Crystallization behavior and crystalline structural changes of poly(glycolic acid) investigated via temperature-variable WAXD and FTIR analysis

CrystEngComm ◽  
2016 ◽  
Vol 18 (40) ◽  
pp. 7894-7902 ◽  
Author(s):  
Chengtao Yu ◽  
Jianna Bao ◽  
Qing Xie ◽  
Guorong Shan ◽  
Yongzhong Bao ◽  
...  
Keyword(s):  
Glycolic Acid ◽  
Crystallization Behavior ◽  
Structural Changes ◽  
Ftir Analysis ◽  
Temperature Variable

scholarly journals Complexes of Glycolic Acid with Nitrogen Isolated in Argon Matrices. II. Vibrational Overtone Excitations

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3245 ◽  
Author(s):  
Iwona Kosendiak ◽  
Jussi M.E. Ahokas ◽  
Justyna Krupa ◽  
Jan Lundell ◽  
Maria Wierzejewska
Keyword(s):  
Glycolic Acid ◽  
Structural Changes ◽  
Near Infrared ◽  
Theoretical Calculations ◽  
Vibrational Overtone ◽  
Highly Sensitive ◽  
The Matrix ◽  
Argon Matrices ◽  
Site Selective ◽  
Different Levels

Structural changes of glycolic acid (GA) complex with nitrogen induced by selective overtone excitation of the νOH mode were followed in argon matrices using FTIR spectroscopy. For the most stable SSC1 complex present in different trapping sites directly upon deposition site, selective changes in the νOH region were achieved upon near-infrared irradiation. Simultaneously, new conformers of the GA…N2 complex were formed, giving rise to several sets of bands in the νOH and νC=O regions of the spectra. Both position and intensity of new absorptions appeared to be highly sensitive on the wavelength of radiation used, as well as on the annealing of the matrix. Based on theoretical calculations at different levels of theory, an assignment of the observed bands is proposed and discussed.

scholarly journals Reliable and Sophisticated Techniques to Evaluate LDPE Degraded Compounds by Streptomyces werraensis SDJM

2021 ◽  
Vol 20 (3) ◽  
Author(s):  
N. Deepika ◽  
R. Jaya Madhuri
Keyword(s):  
Weight Loss ◽  
Structural Changes ◽  
Morphological Changes ◽  
Field Trials ◽  
Sem Analysis ◽  
Modern World ◽  
Ftir Analysis ◽  
Test Results ◽  
Laboratory Test Results ◽  
The World

The modern world in the present era made life miserable due to extensive usage of plastic. Low-density polyethylene (LDPE) is widely consumed in every part of the world starting from baby products to garbage bags. Humans and animals are affected due to the usage and disposal of LDPE in the environment. To safeguard the environment from deleterious effects, biodegradation of LDPE was studied by isolating a potent Streptomyces werraensis SDJM strain from garbage soil. The degradation assessment was performed to identify the LDPE degraded compounds such as octane, decane, tetracosane, hexacosane, dotriacontene, tetratiacontene, tridecone, tetracontane, and pentacosane, using a sophisticated technique - liquid chromatography-mass spectroscopy (LCMS). The end product of LDPE biodegradation, carbon dioxide was measured by the GCMS-SPME technique. Field trials in garbage soil for a period of three months reveal 71.26% weight loss compared to laboratory test results where the weight loss was 60.05%. The morphological changes and structural changes of the polymer in fields were assessed by SEM analysis and FTIR analysis after one month of incubation. The test results in field trials were promising and convincing to overcome the LDPE pollution in presence of S.werraensis SDJM strain.

FTIR Analysis of Extractable Fractions from FourIndonesian Natural Asphalts

2011 ◽  
Vol 236-238 ◽  
pp. 571-577 ◽  
Author(s):  
Ting Yao ◽  
Zhi Min Zong ◽  
Yu Gao Wang ◽  
Zhe Wen ◽  
Robert Mukasa ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Benzene Ring ◽  
Functional Groups ◽  
Acid Ester ◽  
Structural Changes ◽  
Carboxyl Groups ◽  
Ftir Analysis ◽  
Ftir Spectrometry ◽  
More Care ◽  
Transmission And Reflection

Four natural asphalts (NAs) from Buton Rock, Indonesia, which were abbreviated as BRA-A, BRA-B, BRA-C and BAR-D, were continuously extracted by solvents, subdivided into four fractions and analyzed with Fourier transform infrared (FTIR) spectrometry. The transmission and reflection FTIR techniques were used to distinguish among different samples and fractions and to examine information concerning their structure, composition and structural changes upon fractional extract. Upon FTIR analysis, the methyl, methylene, oxhydryl and carboxyl groups are the major composition of these NAs. Some strong bonds at the zones of 2922-2856 cm-1, 1707-1606 cm-1 , 1453-1373 cm-1 , 1030 cm-1 and 872-748 cm-1 are assigned to >CH2 & -CH3 & –OH in carboxlic acid, ester & benzene ring, >C=O & -C-CH3, –CH2OH, -(CH2)n- & substituted benzene, etc. Much more care should be taken to investigate both N-containing functional groups and mineral multiphase compositions probably present in BRA-B, C and D.

scholarly journals The Effect of Endo-1,4-β-Xylanase From Thermomyces Dupontii KKU−CLD−E2−3 on Eucalyptus Pulp Bleaching and Effluent Treatment

2020 ◽  
Author(s):  
Wasan Seemakram ◽  
Hiroyuki Harada ◽  
Jindarat Ekprasert ◽  
Sophon Boonlue
Keyword(s):  
Structural Changes ◽  
Kappa Number ◽  
Effluent Treatment ◽  
Ftir Analysis ◽  
Pulp Fibers ◽  
Pulp Bleaching ◽  
Eucalyptus Pulp ◽  
Breaking Length ◽  
Thermomyces Dupontii ◽  
Tearing Resistance

Abstract Endo-1,4-β-xylanase-chlorine dioxide bleaching of eucalyptus pulp and analysis of effluent was investigated. The eucalyptus pulp bleaching in D0 stage was prepared with enzyme dose 100 Unit of 10% consistency and incubated at 70 °C for 30 min. The brightness level was achieved up to 72.50 (% ISO). The kappa number and viscosity of eucalyptus pulp was found to be 1.70 and 8.90 (cp), respectively. The paper from pulp bleaching with enzyme has shown an increase in brightness, breaking length, bursting strength, and tearing resistance to be 89.60% IOS, 37.27 Nm/g, 138.81 kPa and 218.02 mN, respectively. The SEM and FTIR analysis of pulp fibers revealed a significance of morphological and structural changes. The analysis of the effluent also showed statistically-significant differences in TOC, BOD, TDS and TSS. The FTIR analysis of the effluent showed the organic compounds and chloride dioxin in cases of those treated by chemicals.

Glass-forming ability and differences in the crystallization behavior of ribbons and rods of Cu36Zr48Al8Ag8 bulk glass-forming alloy

2009 ◽  
Vol 24 (5) ◽  
pp. 1886-1895 ◽  
Author(s):  
Dmitri V. Louzguine-Luzgin ◽  
Guoqiang Xie ◽  
Song Li ◽  
Qingsheng Zhang ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Crystallization Kinetics ◽  
Crystallization Behavior ◽  
Structural Changes ◽  
Glassy Alloy ◽  
Isothermal Calorimetry ◽  
Glass Forming ◽  
Transmission Electron ◽  
Melt Spun ◽  
Melt Spun Ribbons ◽  
Kinetics Of

The crystallization behavior of melt-spun ribbons and bulk samples of the Cu36Zr48Al8Ag8 glassy alloy on heating is presented here. The crystallization kinetics and structural changes in the Cu36Zr48Al8Ag8 glassy alloy were studied using x-ray diffraction, transmission electron microscopy, differential scanning, and isothermal calorimetry methods. A clear comparison is made of the differences in the crystallization kinetics of the melt-spun ribbons and the copper-mold-cast bulk rod samples. It was suggested that the kinetics of crystallization in the rod sample, at any given temperature, are somewhat different than in the ribbon samples, probably because of size and free volume effects. Differences in the crystallization behavior of this alloy with other Cu-Zr-Al-Ag alloys have also been discussed.

Effect of Shearing on the Crystallization Behavior of Poly (Butylene Terephthalate) and PBT Nanocomposites

2006 ◽  
Author(s):  
Gaurav Mago ◽  
Frank T. Fisher ◽  
Dilhan M. Kalyon
Keyword(s):  
Carbon Nanotubes ◽  
Polymer Nanocomposites ◽  
Crystallization Behavior ◽  
Structural Changes ◽  
Complex Deformation ◽  
Small Amplitude Oscillatory Shear ◽  
Butylene Terephthalate ◽  
Linear Viscoelastic Material ◽  
Ultimate Properties ◽  
Induced Crystallization

Poly (butylene terephthalate) (PBT) is an engineering thermoplastic polyester with excellent mechanical properties and a fast crystallization rate widely processed via extrusion and injection molding. Such processes require very complex deformation histories, which can influence the ultimate properties of the processed material and parts. For such systems, flow-induced structural changes in the material as a function of processing are of increasing interest in the field of polymer processing. Linear viscoelastic material functions, including the storage and loss moduli and magnitude of complex viscosity, are very sensitive to the structural changes occurring in the polymer melt. This initial study focuses on the shear-induced crystallization of PBT and PBT nanocomposites with multi-walled carbon nanotubes (MWNTs). (Shear-induced crystallization is a subset of the more general flow-induced crystallization behavior which is the long-term goal of this research.) The effects of shear history on the isothermal crystallization behavior of these materials were investigated. Time sweep experiments at constant frequency, temperature and strain amplitude were carried out employing small-amplitude oscillatory shear within a parallel-plate geometry. Samples obtained upon quiescent crystallization suggested that the rate of crystallization and crystallization temperatures were modestly affected by the presence and concentration of the nanotubes, consistent with the findings of the earlier reports. However, the characterized shear-induced crystallization behavior of the nanocomposites presented here indicate more significant changes in the crystallization temperature and the rate of crystallization occur as a result of the incorporation of the carbon nanotubes. The shear-induced crystallization behavior was affected by the deformation rate, temperature, and the concentration of the carbon nanotubes. These findings indicate that shear-induced crystallization of polymer nanocomposites (and in general flowinduced crystallization effects due to arbitrary flow fields in the melt state during processing) should be an integral part of attempts to generate a comprehensive understanding of the development of the microstructural distributions and the coupled ultimate properties of polymer nanocomposites.

scholarly journals Degradation and Characterisation of Electrospun Polycaprolactone (PCL) and Poly(lactic-co-glycolic acid) (PLGA) Scaffolds for Vascular Tissue Engineering

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4773
Author(s):  
Morteza Bazgir ◽  
Wei Zhang ◽  
Ximu Zhang ◽  
Jacobo Elies ◽  
Morvarid Saeinasab ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Glycolic Acid ◽  
Structural Changes ◽  
Vascular Tissue ◽  
Fibre Diameter ◽  
Great Promise ◽  
Degradation Behaviour ◽  
Nanofibrous Scaffolds ◽  
Significant Difference ◽  
Behaviour Study

The current study aimed to evaluate the characteristics and the effects of degradation on the structural properties of Poly(lactic-co-glycolic acid) (PLGA)- and polycaprolactone (PCL)-based nanofibrous scaffolds. Six scaffolds were prepared by electrospinning, three with PCL 15% (w/v) and three with PLGA 10% (w/v), with electrospinning processing times of 30, 60 and 90 min. Both types of scaffolds displayed more robust mechanical properties with increased spinning times. The tensile strength of both scaffolds with 90-min electrospun membranes did not show a significant difference in their strengths, as the PCL and PLGA scaffolds measured at 1.492 MPa ± 0.378 SD and 1.764 MPa ± 0.7982 SD, respectively. All membranes were shown to be hydrophobic under a wettability test. A degradation behaviour study was performed by immersing all scaffolds in phosphate-buffered saline (PBS) solution at room temperature for 12 weeks and for 4 weeks at 37 °C. The effects of degradation were monitored by taking each sample out of the PBS solution every week, and the structural changes were investigated under a scanning electron microscope (SEM). The PCL and PLGA scaffolds showed excellent fibre structure with adequate degradation, and the fibre diameter, measured over time, showed slight increase in size. Therefore, as an example of fibre water intake and progressive degradation, the scaffold’s percentage weight loss increased each week, further supporting the porous membrane’s degradability. The pore size and the porosity percentage of all scaffolds decreased substantially over the degradation period. The conclusion drawn from this experiment is that PCL and PLGA hold great promise for tissue engineering and regenerative medicine applications.

scholarly journals Curing Time and Temperature Effect on the Resistance to Wet-Dry Cycles of Fly Ash Added Pumice Based Geopolymer

2020 ◽  
Vol 1 (2) ◽  
pp. 19-25
Author(s):  
Engin Yener
Keyword(s):  
Fly Ash ◽  
Structural Changes ◽  
Raw Material ◽  
Liquid Sodium ◽  
Ftir Analysis ◽  
Curing Time ◽  
Reaction Products ◽  
Curing Conditions ◽  
Curing Regimes ◽  
Soluble Carbonate

The effects of curing regimes varying combinations of temperatures (ambient, 60 °C, 75 °C, 90 °C, 105 °C) and durations (4h, 8h, 24h, 48h, 96h, 168h) on the performance of fly ash added pumice based geopolymer pastes were investigated in this study. The precursor raw material consists of 70% pumice dust and 30% fly ash (FA). Alkali activator was prepared by mixing 10M sodium hydroxide (SH) solution and liquid sodium silicate (SS) in the ratio of SS/SH=2. Activator to precursor ratio was fixed as 0.45. Compressive strengths were determined at the 28 days of age as well as after exposure 5 wetting-drying (w-d) cycles. In addition, Fourier Transform Infrared Spectroscopy (FTIR) tests were conducted on the fresh and hardened geopolymer pastes in order to examine the effect of curing conditions to the structural changes and reaction products. The results show that in the case of 60 °C and 75 °C, the strength of the w-d conditioned samples increased steadily as the curing time increased. However, longer curing times of more than 24 hours are not beneficial for high curing temperatures (90 °C and 105 °C). The maximum strength after the w-d cycles is obtained for the curing conditions of 60°C/168h (74.4 MPa). Also, FTIR analysis confirmed that the hardened geopolymer paste transformed into a more coordinated structure and soluble carbonate compounds were reduced at 60 °C and 168 hours curing condition.

scholarly journals Synthesis and Evaluation of Thermoresponsive Boron-Containing Poly(N-isopropylacrylamide) Diblock Copolymers for Self-Assembling Nanomicellar Boron Carriers

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 42 ◽  
Author(s):  
Shuichiro Yoneoka ◽  
Ki Park ◽  
Yasuhiro Nakagawa ◽  
Mitsuhiro Ebara ◽  
Takehiko Tsukahara
Keyword(s):  
Phase Transition ◽  
Diblock Copolymer ◽  
Structural Changes ◽  
Diblock Copolymers ◽  
Radiation Treatment ◽  
Resonance Spectroscopy ◽  
Second Phase ◽  
Water Dispersible ◽  
Human Body Temperature ◽  
Temperature Variable

Development of new boron nanocarriers has been a crucial issue to be solved for advancing boron neutron capture therapy (BNCT) as an effective radiation treatment for cancers. The present study aimed to create a novel double-thermoresponsive boron-containing diblock copolymer based on poly(N-isopropylacrylamide) [poly(NIPAAm)], which exhibits two-step phase transitions (morphological transitions) at the temperature region below human body temperature. The boronated diblock copolymer considerably concentrates boron atoms into the water-dispersible (i.e., intravenous-administration possible) nanomicelles self-assembled by the first phase transition, and furthermore the properly controlled size and hydrophobicity of the second phase-transitioned nanoparticles are expected to make a significant contribution to the selective delivery and long-term retention of boron atoms into tumor tissues. Here we present the detailed synthesis of the strategic NIPAAm-based diblock copolymer with 3-acrylamidophenylboronic acid (PBA), i.e., poly(NIPAAm-block-NIPAAm-co-PBA), through a reversible addition-fragmentation chain transfer polymerization. Furthermore, the stepwise phase transition behavior of the obtained boronic-acid diblock copolymers was characterized in detail by temperature-variable 1H and 11B-nuclear magnetic resonance spectroscopy. The phase-transition-induced molecular structural changes, including the structural compositions and sizes of nanomicelles and nanoparticles, are also discussed here.

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