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Materials Science at Oregon State University

Optical Measurement of Local Strains Development and Load Transfer in Wood-Plastic Composites

Date: Thursday, Feb 24th
Presenter: Lech Muszynski , OSU Wood Science/Materials Science


Wood plastic composites (WPC) are heterogeneous materials comprised of irregular wood flour particles dispersed in thermoplastic polymer matrices. The matrix is typically high-density polyethylene (HDPE), polypropylene (PP) or poly(vinyl
chloride) (PVC). Mechanical properties of the composite are determined by the load transfer between the particle and the matrix. The strength of the internal bond determines whether the particles act as merely filler or as reinforcement. The ability
to model and predict this interaction is crucial for designing improved, more efficient composites. There is no shortage of theories and models for short fiber (fibre) thermoplastic composites, which allow prediction of composite properties based on
mechanical properties of the fiber and the matrix, the size, orientation and distribution of the fiber in the composite, and on the properties of the internal bond between these two phases. However, in most composite models, the internal bond is
assumed a clearly defined interface, an imaginary surface forming a common boundary between the phases (the fiber and the surrounding polymer matrix). Such assumption is a good approximation for composites reinforced with glass or carbon
fibers – solid, impermeable and of regular cross sections. It can hardly be extended to wood plastic composites, where wood particles are porous, permeable and irregular. In fact, the knowledge about load transfer between wood flour particles and
the polymer matrix in WPCs is very limited. The objective of this study is to characterize the full-field deformation and strain distribution in and around wood flour particles embedded in a polymer matrix experimentally, and to use morphology-based material point method (MPM) numerical simulations to determine effective load transfer parameters for calculations and modelling.

Dr. Lech Muszynski is an Associate Professor in the Department of Wood Science and Engineering at Oregon State University. A native of Poland, he received his M.S. in Wood Technology and Ph.D. in Forestry and Wood Technology from the Agricultural University of Poznan (currently Poznan University of Life Sciences). In 1998-2004 he worked at the Advanced Engineered Wood Composites Center at the University of Maine. His research area includes mechanical performance of solid wood, traditional wood-based composites as well as advanced hybrid wood-plastic and wood-FRP composites, and composites based on renewable materials derived from plants. The focus of his research is on structure-property relations with stress on the interface performance. The broader research area includes, bonding, durability, damage assessment, time dependent phenomena, and hydro-mechanical behavior in solid wood and bio-based composite materials.