FIBCs and UV Stabilisation
Big Bags are most commonly made of woven polypropylene, a polymer that, like other materials, is damaged by exposure to sunlight over time.
This degradation process can ultimately cause the fabric to tear when exposed to strain and put both content and personnel at risk.
Fortunately, through the use of UV stabilisers in the polymer and the proper handling of FIBCs, the risk of photochemical damage can be reduced to a minimum.
It is, however, vital that FIBCs are covered or stored away from the sunlight during usage, transport and storage.
ATEA Fibcs are made of UV stabilised fabrics , in which high quality UV masterbatches are used from select brands.
No UV exposure
No UV damage through covering or screening.
Protection through UV light stabilizers (HALS) or UV absorbers and pigmentation.
Materials often undergo rapid photochemical degradation under the influence of sunlight, unless they have been stabilised in a durable fashion.
A number of factors of uncertainty are inherent in the procedure, so comparisons should be available between the method used and exposures in the environment in which the product is to be used.
● Ultra violet degradation may be indicated by the softening of the material, so that the outer surface may be rubbed off or plucked off, and in extreme cases, the outer surface may become powdered.
● Certain types of UV stabilising additives are rapidly leached out, especially in an alkaline environment, which should be taken into consideration in applicable situation.
● The performance of UV stabilised additives may be affected by colour and the type of pigment used. Therefore, each combination of UV stabilising additive and pigment should be tested separately
The test apparatus shall be in accordance with ASTM G53/96 using a fluorescent UV-B lamb.
The specimens are alternately exposed to UV light alone and to condensation alone in a repetitive cycle for at least 200 h using a test cycle of 8 h at 60 C with UV radiation alternating with 4 h at 50 C with condensation.
After exposure is complete, the specimens are checked for breaking force and elongation at break in accordance with ISO 5081
and the values are compared with results performed on simultaneously cut test specimens that have been stored under dark and cool conditions.
All load bearing materials of the FIBC shall, after tested retain at least 50% of the original values of the breaking force and elongation of the materials.
Testing machine for accelerated UV test
Inside the UV tester
Test specimens inside the UV tester
The most obvious way to mitigate the degradation of FIBC due to UV radiation and other weather impacts is to physically protect the big bags from the elements. Although FIBC handling instructions routinely advise against outdoor exposure, this is not always practical for users and certainly not controllable by FIBC producers and traders.
Chemical alternatives are available and widely used to help polymers like polypropylene maintain their properties longer against degradation through environmental influences. To counter the harmful effects of UV light on FIBC, two main methods are used: UV light absorbers, e.g. Triazine or Benzotriazole, and light stabilisers, i.e. HALS (Hindered Amine Light Stabilisers).
These additives, which absorb or stabilise UV light respectively, are often introduced to the base formula for the polypropylene material out of which the FIBC are woven. Both methods can retard the damaging effects of UV light but cannot stop it altogether.
Either way, photochemical degradation remains a reality that must be taken into consideration. The question becomes how well we can predict the lifespan of the FIBC given that it will be exposed to environmental stress. This is the job of the testing system.