P1254503583EtsLp

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Nanoparticles as UV absorbers. Nano Functional
Materials. (NFM) project. ??? ???? ?????? ???
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???? ?????? ??????. ????? 2007.
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MAGNET???? ???? ????????

• Support program for
• Generic Technological RD
• Transfer of technology Academia to industry.
• Operational framework is a consortium
• of industries and research institutes.
• 66 government grant.

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MAGNET/2

• Consortium frame work
• 12 Industries.
• Researchers from 3 academic institutions.
• Three leading projects
• Manufacturing and stabilization of nano particles
  in liquid phase.
• Compounding nano particles into polymers matrix.
• De-agglomeration of nano particles.

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Why nanoparticles additives ?

• Functional properties with almost no outward
  migration from the polymer.
• Transparent.
• Positive interaction with polymer to obtain
  specific advantages. e.g. nanoclays improves
  mechanical properties and transparent.

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Kafrits activities

• Challenges
• Agglomeration interferes with functional
  dispersion.
• Surface treatments, dispersing agents
• Adjusting process parameters.
• Evaluation of the dispersion quality TEM, SEM
  and
• Areas of activity
• UV absorbers/blockers nanosized ZnO, organic UVA
  nano-particles.
• Flame retardants.

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UV absorbed/blocked films for pest control.

• Advantages of UV absorbers in Greenhouse Films
• Distorts harmful insects activity.
• Controls viral plant diseases vectored by
  insects.
• In addition
• Protects the polymer from photo oxidative
• degradation.
• Prevents petal blackening.

This is the reason why, in commercial
applications, UV blocked AgriFilms is also called
AntiVirus
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UV blocking/Packaging.

• Advantages of UV absorbers in Packaging Films
• Benefits UV light filtering can prevent
  undesirable changes of the color, odor, flavor
  and nutrients.
• Effective blocking in thin films no
  migration/blooming.

UV, O2
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Deterioration of UV blockage effect.
UV absorbers are lost as the results of
photodecomposition and migration.
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UV blocking ZnO.
Preliminary particles size 50-60 nm. In practice
aggregates of 1-2 mm.
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ZnO. Homogenous dispersions of
Influence of dispersing aid/surfactant type on
ZnO dispersion.

• Compounding with dispersing aids of different
  functionality.
• Haze (forward light scattering) as the
  dispersions quality parameter.

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Improved dispersion improved UV blocking.
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Dispersion aids and ZnO.
With
Without
By Prof. Y. Cohen (Technion)
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Long lasting UV blocking effect.
ZnO - UV blocking effect maintains for longer
period of time compares to the organic UVA.
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Long lasting UV blockage/Pesticides influence.
Faster deterioration of UV blockage in the
formulations based on nanosized ZnO compares to
the organic UVA as the result of sulfur burning.
There is strong relation between UV blockage
deterioration and amount of sulfur applied.
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ZnO nano - effect on organic UVA migration.
Without ZnO.
With ZnO.

• Nanosized ZnO slows down migration rate of
  organic UVA.
• Potential application for thin packaging films.

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Intermediate conclusions.

• Dispersion is feasible.
• Chemistry Improved dispersion with the proper
  surfactant.
• High transparency and low light scattering.
• Further steps influence of processing conditions
  on the nonoparticles dispersion.
• Long lasting UV blockage
• Long term effect without agrochemicals.
• Further steps influence of particles surface
  treatment on agrochemicals resistance.
• Migration control by nanoparticles.

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Novel UVA organic particles Synthesis of UV
absorbing nano particles (1) Prof. S. Margel

• Emulsion polymerization of UVA monomers (acrylate
  substituted BZT).

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Emulsion polymerization.
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TEM picture of polymerized BZT.
Average particles size 280 ? 20 nm.
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Synthesis of UV absorbing nano particles (2)

• But- synthesis products aggregate.
• Dispersion is possible
• surfactants compatible with polyolefins.
• drying on the porous resin.

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Polymerized BZT / PE film.
Dispersion of polymerized BZT particles in LDPE.
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Polymerized BZT/ UV absorption efficiency.
Higher concentration of polymerized nanoparticles
is needed to achieve UV blockage. Waste of UVA
moieties due to polymerization.
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Further steps

• Reduction of the particles size.
• Grafting of BZT brushes on the surface modified
  silica nano particles

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Nano SiO2 particles.
Nano sized SiO2 .
Surface Modified SiO2
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Organic UVA particles/Summary.

• Novel nanosized UVA particles were synthesized.
• Homogeneous dispersion in PO matrix. (adjustment
  of proper surfactants and drying conditions of
  synthesis products).
• Not sufficient efficiency of UV blockage.
• Further stepsimprovement UV absorption
  efficiency by
• Reduction of particle size.
• Grafting of UVA monomer on nanosized silica.

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End
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UV blockingparticles and organic compounds.
Normalized blocking efficiency
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Surface treated nanoparticles.
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The challenge of nano particles compounding

• Dispersion without agglomeration
• Use dispersion aids.
• Evaluation of the dispersion quality TEM, SEM
  and
• Understanding the effects of the extrusion
  parameters on the dispersion quality.
• Personnel and environmental safety.

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TEM micrograph. ZnO 1.5 in LDPE
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Effect of ZnO loading on AF

• High loading no AF Low loading - AF