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Abstract  

The thermogravimetric analysis (TG) of two series of tri-block copolymers based on poly(L,L-lactide) (PLLA) and poly(ethyleneglycol) (PEG) segments, having molar mass of 4000 or 600 g mol–1, respectively, is reported. The prepared block copolymers presented wide range of molecular masses (800 to 47500 g mol–1) and compositions (16 to 80 mass% PEG). The thermal stability increased with the PLLA and/or PEG segment size and the tri-block copolymers prepared from PEG 4000 started to decompose at higher temperatures compared to those copolymers from PEG 600. The copolymers compositions were determined by thermogravimetric analysis and the results were compared to other traditional quantitative spectroscopic methods, hydrogen nuclear magnetic resonance spectrometry (1HNMR) and Fourier transform infrared spectrometry (FTIR). The PEG 4000 copolymer compositions calculated by TG and by 1HNMR, presented differences of 1%, demonstrating feasibility of using thermogravimetric analysis for quantitative purposes.

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solid bed for testing biodegradability under composting conditions. Polym. Degrad. Stab. , 66 , 65-79. Activated vermiculite, a solid bed for testing biodegradability under composting conditions

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Introduction In the last decades, the paradigm establishing that implants must be inert and corrosion resistant has been displaced by the advent of a new class of metallic biomaterials: biodegradable metallic materials [ 1

Open access
Pollack Periodica
Authors: Jani Tomperi, Tuulikki Luoma, Eva Pongrácz, and Kauko Leiviskä

Tampio E. Yhdyskuntajätteen koostumus ja biohajoavuus — selvitys Kainuussa kesällä 2010, Composition and biodegradability of municipal waste — report in Kainuu summer 2010 (in Finnish), Kainuun elinkeino-, liikenne- ja ympäristökeskus (Centre for

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Abstract  

Massive bleeding from esophagus varices presents a life threatening complication of portal hypertension. No effective method of treatment is available until now, that would guarantee high grade of patient wellness during the conditioning and investigation phase until the definitive treatment could be introduced. The aim of this study was to evaluate the tissue response to esophagus stents - designed for manage acute variceal bleeding - in animal experiment. Self-expandable nitinol stents were introduced into the esophagus of six porcines. Another twelve porcines were undergone the same procedure, using the new biodegradable stents made of PDO (polydioxanon). Histological investigations of the stented esophagus segments were observed after 2 and 4 weeks at the first 12 animals. To monitor the time of stent degradation, histology were performed 7 and 12 weeks after the implantation in the biodegradable group (3–3 animals). Differential scanning calorimetric examination was performed in all esophagus samples. Focal erosion of the esophagus segments was more explicit in the nitinol group at the histology. On the 7th week all of the biodegradable stent were in the stomach and on the 12th week these were completely solved. DSC examination showed significant alterations in the structure of the esophagus in both stented group compared to the healthy control. This experiment showed that the new self-expandable stents are safety and suitable procedure without deterioration of the esophageal wall. According to our DSC results the thermal denaturation of intact esophagus, its mucosa and muscle fragments revealed significant differences compared to healthy sample in favour the new biodegradable stent. Safety and efficiency in the experimental model had encouraged us to apply this method successfully patients with bleeding esophagus varices. The long term goal is to show that stent placement could be an effective way of decreasing or stabilising the acute bleeding from ruptured esophagus varices in cirrhotic patients.

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Summary  

In order to evaluate the use of gamma-ray treatment as a pretreatment to conventional biological methods, the effects of gamma-irradiation on biodegradability (BOD5/COD) of textile and pulp wastewaters were investigated. For all wastewaters studied in this work, the efficiency of treatment based on TOC removal was insignificant even at an absorbed dose of 20 kGy. However, the change of biodegradability was noticeable and largely dependent on the chemical property of wastewaters and the absorbed dose of gamma-rays. For textile wastewaters, gamma-ray treatment increased the biodegradability of desizing effluent due to degradation of polymeric sizing agents such as polyvinyl alcohol. Interestingly, the weight-loss showed the highest value of 0.97 at a relatively low dose of 1 kGy. This may be caused by the degradation of less biodegradable ethylene glycol prior to terephthalic acid decomposition. For pulp wastewater, the gamma-ray treatment did not improve the biodegradability of cooking and bleaching of C/D effluents. However, the biodegradability of bleaching E1 and final effluents was abruptly increased up to 5 kGy then slowly decreased as the absorbed dose was increased. The initial increase of biodegradability may be induced by the decomposition of refractory organic compounds such as chlorophenols, which are known to be the main components of bleaching C/D and final effluents.

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Abstract  

Radiation treatment with gamma-rays was used to improve the biodegradability of EDTA that is known to be a non-biodegradable substance. The effect of metal ions and catalysts on the treatment of EDTA was studied first. The removal of EDTA was definitely decreased in the presence of metal ions such as Cr(III), Cd(II), Pb(II) and Cu(II) at doses greater than 3 kGy. The addition of a TiO2

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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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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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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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