Phase behaviors of binary mixtures composed of banana-shaped and calamitic mesogens

In this work, five mixtures with different concentrations of banana-shaped and calamitic compounds have been prepared and subsequently studied by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction on non-oriented samples. The phase sequences and molecular parameters of the binary systems are presented

Powder diffraction data and mesomorphic properties of 4-butyloxyphenyl 4'-decyloxybenzoate

Unit cell parameters obtained from X-ray powder diffraction data are presented for the crystalline phase of a liquid crystal 4-butyloxyphenyl 4'-decyloxybenzoate: a = 23.098 (4) Å, b = 5.974 (6) Å, c = 12.357 (10) Å, β = 121.53 (8)°, unit-cell volume V = 1453.56 Å3 . Temperature dependent X-ray diffraction data confirmed the existence of smectic A and smectic C mesophases and a more ordered, tilted crystalline smectic phase. Possibility of existence of previously reported smectic B phase as well as another crystalline phase was refuted

Synthesis and properties biobased waterborne polyurethanes from glycolysis product of PET waste and poly(caprolactone) diol

Novel biobased poly(ester-urethane)s (PUDs) were synthesized by solvent free homogeneous solution polymerization of poly(caprolactone) diol (PCL), castor oil-based polyols (COLs), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and 1,4-butane diol (BD) as the chain extender. The polyurethane dispersions were prepared by adding required amount of triethylamine (TEA) and water. In this Work, castor oil-based polyols have been synthesized using the depolymerized oligoester obtained from glycolysis of PET waste with poly(ethylene glycol) (PEG 400) and castor oil. The effects of the soft segments content on the thermal and coatings properties of resulting polyurethane films have been examined by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and measurement of the coatings properties. Phase separation of polyurethane shows a strong correlation with crystallization behaviour of the polyurethane prepared. It is established that all PUD samples containing PCL as a part soft segment with different molar ratio of castor-oil polyol are crystallisable polymers. The results from XRD analysis have showed that highest degree of crystallinity (23 and 22%) is reached in polyurethanes based on the largest content PCL diol (CPU77 and CPU73). The thermal stability of samples based on (COL/PCL molar ratio 0.25:0.75) possesses the best thermal properties but less values hardness coatings which can be ascribed to a decrease of the hard segment i.e. DMPA content in polyurethane dispersions. The long-term stability of polyurethane dispersions has been investigated using UV vis spectroscopy. The physico-mechanical properties such as hardness adhesion test and gloss of the dried films have also been determined considering the effect of soft segment content on coating properties. (C) 2016 Elsevier B.V. All rights reserved

Glycolyzed poly(ethylene terephthalate) waste and castor oil-based polyols for waterborne polyurethane adhesives containing hexamethoxymethyl melamine

Glycolysis of poly(ethylene terephthalate) (PET) waste using different molar ratio of poly(ethylene glycol) (PEG400), was used to produce saturated hydroxyl-functional polyester polyols with castor oil (CO) by transesterification process. The waterborne polyurethane (WBPU) adhesives were synthesized from these saturated polyester polyols, isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA), and hexamethoxymethyl melamine (HMMM) as cross-linking agent by a conventional prepolymer process. The glycolyzed polyols and polyester polyos formations were characterized using Fourier transform infrared spectroscopy (FTIR) and the molecular weights were determined using gel permeation chromatography (GPC). The cross-linking reaction between WBPU and HMMM was verified using FfIR and H-1 NMR analysis. Thermal properties were investigated by thermogravimetric analysis (TG). Thermal stability of cross-linked WBPU significantly increased with decreasing castor oil content in the process of transesterification to obtain polyester polyol as a soft segment. The T-15% and T-50% (the temperature where 15 and 50% weight loss occurred) of WBPU increased with the decreasing of castor oil content in the obtained polyester polyols, caused by the steric hindrance of polyester polyol with higher castor oil content, in the process of cross-linking reactions with HMMM. The physico-mechanical properties of WBPU, such as hardness, adhesion test, and gloss of the dried films were also determined considering the effect of participation of HMMM in cross-linking reactions with polyurethane, on coating properties. (C) 2014 Elsevier B.V. All rights reserved