Nanofibers of aluminum oxide

Слайд 2

Nafen is produced from melt: industrial-scale technology

Nafen is produced from melt: industrial-scale technology

Слайд 3

TEM micrographs / SAXS data

small-angle scattering (SAXS); also indicate high degree of alignment

TEM micrographs / SAXS data small-angle scattering (SAXS); also indicate high degree of alignment

Слайд 4

Nafen nanofibers : summary of properties

* - phase composition can not be

Nafen nanofibers : summary of properties * - phase composition can not
accurately quantified because of lack of structure model for χ-phase

Слайд 5

Is it unique?

Reference 1: AlOOH “aerogel” (FEI)

Reference 2: Nano Technology Inc. (Korea):
“diameter

Is it unique? Reference 1: AlOOH “aerogel” (FEI) Reference 2: Nano Technology
is approximately 5-10 nm, and the aspect ratio is in
the 50 to 200 range”

Слайд 6

Mechanical properties of individual fiber

CNTs (Wiki):
Young's modulus on the order of 270 -

Mechanical properties of individual fiber CNTs (Wiki): Young's modulus on the order
950 GPa and tensile strength of 11 - 63 GPa

Слайд 7

Phase analysis (XRD)

Typical diffraction patterns for low-temperature phases of alumina
chi is identified

Phase analysis (XRD) Typical diffraction patterns for low-temperature phases of alumina chi
by the peak at 2θ=42.8

Diffraction patterns of two samples of Nafen
the phase is identified as mostly chi, with some gamma
crystallite (CSR) size 50-100 nm

Nafen fibers are polycrystalline alumina in gamma and chi phases

Слайд 8

High-temperature phase transformation (XRD)

At 1200–1400 C, transformation to alpha phase occurs

High-temperature phase transformation (XRD) At 1200–1400 C, transformation to alpha phase occurs

Слайд 9

The surface is ‘saw-shaped’ (TEM)

The surface is ‘saw-shaped’ (TEM)

Слайд 10

EP-PP copolymers: “as co-monomer”

Surface treatment type affects the performance, including level of TOD

EP-PP copolymers: “as co-monomer” Surface treatment type affects the performance, including level
stability enhancement

790% / 5.8 MPa

940% / 8.0 MPa

Main application: reinforcing filler for thermoset-based adhesives

Refefence: N.M. Bravaya et al., J. Appl. Polymer Sci. (2017) – accepted for publication

Слайд 11

Technological challenges & solutions

Ultrasonic dispersion and/or targeted surface treatment (functionalization) allows good

Technological challenges & solutions Ultrasonic dispersion and/or targeted surface treatment (functionalization) allows
(almost to single fiber) level of dispersion

Слайд 12

Surface chemistry

1H MAS NMR: three types of surface protons: - terminal -

Surface chemistry 1H MAS NMR: three types of surface protons: - terminal
bridge - hydrogen-bonded

IR spectroscopy / CO absorption:
only weak and medium-strength Brønsted and Lewis centers are present:
max Q(LC) = 39 kJ/mole - considerably lower than for “conventional” Al2O3 types

Слайд 13

Nafen as support for heterogeneous catalysts: first trials

1) HDC of halogen-aromatic compounds: application

Nafen as support for heterogeneous catalysts: first trials 1) HDC of halogen-aromatic
for waste treatment
(unpublished)

2) Emulsion hydrogenation of substituted phenols (unpublished data):
23 compounds tested
Nafen-supported catalyst
showed up to 95% yield and up to 94% selectivity

2) Low-temp CO-oxidation 95% conversion already with unmodified commercial catalyst

Слайд 14

Nafen as support for heterogeneous catalysts: potential / advantages

low-T Al2O3 polymorph
relatively high SSA

Nafen as support for heterogeneous catalysts: potential / advantages low-T Al2O3 polymorph
and “highly-defective” surface: allows easy anchoring of catalytically active components
low acidity: no / minimal side reactions → selectivity
surface chemistry can be tailored: - three subtypes of Nafen available - functionalization is possible
ready masterbatches for liquid dispersion type processes can be produced
“bonus” reinforcement effect (?)
Имя файла: Nanofibers-of-aluminum-oxide.pptx
Количество просмотров: 80
Количество скачиваний: 0