Impact Modifiers: Why this product is important for the Automotive Industry?
The demands of the modern automotive industry are ever challenging – users want high performance cars and at the same time are looking for improved reliability and safety, greater comfort, fuel efficiency, style and competitive pricing. Plastics’ versatility in automotive industry allows them for advanced shapes and forms without compromising on the safety, comfort or stability of a car, thus making them a very attractive resource for designers.
There is one product of plastics family that is rising to the challenge of these potentially conflicting demands- IMPACT MODIFIERS. Technological innovation by the plastics industry is a key feature in the continuing development and use of impact modifiers in the automotive segment. With their unique combination of properties, Impact modifiers have become the key in providing enhanced performance with cost-efficiency and sustainability in mind.
Engineering polymers have been used extensively in automobiles in a variety of applications such as grille opening retainers, bumpers, trim panels, radio housing, door outer panel, handle, fog light cover, decorative panels, fuel tank etc. Originally polymers were specified because they offered good mechanical properties combined with excellent appearance, including the possibility of self-coloring but now general grade polymers are used along with some speciality additives like Impact Modifiers. The use of Impact modifiers in general grade polymers has proved their substitution for Engineering Polymers. Commodity polymers like PE, PP, PVC etc. are tremendously being used in large automotive parts where these must meet the performance requirements and Impact modifiers make it possible.
Stiffness and toughness are two inherent functions of an Impact Modifier. It is also the main additive for increasing flexibility and impact strength to meet physical property requirements of rigid parts. It also exhibits the property which increases the durability of molded or extruded plastics, particularly those subject to impact forces or cold weather service. A broad range of impact modifiers are available for toughened nylon resins, as well as for rigid PVC, PBT, ABS and other commonly specified plastics depending on the host polymer and the required properties. The most commonly used Impact modifiers for engineering polymers like Nylon, PBT, PC etc. are maleic anhydride grafted polymers which impart a degree of elasticity in otherwise brittle polymers. These impact modifiers apart from improving mechanical properties also improve processability.
In recent years, increased safety and comfort features have led to a slight rise in the overall weight of the average car from 1015 kg in 1990 to 1132 kg in 1998. But plastics components have ensured that the balance between safety and lightweight efficiency is maintained by consistently reducing weight without compromising safety features. This has been made possible by Impact Modifiers only. It is estimated that if the traditional materials were to be used in place of impact modified plastics, today’s cars would be at least 200kg heavier resulting in increased fuel consumption.
Some unmodified polymers such as rigid polyvinyl chloride (PVC), polystyrene (PS) or styrene acrylonitrile (SAN) are brittle at ambient temperatures. Others such as polyamides or polyolefins are ductile at ambient temperature but become brittle at low temperatures. Some, such as polycarbonate (PC), may have good dart impact but poor notch impact resistance. An impact modifier is needed whenever the polymer system does not meet the impact requirements for a particular application.
A variety of impact modifiers are available depending on the host polymer and the required properties. Styrenic impact modifiers are growing at an AAGR of less than 3%, while other types are growing at rates of 5-6%. Since PVC is the largest user of impact modifiers, consuming about 80% of the volume, growth of impact modifiers is tied to PVC use. Engineering resins such as PC, polyamides, and polyesters, which consume about 10% of impact modifier volume, are growing strongly, boosting impact modifier use. Polyolefins consume the remaining 10% of impact modifier volume. The continuing trend towards ‘better, cheaper, faster’ is helping drive use of impact modifiers, which can be used to either improve properties or maintain properties of thinner parts.
Looking forward to the 21stcentury, the ongoing development of advanced, high-performance additives has dramatically increased the usage of plastics in the industry. With this the automotive industry is on the brink of a revolution, and the plastics industry poised to play a major role. Thanks to plastics & speciality additives, the cars we dream of today are quickly being developed – offering high performance, cleaner driving and advanced safety and convenience features.