Solid-state morphology of aromatic-aliphatic polyester crystallized from smectic liquid crystal

Takahashi, T.; Nagata, Fumio

doi:10.1080/00222348908215229

Cited by 11 publications

(6 citation statements)

References 11 publications

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“…In other words the scheme of Figure B agrees with all experimental data available in this work. In this connection it should be mentioned that several research groups have discussed and demonstrated − that LC-main chain polyesters containing aliphatic spacers may form folded chain crystals with “loops” of the aliphatic spacers on the long surfaces of the lamellae. Larger loops containing even mesogenic units have also been postulated …”

Section: Resultsmentioning

confidence: 99%

Layer Structures. 5. Influence of the Spacer Length on the Smectic Phases of Poly(ester imide)s Derived from α,ω-Alkane Bis(trimellitimides) and 4,4‘-Dihydroxybiphenyl

Kricheldorf¹,

Linzer²,

Leland³

et al. 1997

Macromolecules

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A series of homopoly(ester imide)s, PEIs, was prepared by polycondensation of 4,4‘-bis(acetoxybiphenyl) with the bis(trimellitimides) of α,ω-diaminoalkanes with 6−12 CH2 groups. Furthermore, a series of copoly(ester imide)s was prepared from equimolar mixtures of 1,12-diaminodocedane bis(trimellitimide) and the bis(trimellitimides) of shorter α,ω-diaminoalkanes. As indicated by well-developed bâttonet textures all homopolyesters form a smectic-A phase before the isotropization. However, wide angle X-ray scattering measurements with synchrotron radiation up to 400 °C suggest that all PEIs also form a smectic-C phase above the melting temperature (T m). The homopolyesters with an even number of CH2 groups have mesogens in upright position in the solid state (smectic-E), whereas the mesogens of the homo PEIs with odd-numbered spacers are tilted relative to the layer plane. WAXS fiber patterns demonstrate that in oriented samples the chain axes may adopt a parallel or perpendicular orientation relative to the draw direction. Also most coPEIs form a smectic-A phase in the melt, but when the difference of the spacer lengths increases (e.q. 6+12 and 5+12 CH2 groups), the layer structure is destabilized and a nematic melt is formed. A fiber drawn from the nematic melt of PEI 6+12 (2g) shows the chain axis parallel to fiber axis, whereas in the case of PEI 5+12 (2h) the chain axis is perpendicular to the fiber axis.

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Section: Resultsmentioning

confidence: 99%

Layer Structures. 5. Influence of the Spacer Length on the Smectic Phases of Poly(ester imide)s Derived from α,ω-Alkane Bis(trimellitimides) and 4,4‘-Dihydroxybiphenyl

Kricheldorf¹,

Linzer²,

Leland³

et al. 1997

Macromolecules

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“…Our results suggest the existence of the chain-folded lamellae. The first implication was constructed from the fact that small-angle X-ray scattering (SAXS) maxima attributed to the stacked chain folded lamellae are well observed in the BB- n polyesters crystallized from smectic melt. − The scattering spots appear along the smectic layer normal, and their spacing is in the range of 220−300 Å, which corresponds to a length of 12−16 repeating units. It is interesting to note that the spacing decreases with an increase in crystallization temperature.…”

Section: Introductionmentioning

confidence: 99%

Two Distinct Types of Orientation Process Observed in Uniaxially Elongated Smectic LC Melt

et al. 2005

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We examine the tensile deformation of the smectic melt of a main-chain liquid crystalline polymer. A film molded in isotropic melt is heated to a smectic temperature of 60 °C and then stretched at selected strain rates. In the initial stage of strain below 100% (defined as {(l − l 0)/l 0} × 100%), smectic layers align parallel to the stretching direction; i.e., polymer chains orient perpendicularly (so-called “perpendicular orientation”). This perpendicular orientation in the low-strain region is invariably observed at any strain rate. Upon succeeding elongation, however, two distinct types of orientation process are observed depending on the strain rate. On elongation at strain rates as low as 5%/min, the perpendicular orientation is improved until the sample breaks at 400% strain (process A). At a high strain rate of 100%/min, in contrast, the perpendicular orientation initially observed is eventually altered to the “parallel orientation” with polymer chains lying parallel to the tensile axis (process B). In this case, the well-known necking takes place, and the sample breaks at an extremely large strain more than 3000%. These two distinct elongation processes are also dependent on temperature; processes A and B are observed in higher and lower temperature regions, respectively. On the basis of these data, the molecular orientation mechanisms in smectic field are discussed by coupling together the nature of smectic liquid crystal and dynamics of polymer chains.

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“…Later on, Williams and Walter proved theoretically the formation of hairpin defects in semiflexible polymers . Comprehensive morphological studies of PBs strongly suggested the presence of chain fold domains in the smectic phase. − Tokita et al supported this assumption on the base of the observed orientation of macromolecules in shear flow of PBs, perpendicular to the shear direction. − However, no scattering maximum has been detected in the small-angle X-ray scattering (SAXS) pattern of P6MB quenched from the melt. , This result has been attributed to the disordered stacking of the layer structure. It has been found that the macromolecular orientation in S shear flow of PBs is perpendicular to the shear direction, confirming the lamellar structure of the S phase with defined phase boundaries. − They supposed that the SAXS reflections, observed after crystallization of P6MB, result from the chain folding that may have already existed in the S phase.…”

Section: Introductionmentioning

confidence: 99%

Structure and Phase Transitions of Poly(heptamethylene p,p‘-bibenzoate) As Studied by DSC and Real-Time SAXS/MAXS Employing Synchrotron Radiation

et al. 2003

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The structure and phase transitions of liquid-crystalline poly(heptamethylene p,p ‘-bibenzoate) have been studied by DSC and variable-temperature real-time SAXS/MAXS employing synchrotron radiation. It was suggested that three-dimensional crystal order appeared within the smectic domains during cooling the sample because the crystal correlation length is nearly the same as that of the smectic domains. These estimated domain sizes are of the order of the average macromolecular chain length, so that it seems that no chain folding exists in the present case. It was found that SAXS intensity in Porod's region obeys the power law, and it deviates significantly from Porod's law. These deviations were explained by an assumption of anisotropic density fluctuations within the phases. It was supposed that the melting process is ruled by an increasing quantity of anisotropic fluctuations within the crystallites but not by surface melting.

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Solid-state morphology of aromatic-aliphatic polyester crystallized from smectic liquid crystal

Cited by 11 publications

References 11 publications

Layer Structures. 5. Influence of the Spacer Length on the Smectic Phases of Poly(ester imide)s Derived from α,ω-Alkane Bis(trimellitimides) and 4,4‘-Dihydroxybiphenyl

Layer Structures. 5. Influence of the Spacer Length on the Smectic Phases of Poly(ester imide)s Derived from α,ω-Alkane Bis(trimellitimides) and 4,4‘-Dihydroxybiphenyl

Two Distinct Types of Orientation Process Observed in Uniaxially Elongated Smectic LC Melt

Structure and Phase Transitions of Poly(heptamethylene p,p‘-bibenzoate) As Studied by DSC and Real-Time SAXS/MAXS Employing Synchrotron Radiation

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