Hydrophobicity and fluid absorption in paper cups, plates and biopolymeric films

Abstract

The use of paper packaging and utensils (paper cups, paper plates, cutlery) is increasing due to busy lifestyles. Paper packaging and utensils are cheaper, easy to use and dispose of. Since paper is made from cellulose it is degradable, environment friendly, and an alternative to plastic utensils. However, the paper easily absorbs water or has high wettability, so they need a specific coating to make it waterproof to use in food industries. Turning paper into a hydrophobic utensil is challenging. Therefore, this study is investigating the hydrophobicity of commercial paper cups and plates by studying their wettability and contact angle using commercial orange juice. Contact angle measurement showed that the used cup was not hydrophobic (contact angle paper cup with juice was 83) and absorbed some orange juice. Contact angle measurement showed that the used Walki paper plate was hydrophobic (contact angle with juice was 92) but still absorbed a significant amount of orange juice. The absorbance was increasing with a longer contact time between paper and juice. These paper cups absorbed less juice than plates. A simple hydrophobic coating has improved the wettability and made the paper-based utensils usable but a superhydrophobic coating would have been better for food security i.e., which could have saved 60 ml of orange juice per 100 cups. However, more study with other food and beverage needs to be studied to make a better conclusion.