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1.
Shahla Ataei Rosiyah Yahya Seng Neon Gan 《Journal of Polymers and the Environment》2011,19(2):540-545
The kinetic behavior of polyesterification of the alkyd resins synthesized using glycerol and phthalic anhydride modified
with oleic acid from the palm oil at temperatures between 120 and 240 °C was studied. Three alkyds having oleic acid contents
of 28, 40, and 65% were prepared by employing fatty acid method. The extent of the polyesterification reaction and average
degree of polymerization were monitored by determining the acid number of the aliquot of the reaction mixture at various intervals
of time and by measuring the volume of water evolved. Kinetic studies revealed that initial reaction rates followed a second-order
kinetics up to certain limit and thereafter deviations were observed. The extent of reaction varied from 77.4 to 86.3% before
deviation for all the three samples and exhibited a considerable degree of conversion. The second-order rate constants calculated
from the linear part were found to be of the order of 10−5 g (mg KOH)−1 min−1. Molecular weight of the alkyd samples was determined by GPC; number average molecular weight of the alkyds ranged from 980
to 2,070. 相似文献
2.
Ahmed Abdel-Megeed Mourad A. M. Aboul-Soud Rudolf Mueller Fredua Agyeman Rudolf Salem S. Al-Deyab 《Journal of Polymers and the Environment》2010,18(4):617-625
A gram-negative psychrophilic bacterium, with potential for biodegradation of long-chain n-alkanes was isolated from ice samples collected in Spitzbergen, Denmark. On the basis of results of biochemical and morphological
tests and sequence analysis of 16S rRNA, the strain was identified as Pseudomonas
frederiksbergensis. In this work, a short-chain NAD+-dependent alcohol dehydrogenase (alcDH) (Accession number: AAR13804) from the P.
frederiksbergensis was cloned and transformed in E. coli BL21 (3DE) competent cells. The alcDH activity was highest in the crude extract of cells induced with 1.0 mM IPTG. The recombinant
alcDH enzyme was purified to 93.4% homogeneity using three consecutive purification steps including ammonium sulphate, Q-Sepharose
Fast Flow column and gel filtration chromatography employing Superdex 200 10/30 HR column. Enzyme enrichment and yield levels
of 31.4 folds and 25.5%, respectively, were achieved. While the subunit molecular mass of the enzyme was determined on SDS-PAGE
to be ~38 kDa, the aggregated native form of the enzyme had a molecular mass of ~238 kDa by gel filtration analysis. Reaction
conditions optima for the recombinant alcDH were determined with propan-1-ol as the substrate. While the optimum pH was 9,
the optimum temperature was 35 °C. The alcDH enzyme exhibited moderate thermal stability with half-lives of 150 min at 55 °C,
27 min at 65 °C and 8 min at 75 °C. Results for kinetic parameters indicated that the apparent K
m value for alcDH with propan-1-ol as the substrate was found to be 1.42 mM and the V
max value was 0.63 mmol mg−1 min−1. Experimental evidence revealed that the recombinant alcDH exhibited a wide range of substrate specificity, with higher levels
of specific activity for aliphatic alcohols as compared to secondary alcohols. Taken together, the present study highlights
the potential of alcDH as a member of cold-adapted enzymes in several key biotechnological applications including environmental
bioremediation and biotransformations. It is envisaged that, with the ongoing screening of microorganisms and metagenomes,
directed evolution approaches and the subsequent overexpression of recombinant proteins, more enzymes will be found that are
suitable for bioremediation purposes. 相似文献
3.
Effects of Nitrogen Supply on the Sensitivity to O3 of Growth and Photosynthesis of Japanese Beech (Fagus crenata) Seedlings 总被引:1,自引:0,他引:1
Masahiro Yamaguchi Makoto Watanabe Naoki Matsuo Junichi Naba Ryo Funada Motohiro Fukami Hideyuki Matsumura Yoshihisa Kohno Takeshi Izuta 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):131-136
To obtain basic information for evaluating critical levels of O3 under different nitrogen loads for protecting Japanese beech forests, two-year-old seedlings of Fagus crenata Blume were grown in potted andisol supplied with N as NH4NO3 solution at 0, 20 or 50 kg ha−1 year−1 and exposed to charcoal-filtered air or O3 at 1.0, 1.5 and 2.0 times the ambient concentration from 16 April to 22 September 2004. The O3 induced significant reductions in the whole-plant dry mass, net photosynthetic rate at 380 μmol mol−1 CO2 (A
380), carboxylation efficiency (CE) and concentrations of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and total soluble protein (TSP) in the leaves.
The concentrations of Rubisco and TSP were negatively correlated with the concentration of leaf acidic amino acid, suggesting
that O3 enhanced the degradation of protein such as Rubisco. The N supply to the soil did not significantly change the whole-plant
dry mass and A
380, whereas it significantly increased the CE and concentrations of Rubisco and total amino acid. No significant interactive effects of O3 and N supply to the soil were detected on the growth, photosynthetic parameters and concentrations of protein and amino acid
in the leaves. In conclusion, N supply to the soil at ≤50 kg ha−1 year−1 does not significantly change the sensitivity to O3 of growth and net photosynthesis of Fagus crenata seedlings. 相似文献
4.
Hydrolytic depolymerization of polyamide waste in water was studied using 0.5 L high pressure autoclave at temperatures of
235, 240, 245, 250 °C and at autogenious pressure 480, 500, 520, and 600 psi (pound per square inch).The reaction rate constant,
energy of activation, enthalpy of activation, entropy of activation and equilibrium constant were calculated from the experimental
data obtained. The maximum depolymerization (59.2%) of polyamide waste into monomer caprolactum was obtained at 250 °C and
600 psi pressure. The reaction rate constant was obtained on basis of measurement of amine value and residual weight. The
depolymerization reaction was found to be pseudo first order with reaction rate constant of the order of 10−3 min−1. The enthalpy, entropy and free energy of activation were recorded as 85.75, −0.1354 and 156.59 kJ mol−1 respectively at the experimental conditions for maximum depolymerization of polyamide waste. The thermodynamic equilibrium
constant for this hydrolysis reaction was found to be 2.3 × 10−16. 相似文献
5.
Junya Katagiri Siqingaowa Borjigin Toshiaki Yoshioka Tadaaki Mizoguchi 《Journal of Material Cycles and Waste Management》2010,12(2):136-146
The formation and decomposition of tetrafluoroborate ions (BF4−) in H3BO3-Al3+-F− solutions were investigated via experiments and thermodynamic calculations. The concentration of the formed BF4− increased with decreasing pH, raising the total fluoride concentration and lowering the total aluminum ion concentration.
Once formed, BF4− was stable under neutral and alkaline conditions. Fluoride in the form of BF4− was converted to fluoroaluminate ions by adding an aluminum compound under acidic conditions. A method for removing fluoride
in the form of BF4− is proposed whereby fluoroaluminate ions formed by the reaction of BF4− with aluminum are decomposed with calcium ions. This process was applied to the treatment of wastewater from flue gas desulfurization
plants, and resulted in a satisfying level of reduction in the range of the fluoride emission limit of 8 mg/l. 相似文献
6.
A. L. S. Schneider D. D. Silva M. C. F. Garcia V. H. Grigull L. P. Mazur S. A. Furlan G. F. Arag?o A. P. T. Pezzin 《Journal of Polymers and the Environment》2010,18(3):401-406
The environmental impact caused by the disposal of plastics has motivated the development of biodegradable materials. Recent
studies showed that supplementation with oleic acid (OA) in cultures producing poly(3-hydroxybutyrate), P(3HB), increased
the polymer productivity. However only few studies have shown the properties and biodegradation profile of the polymer obtained.
This research investigated the influence of OA concentration on the biodegradation of the P(3HB) obtained from cultures of
Cupriavidus necator. The crystallinity of the casting films determined by differential scanning calorimetry (DSC) was reduced from 70% (0 g L−1 of OA) to 52% (3.0 g L−1 of OA). A reduction of 11 °C in the melting temperature was observed with 3.0 g L−1 of OA. The kinetic of biodegradation was: 3.0 > 1.5 > 0.9 > 0.3 > 0 g L−1 of OA. 相似文献
7.
Airborne particulate matter (PM) concentrations were measured in Iksan, a suburban area in South Korea during April, 2003.
PM2.5 (particles with an aerodynamic diameter less than 2.5 μm) and PM10 (particles with an aerodynamic diameter less than 10 μm) samples were collected, and the chemical characteristics of particles
were examined for diurnal patterns, yellow dust/rainfall influences, and scavenging effects. Average concentrations of PM2.5 and PM10 mass measured were 37.3 ± 16.2 μg m−3 and 60.8 ± 29.5 μg m−3, respectively. The sum of ionic chemical species concentrations for PM2.5 and PM10 was 16.9 ± 7.3 and 23.1 ± 10.1 μg/m3, respectively. A significant reduction in PM mass concentrations during rainfall days was observed for coarse mode (PM2.5 − 10) particles, but less reduction was found for fine (PM2.5) mass concentration. SO4
2−, NH4
+, and K+ predominated in fine particulate mode, NO3
− and Cl− predominated in fine particle mode and coarse particle mode, but Na+, Mg2+, and Ca2+ mostly existed in coarse mode. The high concentration of ammonium due to local emissions and long-range transport neutralized
sulfate and nitrate to ammonium sulfate and ammonium nitrate, which were major forms of airborne PM in Iksan. Average mass
concentrations of PM10 in daytime and at night were 57.6 and 70.0 μg m−3, and those of PM2.5 were 35.4 and 42.5 μg m−3, respectively. NO3
− and Cl− in both PM2.5 and PM10 were about double at night than in the daytime, while the rest of the chemical species were equal or a little higher at night
than in the daytime. The results suggest the formation of ammonium nitrate and chloride when high ammonia concentration and
low air temperature are allowed. Backward air trajectory analyses showed that air masses arriving at the site during yellow
dust period were transported from arid Chinese regions, which resulted in high concentrations of airborne PM mass concentrations.
In the meantime, air mass trajectories during a rainfall period were mostly from the Pacific Ocean or the East China Sea,
along with a relatively low PM concentration. 相似文献
8.
Hatam Godini Abbas Rezaee Ali Khavanin Afshin Nili Ahmadabadi Sayedomid Rastegar Hooshyar Hossini 《Journal of Polymers and the Environment》2011,19(1):283-287
The objective of this study was to investigate the feasibility of using a microbial biopolymer produced by Acetobacter xylinum as a carbon source for heterotrophic biological denitrification. The denitrification rate, COD availability and nitrite concentration
were response parameters. Under the experimental conditions, a denitrification rate of about 0.74 kg NO3
−N/m3d at 6 h retention time was achieved with microbial cellulose (MC). The reactor effluent contained significantly COD concentrations
(20–86 mg/L) so it was not carbon limited, and was receiving enough carbon to facilitate the denitrification process. The
maximum nitrite concentration in the effluent was found to be 0.4 mg/L. However, decreasing the retention time to 3 h significantly
reduced the efficiency. It can be concluded that the MC is a suitable carbon source for nitrate removal in a heterotrophic
biological denitrification process. 相似文献
9.
M. N. Satheesh Kumar Zahira Yaakob Siti Maimunah Siddaramaiah S. R. S. Abdullah 《Journal of Polymers and the Environment》2010,18(4):539-544
The kinetics of polyesterification of glycerol, phthalic anhydride and jatropha oil leading to the formation of alkyd resins
were studied. A series of alkyd resins having different amount of jatropha oil viz., 40–80% have been prepared by employing
two stage alcoholysis-polyesterification process. The extent of reaction and average degree of polymerisation were calculated
from the end group analysis of the reaction mixture withdrawn at regular intervals of time. The initial reaction rates followed
the second order kinetics and thereafter deviations were observed. An appreciable degree of conversion was noticed from the
extent of the reaction which lies in the range of 49.5–62.5%. The average degree of polymerisation calculated in the region
of deviation from second order suggested the occurrence of chain branching at relatively shorter intervals along the polymer
chain. The second order rate constants were found to be of the order of 10−5 g (mg KOH)−1 min−1. 相似文献
10.
Regular additions of NH4NO3 (35–140 kg N ha−1 yr−1) and (NH4)2SO4 (140 kg N ha−1 yr−1) to a calcareous grassland in northern England over a period of 12 years have resulted in a decline in the frequency of the
indigenous bryophyte species and the establishment of non-indigenous calcifuge species, with implications for the structure
and composition of this calcareous bryophyte community. The lowest NH4NO3 additions of 35 kg N ha−1 yr−1 produced significant declines in frequency of Hypnum cupressiforme, Campylium chrysophyllum, and Calliergon cuspidatum. Significant reductions in frequency at higher NH4NO3 application rates were recorded for Pseudoscleropodium purum, Ctenidum molluscum, and Dicranum scoparium. The highest NH4NO3 and (NH4)2SO4 additions provided conditions conducive for the establishment of two typical calcifuges – Polytrichum spp. and Campylopus introflexus, respectively. Substrate-surface pH measurements showed a dose-related reduction in pH with increasing NH4NO3 deposition rates of 1.6 pH units between the control and highest deposition rate, and a further significant fall in pH, of
>1 pH unit, between the NH4NO3 and (NH4)2SO4 treatments. These results suggest that indigenous bryophyte composition may be at risk from nitrogen deposition rates of
35 kg N ha−1 yr−1 or less. These effects are of particular concern for rare or endangered species of low frequency. 相似文献
11.
Chemical recycling of polyamide waste in water was studied using 0.5 L high pressure autoclave at temperatures of 150, 200,
210, 220,230 and 240 °C and at various pressures of 100, 200, 300, 400, 500, 600 and 700 psi (pound per square inch). Viscosity
average molecular weight of the polyamide waste sample was determined by Ostwald method and recorded as 1.928 × 103. The reaction was found to be first order with velocity constant in order of 10−2 min−1. The velocity constant and percent conversion of depolymerization reaction at 240 °C and 700 psi pressure were recorded as
2.936 × 10−2 min−1 and 99.99% respectively. The velocity constant was obtained on the basis of measurement of amine value. Kinetic and thermodynamic
parameters such as energy of activation, frequency factor, enthalpy of activation were found to be 10.6 kJ mole−1, 0.3719 min−1 and 6.3 kJ mole−1 respectively, at the optimum conditions for maximum depolymerization of polyamide waste. 相似文献
12.
Ulf Sikström 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):137-142
Liming and/or application of specific nutrients have been proposed as countermeasures to the acidification of forest soils
in southern Sweden. In this study the stem growth of Picea abies (L.) Karst. growing on acidic mineral soils in SW Sweden was investigated 10 years after additions of lime (Ca; 3000 kg lime
ha−1), lime plus P (25 kg ha−1) and K (80 kg ha−1), or N in low doses (2 × 10 kg ha−1 yr−1) (treatments: CaPK, Ca, N, CaPKN, and 2Ca2P2K, respectively). Compared with the control, stem growth was increased following
all treatments involving lime additions, including liming alone. The PK addition did not seem to affect growth. The most plausible
cause of the observed growth increases was that the lime additions indirectly increased the supply of plant-available N. The
annual low-dose N addition did not significantly affect growth. This suggests that air-borne deposition of N, which supplies
very small doses of N throughout the year, has a minor or even negligible influence on P. abies growth. 相似文献
13.
Characterizing sorption processes is essential to understand the environmental distribution and toxicity potential of endocrine
disruptors in terrestrial and aquatic systems. The sorption behaviors of three endocrine disruptors (bisphenol A (BPA), 17β-estradiol
(E2), and 17α-ethynylestradiol (EE2)) on sediments were investigated using batch techniques. Samples were taken from some
representative reaches in several major Chinese rivers. More attention has been paid to the effect of sediment organic components
on the sorption of BPA, E2, and EE2. The results show that the sediment organic carbon-normalized partition coefficients (K
oc
(sed)) for three endocrine disruptors are in the order of EE2 > E2 > BPA, which corresponds to the octanol-water partitioning
coefficients (logK
ow) of the compounds. Moreover, the K
oc
values for humic substances (K
oc
(hs)) are comparable with the K
oc
(sed) values and highly dependent on the physico-chemical properties of humic substances in sediments. The UV absorptivity
at 272 nm (A
272), which suggests the abundance of aromatic rings in humic substance structure, correlates well with the K
oc
(hs) values. In addition, the infrared spectra of the humic substances extracted from sediments show four strong bands centered
at 3,400 cm−1, 1,625 cm−1, 1,390 cm−1, and 1,025 cm−1. The K
oc
(hs) values have a positive linear relation with the peak area ratio for peak at 1,025 cm−1 and a negative linear relation with the peak area ratio between peaks at 1,625 cm−1 and 1,025 cm−1. Hence, the hydrogen bonds play a critical role to the sorption of selected endocrine disruptors. 相似文献
14.
Biofouling and ensuing microbial mediated degradation of Bisphenol A polycarbonate was studied by immersing the samples in
sea water of Bay of Bengal (Chennai, India) for 3 months and also under controlled laboratory conditions with marine mixed
microbial consortia for 12 months. A 9% weight loss in the sample was observed after 1 year of incubation under in vitro laboratory
conditions. A 5% reduction in number average molecular weight and an additional oligomer with a molecular weight of 930 was
observed in the same sample. Contact angle decreased by 11% indicating an increase in the surface hydrophilicity. The specific
heat decreased by 44% and glass transition temperature decreased by 3 °C with respect to the control indicating chain scission.
Formation of new hydroxyl groups and cleavage of carbonate bonds in polycarbonate suggested biodegradation. About 9 μg mL−1 of Bisphenol A, a monomer of polycarbonate, as well as its oxidized products were detected in the supernatant. The nature
of degradation in field and in vitro was different. It was predominantly oxidation in the former and hydrolysis in the later
environment. A strain exhibiting hydrolase activity was isolated at the end of the 12 months from the in vitro mixed consortia
and was identified, based on biochemical and 16S rDNA tests, as Pseudomonas sp. BP2 (GenBank accession no. EU920674). 相似文献
15.
Nanocrystalline cellulose (NCC) was isolated from a totally chlorine free (TCF) bleached oil palm empty fruit bunch (OPEFB) pulp via acid hydrolysis using a 58 % sulfuric acid concentration and ultrasonic treatment. The effects of acid concentration and hydrolysis time were investigated. Characterization of OPEFB–NCC was carried out using TEM, FTIR, 13C-NMR, XRD, zeta potential and TGA. The optimal hydrolysis time was 80 min as indicated by the leveling off of the OPEFB–NCC dimensions (length 150 nm and diameter 6.5 nm) with no significant loss of crystallinity at this point. The presence of a shoulder peak at 1231 cm?1 (assigned to a sulfate group) in the FTIR spectrum of NCC is indicative of a successful esterification. This is further corroborated by the 13C-NMR analysis whereby the distinct C4 amorphous and crystalline peaks present in OPEFB–TCF pulp had almost disappeared and the cluster of signals for C2, C3, C5, and a well separated signal of C6 had merged into one single peak in the OPEFB–NCC sample. These observations allude to most of the amorphous region having been removed and to the strong possibility of sulfonation having not only occurred on the C6, but also on C2 and C3. OPEFB–NCC isolated over shorter hydrolysis time was more thermally stable; however, the char fraction decreases with hydrolysis time despite having a higher zeta potential. The results of this investigation demonstrate that NCC can be produced from pulp made by chlorine free environmentally benign processes with ensuing savings in energy and chemicals. 相似文献
16.
Pierre Sicard Patrice Coddeville Stéphane Sauvage Jean-Claude Galloo 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):49-58
The long-term monitoring of precipitation and its chemical composition are important for identifying trends in rain quality
and for assessing the effectiveness of pollution control strategies. A statistical test has been used to the atmospheric concentrations
measured in the French rural monitoring network (MERA) in order to bring out spatio-temporal trends in precipitation quality
in France over the period 1990–2003. The non-parametric Mann–Kendall test which has been developed for detecting and estimating
monotonic trends in the time series was used and applied in our study at annual values of wet-only precipitation concentrations.
The emission data suggest that SO2 and NO
x
emissions decreased (−3.3 and −2.0% year−1, respectively) contrary to NH3 emissions that increased slightly (+0.2% year−1) over the period 1990–2002 in France. On the national scale, the pH values have a significant decreasing trend of −0.025 ± 0.02
unit pH year−1. and concentrations in precipitation have a significant decreasing trend, −3.0 ± 1.6 and −3.3 ± 0.6% year−1, respectively, corresponding with the downward trends in SO2 emissions in France (−3.3% year−1). A good correlation (R
2 = 0.84) between SO2 emissions and concentrations was obtained. The decreasing trend of was more significant (−5.4 ± 5.2% year−1) than that of (−1.3 ± 2.4% year−1). Globally, the concentration of the major ions showed a clear downward trend including marine and alkaline ions. In addition,
the relative contribution of HNO3 to acidity precipitation increased by 51% over the studied period. 相似文献
17.
Johan Bergholm Hooshang Majdi Tryggve Persson 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):225-234
A nitrogen (N) budget was constructed for a period of 6 years (1988–1993) in a Norway spruce stand with current deposition
of 19 kg N and 22 kg S ha−1 year−1. The stand was fertilized annually by addition of 100 kg N and 114 kg S ha−1 (NS). Above and below ground biomass, litterfall, fine- root litter production, soil solution and net mineralization were
measured to estimate pools, fluxes and accumulation of nitrogen. The average needle litterfall in control (C) and NS plots
in 1993 was 2.2 and 2.5 ton ha−1 year−1, respectively. The fine root litter production prior to treatment (1987) was 4.4 ton ha−1 year−1 and after treatment (1993) it was 4.5 and 3.9 ton ha−1 year−1 in C and NS plots, respectively. Net N mineralization in the soil profile down to 50 cm was estimated to be 86 and 115 kg
ha−1 year−1 in C and NS plots, respectively in 1992. During the treatment period the uptake of N in the needle biomass in C and NS plots
was 29 and 77 kg ha−1 year−1, respectively. No N was accumulated in needles of C plot where the NS plots accumulated 34 kg ha−1 year−1. Of the annually added inorganic N to NS plots 47% was accumulated in the above and below ground biomass and 37% in the soil.
N fluxes via fine-root litter production in the C plots were much higher (54 kg ha−1 year−1) than that via litterfall (29 kg ha−1 year−1). The corresponding values in the NS plots were 65 and 43 kg ha−1 year−1, respectively. Most of the net N mineralization occurred in the FH layer and upper mineral soil. It is concluded that fine
root litter and litterfall play an important role in the cycling of N. Despite a high N uptake the losses of N in litterfall
and fine root litter resulted in an incorporation of N in soil organic matter. 相似文献
18.
Shaodong Xie Yuanhang Zhang Li Qi Xiaoyan Tang 《Water, Air, & Soil Pollution: Focus》2005,5(3-6):217-229
In the Beijing area, March and April have the highest frequency of sand-dust weather. Floating dust, blowing sand, and dust
storms, primarily from Mongolia, account for 71%, 20%, and 9% of sand-dust weather, respectively. Ambient air monitoring and
analysis of recent meteorological data from Beijing sand-dust storm periods revealed that PM10 mass concentrations during dust storm events remained at 1500 μg m−3, which is five to ten times higher than during non-dust storm periods, for fourteen hours on both April 6 and 25, 2000. During
the same period, the concentrations in urban areas were comparable to those in suburban areas, while the concentrations of
gaseous pollutants, such as SO2, NO
x
, NO2, and O3, remained at low levels, owing to strong winds. Furthermore, during sand-dust storm periods, aerosols were created that consisted
not only of many coarse particles, but also of a large quantity of fine particles. The PM2.5 concentration was approximately 230 μg m−3, accounting for 28% of the total PM10 mass concentration. Crustal elements accounted for 60–70% of the chemical composition of PM2.5, and sulfate and nitrate for much less, unlike the chemical composition of PM2.5 on pollution days, which was primarily composed of sulfates, nitrates, and organic material. Although the very large particle
specific surface area provided by dust storms would normally be conducive to heterogeneous reactions, the conversion rate
from SO2 to SO4
2− was very low, because the relative humidity, less than 30%, was not high enough. 相似文献
19.
Suvangshu Dutta Niranjan Karak Jyoti Prasad Saikia Bolin Kumar Konwar 《Journal of Polymers and the Environment》2010,18(3):167-176
Mesua ferrea L. seed oil (MFLSO) modified polyurethanes blends with epoxy and melamine formaldehyde (MF) resins have been studied for
biodegradation with two techniques, namely microbial degradation (broth culture technique) and natural soil burial degradation.
In the former technique, rate of increase in bacterial growth in polymer matrix was monitored for 12 days via a visible spectrophotometer
at the wavelength of 600 nm using McFarland turbidity as the standard. The soil burial method was performed using three different
soils under ambient conditions over a period of 6 months to correlate with natural degradation. Microorganism attack after
the soil burial biodegradation of 180 days was realized by the measurement of loss of weight and mechanical properties. Biodegradation
of the films was also evidenced by SEM, TGA and FTIR spectroscopic studies. The loss in intensity of the bands at ca. 1735 cm−1 and ca. 1050 cm−1 for ester linkages indicates biodegradation of the blends through degradation of ester group. Both microbial and soil burial
studies showed polyurethane/epoxy blends to be more biodegradable than polyurethane/MF blends. Further almost one step degradation
in TG analysis suggests degradation for both the blends to occur by breakage of ester links. The biodegradation of the blends
were further confirmed by SEM analyses. The study reveals that the modified MFLSO based polyurethane blends deserve the potential
to be applicable as “green binders” for polymer composite and surface coating applications. 相似文献
20.
Shadpour Mallakpour Fatemeh Zeraatpisheh Mohammad R. Sabzalian 《Journal of Polymers and the Environment》2012,20(1):117-123
In this paper we studied the synthesis of biodegradable optically active poly(ester-imide)s containing different amino acid
residues in the main chain. These pseudo-poly(amino acid)s were synthesized by polycondensation of N,N′-(pyromellitoyl)-bis-l-tyrosine dimethyl ester as a diphenolic monomer and two chiral trimellitic anhydride-derived diacid monomers containing s-valine and l-methionine. The direct polycondensation reaction of these diacids with aromatic diol was carried out in a system of tosyl
chloride (TsCl), pyridine (Py) and N,N′-dimethylformamide (DMF) as a condensing agent. The structures and morphology of these polymers were studied by FT-IR, 1H-NMR, powder X-ray diffraction, field emission scanning electron microscopy (FE-SEM), specific rotation, elemental and thermogravimetric
analysis (TGA) techniques. TGA profiles indicate that the resulting PEIs have a good thermal stability. Morphology probes
showed these polymers were noncrystalline and nanostructured polymers. The monomers and prepared polymers were buried under
the soil to study the sensitivity of the monomers and the obtained polymers to microbial degradation. The high microbial population
and prominent dehydrogenase activity in the soil containing polymers showed that the synthesized polymers are biologically
active and microbiologically biodegradable. Wheat seedling growth in the soil buried with synthetic polymers not only confirmed
non-toxicity of polymers but also showed possibility of phyto-remediation in polymer-contaminated soils. 相似文献