Expanded polypropylene (EPP) has been steadily gaining global recognition as a material of choice for structural elements of various products. This is due to the unique properties of this material which make it suitable for an extremely wide range of service conditions. This article covers the advantages and popular applications of EPP including ventilation systems. 

EPP up close

Expanded polypropylene is a highly versatile closed-cell bead foam based on polyolefins with a soft structure and a unique range of properties.

Expanded polypropylene was first obtained in 1980s. Thanks to a high strength-to-weight ratio this material first became popular with aircraft model enthusiasts and model kit manufacturers. Demand for EPP has since increased dramatically in all regions of the world. Today this material is widely utilised in construction and automotive industries, shipbuilding, and packaging. It is also used for shock-absorbing layers of cycling and motorcycling safety helmets.

The manufacturing process begins with mechanical mixing of granulated polypropylene resin and expanding agent at high temperature. In order to achieve proper foam expansion, the polypropylene resin used in the process must have a certain molecular structure which ensures a high melt thickness. Expanding agents are represented by various plasticizers as well as antistatic and fire-retardant additives. The choice of expanding agent is based on the technical requirements to the final product. The mixing is followed by extrusion during which the mixture is also subjected to ultrasonic treatment. Ultrasound affects the number, shape and distribution of cells in the polymer as well as the density of the final product. Ultrasonic treatment also reduces the risk of defects in the material and increases its strength.

Strong by design

Despite the complexity the EPP manufacturing process is well worth it as the resulting material is at par with such super-materials as carbon fibre or fibreglass.

Thanks to being air-tight expanded polypropylene provides excellent noise, vibration and thermal insulation. The material is ideally suited for thermal insulation of residential, office and industrial spaces.

Expanded polypropylene is also characterised with outstanding energy absorption and impact resistance which stood behind its successful application in aircraft models. As impacts and collisions are inevitable parts of flying aircraft models they require materials which combine high rigidity and light weight. This is exactly what EPP is like. A high strength-to-weight ratio makes expanded polypropylene an excellent choice for containers, cases and other kinds of packaging as well as casings and internal components of various equipment – for example ventilation units, mobile phones, TVs and even cars. Besides being lightweight this high-density material offers multiple impact resistance and good shape memory after the application of dynamic or static loads.

Expanded polypropylene is chemically neutral and highly resistant to diluted and concentrated acids, alcohols, bases, alkali etc.

EPP is also widely appreciated for its high thermal resistance and excellent UV resistance. The material remains stable in a wide range of temperatures from -40 to +60 °С.

EPP is water-repellent. It retains mechanical properties even at elevated humidity while its buoyancy resulted in its wide adoption in shipbuilding industries. Since closed cells of expanded propylene are water-tight it provides excellent waterproofing for electrical appliances. EPP is widely used as a waterproofing material in steam baths, saunas, bathrooms and showers. Expanded polypropylene also provides a base for various composites used in filters of water treatment facilities.

The material is non-toxic and considered food-grade. Furthermore, expanded polypropylene does not promote the growth of mould and fungi. Since EPP articles are 100% recyclable the material is highly reusable.

Expanded polypropylene also offers numerous machining and processing benefits. EPP sheets are easily drilled and glued allowing efficient large-scale fabrication of high-quality items.

Solutions from VENTS

“Ventilation Systems” is committed to design and engineering innovations to improve the quality of its products, extend their functionality and provide maximum benefits for the end users. The introduction of air handling units in expanded polypropylene casings marked yet another step in this direction. The units include VUT/VUE 180 P5B EC, VUT/VUE 180 P5 A4, VUT/VUE 270 V5B EC and VUT/VUE 230 V5 series models. VENTS is also developing two higher-speed air handling units – the suspended-mounted VUT 400 P5 EC and the horizontally-mounted VUT 300 H mini EC. Furthermore, the company has recently showcased a pioneering concept of a single-room air handling unit in an EPP casing.

The material completely eliminates the need for additional insulation. Besides near-silent operation it also contributes to efficient heat recovery and air heating by eliminating heat losses.

Thanks to a high structural rigidity, the casing keeps the internal components of ventilation units intact. Unlike metal expanded polypropylene is rust-proof making it an ideal choice for high humidity environments.

Thanks to a low weight air handling units in EPP casings are easy to transport and install.

In addition to air handling units in EPP casings VENTS is planning to extend the application of this highly promising material to air ducts.

By introducing equipment components made from EPP, which, just like other premium high-tech materials, offers numerous benefits, VENTS has once again demonstrated its firm commitment to innovation and adoption of state-of-the-art technology.