending of UHMWPE resin powder (GUR1050, Ticona Inc.) with VE (dl-α-tocopherol, Eisai Co. Ltd.) at 0.3wt%. The virgin samples were derived similarly, but without the addition of VE. Both materials underwent crosslinking by irradiation via a 10MeV electron beam at 300kGy and were then heat treated at several temperatures (25, 80, 110, 130 and 150 °C) for 24 hours. Gel content, which can be interpreted as cross-link density, was determined by measuring the weight of the samples before and after soaking in decahydronaphthalene at 150 °C for twelve days. Tensile tests were carried out following JIS K 7113, with the cross head speed set at 50 mm/min. Crystallinity was determined by using DSC and integrating over the enthalpy curve from 80 to 150 °C and normalizing with the enthalpy of melting for 100% crystalline polyethylene. Result Fig. 1 shows the gel content of UHMWPE samples after crosslinking. Raising the annealing temperature caused an increase in the gel content regardless the VE content. Additionally, among samples with the same annealing temperature, VE samples had the lower gel content. Fig. 2 shows the yield strength of UHMWPE samples. Higher annealing temperature decreased the yield strength, and increased elongation. Fig. 3 shows the crystallinity of each UHMWPE sample. Higher annealing temperature decreased the crystallinity of UHMWPE. Discussion In this study, the effect of annealing temperature on the mechanical properties of crosslinked UHMWPE was investigated. The results indicated that a greater volume of crystalline UHMWPE melted and reformed at the higher annealing temperatures. This was thought to occur due to the fact that UHMWPE consists of a range of different molecular weight chains, allowing for melting below 135°C. Therefore, the crystallinity and crosslink density changed for each annealing temperature. The annealing is a simple but effective method for designing the crystallinity and crosslinking of UHMWPE.

  • Tribological Performance of Vitamin E-Blended and Highly Crosslinked UHMWPE Material
    Journal of Bone and Joint Surgery-british Volume, 2013
    Co-Authors: Keita Uetsuki, Tomohiro Sugimoto, Toru Kawasaki, Alex Turner, Naohide Tomita
    Abstract:

    Introduction Vitamin-E (VE)-blended UHMWPE has been developed as a bearing-surface material due to the antioxidant ability of VE and has demonstrated a low wear rate in knee simulator [1]. Additionally, in vitro biological response testing has revealed that wear particles from VE blended UHMWPE induce the secretion of inflammatory cytokines at significantly lower levels compared to conventional UHMWPE [2]. However, as the joint kinematics are different between the knee and the hip, it is not guaranteed that these improvements will be repeated in the hip. In this study, the wear resistance of VE-blended UHMWPE was evaluated in knee and hip simulator tests and the effects of VE concentration and electron-beam irradiation were investigated. Materials and Methods VE blended samples (GUR_VE xx%) were manufactured via Direct Compression Molding following the blending of UHMWPE resin powder with VE at several concentrations (0, 0.1, 0.3, 1.0%). Cross-linking for the VE samples was achieved by 10 MeV electron beam at several irradiance doses (30, 90, 300 kGy) and annealed below the melting point of UHMWPE. Knee and hip simulator testing were carried out according to ISO 14243 and ISO 14242, respectively, and the volumetric wear was calculated. The gel fraction was determined by measuring the weight of the samples before and after soaking in decahydronaphthalene at 150°C. The oxidative resistance of the material was determined by measuring the Oxidation Index (OI) following ASTM F2102 before and after compulsory aging (ASTM2003). Radical measurements were made using high-sensitivity X-band ESR. Results & Discussion In knee simulator testing, the volumetric wear for GUR_VE was lower than that for non-blended UHMWPE (GUR), with this difference amplified by aging. Conversely, in hip simulator testing, the wear rates were the same for the GUR and GUR_VE samples, while the GUR_XL samples showed almost no wear both before and after aging. Additionally, the wear for the non-XL samples (GUR and GUR_VE) actually decreased after aging. Treatment utilizing electron-beam irradiation and annealing below the melting point achieved a high degree of cross-linking in VE-blended UHMWPE, while also preserving the antioxidant ability of VE. These results suggest that electron-beam irradiated VE blended UHMWPE can be used as a bearing surface material for hip prostheses. However, the longevity of prosthesis is determined not only by its wear performance, but also by its biocompatibility. ESR measurements have revealed that VE radicals are formed during radiation crosslinking of VE blended UHMWPE, and it is thought that the VE radicals may reduce the anti-inflammatory effects of UHMWPE particles containing VE. We are now developing a multiDirectional lift-off type aseptic wear simulation device and procedures to measure the biological response to wear particles produced therein [3]. Acknowledgement A part of this study was supported by the “Super special consortia” for supporting the development of cutting edge medical care (Cabinet office, Government of Japan) and Innovation promotion program (NEDO).

  • Annealing Stabilizes Vitamin E Radicals and Accelerates Crosslinking Reaction in Electron-Beam-Irradiated Dl-Alpha-Tocopherol-Blended Ultra High Molecular Weight Polyethylene
    2012
    Co-Authors: Toru Kawasaki, Keita Uetsuki, Daisuke Hamada, Kunihiko Tajima, Yasuhiro Sakurai, Naohide Tomita
    Abstract:

    INTRODUCTION Electron-beam-irradiated dl -α-Tocopherol (Vitamin E)-blended UHMWPE is now being considered as a potential new bearing surface material for hip prosthesis [1]. However, Vitamin E stabilizes some of the primary free-radicals required for crosslinking, thereby reducing the material9s crosslink density [2]. Additionally, some biological-stabilization effects of Vitamin E may also be reduced by oxidation. In this study, Vitamin E radicals in electron-beam-irradiated UHMWPE were measured and identified using Electron Spin Resonance (ESR), and the effects of annealing on radical stabilization and crosslink density were examined. MATERIALS & METHODS Both pure UHMWPE and Vitamin E added (0.3% w/w) resin was used to produce bulk specimens via vacuum Direct Compression Molding at 220°C under 25 MPa for 30 min. Cylindrical pins (3.5 mm diameter, 40 mm length) for ESR measurement were then machined and placed in vacuum packaging. The pins were irradiated at 300 kGy, with half of each test group annealed at 80°C for 24 hours. Free radical measurements were made using a high-sensitive X-band ESR operating at 9.44 GHz. Detection of Vitamin E radicals was performed by comparing the characteristic symmetrical spectrum of oxidized Vitamin E to the spectra observed for the pins using both g-value and linewidth as references. Crosslink density was measured via gel fraction analysis and was performed in accordance with ASTM D2765. Thin sections (20 × 40 mm 2 , 200 μm) were machined from the bulk specimens, which were then placed in vacuum packaging, irradiated and annealed at the same conditions as those for the ESR measurements. Two of these thin sections were then placed in a stainless-steel cage (200 µm pore diameter) and were immersed in decahydronaphtalene at 200°C for 24 hours. These specimens were then extracted using soxhlet extractor at 100°C for 24 hours and dried in vacuum at 150°C for 12 hours. RESULTS The characteristic symmetrical spectrum of oxidized Vitamin E was measured and identified in the electron-beam-irradiated Vitamin E-blended specimens [Fig. 1]. For the annealed samples, this spectrum was reduced [Fig. 2]. The annealing treatments increased gel fraction [Fig. 3] and decreased the total amount of primary free-radicals [Fig. 4] in the electron-beam-irradiated Vitamin E-blended specimens at the same rate as that for the Virgin specimens. DISCUSSION & CONCLUSIONS Electron-beam-irradiated Vitamin E-blended specimens showed the same characteristic symmetrical spectrum as that of oxidized Vitamin E. Thus, measurement and identification of Vitamin E radicals in electron-beam-irradiated UHMWPE was confirmed. Also, annealing treatment at 80°C for 24 hours was effective in stabilizing Vitamin E radicals. The results showed in [Fig. 3] and [Fig. 4] suggest that the treatments increased gel fraction by accelerating the reaction between primary free-radicals. The results also suggest that Vitamin E radical stabilization was achieved through the interaction of Vitamin E radicals amongst themselves, and not through the interchange between Vitamin E radicals and primary free-radicals.

  • reduction of wear volume from ultrahigh molecular weight polyethylene knee components by the addition of vitamin e
    Journal of Orthopaedic Research, 2008
    Co-Authors: Satoshi Teramura, Hideyuki Sakoda, Tomohiro Terao, Miguel M Endo, Kunihiko Fujiwara, Naohide Tomita
    Abstract:

    Wear performance and debris-size distribution of vitamin E (DL-α tocopherol, VE)-added ultrahigh molecular weight polyethylene (UHMWPE) was evaluated using a knee-simulator test. VE was mixed with GUR 1050 UHMWPE powder at 0.3 wt%, and the tibial components of the knee joint were made by Direct Compression Molding. The VE-added UHMWPE showed consistently lower wear volume throughout the test. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:460–464, 2008

Zlatan Denchev - One of the best experts on this subject based on the ideXlab platform.

  • A new approach for preparation of metal-containing polyamide/carbon textile laminate composites with tunable electrical conductivity
    Journal of Materials Science, 2018
    Co-Authors: Filipa Oliveira, Nadya Dencheva, Pedro Martins, Senentxu Lanceros-méndez, Zlatan Denchev
    Abstract:

    Multiscale thermoplastic laminate composites based on polyamide 6 (PA6) dually reinforced by carbon fiber woven textile structures (CFT) and different micron-sized metal particles are prepared for the first time by microencapsulation strategy. In a first step, activated anionic ring-opening polymerization (AAROP) of ε-caprolactam is carried out in suspension, in the presence of different metal particles, to produce shell-core PA6 microcapsules (PAMC) loaded with 13–19% metal. In a second step, the loaded PAMC are distributed between CFT plies with fiber volume fractions Vf  = 0.25 or Vf = 0.50 and then the ply arrays are consolidated by Compression Molding. Separately, metal-loaded PA6 hybrid composites are prepared by Direct Compression Molding of PAMC and used to compare their properties to the CFT-metal laminates. Light- and scanning electron microscopy are used to study the morphology and the interfaces between the fillers and the polymeric matrix. These structural results are related to the mechanical behavior in tension and the electrical properties. A notable increase of the d.c. electrical conductivity in 7 orders of magnitude is observed for the CFT-metal laminates with respect to the neat PA6. This increase is accompanied by a 2.5–3.0 times growth of the Young’s modulus and of the strength at break. It is concluded that the microencapsulation strategy can be applied to produce multifunctional CFT-metal-PA6 thermoplastic composites with tailored electrical and improved mechanical properties for advanced applications.

  • A new approach for preparation of metal-containing polyamide/carbon textile laminate composites with tunable electrical conductivity
    Journal of Materials Science, 2018
    Co-Authors: Filipa D. Oliveira, Pedro Martins, Nadya Dencheva, Senentxu Lanceros-méndez, Zlatan Denchev
    Abstract:

    Multiscale thermoplastic laminate composites based on polyamide 6 (PA6) dually reinforced by carbon fiber woven textile structures (CFT) and different micron-sized metal particles are prepared for the first time by microencapsulation strategy. In a first step, activated anionic ring-opening polymerization (AAROP) of e-caprolactam is carried out in suspension, in the presence of different metal particles, to produce shell-core PA6 microcapsules (PAMC) loaded with 13–19% metal. In a second step, the loaded PAMC are distributed between CFT plies with fiber volume fractions V f = 0.25 or V f = 0.50 and then the ply arrays are consolidated by Compression Molding. Separately, metal-loaded PA6 hybrid composites are prepared by Direct Compression Molding of PAMC and used to compare their properties to the CFT-metal laminates. Light- and scanning electron microscopy are used to study the morphology and the interfaces between the fillers and the polymeric matrix. These structural results are related to the mechanical behavior in tension and the electrical properties. A notable increase of the d.c. electrical conductivity in 7 orders of magnitude is observed for the CFT-metal laminates with respect to the neat PA6. This increase is accompanied by a 2.5–3.0 times growth of the Young’s modulus and of the strength at break. It is concluded that the microencapsulation strategy can be applied to produce multifunctional CFT-metal-PA6 thermoplastic composites with tailored electrical and improved mechanical properties for advanced applications.

Pedro Martins - One of the best experts on this subject based on the ideXlab platform.

  • A new approach for preparation of metal-containing polyamide/carbon textile laminate composites with tunable electrical conductivity
    Journal of Materials Science, 2018
    Co-Authors: Filipa Oliveira, Nadya Dencheva, Pedro Martins, Senentxu Lanceros-méndez, Zlatan Denchev
    Abstract:

    Multiscale thermoplastic laminate composites based on polyamide 6 (PA6) dually reinforced by carbon fiber woven textile structures (CFT) and different micron-sized metal particles are prepared for the first time by microencapsulation strategy. In a first step, activated anionic ring-opening polymerization (AAROP) of ε-caprolactam is carried out in suspension, in the presence of different metal particles, to produce shell-core PA6 microcapsules (PAMC) loaded with 13–19% metal. In a second step, the loaded PAMC are distributed between CFT plies with fiber volume fractions Vf  = 0.25 or Vf = 0.50 and then the ply arrays are consolidated by Compression Molding. Separately, metal-loaded PA6 hybrid composites are prepared by Direct Compression Molding of PAMC and used to compare their properties to the CFT-metal laminates. Light- and scanning electron microscopy are used to study the morphology and the interfaces between the fillers and the polymeric matrix. These structural results are related to the mechanical behavior in tension and the electrical properties. A notable increase of the d.c. electrical conductivity in 7 orders of magnitude is observed for the CFT-metal laminates with respect to the neat PA6. This increase is accompanied by a 2.5–3.0 times growth of the Young’s modulus and of the strength at break. It is concluded that the microencapsulation strategy can be applied to produce multifunctional CFT-metal-PA6 thermoplastic composites with tailored electrical and improved mechanical properties for advanced applications.

  • A new approach for preparation of metal-containing polyamide/carbon textile laminate composites with tunable electrical conductivity
    Journal of Materials Science, 2018
    Co-Authors: Filipa D. Oliveira, Pedro Martins, Nadya Dencheva, Senentxu Lanceros-méndez, Zlatan Denchev
    Abstract:

    Multiscale thermoplastic laminate composites based on polyamide 6 (PA6) dually reinforced by carbon fiber woven textile structures (CFT) and different micron-sized metal particles are prepared for the first time by microencapsulation strategy. In a first step, activated anionic ring-opening polymerization (AAROP) of e-caprolactam is carried out in suspension, in the presence of different metal particles, to produce shell-core PA6 microcapsules (PAMC) loaded with 13–19% metal. In a second step, the loaded PAMC are distributed between CFT plies with fiber volume fractions V f = 0.25 or V f = 0.50 and then the ply arrays are consolidated by Compression Molding. Separately, metal-loaded PA6 hybrid composites are prepared by Direct Compression Molding of PAMC and used to compare their properties to the CFT-metal laminates. Light- and scanning electron microscopy are used to study the morphology and the interfaces between the fillers and the polymeric matrix. These structural results are related to the mechanical behavior in tension and the electrical properties. A notable increase of the d.c. electrical conductivity in 7 orders of magnitude is observed for the CFT-metal laminates with respect to the neat PA6. This increase is accompanied by a 2.5–3.0 times growth of the Young’s modulus and of the strength at break. It is concluded that the microencapsulation strategy can be applied to produce multifunctional CFT-metal-PA6 thermoplastic composites with tailored electrical and improved mechanical properties for advanced applications.

Nadya Dencheva - One of the best experts on this subject based on the ideXlab platform.

  • A new approach for preparation of metal-containing polyamide/carbon textile laminate composites with tunable electrical conductivity
    Journal of Materials Science, 2018
    Co-Authors: Filipa Oliveira, Nadya Dencheva, Pedro Martins, Senentxu Lanceros-méndez, Zlatan Denchev
    Abstract:

    Multiscale thermoplastic laminate composites based on polyamide 6 (PA6) dually reinforced by carbon fiber woven textile structures (CFT) and different micron-sized metal particles are prepared for the first time by microencapsulation strategy. In a first step, activated anionic ring-opening polymerization (AAROP) of ε-caprolactam is carried out in suspension, in the presence of different metal particles, to produce shell-core PA6 microcapsules (PAMC) loaded with 13–19% metal. In a second step, the loaded PAMC are distributed between CFT plies with fiber volume fractions Vf  = 0.25 or Vf = 0.50 and then the ply arrays are consolidated by Compression Molding. Separately, metal-loaded PA6 hybrid composites are prepared by Direct Compression Molding of PAMC and used to compare their properties to the CFT-metal laminates. Light- and scanning electron microscopy are used to study the morphology and the interfaces between the fillers and the polymeric matrix. These structural results are related to the mechanical behavior in tension and the electrical properties. A notable increase of the d.c. electrical conductivity in 7 orders of magnitude is observed for the CFT-metal laminates with respect to the neat PA6. This increase is accompanied by a 2.5–3.0 times growth of the Young’s modulus and of the strength at break. It is concluded that the microencapsulation strategy can be applied to produce multifunctional CFT-metal-PA6 thermoplastic composites with tailored electrical and improved mechanical properties for advanced applications.

  • A new approach for preparation of metal-containing polyamide/carbon textile laminate composites with tunable electrical conductivity
    Journal of Materials Science, 2018
    Co-Authors: Filipa D. Oliveira, Pedro Martins, Nadya Dencheva, Senentxu Lanceros-méndez, Zlatan Denchev
    Abstract:

    Multiscale thermoplastic laminate composites based on polyamide 6 (PA6) dually reinforced by carbon fiber woven textile structures (CFT) and different micron-sized metal particles are prepared for the first time by microencapsulation strategy. In a first step, activated anionic ring-opening polymerization (AAROP) of e-caprolactam is carried out in suspension, in the presence of different metal particles, to produce shell-core PA6 microcapsules (PAMC) loaded with 13–19% metal. In a second step, the loaded PAMC are distributed between CFT plies with fiber volume fractions V f = 0.25 or V f = 0.50 and then the ply arrays are consolidated by Compression Molding. Separately, metal-loaded PA6 hybrid composites are prepared by Direct Compression Molding of PAMC and used to compare their properties to the CFT-metal laminates. Light- and scanning electron microscopy are used to study the morphology and the interfaces between the fillers and the polymeric matrix. These structural results are related to the mechanical behavior in tension and the electrical properties. A notable increase of the d.c. electrical conductivity in 7 orders of magnitude is observed for the CFT-metal laminates with respect to the neat PA6. This increase is accompanied by a 2.5–3.0 times growth of the Young’s modulus and of the strength at break. It is concluded that the microencapsulation strategy can be applied to produce multifunctional CFT-metal-PA6 thermoplastic composites with tailored electrical and improved mechanical properties for advanced applications.

Senentxu Lanceros-méndez - One of the best experts on this subject based on the ideXlab platform.

  • A new approach for preparation of metal-containing polyamide/carbon textile laminate composites with tunable electrical conductivity
    Journal of Materials Science, 2018
    Co-Authors: Filipa Oliveira, Nadya Dencheva, Pedro Martins, Senentxu Lanceros-méndez, Zlatan Denchev
    Abstract:

    Multiscale thermoplastic laminate composites based on polyamide 6 (PA6) dually reinforced by carbon fiber woven textile structures (CFT) and different micron-sized metal particles are prepared for the first time by microencapsulation strategy. In a first step, activated anionic ring-opening polymerization (AAROP) of ε-caprolactam is carried out in suspension, in the presence of different metal particles, to produce shell-core PA6 microcapsules (PAMC) loaded with 13–19% metal. In a second step, the loaded PAMC are distributed between CFT plies with fiber volume fractions Vf  = 0.25 or Vf = 0.50 and then the ply arrays are consolidated by Compression Molding. Separately, metal-loaded PA6 hybrid composites are prepared by Direct Compression Molding of PAMC and used to compare their properties to the CFT-metal laminates. Light- and scanning electron microscopy are used to study the morphology and the interfaces between the fillers and the polymeric matrix. These structural results are related to the mechanical behavior in tension and the electrical properties. A notable increase of the d.c. electrical conductivity in 7 orders of magnitude is observed for the CFT-metal laminates with respect to the neat PA6. This increase is accompanied by a 2.5–3.0 times growth of the Young’s modulus and of the strength at break. It is concluded that the microencapsulation strategy can be applied to produce multifunctional CFT-metal-PA6 thermoplastic composites with tailored electrical and improved mechanical properties for advanced applications.

  • A new approach for preparation of metal-containing polyamide/carbon textile laminate composites with tunable electrical conductivity
    Journal of Materials Science, 2018
    Co-Authors: Filipa D. Oliveira, Pedro Martins, Nadya Dencheva, Senentxu Lanceros-méndez, Zlatan Denchev
    Abstract:

    Multiscale thermoplastic laminate composites based on polyamide 6 (PA6) dually reinforced by carbon fiber woven textile structures (CFT) and different micron-sized metal particles are prepared for the first time by microencapsulation strategy. In a first step, activated anionic ring-opening polymerization (AAROP) of e-caprolactam is carried out in suspension, in the presence of different metal particles, to produce shell-core PA6 microcapsules (PAMC) loaded with 13–19% metal. In a second step, the loaded PAMC are distributed between CFT plies with fiber volume fractions V f = 0.25 or V f = 0.50 and then the ply arrays are consolidated by Compression Molding. Separately, metal-loaded PA6 hybrid composites are prepared by Direct Compression Molding of PAMC and used to compare their properties to the CFT-metal laminates. Light- and scanning electron microscopy are used to study the morphology and the interfaces between the fillers and the polymeric matrix. These structural results are related to the mechanical behavior in tension and the electrical properties. A notable increase of the d.c. electrical conductivity in 7 orders of magnitude is observed for the CFT-metal laminates with respect to the neat PA6. This increase is accompanied by a 2.5–3.0 times growth of the Young’s modulus and of the strength at break. It is concluded that the microencapsulation strategy can be applied to produce multifunctional CFT-metal-PA6 thermoplastic composites with tailored electrical and improved mechanical properties for advanced applications.