Maria Regina Calil

Biodegradabilidade e Propriedades Mecânicas de Novas Misturas Poliméricas

Plastics are finding increasing application in our daily life, in products such as bottles and automobiles, for packing, etc. Several possibilities have been considered to minimize the environmental impact caused by the use of conventional polymers. An important alternative is the biodegradable polymer, which can be degraded through the action of naturally occurring microorganisms, such as bacteria, fungi or algae. Technological applications of biodegradable polymers usually require improvements on their mechanical properties. In this context, novel polymer blends have been obtained for inexpensive applications. In the present work, the methodology of preparation of new polymer blends is described. The blends contain different quantities of starch, with Poly (e-caprolactone)-(PCL), Poly (s-hydroxybutyrate)-(PHB) and Poly (s-hydroxybutyrate-co-b-hydroxyvalerate)-(PHBV). The resistance to the tensile strength of the blends with 50% in mass of starch was 35% and 60% lower than for the pure PCL and PHBV, respectively. Upon exposure to microorganisms in activated mud, the mixtures of PCL or PHBV with larger amounts of starch display higher rates of degradation.

The biodegradation of poly-β-(hydroxybutyrate), poly-β-(hydroxybutyrate-co-β-valerate) and poly(ε-caprolactone) in compost derived from municipal solid waste

Understanding the behavior of polymeric materials, particularly their biodegradation, is fundamental for solving problems in the management of environmental residues. In this work, we used a monitoring system based on an aerobic biodegradation technique known as the Sturm test to investigate the biodegradation of poly-β-(hydroxybutyrate), poly-β-(hydroxybutyrate-co-β-valerate) and poly(e-caprolactone), in compost derived from municipal solid waste. The thermal analysis of these polymers was done using differential scanning calorimeter. The melting temperature and crystallinity were also determined. The results showed that poly-β-(hydroxybutyrate) degraded faster than the other two polymers, probably because the chemical structure of this polymer made attack by microorganisms easier.

The Effect of UV-B Irradiation on the Biodegradability of Poly-β-Hydroxybutyrate (PHB) and Poly-ɛ-Caprolactone (PCL)

The biodegradability of poly-β-hydroxybutyrate and poly-ɛ-caprolactone in soil compostage before and after irradiation of the polymers for 192, 425, and 600 h in a Weather-Ometer was examined. The biodegradability tests were done in soil compostage at pH 7.0, 9.0, and 11.0 to assess the influence of this parameter on degradation. The rate of degradation was directly proportional to the soil alkalinity. Poly-β-hydroxybutyrate showed the greatest weight loss and aging in a Weather-Ometer did not significantly increase the biodegradation, except when the polymer was aged for 425 h and buried in soil compostage of pH 11.0.