What plastic ultrasonic welding effect is better?

Amorphous polymer (ABS, PC, PS, PVC, PMMA, etc.) : the molecular arrangement is disorderly, there is an obvious temperature that makes the material gradually soft, melting and flow (Tg glass transition temperature). Such resins are generally effective at transmitting supersonic vibrations and achieving good welding over a fairly wide range of pressures/amplitudes. Crystalline polymers (PE, PP, POM,PA6,PA66, PBT, PET, etc.) : the molecules are orderly arranged and have obvious melting point (Tm melting temperature) and refreezing point. Solid crystalline polymers are elastic and can absorb some of the high frequency mechanical vibrations. Therefore, such polymers are not easy to transmit ultrasonic vibration energy to the bonding surface, which requires higher amplitude. High energy (high melting heat) is required to break the semi-crystalline structure and make the material change from the crystalline state to the viscous state, which also determines the obvious melting point of this kind of material. Once the molten material leaves the heat source, the temperature decreases to a certain extent, leading to the rapid solidification of the material. Secondly, generally speaking, non-polar compounds (such as PP and PE) are more difficult to ultrasonic (not impossible), polar compounds can be ultrasonic, and between polar compounds can also be ultrasonic, such as ABS and PMMA is ultrasonic. In addition, there are some characteristics that will affect the effect of ultrasonic, such as hardness (generally, the higher the hardness, the better the ultrasonic welding), melting point (the higher the melting point, the more ultrasonic energy needed), purity (the welding effect of raw materials is good, the effect of recycled materials with impurities is slightly worse).