Biomedical Engineering Reference
In-Depth Information
Nanoclay addition also clearly improved the oxygen barrier properties of pectin
films in high humidity conditions (Figure 3). Oxygen transmission rate was reduced
by 80% with pectin films containing 30 wt% of nanoclay as compared with the pectin
film without nanoclay. Water vapor transmission results indicated the improved bar-
rier properties as well. However, the water-soluble pectin was lacking the capability
of fully preventing the transmission of water vapor, and thus, total barrier effect of
films with 30 wt% nanoclay was not more than 23%. Pectin itself formed an excel-
lent barrier property against grease and nanoclay addition did not improve this barrier
property anyhow. All films were totally impermeable to grease under the conditions
tested. Barrier improvements are explained using tortuous path theory which relates
to alignment of the nanoclay platelets. As a result of the sufficient defoliation, the
effective path length for molecular diffusion increases and the path becomes highly
tortuous to reduce the effect of gas transmission.
Figure 3. Oxygen transmission rates of pectin films (100 µm) with different amounts of nanoclay.
up-scaling the Production with roll-to-roll Pilot line
The VTT has a roll-to-roll surface treatment concept that can be used for coating and
surface treatment of fiber-based webs and plastics. It consists of separate one me-
ter wide operational units build from aluminum frames. Each frame has four wheels
placed under the frame. All operational units are placed on rails to eliminate need for
leveling of units after changing the order of the units. Rails also eliminate need for
guidance and other roll alignment after re-arranging the units. The units are attached
together by a system called Click and Coat developed by manufacturer of equipment,
Coatema and Germany. The concept includes several coating methods, pre-treatments
and curing options. Coating methods include flexo-type roll coating, soft bar coating,
kiss type coating and spray coating. All three first mentioned methods can be followed
by spray coating to make wet on wet coatings. The sealable coating unit followed by
exhaust air removal during drying makes it possible to test also coatings containing
 
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