Kinetic Studies of Isophorone Diisocyanate-Polyether Polymerization with in situ FT-IR

2011 ◽  
Vol 16 (8) ◽  
pp. 584-590 ◽  
Author(s):  
Peng Fei Yang ◽  
Yan Hong Yu ◽  
Shun Ping Wang ◽  
Tian Duo Li
Keyword(s):  
Kinetic Studies ◽  
Isophorone Diisocyanate ◽  
Ft Ir

Kinetic Studies on the Polymerization of Dicyclohexylmethylmethane-4,4'-Diisocyanate with Polyoxytetramethylene Diol

2013 ◽  
Vol 791-793 ◽  
pp. 32-35
Author(s):  
Jian Cheng Wang
Keyword(s):  
Rate Constant ◽  
Arrhenius Equation ◽  
Activation Enthalpy ◽  
Kinetic Studies ◽  
Activation Entropy ◽  
Dimethyl Acetamide ◽  
Different Temperatures ◽  
Ft Ir ◽  
Temperature Activation

Dicyclohexylmethylmethane-4,4'-diisocyanate is used to react with polyoxytetramethylene diol at different temperatures. N,N-Dimethyl acetamide is used as solvent.In situFT-IR is used to monitor the reaction to work out rate constant, Arrhenius equation and Eyring equation. The polymerization has been found to be a second order reaction, and the rate constant increases with the rise of temperature. Activation energy (Ea), activation enthalpy (ΔH) and activation entropy (ΔS) for the polymerization are respectively calculated out, which are very useful to reveal the reaction mechanism.

Use of Entropy Minimization for the Preconditioning of Large Spectroscopic Data Arrays: Application to in Situ FT-IR Studies from the Unmodified Homogeneous Rhodium Catalyzed Hydroformylation Reaction

2002 ◽  
Vol 56 (11) ◽  
pp. 1422-1428 ◽  
Author(s):  
Li Chen ◽  
Marc Garland
Keyword(s):  
Spectroscopic Data ◽  
Kinetic Studies ◽  
Critical Issue ◽  
Pure Component ◽  
Sequential Reaction ◽  
Single Experiment ◽  
Entropy Minimization ◽  
Ir Studies ◽  
Ft Ir

In situ spectroscopic measurements are fairly common in homogeneous catalysis. However, although it is easy to accumulate vast amounts of data, their appropriate analysis becomes a critical issue. Accordingly, we have developed a simple-to-implement but numerically sophisticated tool. Let A denote a matrix of absorbance data, n denote the number of preliminary spectra obtained from the stepwise addition of reagents, k denote the number of sequential reaction spectra, and v the spectroscopic channels. Then the preconditioning problem can be stated as [Formula: see text]. A single experiment results in (1) a set of n “pure” component reference spectra and (2) a set of k preconditioned reaction spectra where the reagents have been optimally subtracted. Entropy minimization is examined as a means of achieving both objectives. The developed algorithm was applied to a set of FT-IR spectra obtained from a complex transition-metal homogeneous catalyzed organic synthesis. Excellent reference spectra and excellent preconditioned reaction spectra were readily obtained. In addition, the absorbance of the products in the preconditioned spectra was compared to the absorbance obtained after manual user-defined subtraction. Comparable results were obtained. The present approach is clearly useful for the automated numerical treatment of very large sequential spectroscopic data arrays arising from in situ kinetic studies. Extension to related types of problems in the chemical sciences and to other spectroscopic methods such as NMR are obvious.

Chemical Kinetic Studies on Polyurethane Formation of GAP and HTPB with IPDI by Using In Situ FT-IR Spectroscopy

2014 ◽  
Vol 1061-1062 ◽  
pp. 337-341
Author(s):  
Abbas Tanver ◽  
Mu Hua Huang ◽  
Yun Jun Luo ◽  
Ze Huan Hei
Keyword(s):  
Chemical Kinetics ◽  
High Performance ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Chemical Kinetic ◽  
Glycidyl Azide Polymer ◽  
Oh Groups ◽  
Ft Ir ◽  
Glycidyl Azide

The high-performance solid propellants play very important role in defense industry, which required highly energetic binders with good mechanical properties. In order to get the activation parameters for energetic binders, In-Situ FT-IR spectroscopic technique is used to study the chemical kinetics of glycidyl azide polymer (GAP) and hydroxyl terminated poly butadiene (HTPB) with isophorone diisocyanate (IPDI) at various temperatures. The reaction was followed by monitoring the change in intensity of the absorption band of NCO stretching at 2257cm-1and CO stretching at 1731cm-1. The polyurethane reaction has been found to be second order and the rate constant seems to be different between GAP/IPDI and HTPB/IPDI due to reactivity difference of OH groups. Dibutyl tin dilurate (DBTDL) was used as curing catalyst. By using Arrhenius and Eyring equations, the activation parameters were obtained at different temperatures (60, 70, 80 and 90°C). The apparent activation energy for the two systems GAP/IPDI and HTPB/IPDI were found to be 63.51 kJ mol-1and 41.06 kJ mol-1while the enthalpy and entropy of activation were found to be 62.35 kJ mol-1and-36.24 kJ.mol-1K-1, 39.08 J mol-1and-98.84 J mol-1K-1respectively.Key words: In-Situ FT-IR; glycidyl azide polymer (GAP); hydroxyl terminated poly butadiene (HTPB); chemical kinetics; polyurethane; dibutyl tin dilurate (DBTDL).

In Situ FT-IR Studies on the Catalytic Reaction of Isophorone Diisocyanate with Benzyl Alcohol

2012 ◽  
Vol 476-478 ◽  
pp. 2197-2200
Author(s):  
Peng Fei Yang
Keyword(s):  
Benzyl Alcohol ◽  
Rate Constant ◽  
Dibutyltin Dilaurate ◽  
Activation Entropy ◽  
Isophorone Diisocyanate ◽  
Ir Studies ◽  
Initial Stage ◽  
Different Temperatures ◽  
Ft Ir

Benzyl alcohol is used to react with isophorone diisocyanate at different temperatures. Dibutyltin dilaurate is used as catalyst. In-situ FT-IR is used to monitor the reaction to work out rate constant, Arrhenius equation and Eyring equation. The urethane reaction has been found to be a second order reaction, and the rate constant seems different between initial stage and final stage. The activation energy (Ea), activation enthalpy (ΔH) and activation entropy (ΔS) for the urethane reaction of different isocyanates groups are respectively calculated out, which are very useful to reveal the reaction mechanism.

FT-IR microspectroscopic analysis of diseased white matter brain tissues

1995 ◽  
Vol 53 ◽  
pp. 968-969
Author(s):  
Steven M. Le Vine ◽  
David L. Wetzel
Keyword(s):  
White Matter ◽  
Gray Matter ◽  
Twitcher Mouse ◽  
Grid Pattern ◽  
Marked Contrast ◽  
Spatially Resolved ◽  
Ft Ir ◽  
Ir Microspectroscopy ◽  
Chemical Evidence

In situ FT-IR microspectroscopy has allowed spatially resolved interrogation of different parts of brain tissue. In previous work the spectrrscopic features of normal barin tissue were characterized. The white matter, gray matter and basal ganglia were mapped from appropriate peak area measurements from spectra obtained in a grid pattern. Bands prevalent in white matter were mostly associated with the lipid. These included 2927 and 1469 cm-1 due to CH2 as well as carbonyl at 1740 cm-1. Also 1235 and 1085 cm-1 due to phospholipid and galactocerebroside, respectively (Figs 1and2). Localized chemical changes in the white matter as a result of white matter diseases have been studied. This involved the documentation of localized chemical evidence of demyelination in shiverer mice in which the spectra of white matter lacked the marked contrast between it and gray matter exhibited in the white matter of normal mice (Fig. 3).The twitcher mouse, a model of Krabbe’s desease, was also studied. The purpose in this case was to look for a localized build-up of psychosine in the white matter caused by deficiencies in the enzyme responsible for its breakdown under normal conditions.

scholarly journals Hydrothermal Synthesis of Sodalite-Type N-A-S-H from Fly Ash to Remove Ammonium and Phosphorus from Water

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2741
Author(s):  
Pengcheng Lv ◽  
Ruihong Meng ◽  
Zhongyang Mao ◽  
Min Deng
Keyword(s):  
Fly Ash ◽  
Adsorption Capacity ◽  
Removal Rate ◽  
Kinetic Studies ◽  
Solute Concentration ◽  
Raw Material ◽  
Sodium Aluminosilicate ◽  
Equilibrium Data ◽  
One Step ◽  
Ft Ir

In this study, the hydrated sodium aluminosilicate material was synthesized by one-step hydrothermal alkaline desilication using fly ash (FA) as raw material. The synthesized materials were characterized by XRD, XRF, FT-IR and SEM. The characterization results showed that the alkali-soluble desilication successfully had synthesized the sodium aluminosilicate crystalline (N-A-S-H) phase of sodalite-type (SOD), and the modified material had good ionic affinity and adsorption capacity. In order to figure out the suitability of SOD as an adsorbent for the removal of ammonium and phosphorus from wastewater, the effects of material dosing, contact time, ambient pH and initial solute concentration on the simultaneous removal of ammonium and phosphorus are investigated by intermittent adsorption tests. Under the optimal adsorption conditions, the removal rate of ammonium was 73.3%, the removal rate of phosphate was 85.8% and the unit adsorption capacity reached 9.15 mg/L and 2.14 mg/L, respectively. Adsorption kinetic studies showed that the adsorption of ammonium and phosphorus by SOD was consistent with a quasi-secondary kinetic model. The adsorption isotherm analysis showed that the equilibrium data were in good agreement with the Langmuir and Freundlich model. According to thermodynamic calculations, the adsorption of ammonium and phosphorus was found to be a heat-absorbing and spontaneous process. Therefore, the preparation of SOD by modified FA has good adsorption properties as adsorbent and has excellent potential for application in the removal of contaminants from wastewater.

scholarly journals Experimental and Theoretical Studies of Sonically Prepared Cu–Y, Cu–USY and Cu–ZSM-5 Catalysts for SCR deNOx

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 824
Author(s):  
Przemysław J. Jodłowski ◽  
Izabela Czekaj ◽  
Patrycja Stachurska ◽  
Łukasz Kuterasiński ◽  
Lucjan Chmielarz ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Ultrasonic Irradiation ◽  
Active Phase ◽  
Spectroscopic Studies ◽  
In Situ Drifts ◽  
Ft Ir ◽  
Diffuse Reflectance Infrared ◽  
Experimental And Theoretical Studies

The objective of our study was to prepare Y-, USY- and ZSM-5-based catalysts by hydrothermal synthesis, followed by copper active-phase deposition by either conventional ion-exchange or ultrasonic irradiation. The resulting materials were characterized by XRD, BET, SEM, TEM, Raman, UV-Vis, monitoring ammonia and nitrogen oxide sorption by FT-IR and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). XRD data confirmed the purity and structure of the Y/USY or ZSM-5 zeolites. The nitrogen and ammonia sorption results indicated that the materials were highly porous and acidic. The metallic active phase was found in the form of cations in ion-exchanged zeolites and in the form of nanoparticle metal oxides in sonochemically prepared catalysts. The latter showed full activity and high stability in the SCR deNOx reaction. The faujasite-based catalysts were fully active at 200–400 °C, whereas the ZSM-5-based catalysts reached 100% activity at 400–500 °C. Our in situ DRIFTS experiments revealed that Cu–O(NO) and Cu–NH3 were intermediates, also indicating the role of Brønsted sites in the formation of NH4NO3. Furthermore, the results from our experimental in situ spectroscopic studies were compared with DFT models. Overall, our findings suggest two possible mechanisms for the deNOx reaction, depending on the method of catalyst preparation (i.e., conventional ion-exchange vs. ultrasonic irradiation).

scholarly journals Synthesis of Poly(methacrylic acid-co-butyl acrylate) Grafted onto Functionalized Carbon Nanotube Nanocomposites for Drug Delivery

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 533 ◽  
Author(s):  
Josué A. Torres-Ávalos ◽  
Leonardo R. Cajero-Zul ◽  
Milton Vázquez-Lepe ◽  
Fernando A. López-Dellamary ◽  
Antonio Martínez-Richa ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Drug Delivery ◽  
Methacrylic Acid ◽  
Butyl Acrylate ◽  
Chemical Vapor ◽  
Vis Spectroscopy ◽  
Ir And Raman Spectroscopies ◽  
Ft Ir

Design of a smart drug delivery system is a topic of current interest. Under this perspective, polymer nanocomposites (PNs) of butyl acrylate (BA), methacrylic acid (MAA), and functionalized carbon nanotubes (CNTsf) were synthesized by in situ emulsion polymerization (IEP). Carbon nanotubes were synthesized by chemical vapor deposition (CVD) and purified with steam. Purified CNTs were analyzed by FE-SEM and HR-TEM. CNTsf contain acyl chloride groups attached to their surface. Purified and functionalized CNTs were studied by FT-IR and Raman spectroscopies. The synthesized nanocomposites were studied by XPS, 13C-NMR, and DSC. Anhydride groups link CNTsf to MAA–BA polymeric chains. The potentiality of the prepared nanocomposites, and of their pure polymer matrices to deliver hydrocortisone, was evaluated in vitro by UV–VIS spectroscopy. The relationship between the chemical structure of the synthesized nanocomposites, or their pure polymeric matrices, and their ability to release hydrocortisone was studied by FT-IR spectroscopy. The hydrocortisone release profile of some of the studied nanocomposites is driven by a change in the inter-associated to self-associated hydrogen bonds balance. The CNTsf used to prepare the studied nanocomposites act as hydrocortisone reservoirs.

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