Impact modifiers compensate for inherent brittleness, or embrittlement caused at sub-zero temperatures, crack propagation, and notch sensitivity. It involves introducing a rubbery or elastomeric component in nature, that can absorb or dissipate the impact’s energy.
The toughness and durability of various plastic resins can be improved by adding impact modifiers to plastic compounded materials. The quantity of impact modifiers for addition relies on the impact resistance level that needs to be achieved for end-use applications.
Mechanism of Impact Modifiers for Functioning:
Craze Propagation: This mechanism involves the dispersion of impact modifiers into the brittle matrix, usually a dampening phase for the absorption of energy and stopping the craze propagation.
Shear Band: The other mechanism involves shear bands formation around elastomeric particles for absorption of deformation energy. It involves dampening particle cavitation for energy absorption. The shear bands’ apparition absorbs the majority of energy.
Properties essential for the dispersion phase to attain higher efficiency:
Dampening Capability: For this, the elastomeric phase is preferred. Usually, low crystallinity and low glass transition materials are utilized. The low Tg is more specifically required for toughening at low-temperature. Moreover, polyolefin copolymers are considered ideal for this.
Good Cohesion with Continuous Phase: It is crucial for acquiring efficient toughening. The absence of cohesion may result in numerous crazes that can propagate until they fail. Good cohesion can be achieved by specific interaction by reactivity or at the surface. Its formation causes compatibilization at the interface of amphiphilic copolymers increases adhesion and reduces the surface tension.
Functional Polyolefin Impact Modifiers
Polymers such as polyester, polyamide, bioplastics, and PVC are used to fulfil the industry requirements to enhance impact resistance.
Polymeric impact modifiers, also recognized as functionalized polyolefins, provide a range of toughening performances, from usual purpose to extreme toughening in multiple polymer systems.
Polyamide (PA)
Impact modifiers based on functionalized or non-functionalized ethylene copolymers or ionomers are offered to cater to needs for PA6, 6, PA 6, or glass-reinforced PA compounds.
The industry-leading impact resistance performance offers:
• Extremely-Tough Impact Resistance
• Low-Temperature Toughness
• Inexpensive Intermediate Toughness
Polyesters (PBT, PET)
The polymeric impact modifiers offer a huge range of performance levels in engineering polymer or cast sheet applications to provide solutions that cater to unique requirements.
Engineering Polymers: Several polymeric impact modifiers offer extreme impact resistance in glass fiber-reinforced compounds. Moreover, the compounding PBT engineering polymers involve challenging the impact strength for original properties maintenance.
Cast Sheet Applications: The rising productivity in achieving the right impact strength properties is crucial for PET-based cast sheet applications.
Polyvinyl Chloride (PVC): Based on end use, various types of PVC resins are needed for various impact modification additives to acquire the optimum performance goals.
Polypropylene: It is a semi-crystalline polymer that offers easy processability and a massive cost-performance balance. However, PP needs to improve impact resistance in order to fulfill the requirements of several industries.
Acrylonitrile Butadiene Styrene (ABS): ABS resins offer performance between engineering plastics, including polycarbonate, and commodity materials, including polystyrene. These are massively used in applications, such as consumer electronics, garden equipment, computer and printer housings, toys, and automotive parts.
