scholarly journals Activity and Thermal Stability of Cobalt(II)-Based Olefin Polymerization Catalysts Adorned with Sterically Hindered Dibenzocycloheptyl Groups

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 2007 ◽  
Author(s):  
Muhammad Zada ◽  
Liwei Guo ◽  
Yanping Ma ◽  
Wenjuan Zhang ◽  
Zygmunt Flisak ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Active Sites ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Linear Polyethylene ◽  
Order Of Magnitude ◽  
Ft Ir ◽  
Sterically Hindered ◽  
Thermal Stability Of

Five examples of unsymmetrical 2-(2,4-bis(dibenzocycloheptyl)-6-methylphenyl- imino)ethyl)-6-(1-(arylyimino)ethyl)pyridine derivatives (aryl = 2,6-Me2C6H3 in L1; 2,6-Et2C6H3 in L2; 2,6-i-Pr2C6H3 in L3; 2,4,6-Me3C6H2 in L4 and 2,6-Et2-4-MeC6H2 in L5) were prepared and characterized. Treatment with CoCl2 offered the corresponding cobalt precatalysts Co1–Co5, which were characterized by FT-IR and NMR spectroscopy as well as elemental analysis. The molecular structures of Co3 and Co4 determined by single crystal X-ray diffraction revealed distorted square pyramidal geometries with τ5 values of 0.052–0.215. Activated with either MAO or MMAO, the precatalysts displayed high activities in ethylene polymerization, where Co1 with the least bulky substituents exhibited a peak activity of 1.00 × 107 g PE mol−1 (Co) h−1 at 60 °C. With MAO as a cocatalyst, the activity was reduced only by one order of magnitude at 90 °C, which implies thermally stable active sites. The polymerization product was highly linear polyethylene with vinyl end groups. Co3 with the most sterically hindered active sites was capable of generating polyethylene of high molecular weight, reaching 6.46 × 105 g mol−1. Furthermore, high melting point and unimodal molecular weight distribution were observed in the resulting polyethylene. It must be stressed that the thermal stability of the catalyst and the molecular weight of the obtained polyethylene attain the highest values reported for the unsymmetrical 2,6-bis(imino)pyridylcobalt (II) chloride precatalysts.

Preparation of Polyaniline/SiO2 Composites by Modified Silica Using Succinic Acid

2012 ◽  
Vol 535-537 ◽  
pp. 149-153 ◽  
Author(s):  
Er Yuan Li ◽  
Xiu Feng Wang ◽  
Xue Zhi Wang ◽  
Hao Wang
Keyword(s):  
Thermal Stability ◽  
Succinic Acid ◽  
X Ray Diffraction ◽  
Modified Silica ◽  
X Ray ◽  
Surface Character ◽  
Ft Ir ◽  
Thermal Stability Of ◽  
Scanning Electron ◽  
Ft Ir Spectroscopy

Polyaniline/SiO2 composites were prepared by the SiO2 particles whose surface character was modified by succinic acid. The composites were characterized by Fourier transform infrared (FT–IR) spectroscopy, X–ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM). The results demonstrated that the thermal stability of PANI had improved.

Sonochemically Synthesis of Antimonite Nanoparticles and Its Influence on the Thermal Stability of the ABS Terpolymer

2013 ◽  
Vol 32 (4) ◽  
pp. 339-343 ◽  
Author(s):  
Siyamak Bagheriyan
Keyword(s):  
Thermal Stability ◽  
Acrylonitrile Butadiene Styrene ◽  
X Ray Diffraction ◽  
Limiting Oxygen Index ◽  
X Ray ◽  
Sonochemical Reaction ◽  
Ft Ir ◽  
Higher Temperature ◽  
Thermal Stability Of ◽  
Butadiene Styrene

AbstractSb2S3 nanoparticles were synthesized via a simple sonochemical reaction between SbCl3 and thioacetamide. The effect of different parameters such as power and time of pulsation on the morphology of the product has been investigated. The Sb2 S3 nanostructures were then added to acrylonitrile-butadiene-styrene terpolymer. The effect of Sb2 S3 nanostructures on the thermal stability of the polymeric matrix has been examined. The thermal decomposition of the nanocomposite shifts towards higher temperature in the presence of the Sb2 S3 . Nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), photoluminescence (PL) spectroscopy, thermogravimetric analysis (TGA), UL-94 and limiting oxygen index (LOI) analysis.

Preparation and Thermal Stability of Pyrrole and m-Toluidine Copolymer/Montmorillonite Composites

2014 ◽  
Vol 915-916 ◽  
pp. 780-783
Author(s):  
Hong Wang ◽  
Ming Tian Li ◽  
Yue Lu ◽  
Di Liu
Keyword(s):  
Thermal Stability ◽  
Interfacial Interaction ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Chemical Polymerization ◽  
X Ray ◽  
Ft Ir ◽  
Clay Layers ◽  
Thermal Stability Of

Pyrrole and m-toluidine copolymer (P(PY/MT)) / montmorillonite (MMT) Composites were prepared by in situ chemical polymerization of pyrrole with m-toluidine monomer in the presence of montmorillonite. The structural, morphological and thermal properties of these composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). X-ray diffraction result for P(PY/MT)-MMT illuminated the intercalation of P(PY/MT) copolymer between the clay layers. The FT-IR result showed the successful incorporation of montmorillonite clay in the prepared P(PY/MT)/MMT composite. The higher thermal stability of high MMT content rate might be attributed to its higher chain compactness due to the interfacial interaction between the P(PY/MT) and the clay.

Synthesis and Characterization of Polyaniline Copolymer

2012 ◽  
Vol 217-219 ◽  
pp. 551-554
Author(s):  
Ting Xi Li ◽  
Yu Hua Zhao ◽  
Qian Li ◽  
Cheng Qian Yuan ◽  
Quan Liang Chen ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Infrared Spectroscopy ◽  
Thermogravimetric Analysis ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir ◽  
The Difference ◽  
Thermal Stability Of

Abstract. Polyaniline (PANI) and p-phenylenediamine (p-PDA)-aniline copolymer were prepared via a same microemulsion method. The structures of the PANI and p-PDA-aniline copolymer were characterized by infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis（TGA）. The results revealed the difference of synthesis and characterization between PANI and p-PDA-aniline copolymer. It was shown that structure of the copolymer is almost similar to that of PANI, but the p-PDA-aniline copolymer has a better crystallization than PANI, and the thermal stability of the copolymer is higher than that of pure PANI.

scholarly journals Synthesis, Characterization and Copolymerization of N-(phenylamino)maleimide with MMA

2007 ◽  
Vol 4 (2) ◽  
pp. 265-271
Author(s):  
B. L. Hiran ◽  
S. N. Paliwal ◽  
Jyoti Choudhary ◽  
P. R. Choudhary
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Density Measurement ◽  
Gel Permeation Chromatography ◽  
Radical Copolymerization ◽  
Free Radical Copolymerization ◽  
H Nmr ◽  
Gel Permeation ◽  
Ft Ir ◽  
Thermal Stability Of

The free radical copolymerization of N-(phenylamino)maleimide (N-PAMI) was carried. The copolymerization with methyl methacrylate (MMA) was performed at 65°C with AIBN as the initiator in THF solvent. Resulting copolymer was characterized by density measurement, intrinsic viscosity, solubility, FT-IR &1H NMR spectroscopy. Effect of the solvent and time on copolymer yield was also investigated. The molecular weight of copolymer was determined by gel permeation chromatography (GPC). The thermal stability of copolymer was determined by Thermogravimetric analysis (TGA).

Preparation and Thermal Stability of Micro/Nano Silicone Rubber Particles

2011 ◽  
Vol 399-401 ◽  
pp. 718-721
Author(s):  
Fei Wang ◽  
Xin Long Wang
Keyword(s):  
Thermal Stability ◽  
Silicone Rubber ◽  
Crosslinking Agent ◽  
Nano Particles ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Ft Ir ◽  
And Performance ◽  
Polymerization Method ◽  
Thermal Stability Of

The micro/nano particles of silicone rubber were prepared with α, ω-dihydroxy polyorganosiloxane, as basic polymer and crosslinking agent via emulsion polymerization method at room temperature. The structure and performance of the particles were characterized by transmission electron microscopy (TEM), FT-IR, thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The results indicated that the particles had certain ordered structure and thermal stability.

Thermally Stable Metal(Cu, Fe)-Substituted Mesoporous Aluminophosphates: Synthesis and Application as Oxidation Catalysts

2012 ◽  
Vol 550-553 ◽  
pp. 306-311 ◽  
Author(s):  
Bin Xu ◽  
Kai Feng Lin ◽  
Yan Qiu Jiang ◽  
Jian Min Sun ◽  
Xian Zhu Xu
Keyword(s):  
Thermal Stability ◽  
Active Sites ◽  
Nitrogen Adsorption ◽  
Metal Species ◽  
X Ray Diffraction ◽  
Catalytic Activities ◽  
Ft Ir ◽  
Adsorption Desorption ◽  
Ft Ir Spectroscopy ◽  
Mesoporous Aluminophosphates

Metal-substituted mesoporous aluminophosphates with high thermal stability (Fe-JLU-50 and Cu-JLU-50) has been prepared by using preformed microporous aluminophosphate precursors. The materials were characterized by X-ray diffraction, nitrogen adsorption/desorption isotherms and FT-IR spectroscopy. The characterization results showed the presence of zeolite aluminophosphate structural building units in the framework of the mesoporous aluminophosphates, which is responsible for their highly thermal stability. Also, the metal species such as Fe and Cu were successfully incorporated in the framework of the mesoporous aluminophosphates via this approach. Fe-JLU-50 and Cu-JLU-50 were evaluated in the oxidations of phenol and trimethylphenol (TMP) with aqueous H2O2, giving highly catalytic activities in both reactions. This result suggests that the materials are versatile catalysts for both small and bulky substrates, ascribed to the accessibility of the substrates to the active sites in the framework of Fe-JLU-50 and Cu-JLU-50 by the retained mesopores after calcination.

Biodegradable Poly(lactic Acid)/TDI-Montmorillonite Nanocomposites: Preparation and Characterization

2011 ◽  
Vol 221 ◽  
pp. 211-215 ◽  
Author(s):  
Na Li Chen ◽  
Hui Xia Feng ◽  
Jing Wei Guo ◽  
He Ming Luo ◽  
Jian Hui Qiu
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Decomposition Temperature ◽  
Toluene Diisocyanate ◽  
Poly Lactic Acid ◽  
Infrared Spectrometry ◽  
Ft Ir ◽  
Thermal Stability Of

Activated montmorillonite(MMT) was modified by toluene diisocyanate(TDI) and TDI-montmorillonite(TDI-MMT) was prepared. The characterization of TDI-MMT was carried out by X-ray diffraction(XRD) and fourier transform infrared spectrometry (FT-IR). The results showed that TDI had been inserted to the interlayer of MMT and the interlayer spacing of MMT increased by 0.26nm. With stannous chloride as catalyst, the biodegradable polylactide acid/TDI-montmorillonite(PLA/TDI-MMT) nanocomposites were synthesized through ring-opening polymerization of lactide in the layer of TDI-MMT by in-situ polymerization. The structure and thermal stability of nanocomposites were investigated by XRD, FT-IR and thermogravimetry (TG). Exfoliated nanocomposites were obtained as shown by XRD results. FT-IR spectra confirmed that TDI-MMT participated in the ring-opening polymerization of lactide. TG analysis indicated the decomposition temperature of nanocomposites rose and the thermal stability was improved contrast to the neat PLA. The effect of the content of TDI-MMT on the molecular weight and thermal stability of nanocomposites was studied. With the increase of the proportion of TDI-MMT, the molecular weight of resultant nanocomposites decreased and the decomposition temperature rose at the range of experiment research.

Preparation of Poly(m-toluidine)/Montmorillonite Composites and its Thermal Stability

2014 ◽  
Vol 941-944 ◽  
pp. 334-337
Author(s):  
Hong Wang ◽  
Rui Song Yang ◽  
Ying Wang
Keyword(s):  
Thermal Stability ◽  
Interfacial Interaction ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Chemical Polymerization ◽  
X Ray ◽  
Ft Ir ◽  
Clay Layers ◽  
Thermal Stability Of

Poly (m-toluidine)(PMT) / montmorillonite (MMT) Composites with thermal stability were synthesized by in situ chemical polymerization of m-toluidine monomer in the presence of montmorillonite. The PMT /MMT composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The FT-IR result displayed the successful incorporation of montmorillonite clay in the prepared PMT/MMT composite. X-ray diffraction result for PMT/MMT showed the intercalation of PMT between the clay layers. The higher thermal stability of high MMT content rate might be attributed to its higher chain compactness due to the interfacial interaction between the PMT and the .MMT.

scholarly journals Physicochemical characteristics of chitosan from swimming crab (Portunus trituberculatus) shells prepared by subcritical water pretreatment

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gengxin Hao ◽  
Yanyu Hu ◽  
Linfan Shi ◽  
Jun Chen ◽  
Aixiu Cui ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Sodium Hydroxide ◽  
Subcritical Water ◽  
Physicochemical Characteristics ◽  
Ash Content ◽  
Portunus Trituberculatus ◽  
Swimming Crab ◽  
Water Pretreatment ◽  
Thermal Stability Of

AbstractThe physicochemical properties of chitosan obtained from the shells of swimming crab (Portunus trituberculatus) and prepared via subcritical water pretreatment were examined. At the deacetylation temperature of 90 °C, the yield, ash content, and molecular weight of chitosan in the shells prepared via subcritical water pretreatment were 12.2%, 0.6%, and 1187.2 kDa, respectively. These values were lower than those of shells prepared via sodium hydroxide pretreatment. At the deacetylation temperature of 120 °C, a similar trend was observed in chitosan molecular weight, but differences in chitosan yield and ash content were not remarkable. At the same deacetylation temperature, the structures of chitosan prepared via sodium hydroxide and subcritical water pretreatments were not substantially different. However, the compactness and thermal stability of chitosan prepared via sodium hydroxide pretreatment was lower than those of chitosan prepared via subcritical water pretreatment. Compared with the chitosan prepared by sodium hydroxide pretreatment, the chitosan prepared by subcritical water pretreatment was easier to use in preparing oligosaccharides, including (GlcN)2, via enzymatic hydrolysis with chitosanase. Results suggested that subcritical water pretreatment can be potentially used for the pretreatment of crustacean shells. The residues obtained via this method can be utilized to prepare chitosan.

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