PA, PPO and SEBS are blended to improve their toughness and expand the application of alloy materials
The excellent thermodynamic characteristics of polyphenylene oxide (PPO) are determined by its molecular structure. It can operate continuously in the range of -160 to 190 °C, and among thermoplastic engineering polymers, it has one of the best creep resistances.
In a wide temperature range, PPO can maintain good mechanical characteristics, electrical properties, heat resistance, flame retardancy, and chemical stability.
Engineering plastic with good performance is polyamide (PA). High mechanical strength, superior solvent resistance, and ease of processing are all benefits of its high crystallinity.
But because of drawbacks like low impact strength, poor heat resistance, and poor dimensional stability of goods brought on by significant water absorption, it can only be used in a few specific industries.
The method of blending modification may be utilized to create a PA/PPO alloy with outstanding comprehensive qualities by making the properties of PA and PPO complimentary.
However, because PPO is a non-crystalline resin and PA6 is a crystalline resin, the interface bonding strength of the straightforward mixture of the two incompatible polymers is poor. As a result, fractures under stress begin to develop and spread quickly, having an adverse effect on the performance and durability of the material. Poor tensile characteristics may generally be improved by adding a third component.
In addition to having the high elasticity of rubber at ambient temperature, SEBS also demonstrates good plasticization formability at high temperatures and has the thermoplasticity of non-hydrogenated goods.
It has high wear resistance and flexibility because its main chain contains no unsaturated double bonds. In addition, by combining SEBS with the PPO/PA6 alloy, the toughness may be increased and the applications of the alloy material can be broadened since the PS segment in the PPO and SEBS phases can dissolve one another and achieve a thermodynamically compatible state.
To investigate the impact of adding SEBS on the structure and characteristics of PPO/PA6 alloy, several researchers utilized SEBS as a toughening agent. As a result of the alloy system's low compatibility, some SEBS-g-MAH was introduced to the experiment as a reactive compatibilizer for the PPO/PA6 alloy, which may significantly increase the contact force at the PPO/PA6 phase interface. A persistent submicroscopic dispersion state results from the dispersed phase's tiny, uniform particle distribution in the matrix.
Because SEBS is compatible with PPO and has a high elongation at break due to its nature as an elastomer, it has a low yield strength. As a result, as the amount of SEBS grows, the blended alloy system's tensile strength reduces and the fracture toughness increases. The rate of elongation kept rising.
The inclusion of SEBS, an elastomer with strong chain flexibility, lowers the material's resistance to external force deformation, lowering the alloy's bending strength and bending modulus.
The brittle-ductile transition happens when the quantity of toughening agent SEBS is between 5 and 7.5 parts. At the same time, when the amount of SEBS is increased, the blended alloy's notched impact strength steadily rises.
This is due to the fact that when the amount of SEBS rises, there are more stress concentration spots. This might encourage the PPO/PA6 alloy to develop a lot of silver streaks, shear bands, and other energy-dissipating structures in order to fulfill the goal of toughening.
Since PPO and the PS segment in SEBS are indefinitely miscible, SEBS is particularly good at enhancing PPO's toughness and impact resistance.
A new idea for enhancing the temperature resistance and mechanical properties of TPE materials in the application of TPE cables, sealing strips, and other products is provided by PPO, which also significantly improves the temperature resistance, flame retardancy, and compression permanent properties of SEBS.