Comparative study of the effect of PEG and Crodamide on the scratch resistance of PMMA

Abstract

Scratch durability of polymer surfaces and coatings is becoming crucial for the growing use of these materials in innovative applications, replacing former materials with more resistant surfaces. A variety of physico-chemical processes such as annealing and a range of ion plantation techniques have been proved very valuable for the renovation of polymeric surfaces but their applications are restricted to some certain polymers due to a number of disadvantages. In particular, several of them can not be applied to translucent polymers like PMMA due to their darkening outcome. Enhancement of the scratch resistance must be investigated for the most part as a consequence due to decreasing the friction coefficient. The recovery increases if the tip is smooth or if the local friction coefficient is low. Discovery of appropriate plasticizers for different polymers to decrease their surface friction is yet to be made in order to improve their scratch resistance. The effect of PEG and crodamide on both surface properties and bulk mechanical properties of PMMA was studied over a wide range of temperature (ranging from -40 to +85°C). Our experimental results show that a decrease in friction coefficient is possible by the introduction of appropriate plasticizer without having a significant effect on its bulk behaviour and this decrease in friction depends upon the nature and the content of plasticizer. Moreover, fatty acid amides have been proved more effective in decreasing friction than PEG. The friction decreases directly with the percentage of crodamide. The values of the rear contact angle and in-situ photographs during scratching confirm that the decrease in friction is associated with the decrease of yielding of the contact between the tip and the polymer surface.