A need exists for the development of totally biodegradable packaging materials. Chitosan is an under‐utilized polymer which possesses many of the desired characteristics for this application. This article describes the crosslinking of chitosan fibers. Epichlorohydrin (ECH) was selected as a convenient base catalyzed crosslinking agent. The strength of chitosan fibers, especially wet tenacity, is improved by crosslinking. © 1992 John Wiley & Sons, Inc.

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The optimal production of the fructan biopolymer levan by the bacterium Erwinia herbicola was investigated, including variations in nitrogen, carbon and phosphorous sources, pH, incubation time, culture yields up to 19% by weight produced based on conversion of sucrose as the carbon source when grown in a continuous culture system and processed by tangential flow filtration. Product identity was confirmed with gas chromatography (GC) and (13)C nuclear magnetic resonance (NMR). Gel permeation chromatography (GPC) and low-angle laser light scattering (LALLS) determination of the molecular weight of the product showed a significant difference in molecular weight values dependent on the method of analysis. Analysis by GPC resulted in molecular weight one order of magnitude lower than LALLS independent of sample, underscoring the unusual nature of this biopolymer.

The emergence of biodegradable plastics has necessitated the development of standard methods to determine biodegradation rates in various environments. Standardized accelerated marine and soil laboratory biodegradation test systems were developed in which comparative polymer biodegradation rates could be determined by quantifying and plotting the weight loss/surface area of each sample over time and determining the maximum slopes of the curves generated. The results indicate that, in general and depending on the environment, biodegradation rates for unblended polymers were: polyhydroxybutyrate-co-valerate > cellophane > chitosan > polycaprolactone. Results from blends are more difficult to interpret since different biodegradation rates of the component polymers and leaching of plasticizers and additives can impact the data.The assessment of biodegradability of polymer films in natural environments is a difficult problem because of the inherent variations in environmental conditions from one site to another. This is further confounded by the need to balance material performance vs. rates of biodégradation (1,2). Therefore, many laboratory approaches have been developed to simulate natural biodégradation processes, but in a more controlled setting to try and predict natural environmental susceptibility of materials to biodégradation. These methods recently have been summarized and include enzyme assays, plate tests, clearing zones or changes in optical absorbance, biological oxygen demand, changes in carbon isotope ratios, release of radioactive products from radioactively labeled polymers, automated respirometry in biometer flasks, and acceleratated simulated laboratory systems or mesocosms (3-5). Many of these methods are coupled to assessments of changes in weight, molecular weight, mechanical properties, morphological appearance, or chemical functionalities of the This chapter not subject to U.S.

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