Surface energy of thermoplastics

[heman2727]

I was reading something related to surface energy of plastics. And I came across a self made conclusion: Amorphous thermoplastics have high surface energy while Semi-crystalline thermoplastics have low surface energy. I need to know am I right or wrong? and what is the reason behind a plastic having high or low surface energy? Please help me with your expertise.

Thanks in advance
Himanshu

[Gordon]

Hi Himanshu

to the Surface Engineering Forum.

No expert on this subject, but as I see it surface energy is related to the materials surface attraction or wetting ability with another materials surface. Like water with a relatively high surface energy (HSE) will bead up and be repelled by relatively low surface energy (LSE) material say like paint on your car, while adding detergent to the water may lower the surface energy and allow wetting and attraction to the painted surface. Polishing the painted surface with wax, reducing surface energy will again cause water to bead up and lose attraction.

For a liquid to effectively wet and be attracted to a substrate, the surface energy of the liquid must be as low or lower than the surface energy of the substrate. Or, the surface energy of the substrate must be raised.

This property, certainly has its implications in surface engineering - joining adhesives, bonding surface coatings, non-stick properties, adhesive wear, lubrication etc..

Quote:I was reading something related to surface energy of plastics. And I came across a self made conclusion: Amorphous thermoplastics have high surface energy while Semi-crystalline thermoplastics have low surface energy. I need to know am I right or wrong?

Looking at a small range of thermoplastics there does tend to be a trend for semi-crystalline thermoplastics to have lower surface energy.

Quote:and what is the reason behind a plastic having high or low surface energy? Please help me with your expertise.

I think it is down to the atomic/molecular arrangements/ bonds at the surface as to whether another material surface is attracted or repelled.