Synthesis and characterization of main-chain liquid crystalline copolyesters containing phosphaphenanthrene side-groups

Qian, Lijun; Zhi, Junge; Tong, Bin; Shi, Jianbing; Yang, Fan; Dong, Yuping

doi:10.1016/j.polymer.2009.08.016

Cited by 25 publications

(8 citation statements)

References 37 publications

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“…Therefore, much effort has been made to improve the processability of thermotropic liquid crystalline polyarylates. The main methods are as follows: (1) introduction of non‐mesogenic flexible spacers in the main chain; (2) introduction of side substituents to reduce the symmetry of the chains; (3) copolymerization of several aromatic monomers to obtain a more random backbone composition . The representative examples are enumerated as follows.…”

Section: Introductionmentioning

confidence: 99%

Novel polyarylates containing aryl ether units: synthesis, characterization and properties

Liu

et al. 2012

Polymer International

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To improve the processability of the poly(p‐hydroxybenzoic acid), copolyarylates containing m‐aryl ether units were synthesized using p‐acetoxybenzoic acid, 1,4‐diacetoxybenzene and 1,3‐bis(4'‐carboxyphenoxy)benzene by melt transesterification reaction. The structure and properties of these polyarylates were characterized using infrared spectra, differential scanning calorimetry, thermogravimetric analyses, wide‐angle X‐ray diffraction and polarized optical microscopy etc. The results showed that all polyarylates were semicrystalline materials and could form a thermotropic liquid crystalline intermediate state. As the content of aryl ether units increased, the crystallization and melting temperatures of the polyarylate decreased; meanwhile, the crystalline ability became lower. The introduction of the aryl ether could restrain the formation of a liquid crystalline structure and reduce the thermal stability to some extent. After solid state polymerization (SSP), the intrinsic viscosity, melting temperature, crystallinity and thermal stability of the polyarylate increased while the melting range narrowed. However, the SSP reaction might be accompanied by degradation and crosslinking.

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Section: Introductionmentioning

confidence: 99%

Novel polyarylates containing aryl ether units: synthesis, characterization and properties

Liu

et al. 2012

Polymer International

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“…Observing the peak at 744 cm −1 , the peak height sequence 0.5%OMMT/2.5%TGD/EP = 3%TGD/EP > EP = 3%OMMT/EP, suggested a particular contribution from TGD, a compound rich in phosphorus. An evidence of this opinion was that the gas‐phase spectrum of DOPO generated a characteristic peak at 750 cm −1 . Phosphorus‐containing structure has a free‐radical quenching effect, and it was the reason that samples with TGD shows good flame retardant properties which was shown in LOI and UL94 test.…”

Section: Resultsmentioning

confidence: 99%

Strengthen flame retardancy of epoxy thermoset by montmorillonite particles adhering phosphorus‐containing fragments

Liu

Qiu

Qian

et al. 2019

J of Applied Polymer Sci

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Phosphaphenanthrene derivative tri-(3-DOPO-2-hydroxypropan-1-yl)-1,3,5-triazine-2,4,6-trione (TGD) and organo-modified montmorillonite (OMMT) were jointly introduced into the diglycidyl ether of bisphenol A cured by 4,4-diamino-diphenylmethane (EP) to investigate their flame retardant behaviors. With only addition of 0.5%OMMT and 2.5%TGD, epoxy thermoset achieved a limiting oxygen index value of 33.7% and passed UL 94 V-0 rating test. Compared with the combustion behaviors of 3%OMMT/EP and 3%TGD/EP, an obvious synergistic flame retardant effect between OMMT and TGD can be concluded in OMMT/TGD/EP. Meanwhile, the FTIR spectra of gas-phase and condensed-phase products further proved this synergistic effect working in a physical way. On one hand, the co-existence of hydroxyl-containing TGD enabled montmorillonite (MMT) particles to filtrate and adhere more smoke fragments. On the other hand, the co-action of MMT help the polar phosphorus-containing fragments from TGD better strengthened char layer, enhancing the barrier and protective effect of residue. The synergistic flame retardant effect from OMMT/TGD system endowed themselves with higher flame retardant efficiency, and epoxy thermoset with better flame retardant performance.

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“…Thus, the thermal oxidative stability of PP/SiO 2 –WD70 (5 wt%) nanocomposite was a little lower than that of PP/SiO 2 (5 wt%) nanocomposite. As shown in Table 2, DOPO could improve the thermal stability, but it could not significantly improve the thermal stability even with the addition of 5 wt% [40, 41]. It was speculated that DOPO could induce cross-linking reaction and carbonization and form thermally-stable char, and therefore reduced the releasing rate of degradation volatiles.…”

Section: Resultsmentioning

confidence: 99%

Improvement of thermal stability of polypropylene using DOPO-immobilized silica nanoparticles

et al. 2012

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After the surface silylation with 3-methacryloxypropyltrimethoxysilane, silica nanoparticles were further modified by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The immobilization of DOPO on silica nanoparticles was confirmed by Fourier transform infrared spectroscopy, UV–visible spectroscopy, magic angle spinning nuclear magnetic resonance, and thermogravimetric analysis. By incorporating the DOPO-immobilized silica nanoparticles (5 wt%) into polypropylene matrix, the thermal oxidative stability exhibited an improvement of 62 °C for the half weight loss temperature, while that was only 26 °C increment with incorporation of virgin silica nanoparticles (5 wt%). Apparent activation energies of the polymer nanocomposites were estimated via Flynn–Wall–Ozawa method. It was found that the incorporation of DOPO-immobilized silica nanoparticles improved activation energies of the degradation reaction. Based on the results, it was speculated that DOPO-immobilized silica nanoparticles could inhibit the degradation of polypropylene and catalyze the formation of carbonaceous char on the surface. Thus, thermal stability was significantly improved.

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Synthesis and characterization of main-chain liquid crystalline copolyesters containing phosphaphenanthrene side-groups

Cited by 25 publications

References 37 publications

Novel polyarylates containing aryl ether units: synthesis, characterization and properties

Novel polyarylates containing aryl ether units: synthesis, characterization and properties

Strengthen flame retardancy of epoxy thermoset by montmorillonite particles adhering phosphorus‐containing fragments

Improvement of thermal stability of polypropylene using DOPO-immobilized silica nanoparticles

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