Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2009
Publication Date: 4/29/2009
Citation: Byler, R.K., Anthony, W.S. 2009. Ranking Bale Bagging Materials for Cotton Bales on the Rate of Bale Weight Change. Applied Engineering in Agriculture. Vol. 25(2): 167-174. Interpretive Summary: Bales of cotton are placed in bagging to protect them from contamination during shipping and storage. Historically the bags have been permeable to humidity so that the moisture content of the lint would change during storage based on the environment. In many cases the cotton was drier than desirable when it came from the gin and gained moisture during storage so that it was in better condition for spinning when it reached the mill. Recently newer, stronger, lighter in weight, and less expensive plastic-based bagging materials have been adopted. But some of these bags are much less permeable to humidity and the bales do not come to equilibrium with the environment as readily. In this study cotton bales in different bagging materials were held in constant temperature and relative humidity environments and weighed periodically to determine the rate of weight change. The resulting set of bale weights over time were modeled statistically and a single number generated for each different bagging material which would allow the industry to communicate the rate of weight change for these materials. This number will allow the industry to discuss the issues regarding the effect of bagging on bale weight change more clearly and base the discussion on reliable data.
Technical Abstract: Universal Density cotton bales were formed with relatively dry lint, covered with different types of cotton bale bagging materials, and the bales stored in a humid environment for more than 3 months. The bale coverings included coated woven polypropylene with and without holes, linear low density polyethylene film with different hole patterns, and no bale bagging. The bales were weighed periodically during storage. Some bales were then exposed to drier conditions and the weight change over time again recorded. Theoretical diffusion models were considered and the bale weight changes modeled with a single term decaying exponential. Different bales in the same bagging type changed weight consistent with the models. The rate of bale weight change from the models was used to calculate a half time to equilibrium, in days, for each bagging type. The half time for bales with no bagging was 10 days, for bales in coated woven polypropylene bagging with holes punched in it was 34 days, and for bales with a bagging made of polyethylene film with holes was 102 days. This half time number will allow simplified communication of the effect bale bagging has on the rate of change of cotton bale weight during storage.