To maintain its leading position in this
specialist area the company implemented
a major project to develop the next generation
of container that with an internal cargo
volume of 6.38 m3 (224.2 ft3) would be a
capable of handling larger shipments – five
Euro or four US pallets. Key requirements
of the new container were excellent thermal
performance, high structural integrity and
good impact resistance.
Following a four year development program,
Envirotainer has launched its new
RAP e2 container. This container represents
a step change not only in terms of
performance but also in the way that the
container is manufactured.
Diab engineers have been working
closely with the Envirotainer development
team throughout the duration of the project
providing materials and technical support.
At the outset it was decided that sandwich
composites based on Diab structural cores
as opposed to the ‘traditional’ aluminum/polyurethane foam construction would offer
improved thermal, structural and impact/damage performance.
With the decision to move to a sandwich
composite design, the Envirotainer engineers
developed a VARTM (vacuum assisted resin
transfer molding) manufacturing process
that would allow the efficient series production
of the containers while at the same time
maximizing the properties of the sandwich
composites. In particular the process that
Envirotainer has developed has allowed it to
achieve high fiber fractions. Normally this is
not the case with VARTM type processes.
With this process, matched rigid and
flexible molds are used to create the two
sandwich components that make up each
container in a single shot. A particular feature
of the Envirotainer VARTM system is
that they have been able to achieve square
internal corners to maximize cargo capacity.
Usually for this type of process mold release
angles would be necessary.
Full scale tests on the container have shown
that it can withstand more than 23 ton static
load on its roof.
In addition the new container offers almost
twice the insulation value of an aluminum/
PUR equivalent container. This reduces
the size of the battery pack for the temperature
control system. In the case of the RAP e2
the interior temperature can be maintained at
constant temperature (from -20 to +40 °C [-13
to +104 °F]) throughout the container’s journey
(minimum of 35 hours).
Envirotainer also expects the RAP e2 to
offer a higher resistance to damage than previous
containers particularly in terms of size
and propagation. However, in the event of
accidental damage, the Envirotainer team has
developed a repair scheme that only requires
minimal composite/sandwich knowledge.