Creep Behavior and Damage

NORMA E. MARCOVICH; MIRTA I. ARANGUREN

Wood-Polymer Composites

Woodhead Publishing

Lugar: Cambridge (UK); Año: 2008; p. 166 - 189

Polymers and polymer composites used in engineering applications are often designed to be in service for extended periods of time, during which they are subjected to various combinations of mechanical and environmental loads. These materials show a time-dependent response (viscoelasticity) that is influenced by the particular viscoelastic properties and history of the material, as well as the external conditions of testing or service. Frequently, engineering applications require that the polymer or composite maintains its structural rigidity during the envisioned service lifetime. This is the case for the wood± plastic composites (WPCs), which are frequently utilized in low-to-medium load-supporting structural applications, such as pallets, decks, window and door components, furniture, water front applications, fendering, outdoor trails and tiles. WPCs, much in the same way as other thermoplastic-based composites, are prone to deform over time (during periods that extend over hours, days or years) under the application of external loads. `Creep´ is the term used to describe the time-dependent deformation or strain that a material undergoes under load and constitutes its viscoelastic response to an externally applied stress. Laboratory testing of the plastic composites rarely can cover periods of time long enough to be comparable to their expected service lifetime. More usually, accelerated test methods together with calculations based on different proposed models are used to predict long-term response based on short-term data.