Plasma Surface Treatment of Ultra High Molecular Weight Polyethylene Rope
The coloring and dyeing of polymers is critically important in today’s society and is used in many sectors of manufacturing, from textiles to automobiles. One industrially important process is the coloring of ultra-high molecular weight polyethylene (UHMWPE). UHMWPE is a particularly lightweight and strong plastic, but it has very poor ink adhesion due to its highly non-polar nature. Plasma surface treatment is a well-known, efficient, and environmentally friendly (compared to a chemical treatment) technique to remedy surface non-polarity. It works by adding radicals on the surface of the sample which are then available to bind with other materials in the region to form polar functional groups which can then create bonds with an ink introduced to the surface. This experiment details the oxygen and argon plasma treatment of UHMWPE rope to improve ink adhesion to its surface. Prior to treatment, abrading a rope resulted in an average grayscale value of the abraded area of ~100 (0 is darkest, 255 is whitest on the grayscale, dyed rope starts at ~30). After oxygen plasma treating the rope for 2 minutes at 400 watts with a gas flow rate of 99 sccm and a pressure of 250 millitorr, abrading the dyed black rope resulted in an average grayscale value of ~45. So, oxygen plasma treatment resulted in the UHMWPE rope being about 70% closer to its original color than an untreated rope, which we hypothesize is due to the surface hardening of the polymer from plasma treatment.