Biodegradable films mechanical testing

Chitosan is a water-insoluble, nontoxic, edible, biodegradable polymer (polysaccharide) that is obtained commercially from chitin by alkaline deacetylation [103]. Chitosan is the second most abundant biopolymer in nature after cellulose. Since chitosan is a polycationic polymer, its high sensitivity to moisture limits its applications. One way to overcome this drawback is to blend the material with humidity resistant polymers such has PLA. Suyatma et al. [104] combined hydrophilic chitosan with hydrophobic PLA (92% L-lactide and 8% mesolactide, Mw = 49,000 Da) by solution and film mixing, resulting in improved water barrier properties and decreased water sensitivity of the chitosan films. However, testing of mechanical and thermal properties revealed that chitosan and PLA blends are incompatible. 

On the other hand, if the substrate is large and insoluble in water, such as a fiber or a film of biodegradable material, physical measurements are commonly used to assess the initial microbial attack on the substrate. These methods include microscopic examination, measure of weight loss, or measure of the loss of mechanical strength. As the biodegradation of the fiber continues, individual small molecules are released and chemical analyses of monomers and products of mineralization can be detected. Often, several of these methods are used in a single study to confirm and characterize the biodegradation of the test material. 

Campos et al. [21] studied sisal flber-reinforced TPS and polycaprolactone, both biodegradable pol5miers. Sisal fibers (5% and 10%) were extruded in a twin-screw extruder with TPS/ polycaprolactone (80 20 wt). Films were produced with a single extruder and analyzed by field emission gun scanning electron microscopy, mechanical tests, thermogravimetric analysis, and differential scanning calorimetry. The morphology of the composites with 10% sisal fiber content presented an interface... 

Chiellini, E. Cinelli, P. Corti, A. Kenawy, E.R. Composite films based on waste gelatin Thermal-mechanical properties and biodegradation testing. Polym. Degrad. Stab. 2001, 73, 549 - 555. 

Therefore, for quality control of composites or film-forming mechanisms, many tests like mechanical and rheological characteristics, thermal properties, biodegradability, etc., are necessary [48,49]. 

Chiellini, E., Cinelli, P., Corti, A., and Kenawy, E.R., 2001, Composite Films Based on Waste Gelatin Thermal-Mechanical Properties and Biodegradation Testing. Polym. Degr. Stab. 73 549-555. 

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