Over the years, Polyurethane (PU) has emerged as a highly versatile material commonly used in the automotive industry, owing to its economic and environment-related benefits. Polyurethane combines light weight and flexibility, with durability and design customisation options. Its versatility has been utilised in achieving the precise mechanical properties required for varied automotive applications. The Indian Polyurethane Association (IPUA) has been a leading player in the field of PU applications for automobiles and has been instrumental in spearheading the lightweighting revolution in the segment. Auto Tech Review caught up Mukesh Bhuta, Chairman, Indian Polyurethane Association (IPUA), to discuss the advantages offered by PU and the way forward for the polymer in vehicle applications.
With the properties that it boasts in terms of high density and mechanics, PU offers clear advantages in terms of design, structural flexibility and final finish. As opposed to various other low-density materials, it has better blending properties, which amalgamates well with paint and metallic parts. Over the years, PU has become a valuable polymer as it is compatible with aluminium for body panels.
Industrial polymers offer various solutions for the automotive sector. The foams for seats, headrests, steering wheels and a large number of dashboard parts are made of PU. Indian polymer compounders offer solutions for noise, vibration and harshness (NVH) reduction through the use of PU and similar composites. Bonnet underlays, carpet underlays, roofliners, boot and pillar claddings are areas where the need for sound insulation is growing and PU is finding newer applications.
Most of these functionalities are driven towards reducing NVH levels in the cabin. PU applications can also be instrumental in lowering the environmental impact of cars by reducing vehicle weight. This improves fuel efficiency and can help lower emission levels. In the last five years, PU density for major applications has been reduced by nearly 40 % while still maintaining the same levels of rigidity.
Multi-material design approaches allow automakers to selectively integrate lightweight materials in specific vehicle regions. While spot welds, rivets and fasteners designed for metals cannot be used to join plastic and polymer composite parts to each other or to metals, high-density polymers such as PU offer high-performance structural bonds for joining composites and other dissimilar materials.
In addition to permitting lightweight construction, these polymers can be used to improve vehicle crash behaviour. Advanced polymer compounding methods allow an indispensable bonding technology in vehicle design and are recommended to enable the integration of plastic and polymer composite components in next-generation lightweight multi-material vehicles.
Advanced polymers have been a material of choice for OEMs due to their high strength-to-weight and stiffness-to-weight ratios. The high strength and energy absorption of structural polymer composites can also improve crash safety by strengthening vehicle compartments to help protect passengers during crashes.
LIGHTWEIGHTING, DESIGN VERSATILITY
PU is inherently a lightweight material, and its usage ensures substantial weight reduction for a vehicle. PU is also used as external body coatings as an intermediary between the metal body and the paint, while textile products, dies and chemicals made with PU provide a host of solutions for the upholstery market as well. In addition to reducing vehicle mass, PU has high energy absorption qualities that can help vehicles meet strict collision safety standards in demanding industries such as motorsports and aerospace.
The versatility offered by PU allows for advanced shapes and forms without compromising the safety, comfort or stability of a vehicle. This makes them very attractive for designers, as they can customise designs accordingly. Their strength and durability has also played an important part in expanding the average life span of a car, by providing better protection against corrosion. Most of the seating systems today have moved away from rubber and rubber-based materials to PU and similar polymers. For steering systems, mid- to high-end vehicles today mostly use PU and efforts are underway to enter the low-cost segments as well.
In terms of ensuring environment-friendly production, PU manufacturers around the world are looking towards better recyclability. One of the methods of recycling PU is by pounding it into crumbs and using it as a flooring material for home applications. The auto industry also reuses low-density foams, which are reconstructed and used in low-end applications for automobiles as well as other industries. The aim is to ensure that the product can be injected back into the production cycle as many times as possible, without compromising on quality.
THE ROAD AHEAD
PU is a highly versatile material and in the coming years, most of the in-cabin space in cars is likely to be dominated by PU. Material substitution possibilities are emerging fast and polymer compounders and suppliers are looking at ways and means to use PU across a wider range of applications. The current focus on increasing efficiency and decreasing emissions levels is putting pressure on the automotive industry to take as much weight out of their vehicles as possible, and PU can definitely help in that regard.
Carmakers have recognised that reducing vehicle mass carries trade-offs that may impose significant technological and manufacturing risks. Plastics and polymer composites like PU deliver several key benefits that can enable vehicle mass reduction without compromising performance or safety, allowing OEMs to comply with future emission norms and safety standards.
TEXT: Anwesh Koley