The high flammability rating of plastics has caused a lot of domestic and commercial accidents. Over 23% of domestic fire accidents start from plastic appliances such as television, radio, carpet, kitchen appliances, power adapters, etc.
What if there’s a way to reduce the flammability of plastics? This means fewer fire accidents! Here, you’ll learn in detail the importance of fire resistance and how flammability is rated. You’ll also learn extensively about flame retardant plastic.
Importance of Fire Resistant Plastics
Plastics are undoubtedly one of the most important raw materials in part machining. However, one edge metal has over them is its lower tendency to catch fire. However, with fire resistant plastics, their risk of flammability is reduced. Apart from their reduction in flammability, here are some other reasons why fire resistant plastics are important:
Helps Make Parts Safer for Use
Plastics are one of the most widely used materials in part production. However, using them for parts where a lot of heat is involved might pose a problem due to their high flammability. This is not the case with plastics with a low flammability rating. Due to their ability to withstand fire to an extent, they help to further enhance the use of plastics for high-temperature applications and make them safer for use.
Helps to Protect the User of These Parts
When the part is safer to use, the user is also safe from fire hazards. Especially if the part is a component of a larger contraption, it is quite important to use fire resistant plastics. This is because the fire from the plastic part could lead to a bigger fire if not quickly put out. This might put the part user at risk of carbon dioxide suffocation. The individual may also sustain heavy burns from the fire, which may lead to death as well. However, plastics with low flammability ratings help to prevent this. If there’s no fire outbreak, there’ll be no heavy combustion, and no one will suffer a heavy burn. Thus, fire resistant plastics help to save lives.
How to Determine Fire Resistant Level
As much as fire resistant plastics are important in machining, you must be able to know the degree of their fire resistance before use. This is where UL94 comes into play. UL 94 is one of the most widely accepted plastic flammability testing standards. It is released by independent Underwriters Laboratories of the United States, where it got its acronym (UL). It is a standard that determines the tendency of a material to either ignite or spread the flame once it is ignited.
Therefore, UL ratings are given based on the material burn times, horizontal or vertical burn distance, and the time required for the flame to extinguish. Different samples of similar materials might have different UL 94 results due to their thickness. For instance, the time required for a plastic of 2mm thickness to extinguish will differ from the time needed for the same plastic of 10mm thickness to extinguish. The former will require a lesser time, while the latter will take more time.
There are six UL94 fire-retardant ratings, and they include (From the most fire-retardant to the least fire-retardant):
- 5VA: burning doesn’t exceed 60 seconds on a vertical specimen. It doesn’t allow any drip. Plaque specimens may develop no holes.
- 5VB: burning doesn’t exceed 60 seconds on a vertical specimen. It doesn’t allow any drip. There may be a hole in the plaque specimen.
- V-0: burning doesn’t exceed 10 seconds on a vertical specimen. It allows drips of flaming particles as long as they’re not inflamed.
- V-1: burning doesn’t exceed 30 seconds on a vertical specimen. It allows drips of flaming particles as long as they’re not inflamed.
- V-2: burning doesn’t exceed 30 seconds on a vertical specimen. It allows drips of flaming particles.
- HB: has a burning rate of < 76 mm/min for thickness < 3 mm. Burning stops before 100 mm. It features slow burning on horizontal samples.
The image below gives a visual representation of the UL-94 rating
Some plastics don’t meet the requirement of 5VA, 5VB, and V-0. To meet these criteria, plastics need additives. However, it will add to the manufacturing cost. Thus, it is often not desirable. It also tends to affect the plastic’s mechanical properties and cause other manufacturing issues.
How to Select Flame Retardant Plastics for your Product
Most plastics are naturally flammable. However, you reduce their flammability tendency by including additives in their makeup. These additives are made of chemical compounds that help to inhibit or retard plastic ignition or burning. However, you’re probably wondering how exactly these additives make plastics fire resistant.
These compounds help to keep plastic stable under heat stress and prevent it from combusting. Therefore, flame retardant plastics can withstand heat stress without easily combusting. Fire burns in the presence of three basic elements, oxygen, fuel, and heat. Hence, the science of flame retardant is that they initiate a chemical reaction that helps moderate any or all of these elements. They also release water to prevent the plastic from burning.
How Fire Resistant Plastics Reduce Flammability
Here are some proven ways by which fire resistant plastics can achieve a lower flammability rating:
- Increase the plastic’s ignition resistance: plastics possess a high ignition property. They serve as fuel for a fire. Now, imagine reversing this equation such that they have low ignition property. That is precisely what plastics with low flammability ratings do. It increases their ignition resistance, making them unsuitable for burning.
- Hinders the speed of flame spread: fires continue to burn when they interact with other flammable materials around. Flame retardant compounds help to reduce such speed. Once the fire gets to the flame retardant plastic, it hits a break and prevents it from expanding to other materials. This helps to prevent further damage and makes putting off the fire easier.
- Reduce smoke and fume generation: the more materials that burn, the higher the smoke generation. On the other hand, the lesser the materials that burn, the lesser the smoke generation. As a consequence of preventing further burning of plastic materials, flame retardant thermoplastic helps to reduce smoke and fume generation.
Flame retardant plastics play essential roles in fire protection. A very good example of such fire-resistant plastics includes PEEK.
However, you should also consider the side effects of these fire resistant plastics when choosing them. This is because most flame retardants can also cause some toxic and expensive problems. Some of these side effects include:
- Some flame retardants vaporize and can get into your manufactured products
- Might release toxic decomposition products
- Some flame retardant plastics are expensive and can add to your cost of production
Thus, these are the essential factors you should consider before choosing flame retardant plastics for your products.
Fire accidents caused by plastics are mainly due to their high flammability rating. However, you can protect your parts and other materials by using fire resistance. Besides protecting your materials, fire-resistant can also help to save lives by preventing fire outbreaks.
Do you want a part that can withstand heat? Then, heat resistant plastics are the way to go. We at RapidDirect can design and manufacture such parts for you perfectly. You don’t have to crack your brain any longer; that’s why RapidDirect is here for you. We provide fire-resistant materials at reasonable prices.
Our engineering team of 150 technicians is always ready to help. They will provide you with professional design suggestions case by case, from early-stage material selection, custom prototyping design advice, to money-saving tips and technical reminders before parts manufacturing, all the way to end-use production. We do all these without stressing you.
To seek our expertise, all you have to do is simply select the service you need and upload your CAD files. We will take care of everything from quotation to production and delivery, cost-effectively and efficiently. Every rapid manufacturing process is transparent and will be synchronized in the cloud; you can track your order at any time.
Q: How do you make fire resistant plastic?
A: You can make fire-resistant plastic by adding hydrated magnesium oxide or aluminum oxide alone or with phosphorus or bromine compounds to low-density polyethylene. When there’s a fire outbreak, the compounds decompose and absorb the fire energy, preventing the plastic from burning.
Q: What is plastic fire resistance level?
A: this is the ability of a plastic material to withstand a fire under test conditions for a certain period of time.