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  • 1. Carosio, F.
    et al.
    Ghanadpour, Maryam
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Alongi, J
    Wågberg, L
    Layer-by-layer assembled chitosan/phosphporylated nanocellulose as a bio-based and flame protecting nano-exoskeleton on PU foams2018Ingår i: Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 2. Carosio, F.
    et al.
    Ghanadpour, Maryam
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Alongi, J.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Layer-by-layer-assembled chitosan/phosphorylated cellulose nanofibrils as a bio-based and flame protecting nano-exoskeleton on PU foams2018Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 202, s. 479-487Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The layer-by-layer (LbL) assembly of chitosan (CH) and phosphorylated cellulose nanofibrils (P-CNF) is presented as a novel, sustainable and efficient fire protection system for polyurethane foams. The assembly yields a linearly growing coating where P-CNF is the main component and is embedded in a continuous CH matrix. This CH/P-CNF system homogenously coats the complex 3D structure of the foam producing a nano-exoskeleton that displays excellent mechanical properties increasing the modulus of the foam while maintaining its ability of being cyclically deformed. During combustion the CH/P-CNF exoskeleton efficiently prevents foam collapse and suppresses melt dripping while reducing the heat release rate peak by 31% with only 8% of added weight. The coating behavior during combustion is investigated and correlated to the observed performances. Physical and chemical mechanisms are identified and related to the unique composition and structure of the coating imparted by the LbL assembly.

  • 3.
    Ghanadpour, Maryam
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Phosphorylated Cellulose Nanofibrils: A Nano-Tool for Preparing Cellulose-Based Flame-Retardant Materials2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The growing awareness of the need for a circular society and a circular chemistry has spurred the interest in using wood-based cellulose as a raw material for the preparation of new macroscopic devices and construction materials. The interest has been particularly focused on cellulose nanofibrils (CNF), which has led to the development of new material concepts through a nanoscale bottom-up engineering using renewable CNF. In order to be industrially applicable, the CNF must however possess a set of properties among which good flame-retardation is crucial. This thesis presents a) a way to chemically modify delignified wood fibers by phosphorylation to produce phosphorylated CNF, b) the fabrication and characterization of flame-retardant thin films, coatings and nanocomposite foams from the phosphorylated fibrils and c) the flame-retardant mechanisms of the phosphorylated CNF-based substances.

    Chemically delignified fibers have been phosphorylated by (NH4)2HPO4 in the presence of urea, and the resulting material has been used to prepare phosphorylated CNF (P-CNF). The flame-retardant properties of the phosphorylated fibrils were significantly improved by the phosphorus functionalization of the cellulose chain, converting the fibrils to an inherently flame-retardant material. The P-CNF was applied to make thin films/coatings using the Layer-by-Layer (LbL) technique. All-cellulose free-standing films were prepared through LbL self-assembly of the P-CNF and fibrils prepared from aminated cellulose-rich fibers (cationic CNF). The LbL-assembled film showed a high thermal stability, excellent flame resistance and superior mechanical performance. P-CNF/chitosan (CH) assemblies were also prepared as a fire protection for polyurethane (PU) foams. The five bilayer CH/P-CNF coating yielded a nano-exoskeleton on the surface of PU foam, shown to be capable of increasing the modulus of the foam by a factor of three and entirely preventing its melt dripping during the flammability testing.

    P-CNF/montmorillonite (MMT), sepiolite (Sep) clay or sodium hexametaphosphate (SHMP) films were also fabricated by vacuum filtration/solvent casting of the composite suspensions, and the structural and compositional features of these different films were used to study the mechanisms behind their flame-retardant properties. Only the P-CNF/MMT films were able to completely prevent ignition during cone calorimetry, when used as coatings for highly flammable polyethylene (PE) films and this was mainly ascribed to the excellent barrier properties of these films. The results also showed that the excellent strength and stiffness of the P-CNF/MMT samples, compared to those of the P-CNF/Sep and P-CNF/SHMP films, were essential for maintaining the barrier effect during combustion. Finally, nanostructured foams were prepared by freeze-casting of the P-CNF/Sep suspensions. The foams showed extensive flame-resistance, maintaining a temperature drop of more than 600 °C across the thickness during the flame penetration test. This performance was related mainly to the charring capability of the phosphorylated fibrils combined with the significant thermal insulation of Sep clay.

  • 4.
    Ghanadpour, Maryam
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Carosio, F
    Ruda, M.C.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Flame-retardant nanocomposite thin films based on phosphorylated cellulose nanofibrils: A study of flame-retardant mechanisms2018Ingår i: Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 5.
    Ghanadpour, Maryam
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Carosio, Federico
    Larsson, Per Tomas
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Phosphorylated Cellulose Nanofibrils: A Renewable Nanomaterial for the Preparation of Intrinsically Flame-Retardant Materials2015Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, nr 10, s. 3399-3410Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose from wood fibers can be modified for use in flame-retardant composites as an alternative to halogen-based compounds. For this purpose, sulfite dissolving pulp fibers have been chemically modified by phosphorylation, and the resulting material has been used to prepare cellulose nanofibrils (CNF) that have a width of approximately 3 nm. The phosphorylation was achieved using (NH4)(2)HPO4 in the presence of urea, and the degree of substitution by phosphorus was determined by X-ray photoelectron spectroscopy, conductometric titration, and nuclear magnetic resonance spectroscopy. The presence of phosphate groups in the structure of CNF has been found to noticeably improve the flame retardancy of this material. The nanopaper sheets prepared from phosphorylated CNF showed self-extinguishing properties after consecutive applications of a methane flame for 3 s and did not ignite under a heat flux of 35 kW/m(2), as shown by flammability and cone calorimetry measurements, respectively.

  • 6.
    Ghanadpour, Maryam
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Carosio, Federico
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Ultrastrong and flame-resistant freestanding films from nanocelluloses, self-assembled using a layer-by-layer approach2017Ingår i: Applied Materials Today, ISSN 2352-9407, Vol. 9, s. 229-239Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanosized cellulose nanofibrils (CNF) prepared from phosphorylated pulp fibers (P-CNF) are combined with CNF prepared from aminated fibers (cationic CNF) through a layer-by-layer (LbL) assembly to prepare a freestanding, transparent all-cellulose film. It is shown that the thermal stability and flame-retardant properties of the all CNF film are significantly improved when phosphorylated CNF is combined with cationic fibrils in an LbL assembled structure. The freestanding films also show a tensile strength of 160 MPa and a Young's modulus of 9 GPa, placing it among strongest freestanding LbL films fabricated so far, showing large promise for the use of these types of ultrathin films in advanced applications. The LbL build-up of the cationic CNF/P-CNF multilayer film is carefully studied by quartz crystal microbalance with dissipation (QCM-D) and atomic force microscopy (AFM). Hydrophobized silicon substrates are used for the LbL deposition and it is shown that the (cationic CNFIP-CNF)(300) film, 2.3 pin thick, can be easily detached from the substrate using tweezers. The thermal stability, combustion behavior and mechanical properties of the films are further studied by thermogravimetric analysis, combustion and tensile tests respectively.

  • 7.
    Ghanadpour, Maryam
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Wicklein, Bernd
    Carosio, Federico
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    All-natural and highly flame-resistant freeze-cast foams based on phosphorylated cellulose nanofibrils2018Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, nr 8, s. 4085-4095Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pure cellulosic foams suffer from low thermal stability and high flammability, limiting their fields of application. Here, light-weight and flame-resistant nanostructured foams are produced by combining cellulose nanofibrils prepared from phosphorylated pulp fibers (P-CNF) with microfibrous sepiolite clay using the freeze-casting technique. The resultant nanocomposite foams show excellent flame-retardant properties such as self-extinguishing behavior and extremely low heat release rates in addition to high flame penetration resistance attributed mainly to the intrinsic charring ability of the phosphorylated fibrils and the capability of sepiolite to form heat-protective intumescent-like barrier on the surface of the material. Investigation of the chemical structure of the charred residue by FTIR and solid state NMR spectroscopy reveals the extensive graphitization of the carbohydrate as a result of dephosphorylation of the modified cellulose and further dehydration due to acidic catalytic effects. Originating from the nanoscale dimensions of sepiolite particles, their high specific surface area and stiffness as well as its close interaction with the phosphorylated fibrils, the incorporation of clay nanorods also significantly improves the mechanical strength and stiffness of the nanocomposite foams. The novel foams prepared in this study are expected to have great potential for application in sustainable building construction.

  • 8.
    Qin, Shuang
    et al.
    3123 TAMU, Dept Mat Sci & Engn, College Stn, TX 77843 USA..
    Ghanadpour, Maryam
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Lazar, Simone
    3123 TAMU, Dept Chem, College Stn, TX 77843 USA..
    Köklükaya, Oruç
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Gerringer, Joseph
    3123 TAMU, Dept Mat Sci & Engn, College Stn, TX 77843 USA..
    Song, Yixuan
    3123 TAMU, Dept Mat Sci & Engn, College Stn, TX 77843 USA..
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Grunlan, Jaime C.
    3123 TAMU, Dept Mat Sci & Engn, College Stn, TX 77843 USA.;3123 TAMU, Dept Chem, College Stn, TX 77843 USA..
    Super Gas Barrier and Fire Resistance of Nanoplatelet/Nanofibril Multilayer Thin Films2019Ingår i: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 6, nr 2, artikel-id 1801424Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose nanofibrils (CNF) are abundant in the fiber cell walls of many plants and are considered a nearly inexhaustible resource. With the goal of improving the flame resistance and gas barrier properties of cellulose-based films, cationic CNF are assembled with anionic vermiculite (VMT) clay using the layer-by-layer deposition process. The highly aligned VMT nanoplatelets, together with cellulose nanofibrils, form a nanobrick wall structure that exhibits high optical transparency, flame resistance, super oxygen barrier, and high modulus. A 20 CNF/VMT bilayer (BL) nanocoating, with a thickness of only 136 nm, exhibits an oxygen transmission rate of 0.013 cc (m(2) day atm)(-1). With only 2 BL of CNF/VMT, the melting of flexible polyurethane foam exposed to a butane torch is prevented. These nanocoatings also exhibit a high elastic modulus (20 GPa) and hardness (1 GPa). This study demonstrates a unique, renewable, cellulose-based nanocoating that could be used in a variety of packaging and protection applications.

  • 9.
    Wågberg, Lars
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Ghanadpour, Maryam
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Koklukaya, Oruc
    Carosio, Federico
    Politecn Torino, Alessandria, Italy..
    Fire protection of cellulose materials, procedures and mechanisms2017Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253Artikel i tidskrift (Övrigt vetenskapligt)
1 - 9 av 9
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