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UV Light Resistance

UV Light ResistanceUV Light and its Effect on Plastics


Ultraviolet (UV) light is probably the most damaging environment for plastics. Although to be fair to plastics, it attacks, to a greater or lesser extent, most other materials as well.

All applications of plastics which are used outdoors are therefore at risk, from roofing and window frames to vehicles.

UV light is part of the electromagnetic spectrum. It is at the higher end of energy compared to visible light and is followed in energy by X-rays and the Gamma rays.

UV energy absorbed by plastics can excite photons, which then create free radicals.

While many pure plastics cannot absorb UV radiation, the presence of catalyst residues
and other impurities will often act as receptors, causing degradation

Elecromagnetic Resistance


Continue reading or check out more on UV Light Resistance:

 » UV Light Resistance Behavior of Various Polymers
 » How to Avoid Damage Caused by Ultraviolet (UV) Light?
 » Methods to Predict Plastic Material behavior in UV Light

UV radiation attacks all types of polymers, but a few (such as acrylonitriles and methyl methacrylates) show better UV resistance than most.

It can cause color change and degradation of physical properties, especially in:


 » View All Commercially Available Polymer Grades with Good UV Resistance! 

The effect is very familiar: discoloration, especially yellowing or whitening ('chalking'), is the most apparent. But, underneath, there is usually the beginning of a loss of physical properties such as:


The UV breaks down the chemical bonds in a polymer in a process called photodegradation, which ultimately causes the change in appearance and deterioration in properties.

Hence, any attempt to design plastic parts without a clear understanding of the degradation mechanisms
induced by the environment would result in a premature failure of the product
.



How to Avoid Damage Caused by Ultraviolet (UV) Light?


The counter-measures to prevent/terminate oxidation of plastics by UV light include:

  • Coating
  • Introducing pigments which effectively screen out the rays, or
  • Neutralizing the UV energy within the compound and dissipate it harmlessly

Also, there exists many more technologies such as polymeric stabilizers, concentrates and masterbatches, fine particle technologies etc. which help in preventing UV radiation from reaching the polymer and hence avoid damage. (please note that every technology is not discussed here.)

Screening


The most effective screening pigment is carbon black (however its applications are limited to black-colored products). Titanium dioxide is used, but it is expensive. Calcium carbonate can also have a screening effect (but usually at a high loading, which might impair mechanical properties).


Absorption


UV absorbers are receptive to UV radiation but, while not themselves degrading rapidly, they convert UV energy and dissipate it harmlessly as heat. They prevent the oxidation caused by UV radiation, but should not be confused with antioxidants, which are not UV deactivators as such.

  • Benzophenones are good general-purpose UV absorbers for clear polyolefin systems, and can also be used in pigmented compounds.
  • Benzotriazoles are used mainly in polystyrene and PVC, but can also be used in acrylics and polycarbonates, and in polyurethanes and unsaturated polyesters. They also improve the light stability of polyacetals, urea, melamines and epoxies.


Stabilization


Ultraviolet stabilizers, unlike UV absorbers, inhibit the bond rupture by chemical means or dissipate the energy to lower levels that do not attack the bonds.

Quenchers


Quenchers reduce the UV energy by means of deactivating metal ions. In effect, they intercept the energy before it can break any molecular bonds, but in a different way from absorbers.

Scavengers


Scavengers act by inhibiting the free radicals generated by UV light, so stopping any further decomposition. The most important are hindered amine light stabilizers (HALS). They are efficient scavengers and function by inhibiting the degradation of a polymer which has already formed free radicals.

HALS have the advantage that they bind additives to the polymer at the molecular level, so causing less antagonism towards other additives. They can be used with most polymers.

Polymeric HALS offer:

  • Superior compatibility
  • Low volatility
  • Excellent resistance to extraction, and
  • Contribute to heat stability

A combination of two high molecular weight grades gives a good balance of properties, for greenhouse film, which is the main low density polyethylene (LDPE) film use of HALS.


Synergists with HALS


In conjunction with other light stabilizers, HALS can exhibit synergistic effects, which are being actively explored. For example, some cyanoacrylate-based UV absorbers offer particular benefits (such as in acrylonitrile butadiene styrene (ABS) and polyamide (PA) and as individual components in rigid or plasticized PVC, polyurethane foams and styrene butadiene (SB) rubber).

 » View All Commercially Available Polymer Grades with Good UV Resistance 

Methods to Predict Plastic Material Behavior in UV Light


There exist several test methods used to predict the behavior of a plastic material to UV light. These test methods can be used to characterize material performance when subjected to specific and well-defines factors. (ofcourse there are several other methods as well, but they are not discussed here)

However, it is also important to note that no one test can be employed to evaluate completely the effects of UV light on any material.

  • ASTM D2565 - Standard Practice for Xenon-Arc Exposure of Plastics Intended for Outdoor Applications
  • ASTM D 4459 - Standard Practice for Xenon-Arc Exposure of Plastics Intended for Indoor Applications
  • ASTM G154 - Standard Practice for Operating Fluorescent Ultraviolet (UV) Lamp Apparatus for Exposure of Nonmetallic Materials
  • ISO 4892 - Methods of Exposure to Laboratory Light Sources – is a four-part standard covering different light sources.
    • Part 1: General guidance
    • Part 2: Xenon-arc exposure
    • Part 3: Fluorescent UV exposure
    • Part 4: Carbon-arc exposure
  • ASTM D 4329 - Standard Practice for Fluorescent Ultraviolet (UV) Lamp Apparatus Exposure of Plastics
  • And many more…


UV Light Resistance Behavior of Various Polymers


Ratings in the table below are based on an overall qualitative assessment.

Click to find polymer you are looking for:
A-C     |      E-M     |      PA-PC     |      PE-PL     |      PM-PP     |      PS-X

Polymer Name Value
ABS - Acrylonitrile Butadiene Styrene Poor
ABS Flame Retardant Fair
ABS Flame Retardant Poor
ABS High Heat Poor
ABS High Impact Poor
ABS/PC Blend - Acrylonitrile Butadiene Styrene/Polycarbonate Blend Fair
ABS/PC Blend 20% Glass Fiber Fair
ABS/PC Flame Retardant Poor
ASA - Acrylonitrile Styrene Acrylate Good
ASA/PC Blend - Acrylonitrile Styrene Acrylate/Polycarbonate Blend Good
ASA/PC Flame Retardant Poor
ASA/PVC Blend - Acrylonitrile Styrene Acrylate/Polyvinyl Chloride Blend Good
CPVC - Chlorinated Polyvinyl Chloride Fair
ECTFE - Ethylene Chlorotrifluoroethylene Good
ETFE - Ethylene Tetrafluoroethylene Good
EVA - Ethylene Vinyl Acetate Poor
FEP - Fluorinated Ethylene Propylene Good
HDPE - High Density Polyethylene Poor
HIPS - High Impact Polystyrene Poor
HIPS Flame Retardant V0 Poor
Ionomer (Ethylene-Methyl Acrylate Copolymer) Good
LCP - Liquid Crystal Polymer Good
LCP Carbon Fiber-reinforced Good
LCP Glass Fiber-reinforced Good
LCP Mineral-filled Good
LDPE - Low Density Polyethylene Fair
LLDPE - Linear Low Density Polyethylene Fair
MABS - Transparent Acrylonitrile Butadiene Styrene Fair
PA 11 - (Polyamide 11) 30% Glass fiber reinforced Fair
PA 11, Conductive Fair
PA 11, Flexible Fair
PA 11, Rigid Fair
PA 11 or 12 Fair
PA 12 (Polyamide 12), Conductive Fair
PA 12, Fiber-reinforced Fair
PA 12, Flexible Fair
PA 12, Glass Filled Fair
PA 12, Rigid Fair
PA 46 - Polyamide 46 Fair
PA 46, 30% Glass Fiber Fair
PA 6 - Polyamide 6 Fair
PA 6-10 - Polyamide 6-10 Fair
PA 66 - Polyamide 6-6 Poor
PA 66, 30% Glass Fiber Poor
PA 66, 30% Mineral filled Poor
PA 66, Impact Modified, 15-30% Glass Fiber Poor
PA 66, Impact Modified Poor
Polyamide semi-aromatic Fair
PAI - Polyamide-Imide Excellent
PAI, 30% Glass Fiber Excellent
PARA (Polyarylamide), 30-60% glass fiber Good
PBT - Polybutylene Terephthalate Fair
PBT, 30% Glass Fiber Fair
PC - Polycarbonate Fair
PC (Polycarbonate) 20-40% Glass Fiber Fair
PC (Polycarbonate) 20-40% Glass Fiber, Flame Retardant Poor
PC - Polycarbonate, high heat Fair
PC/PBT Blend - Polycarbonate/Polybutylene Terephthalate Blend Fair
PC/PBT blend, Glass Filled Fair
PCTFE - Polymonochlorotrifluoroethylene Good
PE - Polyethylene 30% Glass Fiber Fair
PEEK - Polyetheretherketone Good
PEEK 30% Carbon Fiber-reinforced Good
PEEK 30% Glass Fiber-reinforced Good
PEI - Polyetherimide Fair
PEI, 30% Glass Fiber-reinforced Fair
PEI, Mineral Filled Fair
PESU - Polyethersulfone Fair
PESU 10-30% glass fiber Fair
PET - Polyethylene Terephthalate Fair
PET, 30% Glass Fiber-reinforced Fair
PET, 30/35% Glass Fiber-reinforced, Impact Modified Poor
PETG - Polyethylene Terephthalate Glycol Fair
PE-UHMW - Polyethylene -Ultra High Molecular Weight Fair
PFA - Perfluoroalkoxy Fair
PI - Polyimide Excellent
PMMA - Polymethylmethacrylate/Acrylic Good
PMMA (Acrylic) High Heat Good
PMMA (Acrylic) Impact Modified Fair
PMP - Polymethylpentene Fair
PMP 30% Glass Fiber-reinforced Fair
PMP Mineral Filled Fair
POM - Polyoxymethylene (Acetal) Poor
POM (Acetal) Impact Modified Poor
POM (Acetal) Low Friction Poor
POM (Acetal) Mineral Filled Poor
PP - Polypropylene Fair
PP - Polypropylene 10-20% Glass Fiber Fair
PP, 10-40% Mineral Filled Fair
PP, 10-40% Talc Filled Fair
PP, 30-40% Glass Fiber-reinforced Fair
PP (Polypropylene) Copolymer Fair
PP (Polypropylene) Homopolymer Fair
PP, Impact Modified Poor
PPE - Polyphenylene Ether Fair
PPE, 30% Glass Fiber-reinforced Fair
PPE, Flame Retardant Poor
PPE, Impact Modified Poor
PPE, Mineral Filled Fair
PPS - Polyphenylene Sulfide Good
PPS, 20-30% Glass Fiber-reinforced Good
PPS, 40% Glass Fiber-reinforced Good
PPS, Conductive Good
PPS, Glass fiber & Mineral-filled Good
PPSU - Polyphenylene Sulfone Good
PS - Polystyrene Poor
PS - Polystyrene, 30% Glass Fiber Poor
PS (Polystyrene) Crystal Poor
PS, High Heat Poor
PSU - Polysulfone Fair
PSU, 30% Glass finer-reinforced Fair
PSU Mineral Filled Fair
PTFE - Polytetrafluoroethylene Good
PTFE, 25% Glass Fiber-reinforced Good
PVC - Polyvinyl Chloride Good
PVC (Polyvinyl Chloride), 20% Glass Fiber-reinforced Good
PVC, Plasticized Fair
PVC, Plasticized Filled Fair
PVC Rigid Fair
PVDC - Polyvinylidene Chloride Fair
PVDF - Polyvinylidene Fluoride Good
SAN - Styrene Acrylonitrile Poor
SAN, 20% Glass Fiber-reinforced Poor
SMA - Styrene Maleic Anhydride Flame Retardant V0 Poor
SRP - Self-reinforced Polyphenylene Good
XLPE - Crosslinked Polyethylene Good


Commercially Available Polymer Grades with High UV Resistance



Disclaimer: all data and information obtained via the Polymer Selector including but not limited to material suitability, material properties, performances, characteristics and cost are given for information purpose only. Although the data and information contained in the Polymer Selector are believed to be accurate and correspond to the best of our knowledge, they are provided without implied warranty of any kind. Data and information contained in the Polymer Selector are intended for guidance in a polymer selection process and should not be considered as binding specifications. The determination of the suitability of this information for any particular use is solely the responsibility of the user. Before working with any material, users should contact material suppliers in order to receive specific, complete and detailed information about the material they are considering. Part of the data and information contained in the Polymer Selector are genericised based on commercial literature provided by polymer suppliers and other parts are coming from assessments of our experts.

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