Advantages and its areas of application
Physically foamed polypropylene or polypropylene foam (further on EPP) is an excellent material for civil engineering, automotive and food industries. EPP is a much more “crystalline” material compared to the more amorphous low-density polyethylene foam (LDPE foam), allowing this material to replace a large number of rigid foams on the market.
Due to its excellent physical and mechanical characteristics, the possibility of use in environments with high operating temperatures (up to +130 degrees Celsius), much greater environmental friendliness in contrast to cross-linked polymers and many other types of insulating materials, this type of insulating materials is increasingly attracting the interest of consumers.
Unfortunately, today we see that manufacturers of physically foamed polymers are reluctant to launch EPP into their productions, since they do not have the technology knowledge for producing this product. Additionally, extrusion lines (in the most cases single screw) used to produce polyethylene foam for packaging are not capable to produce a high-quality polypropylene foam material.
Here in FAP we contribute to the development of EPP in the global market. In addition to our foam machineries, we provide training for foam polymers producers, providing a full range of services for calculating production indicators, launching the production of EPP and EPE, preparing all technological and technical documentation.
Physically foamed polypropylene (EPP) and cross-linked polyethylene foam (XLPE)
There is no point in comparing non-crosslinked physically foamed polyethylene (EPE) with physically foamed polypropylene (EPP), since these materials are completely different in performance characteristics.
But we will look at some comparative characteristics of EPP and physically cross-linked polyethylene foam (further on XLPE), since the last one is closer in performance characteristics to EPP.
It can be seen that in terms of the comparative characteristics of thermal conductivity, elastic modulus and application temperature, EPP is superior to XLPE. Does this mean that EPP can replace XLPE in all applications? Of course not.
XLPE has excellent shock-absorbing properties, are much more elastic materials, have the same low thermal conductivity and a number of other qualities that differ from non-cross-linked polypropylene foam, which are necessary in some industries.
Global Goal
One of the main tasks of the global community today is to create a closed-cycle industry and introduce easily recyclable materials into our daily lives.
Physically and chemically cross-linked foams (XLPE) are very difficult and expensive to recycle, and the process is poorly organized. As EPP can be recycled by a rather simple granulation process and can be reused a large number of times. This fact creates closed-cycle production or closed-loop manufacturing, where all waste generated during the production process does not end up in landfills, but is very easily recycled internally in companies and used more times in the same foam manufacturing with different persantages. In addition, the production process of EPP is simpler and more efficient compared to the production of XLPE.
Applications where Physically Polypropylene foam EPP will dominate
Due to its superior characteristics described above, physically foamed polypropylene (EPP) is set to become a leading material in the following areas:
Insulation in construction:
- Soundproofing of impact and airborne noise during the construction of multi-storey 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 in the car interior:
- Sound insulation of the car floor and roof structure.
Food industry:
- Production of single-use tableware instead of polystyrene foam (EPS).
We have already talked about the possibilities and advantages of using EPP in single-use tableware and the reflection of thermal insulation in the “warm floor” design in our articles and posts. In this article we will consider exclusively those qualities of physically foamed polypropylene (EPP) that are necessary for using insulation under high loads and in environments with high operating temperatures.
Sound and heat insulation of "floating floor" systems under concrete screed using EPP in the construction of multi-storey buildings
The issue of sound insulation always concerns the floor of the room in building. In the most countries there is a strictly established standard (the permissible number of decibels transmitted through floor structures). To meet this standard, when building or renovating constructions, it is important to ensure that the floor is insulated as much as possible from airborne and impact noise.
In the construction of the so-called “floating floor”, a variety of insulating materials are used from chemically and physically cross-linked polyethylene foam to polypropylene foam, foam rubber, stone wool, as well as non-cross-linked polyethylene foam.
Physically foamed polypropylene (EPP) is the best way to soundproof a floor under a cement screed.
Below are the results of the durability test "12 months under a load of 2000 N/m2", which shows the change in the thickness of sound insulation from foamed polypropylene (EPP) and cross-linked polyethylene (XLPE) over 12 months.
From the diagramm above we read that the stabilization of the thickness of physically foamed polypropylene (EPP) occurred at the end of the third month, and the loss of thickness at the end of 1 year was 10-11% of the original. Stabilization of the thickness of the crosslinked polyethylene foam (XLPE) occurred at the end of the fifth month, but the overall thickness loss was 20%.
Thus, after a year, the impact noise reduction rates for physically foamed polypropylene (EPP) decrease by approximately 4%, for cross-linked foamed polyethylene (XLPE) by 10%.
Decreasing impact noise reduction results in increased sound transmission through the floor in the room.
Thermal insulation of rooms and structures with high operating temperatures
Another useful property of EPP, it can be used at high ambient temperatures, where the vast majority of polymer materials are not able to maintain their physical properties. Insulating a sauna is one of the most common ways to use insulation made from physically foamed polypropylene (EPP). This can also be the insulation of a metal roof in countries with large differences in average annual temperatures (Italy, Spain, Egypt, etc.), when in summer the temperature of a metal roof can reach +90-95 °C.
Below are the shrinkage test results of physical polypropylene foam (EPP) and cross-linked polyethylene foam (XLPE) under various temperature conditions for 48 hours.
Please note that after the use temperature exceeds 105 °C for a long time of use, XLPE begins to deform quite severely.
As for physically foamed polypropylene (EPP), it can be used in conditions of constant high temperatures up to 125-130 °C, which gives this type of insulation additional advantages.
Physically foamed polypropylene (EPP) is an ideal solution in many industries
The production of this unique material is safe and environmentally friendly, which is one of the most important factors. Due to its molecular structure and a number of other qualities, EPP is quite easy to produce using carbon dioxide as a foaming agent, which creates additional value for this product.
We are confident that expanding the use of non-cross-linked Polypropylene Foam on the market replacing a number of difficult-to-recycle materials will allow to make our planet much better.