Samples (IMAGE) Spanish Foundation for Science and Technology Caption Tests to see the ability to form layers of a mixture of material with 3% urea (sample U) and another with 3% naphthalene, a common plasticizer (sample N) Credit Shima Pilehvar et al. / Journal of Cleaner Production Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.