Methods for forming ultra high molecular weight polyethylenes and methods for reducing contaminant content in such

A method for forming an ultra high molecular weight polyethylene, the method comprising:

• oligomerizing ethylene in the presence of at least an oligomerization catalyst and an anti-fouling agent, wherein one or both of the oligomerization catalyst and an anti-fouling agent comprise one or more contaminants selected from the group consisting of titanium, aluminum, zirconium, chromium, nickel, hafnium, scandium, magnesium, boron, phosphorus, fluorine, chlorine, nitrogen, silicon, and combinations of these;
• forming an initial ultra high molecular weight polyethylene composition as a byproduct of the oligomerizing of the ethylene, wherein the initial ultra high molecular weight polyethylene composition comprises at least 0.02 wt. % of the one or more contaminants of the oligomerization catalyst, the anti-fouling agent, or both, and wherein the initial ultra high molecular weight polyethylene composition comprises at least 0.02 wt. % of one or more contaminants;
• and
• contacting the initial ultra high molecular weight polyethylene composition with an acid to form a processed ultra high molecular weight polyethylene composition, wherein the contacting of the acid with the initial ultra high molecular weight polyethylene composition is for a time, at a pressure, and at a temperature sufficient to reduce the amount of the one or more contaminants in the initial ultra high molecular weight polyethylene composition by at least 5 wt. %.

A method for reducing the amount of one or more contaminants in an initial ultra high molecular weight polyethylene composition, the method comprising:

• contacting the initial ultra high molecular weight polyethylene composition with an acid to form a processed ultra high molecular weight polyethylene composition, wherein:
• the contacting of the acid with the initial ultra high molecular weight polyethylene composition is for a time, at a pressure, and at a temperature sufficient to reduce the amount of the one or more contaminants in the initial ultra high molecular weight polyethylene such that the total amount of contaminants in the processed ultra high molecular weight polyethylene composition is less than or equal to 95% by weight of the total amount of contaminants in the initial ultra high molecular weight polyethylene composition;
• the initial ultra high molecular weight polyethylene composition comprises at least 0.02 wt. % of one or more contaminants;
• the acid comprises hydrochloric acid, nitric acid, or combinations of these;
• the contacting of the acid with the initial ultra high molecular weight polyethylene composition occurs at a temperature from 25° C. to 200° C. and pressure from ambient pressure to 60 bar;
• the one or more contaminants are selected from the group consisting of titanium, aluminum, and combinations of these;
• and
• the processed ultra high molecular weight polyethylene composition comprises less than or equal to 5 wt. % of the one or more contaminants;
• washing the processed ultra high molecular weight polyethylene composition with water;
• and
• drying the processed ultra high molecular weight polyethylene composition.