3. U.V Radiations
• Ultraviolet Radiations
are electromagnetic
rays with a wavelength
between 100-400nm.
• Solar UVR that reaches
earth have wavelength
between 290-400nm.
4. Classification Of U.V Rays
• U.V rays has three regions depending upon wavelength:
Ultraviolet region – A (UVA) (320-400nm)
Ultraviolet region – B (UVB) (290-320nm)
Ultraviolet region – C (UVC) (100 nm and 290 nm)
UV-C completely absorbed by the ozone layer
UV-B and UV-A reach the earth’s surface and cause
serious health problems, particularly skin cancer.
5. Melanoma
• The most dangerous form of skin cancer, these cancerous
growths develop when unrepaired DNA damage to skin
cells (most often caused by ultraviolet radiation from
sunshine or tanning beds) triggers mutations (genetic
defects) that lead the skin cells to multiply rapidly and form
malignant tumors.
6. Erythema
• superficial reddening of the skin, usually in patches, as a
result of injury or irritation causing dilatation of the blood
capillaries.
7. Characteristics Of U.V regions
Region Wavelength
(nm)
Relative
Intensity(%)
Av. Photon
Energy(kj/mol)
UV-A 315-400 3.2 315
UV-B 280-315 2.4 350
UV-C 100-280 0.5 400
8. Factors Affecting Solar U.V Level
Sun angle
Geographical Position
Seasonal Effects
Clouds
Ozone
Scattering
Altitude
Time of day
11. Effects Of U.V radiations
• Human Skin
The major effects of UV
are
• Sunburn
• Erythema(skin
reddening)
• Skin cancer (Melanoma)
• DNA damage.
• Acceleration of Skin
Ageing
• Eye damage.
DNA damage
12. Protection Factor
• Protection factor is used to quantify the protective
effect of material.
• SPF/UPF is the ratio of actual potential erythemal
effect to the erythemal effect transmitted through
the fabric.
• Larger the UPF/SPF, the more protective the fabric to
UV radiation.
13. where
Sλ is Solar spectral irradiance in Wm-2nm-1
Eλ is relative erythemal spectral effectiveness
T λ is spectral transmission of object
∆ λ is band width in nm
λ is wavelength in nm
ED is effective dose of UVR for unprotected skin
EDM is the effective dose of UVR for protected skin
14. Ultraviolet protection factor
Classification UPF Approximate % UV
blocked
Good UV
protection
15-24 93.3%-95.8%
Very good UV
protection
25-39 96%-97.4%
Excellent UV
protection
40-50 97.5%-98%
Textile’s UV protection performance is determined by
ultraviolet protection factor
15. When light falls on a fabric or fiber it will either
reflected, transmitted or absorbed.
The UV protection by textile is a function of
the physio-chemical characteristics.
Mechanism of UV transmittance
17. UPF Factors
Cover Factor
• To optimize the fabric construction so as
to increase the skin cover by fibers, which
can be achieved by spacing the yarns as
closely as possible. UV transmittance can
also be reduced by improving the
absorption & reflection properties.
• The more the cover factor, high is UPF.
Color (Dye)
Humidity
The UPF increased as the relative
humidity increased, but this increase is
fibre dependent, more pronounced in
viscose & silk
24. Polyester, silk and wool fabrics are
better UV blockers than cotton or rayon
Polyester fibers show a better absorption-
due their aromatic nature
FACTORS INFLUENCING THE UV
PROTECTION OFFERED BY
TEXTILES
Fiber type
25. Fabric construction
• Tighter the weave, the greater is protection as the
transmission is reduced.
• With the same weave structure, the UPF of the
fabric increases with its thickness
• Closed textured (have low porosity)hence low
transmission of UVR.
• Cover factor-UPF increases with the cover factor
26. • UPF increases as the relative humidity is raised
• The effect of relative humidity is strongly
dependent on the fiber type(natural swelling
behaviour of fibers)
• Swelling-reduces space between ends and
picks
Moisture content
27. • Dyes have a considerable influence on UV permeability.
• They absorb light in the UVR spectral region
• Absorbing property of each dye is unique to that dyestuff
• Their UV protection power is dependent on
concentration. Binary mixture of monochlorotriazine
dyes provide higher UPF than the individual ones.
• Lengthening of the chromophoric chain of two linked
dyes owing to their interaction leads to an increase of the
UPF of fabric.
Dyes
28. Color
The effect of colour on the UPF of samples with
identical weaves and weights
Colors Polyester
White 16
Pink 19
Green 19
Dark Red 29
Black 34
Color Cotton
White 12
Azure 18
Royal 27
Black 32
Navy 37
29. U.V Absorbers
• UV absorbers are colorless compounds with
very strong absorption in the UV range of 290-
400nm.
• UV Absorbers incorporated into fibres convert
electronic excitation energy into thermal
energy.
• They function as radical scavengers and
oxygen scavengers.
30. UV Absorbers
• Selectively absorb UVR and convert it in to heat.
Cibatex UPF
• It is UV absorber with two reactive groups
• It is stable to repeated washing due to bi-reactive
structure
• Applied to cotton and cotton blend fibers.
Cibafast W
• a monosulphonated benotriazole derivative
• Applied to wool, silk, polyamide fibers and their
blends.
• Are joined to the fiber by covalent bond in order
to improve UV protection permanently.
31. • UV absorption of synthetics can be modified by
pigmentation
• This results in scattering of UV rays
• They are wrapped up in the fiber and are fast to
washing.
• leads to a permanent improvement of UV protection
Special Finishing Agents
TiO2 particles
Rayosan finish
• Rayosan is a commercial UV-absorber
• React with fibers like reactive dyes
• Rayosan C paste and CO liquid products
• Used for finishing cellulose; polyamide
• The Rayosan finish has a good washing fastness
33. • American Association of Textile Chemists and
Colorists (AATCC) Test Method 183 and American
Society for Testing and Materials (ASTM) D 6544 for
the rigorous evaluation of a fabric’s life cycle UV
protection.
• Australian/New Zealand Standard 4399-which is the
original globally recognized standard for sun protective
clothing.
• In addition, American Society for Testing and
Materials D 6603 for labelling sun protective clothing.
