Synthesis and characterization of new aromatic polyesters and poly(ester-imide)s containing phosphorous cyclic bulky groups

Synthesis, characterization and thermal degradation kinetics of azomethine-based halogen-free flame-retardant polyphosphonates

In this study, azomethine polyphosphonates were synthesized by solution polycondensation of phenylphosphonic dichloride with various azomethine diols such as [4-(4-hydroxy phenyl) iminomethyl] phenol, [(4-(4-hydroxy-3-methoxy phenyl) iminomethyl)] phenol and [4-(4-hydroxy-3-ethoxy phenyl) iminomethyl] phenol using triethylamine catalyst at ambient temperature. The structure of the synthesized polymers was confirmed by Fourier transform infrared and 1H-, 13C- and 31P- nuclear magnetic resonance spectroscopic techniques. Thermal properties of the polymers were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry under nitrogen atmosphere. The TGA data showed that the synthesized polyphosphonates produce high char yield at 600°C due to the presence of phosphorous atom in the polymer chain and hence have good flame-retardant properties. One of the synthesized polyphosphonate was blended with commercial diglycidyl ether of bisphenol-A (DGEBA) resin in various weight percentage and cured with commercial curing agent triethylene tetramine (TETA). The polyphosphonates-blended epoxy thermosets have tensile strength in the range of 5–41 MPa and the percentage of elongation at breaks was 4–18. It was found that the incorporation of polyphosphonates into epoxy thermoset decreased the tensile strength from 41 MPa to 5 MPa, whereas the elongation at break value increased with increase in the weight percentage of polyphosphonate. The influence of polyphosphonates on the flame retardancy of blended thermosets was examined by limiting oxygen index (LOI) and vertical burning (UL-94) tests and found that the polymer samples achieved an increased UL-94 rating and the LOI values were in the range of 24–26. Broido and Horowitz–Metzger methods have been used to study the thermal degradation kinetic parameters.

Synthesis and characterization of cardo-based phosphorous–containing flame-retardant aromatic polyesters

Phosphorous-containing cardo polyesters were synthesized by interfacial polycondensation of phenylphosphonic dichloride with various bisphenols using a phase-transfer catalyst at ambient temperature. The structure of the synthesized polymers was confirmed using Fourier transform infrared and proton, carbon 13, and phosphorous 31 nuclear magnetic resonance spectroscopic techniques. The thermal properties of the polymers were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry under nitrogen atmosphere. All the polyesters showed high thermal stability, the maximum decomposition temperature being in the range of 475–523°C. The TGA data showed that all the synthesized phosphorous-containing polyesters produce high char yield at 700°C due to the presence of phosphorous atom in the polymer chain and hence have good flame-retardant properties. The synthesized phosphorus-containing polyesters have tensile strength in the range of 38.2–48 MPa, and the percentage of elongation at breaks of 3.3–16.8. The flame retardancy of all synthesized polymers was investigated by limiting oxygen index (LOI) and vertical burning (UL-94) tests. The results showed that the synthesized polymers have excellent flame retardancy, that is, the polymer samples achieved an increased UL-94 rating and the LOI values were in the range of 28.5–34. Broido model has been used to study the thermal degradation kinetic parameters.

Potentially eco-friendly poly (amide–ester–imide)/diacid-grafted titanium dioxide/modified montmorillonite nanocomposites containing natural amino acids

The progress of organic/inorganic composite materials has been specifically trendy in the last decade. This article focused on the fabrication and characterization of nanocomposites (NCs) with two different nanoparticles. Poly(amide–ester–imide) (PAEI) matrix was prepared by reacting N,N′-(1,3,5,7-tetraoxo-5,7-dihydropyrrolo[3,4-f]isoindole-2,6(1H,3H)-diyl)bis(4-hydroxybenz-amide) with N-trimellitylimido-l-leucine (TML) via tosyl chloride, pyridine, and N,N-dimethylformamide as a condensing agent. The surface of titanium dioxide (TiO2) nanoparticles was modified with diacid TML. Diacid-grafted TiO2 (D-TiO2) was mixed with the obtained PAEI and sonicated to form a PAEI/D-TiO2 NC. Then, the surface of a sodium montmorillonite (MMT) was modified through intercalation with the cationic surfactant of l-leucine using an ion-exchange mechanism. PAEI/D-TiO2/organically modified montmorillonite composites at three different weight fractions of silicate layer were prepared via solution intercalation method. The spectral, morphological, and thermal properties of the aforementioned NCs were investigated in terms of several experimental techniques, including Fourier transform infrared spectroscopy, field-emission scanning electron microscopy (FESEM), X-ray diffraction, thermogravimetric analysis, and transmission electron microscopy (TEM). The obtained novel NCs improved thermal stability from neat polymer. Photographs showing TEM and FESEM results also illustrated that the nanofillers were rather uniformly distributed in the polymer matrix.

Manufacture and microstructure characterization of optically active poly(esterimide)/TiO2 bionanocomposites derived from natural amino acid–based diacid

Bio-based nanocomposites were successfully synthesized by incorporation of bioactive titanium dioxide (TiO2) nanoparticles in biodegradable poly(esterimide) (PEI) matrix via ultrasonic irradiation. The optically active PEI was prepared by direct polycondensation of amino acid–based diacid (4) with 4,4′-thiobis(2-tert-butyl-5-methylphenol) (5) in the presence of tosyl chloride, pyridine, and N,N-dimethylformamide. The obtained bionanocomposites (BNCs) were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, atomic force microscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and thermogravimetric analysis. FE-SEM and TEM images of the nanocomposites revealed homogeneity and uniformity in the distribution of TiO2 nanoparticles in PEI matrix.

Synthesis and Characterization of Some Polyesters and Poly(ester-imide)s Based on Bisphenol-A Derivatives

Aromatic polyesters and poly(ester-imide)s based on bisphenol-A derivatives were prepared by solution polycondensation at high temperature of three diols with an aromatic diacide chloride containing two preformed ester groups, namely terephthaloyl-bis-(4-oxybenzoylchloride) or two diacide chlorides containing preformed imide rings, namely 4-chloroformyl- N ( p-chloroformylphenyl)-phthalimide and 2,2-bis[ N-(4-chloroformylphenyl)phthalimidyl] hexafluoropropane. The polymers were easily soluble in polar organic solvents, such as N-methylpyrrolidone, N , N -dimethylformamide, N , N -dimethylacetamide and chloroform. They showed high thermal stability, the decomposition temperature being above 320 °C and the glass transition temperature in the range 92—196 ° C. Some of the polymers exhibited thermotropic liquid crystalline behavior.