PLASTIC COMPOSITE RAILROAD TIES – THE CHALLENGE OF USING RECYCLED RAW MATERIALS TO PRODUCE A HIGH PERFORMANCE STRUCTURAL COMPOSITE

摘要

Composite railroad crossties, produced from recycled high-density polyethylene (HDPE) andrnreinforcing fibers and fillers, are being used as replacements for hardwood ties in freight andrntransit track. Recycled thermoplastic feedstocks offer promising life cycle economics andrnenvironmental benefits but the composition and molecular structure of recycled polyolefins canrnvary widely, depending on origin, recycling history and processing conditions. These variationsrnare subtle and can lead to failure mechanisms in structural products made from recycledrnthermoplastics. The paper will review the origins and mechanisms of composite tie failures andrndiscuss the use of Fourier Transform Infrared Spectroscopy (FTIR) and Differential ScanningrnCalorimetry (DSC) to foresee and avoid potential product failures resulting from feedstockrndeficiencies.