Derval dos Santos Rosa

The use of roughness for evaluating the biodegradation of poly-β-(hydroxybutyrate) and poly-β-(hydroxybutyrate-co-β-valerate)

The biodegradation of poly-β-(hydroxybutyrate) (PHB) and poly-β-(hydroxybutyrate-co-β-valerate) (PHB-V) was assessed by the loss of mass, tensile strength and roughness of the polymer. The melting temperature and crystallinity were also determined. Both polymers showed similar biodegradation in soil composting medium at 46 °C and at room temperature (24 °C) and in a soil simulator. PHB-V had the lowest crystallinity values and PHB had the highest. Soil composting medium at 46 °C favoured the biodegradation of PHB and PHB-V based on the loss of mass. After ageing in soil composting medium at 46 °C for 86 days, both polymers showed a decrease in the tensile strength at break (76% for PHB and 74% for PHB-V). In agreement with this, the roughness of both polymers increased faster in soil composting medium at 46 °C. These results suggest that roughness may be a useful parameter for evaluating the biodegradation of polymers.

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.

Evaluation of PHB, PHB-V and PCL biodegradation in composted soil

In contemporary society, a solution or a minimally satisfying approach to the serious environmental problems stemming from the widespread use of polymers has been one of the great challenges the scientific community has had to cope with. The studies around these compounds, including their biodegradability, have acquired fundamental importance. In this work, we present the results from an evaluation of the biodegradation of poly-b-(hydroxybutyrate) (PHB), poly-b-(hydroxybutyrate-co-valerate) (PHB-V) and poly-(e-caprolactone) (PCL), with products obtained from composting of municipal solid wastes, using the technique of aerobic biodegradation characterization known as Sturm Test. The thermal analysis of these polymers was done using differential scanning calorimeter (DSC). The melting temperature and crystallinity were also determined. The biodegradation test showed that PHB degraded faster than the other two polymers, probably because the chemical structure of this polymer made the 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.

Gelatinized and nongelatinized corn starch/ poly(epsilon-caprolactone) blends: characterization by rheological, mechanical and morphological properties

Poly(e-caprolactone)/corn starch blends containing 25, 50 and 75 wt.% starch were prepared by mechanical processing and characterized by the melt flow index (MFI), tensile test and scanning electron microscopy (SEM). For comparison, starch was used in gelatinized and nongelatinized forms and was also characterized by viscography. The addition of starch to poly(e-caprolactone) reduced the MFI values, the tensile strength and the elongation at break, whereas the modulus increased. The reductions in the MFI and tensile properties were most evident when gelatinized starch was used. Viscography and SEM showed that starch was well gelatinized by the gelatinization process. Blends containing nongelatinized starch showed a good dispersion of starch but poor interfacial interactions.

Desenvolvimento de processo de reciclagem de resíduos industriais de poliuretano e caracterização dos produtos obtidos

Resumo: A busca pela qualidade oriunda do processo de globalizacao emergente tem despertado o interesse de industrias em solucionar os problemas ambientais. Neste trabalho, e apresentado o processo de reciclagem mecânica de residuos industriais de poliuretano, incorporado em diferentes proporcoes em resinas poliuretanas. O processo de reciclagem foi desenvolvido levando-se em consideracao o efeito da temperatura durante o processamento e as diferentes proporcoes (massa de resina nova: massa de residuo → 1:4, 1:8, 1:12,5, 1:20) dos residuos incorporados na mistura. Os produtos obtidos em diferentes proporcoes foram caracterizados por meio das propriedades mecânicas de resistencia a tracao, resistencia a abrasao, determinacao da dureza e microscopia eletronica de varredura (MEV), com o objetivo de avaliar a viabilidade de possiveis aplicacoes dos produtos desenvolvidos. Os resultados mostraram que foi possivel reciclar proporcoes de ate 1:20 com propriedades de resistencia a tracao, resistencia a perda por abrasao e dureza adequadas para aplicacao em pisos de academia de ginastica e pistas de atletismo. Palavras-chave: Reciclagem mecânica, residuo industrial polimerico, poliuretano, propriedades mecânicas. Development of Recycling Process for Industrial Residues of Polyurethane and the Characterization of the Products Obtained Abstract: The search for quality required in the globalization process has prompted industries to try and solve environmental problems. In this work, we present the mechanical recycling process of industrial polyurethane residues incorporated in different drifts in polyurethane resins. The recycling process was developed by considering conditions such as: effect of temperature in the process and the different proportions (mass of new resin: mass of residue → 1:4, 1:8, 1:12.5, 1:20) of the residues incorporated in the mixture. The products obtained in different proportions were characterized by assessing their tensile stress properties, abrasion resistance, determination of hardness and using Scanning Electron Microscopy (SEM). The aim was to evaluate the viability of possible applications to the products originating from the recycling process. The results showed it to be possible to recycle proportions of up to 1:20 with mechanical properties, abrasion resistance, and hardness suitable for applications in tiles for floors in gymnasium and fitness centers.

Recycling of industrial polyurethane residue and the characterisation of its properties

The globalisation process has forced manufacturers to produce higher quality products with less environmental hazard. The newly developed industrial products produce residues, which pose challenges for recycling. In this work, we present the mechanical recycling of the industrial polyurethane residues incorporated in different proportions with polyurethane resins. Effect of temperature in the process and proportion of residues were considered for the process development. The products obtained in different proportions (weight of new resin: weight of residue) 1:4, 1:8, 1:12.5, 1:20 have been characterised by mechanical properties, resistance to abrasion and hardness which are required for the possible applications of the developed product.