Study on Crystallization Behavior of Liquid Crystalline Polyacrylates Induced Isotactic Polypropylene

2012 ◽  
Vol 182-183 ◽  
pp. 302-306
Author(s):  
Qian Yang Chen
Keyword(s):  
Mass Fraction ◽  
Liquid Crystalline ◽  
Relative Content ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Nucleation Effect ◽  
Β Phase ◽  
Maximum Value ◽  
Pp Blends

A series of polypropylene (PP) blends were obtained by blending isotactic PP and different mass fraction of liquid crystalline polyacylates (LCP-A) at a proper process program. The effect of LCP-A as a new nucleator on crystallization behacior of isotactic PP has been investigated with wide angle X-ray diffraction (WAXD), polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The experimental results showed that LCP-A in the PP played a role in the heterogeneous nucleation effect, supplied much crystal nucleus, enhanced the crystallization velocity and temperature, and the spherulites became smaller and more homogeneous. Moreover, β-phase in the PP was induced. In addition, the relative content of β-crystal (Kβ) increased with increasing LCP-A content or crystallization temperature, reached a maximum value, and then decreased as the temperature or LCP-A content further increased. Kβ of PP with 0.8% LCP-A isothermally crystallized at 125°C for 1h was 21%. POM results that showed the morphology of β and α spherulite disappeared at 156°C and 172°C, respectively.

Liquid crystalline polyureas with oligo(ethylene glycol) sequences

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Shahram Mehdipour-Ataei ◽  
Leila Akbarian-Feizi
Keyword(s):  
Liquid Crystalline ◽  
Spectroscopic Method ◽  
Polymerization Reaction ◽  
X Ray Diffraction ◽  
Subsequent Reaction ◽  
Scanning Calorimetry ◽  
Polar Solvents ◽  
X Ray ◽  
H Nmr ◽  
Ft Ir

AbstractA diamine monomer containing ester, amide and ether functional groups was prepared and its polymerization reaction with different diisocyanates to give main chain poly(ester amide ether urea)s was investigated. The monomer was synthesized via reaction of terephthaloyl chloride with 4-hydroxybenzoic acid and subsequent reaction of the resulted diacid with 1,8-diamino-3,6-dioxaoctane. The polymers were characterized by FT-IR and 1H-NMR spectroscopic method and elemental analysis. The resulting polymers exhibited excellent solubility in polar solvents. Crystallinity of the resulted polymers was evaluated by wide-angle X-ray diffraction (WXRD) method, and they exhibited semi-crystalline patterns. The glass transition temperatures (Tg) of the polymers determined by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) were in the range of 88-112 °C. The temperatures for 10% weight loss (T10) from their thermogravimetric analysis (TGA) curves were found to be in the range of 297-312 °C in air. Also the prepared polyureas showed liquid crystalline character.

Synthesis and Properties of Thermotropic Liquid Crystalline Polyesters with Flexible Polymethylene Spacer

2010 ◽  
Vol 428-429 ◽  
pp. 126-131
Author(s):  
Wei Zhong Lu ◽  
Chun Wei ◽  
Qui Shan Gao
Keyword(s):  
Optical Microscopy ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Structure Morphology ◽  
Temperature Ranges ◽  
Ft Ir ◽  
Diffraction Peaks ◽  
Ubbelohde Viscometer

Polymethylene bis(p-hydroxybenzoates) were prepared from methyl p-hydroxybenzoate and different diols by melted transesterification reaction. Three liquid crystalline polyesters were synthesized from terephthaloyl dichloride and polymethylene bis(p-hydroxybenzoates). Its structure, morphology and properties were characterized by Ubbelohde viscometer, Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), polarized optical microscopy (POM) with a hot stage, and wide-angle X-ray diffraction (WAXD). Results indicated that the intrinsic viscosities were between 0.088 and 0.210 dL/g. Optical microscopy showed that the TLCP has a highly threaded liquid crystalline texture and a high birefringent schlieren texture character of nematic phase and has wider mesophase temperature ranges for all polyesters. DSC analysis were found that the melting point (Tm), isotropic temperature (Ti) of TLCPs decreased and the temperature range of the liquid crystalline phase became wider with increased number of methylene spacers in the polyester. The WAXD results showed that TLCPs owned two strong diffraction peaks at 2θ near 19° and 23°.

scholarly journals Synthesis and mesomorphic properties of calamitic malonates and cyanoacetates tethered to 4-cyanobiphenyls

2012 ◽  
Vol 8 ◽  
pp. 371-378 ◽  
Author(s):  
Katharina C Kress ◽  
Martin Kaller ◽  
Kirill V Axenov ◽  
Stefan Tussetschläger ◽  
Sabine Laschat
Keyword(s):  
Differential Scanning Calorimetry ◽  
Ambient Temperature ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Cyanoacetic Acid ◽  
Scanning Calorimetry ◽  
Isotropic Liquid ◽  
X Ray ◽  
Nematic Phases ◽  
Mesomorphic Properties

4-Cyano-1,1'-biphenyl derivatives bearing ω-hydroxyalkyl substituents were reacted with methyl 3-chloro-3-oxopropionate or cyanoacetic acid, giving liquid-crystalline linear malonates and cyanoacetates. These compounds formed monotropic nematic phases at 62 °C down to ambient temperature upon cooling from the isotropic liquid. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction (WAXS).

Thermotropic behavior of sodium cholesteryl carbonate

2009 ◽  
Vol 24 (1) ◽  
pp. 156-163 ◽  
Author(s):  
Rabkwan Chuealee ◽  
Timothy S. Wiedmann ◽  
Teerapol Srichana
Keyword(s):  
Phase Behavior ◽  
Chemical Structure ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Wave Number ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
C Nmr

Sodium cholesteryl carbonate ester (SCC) was synthesized, and its phase behavior was studied. The chemical structure was assessed by solid-state infrared spectroscopy based on vibration analysis. The wave number at 1705 and 1276 cm−1 corresponds to a carbonyl carbonate and O–C–O stretching of SCC, respectively. Molecular structure of SCC was further investigated with 1H and 13C NMR spectroscopy. The chemical shift, for the carbonyl carbonate resonance appeared at 155.5 ppm. A molecular mass of SCC was at m/z of 452. Differential scanning calorimetry (DSC), video-enhanced microscopy (VEM) together with polarized light microscopy, and small-angle x-ray scattering (SAXS) were used to characterize the phase behavior as a function of temperature of SCC. Liquid crystalline phase was formed with SCC. Based on the thermal properties and x-ray diffraction, it appears that SCC forms a structure analogous to the type II monolayer structure observed with cholesterol esters.

Inosose-Flüssigkristalle / Inosose Liquid Crystals

1990 ◽  
Vol 45 (7) ◽  
pp. 1084-1090 ◽  
Author(s):  
Klaus Praefcke ◽  
Bernd Kohne ◽  
Andreas Eckert ◽  
Joachim Hempel
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
High Temperature ◽  
Liquid Crystalline ◽  
Structural Features ◽  
Lyotropic Liquid Crystal ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Alkyl Chains

Six S,S-dialkyl acetals 2a-f of inosose (1), tripodal in structure, have been synthesized, characterized and investigated by optical microscopy and differential scanning calorimetry (d.s.c.). The four S,S-acetals 2c-f with sufficiently long alkyl chains are thermotropic liquid crystalline; 2 e and 2 f are even dithermomesomorphic. Each of these four inosose derivatives 2c-f exhibits monotropically a most likely cubic mesophase (MI); in addition 2e and 2f show enantiotropically a hexagonal mesophase (Hx) with a non-covalent, supramolecular H-bridge architecture. Whereas the nature of the optically isotropic mesophase MI needs further clarification the stable high temperature mesophase Hx of 2 e and 2 f has been established by a miscibility test using a sugar S,S-dialkyl acetal also tripodal in structure and with a Hx phase proved by X-ray diffraction, but in contrast to 2 with an acyclic hydrophilic part. Similarities of structural features between the Hx-phases of 2e and 2f as well as of other thermotropic and lyotropic liquid crystal systems are discussed briefly.

Effects of Cooling Rate and Sn Addition on the Microstructure of Ti-Nb-Sn Alloys

2011 ◽  
Vol 172-174 ◽  
pp. 190-195 ◽  
Author(s):  
Giorgia T. Aleixo ◽  
Eder S.N. Lopes ◽  
Rodrigo Contieri ◽  
Alessandra Cremasco ◽  
Conrado Ramos Moreira Afonso ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Melting Furnace ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Β Phase ◽  
Arc Melting ◽  
Ti Alloys ◽  
Ω Phase

Ti-based alloys present unique properties and hence, are employed in several industrial segments. Among Ti alloys, β type alloys form one of the most versatile classes of materials in relation to processing, microstructure and mechanical properties. It is well known that heat treatment of Ti alloys plays an important role in determining their microstructure and mechanical behavior. The aim of this work is to analyze microstructure and phases formed during cooling of β Ti-Nb-Sn alloy through different cooling rates. Initially, samples of Ti-Nb-Sn system were prepared through arc melting furnace. After, they were subjected to continuous cooling experiments to evaluate conditions for obtaining metastable phases. Microstructure analysis, differential scanning calorimetry and X-ray diffraction were performed in order to evaluate phase transformations. Depending on the cooling rate and composition, α” martensite, ω phase and β phase were obtained. Elastic modulus has been found to decrease as the amount of Sn was increased.

scholarly journals Discotic Liquid Crystals Based on Cu(I) Complexes with Benzoylthiourea Derivatives Containing a Perfluoroalkyl Chain

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Monica Iliş ◽  
Viorel Cîrcu
Keyword(s):  
Liquid Crystalline ◽  
Large Temperature ◽  
Discotic Liquid Crystals ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
X Ray ◽  
Ir And Nmr Spectroscopy ◽  
Hexagonal Columnar ◽  
Mesomorphic Properties

Mesomorphic three-coordinate copper(I) complexes ([Cu(BTU)2X], where X = Cl or Br) based on a new N-benzoylthiourea (BTU) ligand with two decyloxy and one perfluorooctyl groups at its periphery were designed and prepared. The BTU ligand coordinates via the S atom in a neutral monodentate fashion as confirmed by IR and NMR spectroscopy data. The liquid crystalline behavior of these copper(I) complexes was investigated by a combination of polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction analysis (XRD), while their thermal stability was studied by thermogravimetric analysis (TGA). These new copper(I) complexes have mesomorphic properties and exhibit a hexagonal columnar mesophase over a large temperature range, more than 100°C.

Study of the Liquid Crystalline Phases in Some Compounds of 4-Trans-(4-Alkyl)Cyclo-Hexylphenyl-Alkylcarboxylate

1983 ◽  
Vol 38 (12) ◽  
pp. 1362-1364 ◽  
Author(s):  
I. H. Ibrahim ◽  
W. Haase
Keyword(s):  
Differential Scanning Calorimetry ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Intermolecular Distance ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Enthalpy Changes ◽  
Liquid Crystalline Phases ◽  
Nematic Phases

Abstract Three mesogenic compounds of the general formula have been investigated by differential scanning calorimetry. thermal optical microscopy and X-ray diffraction methods/Enthalpy changes of The different phase transitions for these compounds have been determined. H33 exhibits smectic B and nematic phases, whereas H34 and H75 exhibit only smectic B phases. The thickness of the smectic layers and the average intermolecular distance have been evaluated, as well as the corresponding molecular parameters in the nematic phase.

Investigation on β-Polypropylene/Talc Composites

2012 ◽  
Vol 182-183 ◽  
pp. 259-264
Author(s):  
Jia Wei Duan ◽  
Qiang Dou
Keyword(s):  
Polarized Light ◽  
Nucleating Agent ◽  
Mechanical Tests ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Melt Compounding ◽  
Β Phase ◽  
Α Phase ◽  
Melting And Crystallization

In this study polypropylene (PP) composites containing β-nucleating agent (NT-C) and talc filler were prepared by melt compounding. The melting and crystallization behavior, morphology and mechanical properties of the composites were studied by means of differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), polarized light microscopy (PLM) and mechanical tests. The results indicate that talc suppresses the formation of β phase, but promotes the formation of α phase. The Izod notched impact strength and tensile strength of β-PP/talc composites are superior to those of PP/talc composites, indicating an outstanding balance of stiffness and toughness of β-PP/talc composites.

Star mesogens — Synthesis and structural characterization using 1D and 2D solution NMR techniques and mesophase characterization

2013 ◽  
Vol 91 (3) ◽  
pp. 196-205 ◽  
Author(s):  
A. Shanavas ◽  
T. Narasimhaswamy ◽  
B.V.N. Phani Kumar ◽  
A. Sultan Nasar
Keyword(s):  
Chain Length ◽  
Liquid Crystalline ◽  
Variable Temperature ◽  
2D Nmr ◽  
Smectic Layer ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Xrd Techniques ◽  
Terminal Chain

Novel star mesogens based on trimesic acid and symmetrical side arm cores with terminal alkoxy groups were synthesized via a divergent approach. The central core and side arms were connected through alkyl spacers. All the synthesized mesogens and their intermediates were characterized thoroughly using Fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (NMR), 13C NMR, and mass spectrometers. One representative mesogen was subjected to the two-dimensional (2D) NMR experiments to ascertain the structure of the mesogens. The mesophase characterization was carried out using hot-stage optical polarizing microscopy (HOPM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) techniques. Many of the molecules with an ethyloxy spacer were found to be nonmesogenic, whereas all the molecules with a butyloxy spacer showed liquid crystalline phases. The increase of terminal chain length decreased the transition temperatures. The nematic phase was observed for the mesogens with short terminal chain length, whereas smectic polymorphism was observed on increasing the terminal chain length. The results of a variable temperature powder X-ray diffraction of the representative sample support the smectic layer ordering.

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