Foamed Polypropylene produced by physical expansion (EPP) also known as physically foamed polypropylene has several advantages over other rigid foams in the market. EPP is also highly versatile and offers enhanced performance characteristics that are valuable in different industries including civil engineering, automotive, and food packaging.
Advantages and Applications
When compared to more amorphous rigid foams such as low-density polyethylene foam (LDPE foam), EPP is a much more crystalline material which allows it to replace several types of rigid foams currently on the market. EPP also exhibits excellent physical and mechanical properties, which enable its use in environments with high operating temperatures of up to 130 degrees Celsius. Furthermore, EPP is much more environmentally friendly than cross-linked polymers and other insulating materials, a fact that has contributed to its increasingly higher popularity among consumers. Manufacturers of physically foamed polymers are often reluctant to incorporate EPP into their productions. Lack of technological knowledge is often the reason many foam manufacturers prefer to forgo the production of EPP and instead opt to produce lower-quality Polyethylene foam for packaging applications. This material is usually manufactured using inefficient single-screw extruders, which are unable to create high-quality polypropylene foam material.
Comparing Physically foamed polypropylene (EPP) and cross-linked polyethylene foam (XLPE)
PP foam outperforms XLPE regarding thermal conductivity, elastic modulus, and application temperature. However, this does not mean that EPP can replace XLPE in all applications. XLPE has excellent shock-absorbing properties, is significantly more elastic, and has similar low thermal conductivity. Additionally, XLPE possesses many other qualities that are essential in certain industries. On the other hand, EPP is a much more sustainable material than physically or chemically cross-linked foams (XLPE). Recycling XLPE is challenging, costly, and the process is poorly organized. In contrast, EPP can be recycled through a relatively simple granulation process and reused multiple times. This enables closed-loop manufacturing, allowing companies to easily recycle all production waste internally. Furthermore, the production process for EPP is simpler and more efficient compared to that of XLPE.
EPP will soon dominate in several applications
Physically foamed polypropylene (EPP) is set to become a leading material in several applications thanks to its superior quality and characteristics. Areas where it will become prominent include:
Insulation in Construction
Insulation of car interiors
Food industry
Insulation in Construction
- Soundproofing of impact and airborne noise during the construction of multi-story buildings;
- Thermal insulation of constructions with high operating temperatures (saunas, hot water boilers, hot pipes);
- Reflective thermal insulation in the “warm floors”;
- Thermal insulation and sound insulation of metal roofing of buildings.
Insulation of car interiors
- Sound insulation of the car floor and roof structure.
Food industry
- Production of single-use tableware instead of polystyrene foam (EPS).
EPP for sound and heat insulation of “floating floor” systems under concrete screed
Most countries have established policies that limit the number of decibels that can be transmitted through floor structures. This highlights the importance of providing adequate sound insulation to minimize airborne and impact noise. The construction of a “floating floor” often involves using specific insulating materials, such as chemically and physically cross-linked polyethylene foam, polypropylene foam, foam rubber, stone wool, and non-cross-linked polyethylene foam. A recent test showed that physically foamed polypropylene (EPP) is the best material for soundproofing floors under cement screed. The durability test, which involved a load of 2000 N/m² over 12 months, examined the change in thickness of the sound insulation provided by both foamed polypropylene (EPP) and cross-linked polyethylene (XLPE). The study found that the thickness of EPP stabilized by the end of the third month, with a thickness loss of 10-11% after one year. In contrast, the thickness of XLPE stabilized by the end of the fifth month, with an overall loss of 20%. As a result, after one year, the impact noise reduction rates for EPP decreased by approximately 4%, while the reduction for XLPE declined by 10%. This decrease in impact noise reduction results in increased sound transmission through the floor in the room.
EPP for Thermal insulation
Expanded Polypropylene (EPP) is effective at high ambient temperatures, where other polymer materials often fail to retain their physical properties. This makes EPP a popular choice for insulation in saunas. Additionally, it is suitable for insulating metal roofs and is particularly beneficial in areas with significant variations in average annual temperatures. It's important to note that cross-linked polyethylene (XLPE) starts to deform considerably when exposed to temperatures exceeding 105 °C for extended periods. In contrast, EPP can withstand constant high temperatures up to 125-130 °C, providing it with distinct advantages in thermal insulation. EPP has several qualities that make it an attractive option. Its environmentally friendly production and recycling processes differentiate it from other foam materials. Moreover, its molecular structure allows for the use of carbon dioxide as a foaming agent during production, significantly enhancing its value.