Recycling Polyethylene from Automotive Fuel Tanks Giuliana Gorrasi, 1 Luciano Di Maio, 1 Vittoria Vittoria, 1 Domenico Acierno 2 1 Department of Chemical and Food Engineering, University of Salerno, Via Ponte don Melillo, 84084 Fisciano (SA), Italy 2 Department of Materials and Production Engineering, University of Naples, 80125 Naples, Italy Received 22 March 2001; accepted 4 January 2002 Published online 30 July 2002 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/app.10967 ABSTRACT: Polyethylene (PE) from postuse automotive fuel tanks is considered a valuable material for mechanical recycling, and we assessed its properties, paying particular attention to transport properties and processability. The characterization included the study of the sorption– desorp- tion isotherms, the rheological analysis of the molten mate- rials and their processability. In particular, we obtained, sorption-– desorption isotherms using a model molecule (n- heptane) to simulate contact with the fuel. The measure- ments were carried out on films of PE blend for tanks and separately on the components of the blend. Rotational rhe- ometry was carried out on scraps from used tanks and on virgin material for comparison. We performed some extru- sion tests to evaluate the possibility of mechanical recycling of the postuse materials. In particular, we examined the melt-fracture incoming conditions by making use of a twin- screw extruder with a round die. Stress–strain measure- ments were carried out on films of virgin and used material, obtained with a press on a laboratory scale to evaluate the change of the mechanical properties of a manufacture ob- tained by reprocessing a polymer aged in contact with a mixture of liquids. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 347–351, 2002 Key words: polyethylene (PE); recycling; degradation INTRODUCTION In the last few years, there has been an increasing demand, in terms of ecology, from car producers to find new solutions to decrease the negative impact of vehicles on the surrounding environment. The possibility of recycling the major part of vehi- cles at the end of their useful lives is one of the most discussed matters. Currently, much interest is focused on the possibility of recycling the plastic components, which represent about 15% of the vehicle. The recycling of plastics used from cars, besides being important from an ecological point of view, provides many economical advantages. The recovery operations are not very difficult to carry out, principally because plastic components are easily recognized and separated from the other parts when the vehicle components are dismantled and also because they could be reprocessed to obtain the same manufactures they were in their “first lives,” in a closed-loop recycling. Polymeric materials are applied in dashboards, roof covers, and fuel tanks. Currently, there are some data about the possibility of recycling dashboards and roof covers, mainly regarding the rheology of the used material and the mechanical properties of the new manufactures, 1,2 whereas few data are available on fuel tanks. 3 The recycling operations, in the case of the fuel tanks, appear complicated by the fact that the plastic containers are used in contact with a mixture of liquids composing the fuel, and some solvent remains in the material even after many hours of drying under vacuum. This could cause problems and risks during the steps of regranulation and successive processing. This investigation was a part of a wider project based on the possibility of recycling polymeric parts of civil and industrial vehicles. In this article, we present the results of absorption and desorption studies of a hydrocarbon molecule in a high-density polyethylene (HDPE) blend composing the fuel tanks. We chose the hydrocarbon n-heptane as a model molecule to stimulate contact with the fuel. A simple molecule whose vapor activity (a) could be easily var- ied between 0.1 and 1 could help clarify many impor- tant aspects of the problem. We also performed rheological and mechanical studies to analyze the behavior of the used material in the melt and also to investigate possible degra- dation phenomena that occurred in the material reprocessed after a prolonged contact with the liq- uids. We thus simulated mechanical recycling by extrusion tests performed on a laboratory scale to make a preliminary evaluation about the process- ability of tank scraps. EXPERIMENTAL All the materials were kindly supplied by FIAT (Torino, Italy). Correspondence to: V. Vittoria (vvittoria@unisa.it). Contract grant sponsor: National Council of Research (CNR)-Progetto Finalizzato Materiali Speciali per Technolo- gie Avanzatell. Journal of Applied Polymer Science, Vol. 86, 347–351 (2002) © 2002 Wiley Periodicals, Inc.