Rod shape nano particles and and structure formations
  • FENS
  • Rod shape nano particles and and structure formations

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Seminar 1
A Breakthrough Thickener Technology for Aircraft Anti-icing Fluids - A Successful Product
Commercialization Story
With an increasing amount of airline traffic, aircrafts spend longer time between the gate
departure and takeoff time. Under freezing precipitation conditions aircrafts are needed to be
anti-iced to keep the aircraft surfaces clean during this longer waiting time. Aircraft Anti-icing
Fluids (AAF) are thickened Non-Newtonian glycol solutions which meet complex multiple
performance requirements. The most important and conflicting two performance requirements
are: 1) protection time against freezing precipitation and; 2) lift loss due to the presence of AAF
during the takeoff. Making AAF with longer protection time also causes higher undesired lift
loss effect. Effects of fluid rheology on protection time and lift loss were identified by
investigating fluid behavior in environmental col chamber and cold wind tunnel. Then an
associative thickener technology was developed to formulate an Aircraft Anti-icing Fluid which
gave a longer protection time with very little lift loss. The research resulted the
commercialization of a breakthrough Society of Automotive Engineers (SAE) Type IV Anti-icing
Fluid.
Seminar 2
Reinventing cellulose: Nanocrystalline Cellulose (NCC)
The discovery of cellulose by Anselme Payen goes back to 1838 and it has been used as a raw
material for the preparation of polymers and plastics since 1870. Nowadays cellulose becomes an
attractive material again for few reasons. First of all, it is renewable, carbon neutral and also
available from abundant wood and other plant fibres supplies. Secondly it is a non-toxic and
biocompatible material for the human body and biodegradable. And last but most importantly,
cellulose can be decomposed to nanosized fibres which reveal unique bulk, surface, and colloidal
properties. These nanocellulose fibres with their unique supramolecular structure combined with
high crystallinity, hydrophilicity, chirality, surface grafting potential and structure-forming
capacity create ceaseless opportunities for researchers to develop new materials.
Nanocellulose fibres can be produced either in the form of nanocrystalline cellulose (NCC) or
nanofibrillated cellulose (NFC). Elongated crystalline rigid rod-like nanoparticles (diameter:
4-10 nm, length: 100-300 nm) are described as NCC, whereas flexible and entangled nanofibres
(diameter: 10-50 nm, length: 500-1500 nm) consisting of alternating crystalline and amorphous
strings are called as NFC. Production of NCC involves the digestion of amorphous cellulosic
domains, generally by acid hydrolysis, whereas NFC is obtained mostly by mechanical treatment
with some acid or enzymatic hydrolysis. Both of them offer an array of uniquely desirable
mechanical, optical, surface and transport characteristics that have placed them at the core of a
variety of potential applications. High performance nanocomposites (as reinforcing fibres),
paints/coatings, cosmetics/creams, medical/pharmaceuticals, cosmetics/skin creams, oilfield
chemicals, hygiene/absorbent products, emulsion/dispersion applications, food products (non
calorific thickening agent, flavour carrier) and functional fluids and materials are some of the
examples.
Whether composites or any other applications are targeted, nanocellulose fibres are always
incorporated in a continuous phase (i.e. polymer melts, organic liquids and aqueous solutions)
which we describe as nanocollodial suspensions. Therefore, the foundation of any nanocellulose
related product and process development research shall be the understanding and manipulation of
the interfacial phenomena, thermodynamic and kinetic stability of dispersions and rheology of
nanocellulose fibre contained colloidal systems. Advances on those topics will lead to the rapid
development of breakthrough applications of nanocellulose in diverse areas. This seminar
assembles current research, development and applications from recent literature together with the
work from our laboratories. Consecutively future research directions will be discussed.
Seminar 3:
Rod shape nano particles and and structure formations in colloidal systems
The steady-state shear and linear viscoelastic deformations of semidilute suspensions of rodshaped
nanocrystalline cellulose (NCC) particles in 1.0% hydroxyethyl cellulose and
carboxymethyl cellulose solutions were investigated. Addition of NCC at the onset of semidilute
suspension concentration significantly altered the rheological and linear viscoelastic properties of
semidilute polymer solutions. The low-shear viscosity values of polymers solutions were
increased 20-500 times (depending on polymer molecular weight and functional groups)
by the presence of NCC. NCC suspensions in polymer solutions exhibited yield stresses up to
7.12 Pa. Viscoelasticity measurements also showed that NCC suspended polymer solutions had
higher linear elastic moduli than the loss moduli. All of those results revealed the gel formation
of NCC particles and presence of internal structures. The formation of a weak gel structure was
due to the nonadsorbing macromolecules which caused the depletion-induced interaction among
NCC particles. A simple interaction energy model was used to show successfully the flocculation
of NCC particles in the presence of nonadsorbing polymers. The model is based on the
incorporation of the depletion interaction term between two parallel plates into the DLVO theory
for cubic prismatic rod shaped NCC particles