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.
Authors:Maksym Pogorielov, Eugenia Husak, Alexandr Solodivnik, and Sergii Zhdanov
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
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
Authors:L. Benkő, J. Danis, R. Hubmann, G. Kasza, Éva Gömöri, Erzsébet Rőth, and D. Lőrinczy
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.
Authors:H. J. Jo, S. M. Lee, H. J. Kim, J. G. Kim, J. S. Choi, Y. K. Park, and J. Jung
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.
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
Authors:Y. Chen, L. Tan, W. Zhou, J. Su, Y. Yang, and Y. Hu
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 Tm but higher Tg 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.
Authors:H.-S. Kim, H.-S. Yang, H.-J. Kim, B.-J. Lee, and T.-S. Hwang
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 (Tg) and melting (Tm) 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.
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.