UV protection in Composite material
Fiber Reinforced Polymers (FRP) are unique composite
materials in many respects. They can be formulated to be corrosion, abrasion,
and UV resistant, as well as smoke and fire retardant.
Accelerated Outdoor Weathering Test (ASTM G90) indicates
that the degradation of resin caused by UV light which is the primary reason
for the loss of bond between concrete and FRP. This results in fiber blooming
which is an undesirable condition where the polymer matrix undergoes UV
degradation, exposing the glass fibers underneath. Effects of fiber blooming include Poor
aesthetics, degraded mechanical properties and shortened service life for
To protect the effect of UV degradation, UVA (ultraviolet
absorbers) additives need to be added while manufacturing the FRP structures.
Also Fiberglass with a UV protective 2 part painting has much better UV
stability to prevent UV-induced polymer degradations when exposed to sunlight
and therefore have a longer service life than those without any coating.
Why UV Protection is a must for Pultruded fiber sections?
Degradation of Fiber Reinforced Polymer (FRP) composite
due to exposure to ultraviolet (UV) radiation is an important challenge as it
reduces the quality and function of FRP thereby impacting its tensile strength
and load carrying capacity.
It also leads to polymer disassociation and
micro-cracking which invites an implicit loss to durability and safety of the
composite. Moreover, extreme environments can severely damage the mechanical
and structural integrity, thereby making UV protection essential for pultruded
fiber sections and that is only why it is highly recommended.
Scientific Impact of UV radiation on FRP
• Fiber Blooming - A chemical attack on the fiber in the
matrix that leads to the deterioration. It makes the free fibers come out of
the FRP material and can cause skin infection when touched.
• Discoloration - The intensity of the UV radiation and
aggressive environments can lead to the discoloration of the FRP structure
leading to less stable coloring pigment thereby influences the quality of the
• Chalking - A chalking effect appears on the upper
material making the UV radiations penetrate more into the fiber section thereby
causing in-depth damage.
How UV protection can be done?
• Using Pigmentation – As standard resins are more or
less transparent so color pigments can be used to prevent the penetration of UV
• High quality Additives - Numerous UV inhibitors,
anti-oxidants, UV absorbers and UV light stabilizers can be used.
• Safe Synthetic outer veil - This veil prevents the
penetration of fibres to the outside as it is processed during the pultrusion
process for various constructions to avoid damage of the human which happens
due to the fiber blooming.
• Resin rich protective layer - Since UV degradation is a
surface phenomenon, so a resin rich protective layer is placed between the
structural fiber and the outer surface so that the integrity of the
reinforcement can be ensured. As a matter of fact, the thicker the coating will
be, there will be better surface weathering toleration.
• Doing Painting – The fiber section can be painted with
high quality polyurethane paint so that neither blooming nor degradation
Special UV cure for pultruded fiber sections at SGS
Since, SGS Frangible offers high quality composite
products and structures; it ensures UV protection by taking care of standard
processes in the steps involved. In this respect, usage of special and
exclusive resins and additives are done along with stable and environment
friendly pigmentation that offers the true sense of UV protection. It also
makes the pultruded fiber sections hold the mechanical and structural
properties for achieving durability, good tensile strength and load capacity.
Moreover, plasticization, cracking, polymer disassociation and degradation are
prevented in the most desired manner and thus lead to high performance and
safety of the structures.