Biodegradable and non retrogradable eco films based on starch glycerol with citric acid as crosslinking agent.
Biodegradable and non retrogradable starch glycerol based films were obtained using citric acid (CA) as crosslinking agent at 75degC. This material allowed decreasing water vapor permeability (WVP) more than 35% remained amorphous for at least 45 days as a result of the network formed by the CA that avoided starch retrogradation and maintained the degradability in compost, occurring only six days after the films without citric acid. A simulation of the gelatinization process of starch glycerol with and without CA, using a differential thermal analysis device, showed that the system with CA completed the gelatinization 5degC before than the other and, CA first reacted with glycerol and then starch glycerol CA reaction occurred. The temperature at which the gelatinization process was carried out was critical to obtain the best results. An increase of gelatinization process temperature at 85degC in system with CA, led to a worsening on WVP and its integrity after a swelling process with dimethylsulphoxide (DMSO) compared to the films processed at 75degC.
Carbohydrate polymers