Mechanical Property Variables for formed fiber packaging

Introduction Cellulose fibers have unique properties that allow them to be used for a variety of products— from low-density cushioning to high-density structural products. Knowing what types of fibers and processing methods to use for each product application requires an understanding of potential properties. Historically this understanding has tended to be more an art than a science. The paper industry has been gathering information on individual fiber properties, processing conditions, fiber formation, online fiber properties, and mechanical and physical properties of resultant paper. This work is moving papermaking toward a scientific approach that can be modeled and used to predict performance characteristics. Much of this information, however, is geared primarily toward papermaking processes and papers with sheet weights between 0.02 and 0.05 lb/ft 2 (100 to 250 g/m 2) and densities between 31.2 and 50 lb/ft 3 (500 to 800 kg/m 3). Modeling the performance of pulp molding is also starting to move from an art to a scientific approach. While pulp molding uses similar fibers as those used by the paper industry, the forming processes, fiber forming characteristics, densities, and structural functionality are much different than those of paper. Because of this difference, information specific to the pulp molding industry needs to be gathered to assist in developing the modeling constants. Once this information is obtained, some of the same techniques used in the paper industry (as well as those used in other composites industries) can be used to model pulp molded products. The goal is to design and predict product performance through computer modeling based on fundamental fiber characteristics and processing parameters. The data presented here are results from initial tests of a long-term research program at the Forest Products Laboratory (FPL). The program will include both nondestructive and destructive tests to determine the mechanical properties of low-to high-density (15.6 to 62.4 lb/ft 3 (250 to 1000 kg/m 3)) fiber sheets. Various processing schemes and fiber types will be used in fabricating test sheets. For the study reported here, we attempted to simulate sheets that might fit the category of Thermoformed Fiber Packaging. Further testing will include methods to obtain the nine independent orthotropic properties of the sheet material at both 50% and 90% relative humidity (RH) conditions.