Masterbatch production of polyamide 6-clay compounds via continuous in situ polymerization from caprolactam and layered silicates

AbstractNanocomposites based on polyamide 6 (PA6) and montmorillonite-type (MMT) commercial clays, either unmodified or organically modified, were prepared by in-situ polymerization of ε-caprolactam (CL). The above materials were characterized in detail by a number of experimental techniques, including transmission electron microscopy (TEM), wide angle X-ray diffraction (WAXD), infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The formation of nanostructured systems was checked not only for the commonly used ω-aminoacid-modified clay, but also for other types of organoclays. In general, a correlation was found between nanoscopic swelling of the clay in molten CL, measured by X-ray diffraction, and level of clay dispersion in PA6. Specifically, with the most swellable clays, completely exfoliated nanocomposites were obtained. However, also layered silicates modified by compatibilizers having carboxy groups, because of the active role of latter in CL polymerization, formed delaminated nanocomposites despite their low degree of swelling in CL monomer. Both molecular mass and crystallinity of the polyamide matrix were found to be strongly influenced by the presence of specific layered silicates. In particular, some characterization techniques (WAXD, FTIR) have evidenced a close relationship between the MMT used and PA6 crystal structure. Namely, PA6 γ-form is promoted by clay with compatibilizer bearing the carboxy group, which is able to induce the polymer to be tethered on the silicate layers, thus provoking conditions of restricted mobility to occur.

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PA6 and Halloysite Nanotubes Composites with Improved Hydrothermal Ageing Resistance: Role of Filler Physicochemical Properties, Functionalization and Dispersion Technique

Polymers ◽

10.3390/polym12010211 ◽

2020 ◽

Vol 12 (1) ◽

pp. 211 ◽

Cited By ~ 6

Author(s):

Valentina Sabatini ◽

Tommaso Taroni ◽

Riccardo Rampazzo ◽

Marco Bompieri ◽

Daniela Maggioni ◽

...

Keyword(s):

Physicochemical Properties ◽

Polymer Matrix ◽

In Situ Polymerization ◽

Cost Effective ◽

Polyamide 6 ◽

Halloysite Nanotubes ◽

Amide Bonds ◽

Molecular Weights ◽

Dispersion Technique

Polyamide 6 (PA6) suffers from fast degradation in humid conditions due to hydrolysis of amide bonds, which limits its durability. The addition of nanotubular fillers represents a viable strategy for overcoming this issue, although the additive/polymer interface at high filler content can become privileged site for moisture accumulation. As a cost-effective and versatile material, halloysite nanotubes (HNT) were investigated to prepare PA6 nanocomposites with very low loadings (1–45% w/w). The roles of the physicochemical properties of two differently sourced HNT, of filler functionalization with (3-aminopropyl)triethoxysilane and of dispersion techniques (in situ polymerization vs. melt blending) were investigated. The aspect ratio (5 vs. 15) and surface charge (−31 vs. −59 mV) of the two HNT proved crucial in determining their distribution within the polymer matrix. In situ polymerization of functionalized HNT leads to enclosed and well-penetrated filler within the polymer matrix. PA6 nanocomposites crystal growth and nucleation type were studied according to Avrami theory, as well as the formation of different crystalline structures (α and γ forms). After 1680 h of ageing, functionalized HNT reduced the diffusion of water into polymer, lowering water uptake after 600 h up to 90%, increasing the materials durability also regarding molecular weights and rheological behavior.

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The Effect of the Parameters of T-RTM on the Properties of Polyamide 6 Prepared by in Situ Polymerization

Materials ◽

10.3390/ma13010004 ◽

2019 ◽

Vol 13 (1) ◽

pp. 4 ◽

Cited By ~ 1

Author(s):

Orsolya Viktória Semperger ◽

András Suplicz

Keyword(s):

Mechanical Properties ◽

Automotive Industry ◽

Cycle Time ◽

In Situ Polymerization ◽

Rapid Development ◽

Polyamide 6 ◽

Raw Material ◽

Short Cycle ◽

Short Cycle Time

With the rapid development of the automotive industry, there is also a significant need to improve the raw materials used. Therefore, the demand is increasing for polymer composites with a focus on mass reduction and recyclability. Thermoplastic polymers are preferred because of their recyclability. As the automotive industry requires mass production, they require a thermoplastic raw material that can impregnate the reinforcement in a short cycle time. The most suitable monomer for this purpose is caprolactam. It can be most efficiently processed with T-RTM (thermoplastic resin transfer molding) technology, during which polyamide 6 is produced from the low-viscosity monomer by anionic ring-opening (in situ) polymerization in a tempered mold with a sufficiently short cycle time. Manufacturing parameters, such as polymerization time and mold temperature, highly influence the morphological and mechanical properties of the product. In this paper, the properties of polyamide 6 produced by T-RTM are analyzed as a function of the production parameters. We determine the crystallinity and the residual monomer content of the samples and their effect on mechanical properties.

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Features of forming the structure and properties of polyamide-6 via in situ polymerization with oxidized graphite

Journal of Polymer Research ◽

10.1007/s10965-020-02248-5 ◽

2020 ◽

Vol 27 (9) ◽

Author(s):

Dmitriy Leonov ◽

Tatiana Ustinova ◽

Natalia Levkina ◽

Anton Mostovoy ◽

Marina Lopukhova

Keyword(s):

In Situ Polymerization ◽

Polyamide 6 ◽

Structure And Properties ◽

Oxidized Graphite

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In situ Polymerization of Polyamide 6/Boron Nitride Composites to Enhance Thermal Conductivity and Mechanical Properties via Boron Nitride Covalently Grafted Polyamide 6

Polymer Engineering & Science ◽

10.1002/pen.25329 ◽

2020 ◽

Vol 60 (4) ◽

pp. 710-716 ◽

Cited By ~ 2

Author(s):

Hui Fang ◽

Denghui Li ◽

Fangjuan Wu ◽

Xiangfang Peng ◽

Anlin Chen ◽

...

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Boron Nitride ◽

In Situ Polymerization ◽

Polyamide 6

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Characterization of Polyamide 6/Multilayer Graphene Nanoplatelet Composite Textile Filaments Obtained Via In Situ Polymerization and Melt Spinning

Polymers ◽

10.3390/polym12081787 ◽

2020 ◽

Vol 12 (8) ◽

pp. 1787

Author(s):

Jelena Vasiljević ◽

Andrej Demšar ◽

Mirjam Leskovšek ◽

Barbara Simončič ◽

Nataša Čelan Korošin ◽

...

Keyword(s):

Melt Spinning ◽

In Situ Polymerization ◽

Complex Viscosity ◽

Polyamide 6 ◽

High Dispersion ◽

Multilayer Graphene ◽

Main Challenge ◽

Dispersion State ◽

Continuous Filament

Studies of the production of fiber-forming polyamide 6 (PA6)/graphene composite material and melt-spun textile fibers are scarce, but research to date reveals that achieving the high dispersion state of graphene is the main challenge to nanocomposite production. Considering the significant progress made in the industrial mass production of graphene nanoplatelets (GnPs), this study explored the feasibility of production of PA6/GnPs composite fibers using the commercially available few-layer GnPs. To this aim, the GnPs were pre-dispersed in molten ε-caprolactam at concentrations equal to 1 and 2 wt %, and incorporated into the PA6 matrix by the in situ water-catalyzed ring-opening polymerization of ε-caprolactam, which was followed by melt spinning. The results showed that the incorporated GnPs did not markedly influence the melting temperature of PA6 but affected the crystallization temperature, fiber bulk structure, crystallinity, and mechanical properties. Furthermore, GnPs increased the PA6 complex viscosity, which resulted in the need to adjust the parameters of melt spinning to enable continuous filament production. Although the incorporation of GnPs did not provide a reinforcing effect of PA6 fibers and reduced fiber tensile properties, the thermal stability of the PA6 fiber increased. The increased melt viscosity and graphene anti-dripping properties postponed melt dripping in the vertical flame spread test, which consequently prolonged burning within the samples.

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Study of the Proper Sintering Conditions of Anionically-Polymerized Polyamide 6 Matrices for the Fabrication of Greencomposites

Materials Science Forum ◽

10.4028/www.scientific.net/msf.713.121 ◽

2012 ◽

Vol 713 ◽

pp. 121-126

Author(s):

A. Alfonso ◽

J. Andrés ◽

J.A. García

Keyword(s):

Material Characterization ◽

Mechanical Performance ◽

In Situ Polymerization ◽

Research Work ◽

Polyamide 6 ◽

Liquid Composite Molding ◽

Thermoplastic Matrix ◽

Composite Molding ◽

Long Fiber Thermoplastic

The present research work assesses the manufacture of long fiber thermoplastic matrix composite materials (GreenComposites). Thermoplastic matrices are too viscous to be injected into the conventional LCM (Liquid Composite Molding) molds, and then epoxy, polyester or vinylester resins are used. Nevertheless, the groundbreaking anionic polymerization of caprolactam allows such a synthesis of a thermoplastic APA6 matrix inside the mold. This matrix is sintered from the starting monomers, and presents high mechanical performance and recyclability. In order to do the reactive injection in a LCM mold, it is necessary to control the polymerization mechanism of such a thermoplastic matrix. This paper puts special emphasis on detecting and solving all problems which arose during synthesis. For instance, moisture values were assessed for all starting reactants, since humidity keeps polymerization from occurring. It is thought that once the synthesis and the resulting material characterization are well controlled, the manufacture of GreenComposites through in situ polymerization, as well as addition of state-of-the-art fabrics such as basalt, can proceed successfully.

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