UV-resistant plastics should be used wherever possible while producing plastic goods intended for use in the open air. Along the same lines, find out more about plastics resistant to UV rays here, as well as the distinctions between polypropylene and nylon.
Polypropylene and Nylon Are Two Types of UV-Resistant Plastics
Because plastics are so prevalent in today’s environment, it is only inevitable that some of them may be exposed to the sun. Unfortunately, the ultraviolet (UV) radiation present in the sunshine may degrade most plastics over time. Hence, UV-stabilized or UV-resistant plastics are required to produce any product intended for use outside. The primary emphasis of today’s article is the ultraviolet (UV) resistance of two typical commercial polymers, namely nylon and polypropylene.
What Characteristics Define a Plastic as Being UV-Resistant?
Plastics that are subjected to the UV light produced by the sun can absorb the radiation or develop free radicals, both of which have a detrimental impact on the material’s mechanical qualities. Moreover, plastics with poor UV resistance are susceptible to several side effects when exposed to ultraviolet light. These side effects include the following:
- A surface that has the appearance of chalk.
- Fraying and brittleness on the surface of the object.
- Alterations in hue or dilution.
There is a distinction between UV-resistant plastics and UV-stabilized plastics, which must be kept in mind. UV-resistant plastics have a natural resistance to the deterioration caused by ultraviolet light. Plastics that do not inherently resist damage are referred to as UV-stabilized plastics. These plastics need additives to increase their resistance to UV light. As a result of their lack of inherent UV resistance, polypropylene and nylon both need the addition of UV inhibitors.
Polypropylene vs. Nylon in Terms of Their UV Resistance
Because polypropylene and nylon, in their unmodified forms, are susceptible to damage when subjected to ultraviolet (UV) radiation, it is incorrect to refer to either of these polymers as being UV-resistant. Their reactions to UV light are outlined in the following paragraphs.
Polypropylene and the Effects of Ultraviolet Radiation
In its natural state, polypropylene is very vulnerable to deterioration caused by exposure to UV light. The material breaks easily after being exposed for a significant amount of time. In fact, after being subjected to high-intensity UV radiation over six days, primary polypropylene might lose as much as seventy percent of the mechanical strength it once had. However, it is essential to note that even with the additions, polypropylene will still deteriorate quite fast when exposed to sunlight for an extended time. It is the case regardless of whether or not the additives are present.
UV rays with wavelengths between 290 and 300, 330, and 370 nanometers cause polypropylene to degrade. These are the points at which the spectra of polypropylene are at their most intense.
Although polypropylene has remarkable mechanical strength and is highly resistant to chemicals, it should not be exposed to sunlight for an extended period since it will degrade. Because it is so difficult to apply a coating on polypropylene, don’t expose this material to direct sunlight.
Nylon and the Effects of Ultraviolet Radiation
Although nylon may indeed be degraded by exposure to UV light, not all nylons are created equal. For instance, nylon 6 has a higher resistance rating than nylon 6/6. When exposed to UV for an extended period, the color of nylon components will tend to fade. The exact process that causes polypropylene to deteriorate is also responsible for the degradation of nylon: the radiation releases free radicals, further weakening the intermolecular bonds.
Nylon is susceptible to damage from ultraviolet light with wavelengths ranging from 290 to 315 nanometers. This point is referred to as the maximum of the material’s spectrum.
Nylon is an excellent material for use in products that will be exposed to dampness since it is robust and flexible. Both nylon-6 and nylon-12 are appropriate alternatives to consider when there is a possibility of only moderate exposure to UV radiation. Nevertheless, the deterioration process will speed up if it is exposed to UV rays consistently.
Increasing Resistance to UV Radiation
Although nylon and polypropylene are not often considered UV-resistant plastics, the performance of these materials may be improved with particular additives. Stabilizers, absorbers, and blockers are the three forms that these additives may take.
- Blockers: Fillers such as titanium oxide and carbon black pigments may function as UV radiation blockers. The use of these pigments helps extend the material’s lifetime by preventing ultraviolet (UV) radiation from reaching the solid polymers that make up the plastic.
- Absorbers: The process of absorbing ultraviolet light and then converting it to heat is how absorbers operate. The chemical compounds known as benzophenones and benzotriazoles are examples of standard organic absorbers. Even when added in concentrations as low as 0.5 percent by volume, benzotriazoles can dramatically boost a material’s resistance to the sun’s rays.
- Stabilizers: Stabilizers operate by capturing any newly produced free radicals to maintain their effectiveness. Consequently, the ensuing breakdown of the intermolecular bonds inside the plastic is reduced to a minimum. Scavengers are another name for stabilizers because of how they “scavenge” and gather any free radicals that may be present. The hindered amine light stabilizers are among the most frequent light stabilizers.
Additives of all three categories are often used to strengthen the plastic’s resistance to the effects of ultraviolet light in as many ways as possible.
Which Plastics Are Resistant To The Effects Of UV Radiation?
Nylon and polypropylene are not included in the category of being resistant to the effects of ultraviolet light; thus, which plastics are? Fluoropolymers and imides are the most critical types.
By their very nature, fluoropolymers have a high level of resistance to UV light. It is due to the solid carbon-fluorine bonds that are resistant to degradation.
Examples of popular fluoropolymers are:
- Polytetrafluoroethylene (PTFE)
- Polyvinylidene fluoride (PVDF)
- Fluorinated ethylene propylene (FEP)
On the other hand, because of their exceptional resistance to ultraviolet light (UV) rays, imides may also be used in applications that are subjected to high levels of UV.
Typical imides are:
- Polyimide (PI)
- Polyetherimide (PEI)
Picking Out a Material to Use
A variety of variables will determine your choice of polymer. These include:
- Mechanical resistance
- Abrasion resistance
- Temperature resistance
UV resistance is often disregarded. Even if it is not handled, it may have significant long-term repercussions. The amount of UV resistance needed for a product is determined by its intended use, the level of exposure to which it is projected to be subjected (continuous vs. temporary), and any other environmental attributes. If your product is subjected to UV rays and an unfavorable environment over an extended period, fluoropolymers or imides are the superior material choices.
On the other hand, if your components are only sometimes exposed to ultraviolet light, UV-stabilized nylon or polypropylene could be the best option.
Get in touch with us immediately if you want more information on the types of UV-resistant plastics most suited for specific purposes.