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Summary In this study, the thermal properties of agro-flour-filled polybutylene succinate (PBS) bio-composites were investigated. PBS is one of the biodegradable polymers made from the condensation reaction of glycols and dicarboxylic acid and is naturally degraded by natural soil burial system. The thermal properties of the bio-composites were analyzed according to the agro-flour content and mesh size. On increasing agro-flour content, the thermal stability, degradation temperature and derivative thermogravimetric curve (DTGmax) temperature of the bio-composites decreased while the ash content increased. The thermal degradation of the bio-composites was not affected by agro-flour mesh size. The glass transition (T g) and melting (T m) temperatures of the bio-composites were not significantly changed. The storage modulus (E’) of the bio-composites was higher than that of neat PBS, because the incorporation of agro-flour increased the stiffness of the bio-composites. At higher temperatures, E’ of the bio-composites decreased due to the increasing viscosity and chain mobility of neat PBS. The thermal properties of bio-composites have an important effect on the manufacturing system and application methods.

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Abstract  

The purpose of this study was to conduct a thermal analysis of the hydrolysis and degradation behavior of biodegradable polymers and bio-composites at 50°C and 90% relative humidity (RH). With increasing hydrolysis time, the thermal stability and degradation temperature of polybutylene succinate (PBS) slightly decreased. The glass transition temperature (T g) and melting temperature (T m) of PBS and the anti-hydrolysis agent treated PBS did not vary significantly with increasing hydrolysis time, whereas those of the trimethylolpropane triacrylate (TMPTA)-treated PBS slightly increased. With increasing hydrolysis time, the storage modulus (E’) values of the bio-composites decreased, whereas those of the TMPTA treated bio-composites slightly increased. Also, the tan values of the anti-hydrolysis agent and TMPTA treated PBS-BF bio-composites were slightly lower than those of the non-treated bio-composites, due to the reduction in their degree of hydrolysis. The tanδmax peak temperature (T g) of the anti-hydrolysis agent treated bio-composites was not significantly changed, whereas that of the TMPTA treated bio-composites was increased.

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Biodegradable polymers

Part VI. Biodegradable plastics of soy protein isolate modified with thiourea

Journal of Thermal Analysis and Calorimetry
Authors: P. Nanda, K. Rao, R. Kar, and P. Nayak

Abstract  

Potential alternative to petrochemical polymers, soy protein isolate (SPI), a plentily available, natural biopolymer is chemically modified with thiourea at 2.5, 5, 7.5, 10, 15 and 20 mass/mass% for better processing of plastic as a raw material. From the FTIR studies, it has been ascertained that there is no bonding reaction between SPI and thiourea and it acts as a modifier only. Thermogravimetric analysis of the modified material has been followed using a computer analysis method, LOTUS package, developed by us for assigning the degradation mechanism. A number of equations have been used to evaluate the kinetic parameters. The mechanism of degradation of the biopolymer is explained on the basis of the kinetic analysis.

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a few minutes, thus resulting in a tremendous volume of plastic waste. Due to growing environmental awareness and new regulations, bio-filled (natural fibers and bioflour-filled) biodegradable polymer biocomposites have recently attracted

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Abstract  

Aliphatic polyesters are readily degradable polymers, hydrolysis being the dominant mechanism of degradation. On one side, this makes them extremely interesting for industrial applications in which degradability is required. On the other side, they present considerable processing problems due to their sensitivity to process and stocking conditions. In this work, the degradation of two aliphatic polyesters was studied in the molten state by analysing the rheological properties with the aim of defining the significance of previous thermal history and of residence time at a given temperature. Rheological measurements were adopted as a mean of analysis for degradation kinetics because rheological properties are strongly dependent on molecular weight. In particular, the change in complex viscosity (at constant frequency) as a function of time at different temperatures was measured. The experimental results show that a significant reduction of viscosity takes place during the isothermal tests for all the materials analyzed. This reduction was ascribed to the hydrolysis reaction. Indeed, a dried sample showed only a marginal viscosity reduction. After this initial decrease, an increase in viscosity (more pronounced at higher temperatures) was found for all the materials and at all the temperatures investigated. This phenomenon was ascribed to the inverse reaction (esterification) taking place in the absence of water. The dried sample showed, in fact, a much faster increase in viscosity with respect to the undried one. The degradation kinetics was modeled considering both forward and reverse reactions. The relative rate of the two reactions depends on the moisture content, and thus the water evaporation from the sample was kept into account in the rate equations.

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Introduction Biodegradable polymers, such as poly lactic acid (PLA), have been the subject of many studies over the past decade because of the increasing need to reduce petroleum-based plastic pollution [ 1 , 2 ]. PLA, which

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Abstract  

Thermoanalytical studies on specialty polymers in Japan are reviewed. The basic and applied researches for the developments of new specialty polymers such as high-performance polymers, liquid crystalline polymers, and biodegradable polymers during the 1990's are introduced from the standpoint of thermal analysis. Many studies were performed for the improvements of durability and thermal stability of engineering polymers, biodegradable polymers and so on. A special topic of researches on the thermal behavior of polymers by high-pressure differential thermal analysis is included in this review.

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Journal of Thermal Analysis and Calorimetry
Authors: Daniela Schlemmer, E. de Oliveira, and M. Araújo Sales

Abstract  

Conventional plastics has a large impact in increasing the environment’s pollution. That’s why the interest has turned towards novel partially and completely biodegradable polymers. In this work, blends of polystyrene and thermoplastic starch with glycerol and Buriti (Mauritia flexuosa L.) oil as plasticizers were prepared. Samples were analyzed using TG/DTG and DSC techniques. The TG results indicated that the blends with Buriti oil are thermally more stable than those with glycerol. The DSC analysis that Buriti oil provides a higher degree of plasticization of PS, compared to the blends plasticized using glycerol under the studied conditions.

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Abstract  

To obtain a biodegradable polymer material with satisfactory thermal properties, higher elongation and modulus of elasticity, a new copolyester, poly(hexylene terephthalate-co-lactide) (PHTL), was synthesized via direct polycondensation from terephthaloyl dichloride, 1,6-hexanediol and oligo(lactic acid). The resulting copolyesters were characterized by proton nuclear magnetic resonance (1H NMR), differential scanning calorimetry (DSC), thermogravimetry (TG) and wide-angle X-ray scattering (WAXS). By using the relative integral areas of the dyad peaks in 1H NMR spectrum of copolyesters PHTL, the sequence lengths of the hexylene terephthalate and lactide units in the resultant copolyesters are 3.5 and 1.5, respectively. Compared to poly(hexylene terephthalate) (PHT), PHTL has lower T m but higher T g due to the incorporation of lactide unit into the main chains of copolyesters. The degradation test of copolyesters under a physiological condition shows that the degradability of PHTL is sped up due to incorporation of lactide segments.

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