Surface Preparation IV: Treatments for Plastics II
The last article1 reviewed the basic methods for surface treatment of plastics. The high-energy methods include plasma, flame and corona treatments. Chemical oxidative processes include chromic acid, nitric acid and peroxide attack. Some plastics can be etched with strong base such as sodium or potassium hydroxide. In this article, we examine some specific methods for certain types of plastics.
After the same treatments, poly-propylene showed a 200-fold improvement with plasma treatment but a 600-fold improvement in bonding with chromic acid treatment. Why would chromic acid oxidation be so much more effective on polypropylene than on polyethylene and why are the improvements so great?