Liquid crystalline polymer/polyamide 66 (LCP/PA66) and LCP/poly(butyl terephthalate) (LCP/PBT) blends were compounded using
a Brabender Plasticorder equipped with a mixing chamber. The LCP employed was a semi-flexible liquid crystalline copolyesteramide
based on 30 mol% of p-amino benzoic acid (ABA) and 70 mol% of poly(ethylene terephthalate) (PET). The Flory-Huggins interaction parameters (χ12)
of the LCP/ PA66 and LCP/PBT blends are estimated by melting point depression from DSC measurement. The results indicate that
c12 values all are negative for LCP/PA66 and LCP/PBT blends, and when the LCP content in these blends is more than 10 mass%,
the absolute value of χ12 decreases. Thereby, we can conclude that LCP/PA66 and LCP/PBT blends are fully miscible in the molten state, the molecular
interaction between the LCP and PA66 is stronger than that between LCP and PBT. As the LCP content in LCP/PA66 and LCP/PBT
blends is more than 10 mass%, the molecular interaction between LCP and matrix polymer decreases.
Vectra® liquid crystalline polymers (LCP's) were introduced as commercial products in the mid-1980's. The first of these (Vectra
A130) was a wholly aromatic thermotropic copolyester ofp-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. Vectra A130 is a thermotropic LCP that can be melt spun into filaments
that on heat treatment are characterized by high strength and high modulus. Vectra resin can also be extruded into films.
In the fiber or film form this material is commercially known as Vectran®. Heat treatment enhances the tensile strength of Vectran fiber variants. Because of this, the elucidation of the physical
transformations taking place in the internal structure of the material during heating has always been an important subject.
Several thermal techniques are used to indicate clearly that what is observed as a “glass transition” is unlike the conventional
glass transition in typical semicrystalline polymers. There is also an indication of the presence of multiple states of mesophase
aggregation that collapse into a single state when taken to high enough temperatures.
The first experimental evidence of the existence of the rigid amorphous phase was reported by Menczel and Wunderlich :
when trying to clarify the glass transition characteristics of the first main chain liquid crystalline polymers [poly(ethylene
terephthalate-co-p-oxybenzoate) with 60 and 80 mol% ethylene terephthalate units] , the absence of the hysteresis peak at the lower temperature
glass transition became evident when the sample of this copolymer was heated much faster than it had previously been cooled.
Since this glass transition involved the ethylene terephthalate-rich segments of the copolymer, we searched for the source
of the absence of the hysteresis peak in PET. There, the gradual disappearance of the hysteresis peak with increasing crystallinity
was confirmed . At the same time it was noted that the higher crystallinity samples showed a much smaller ΔCp than could be expected on the basis of the crystallinity calculated from the heat of fusion (provided that the crystallinity
concept works). Later it was confirmed that the hysteresis peak is also missing at the glass transition of nematic glasses
When checking other semicrystalline polymers, the sum of the amorphous content calculated from the ΔCp at the glass transition, and the crystallinity calculated from the heat of fusion was far from 100% for a number of semicrystalline
polymers. For most of these polymers, the sum of the amorphous content and the crystalline fraction was 0.7, meaning that
ca. 30% rigid amorphous fraction was present in these samples after a cooling at 0.5 K min−1 rate. Thus, the presence of the rigid amorphous phase was confirmed in five semicrystalline polymers: PET, Nylon 6, PVF,
Nylon 66 and polycaprolactone . Somewhat later poly(butylene terephthalate) and bisphenol-A polycarbonate  were added
to this list.
In this paper we also report details on a special effect of the rigid amorphous phase (RAP) on the mobile amorphous phase
(MAP): the hysteresis peak at the glass transition of the MAF disappears under the influence of the RAP, and this raises the
question whether the glass transition of the MAF becomes time independent in semicrystalline polymers.
Authors:Zoltán Budai, Zsolt Sulyok, and Viktória Vargha
selecting the matrix resin, the reinforcing material and their ratio, during which the interphasial interactions play the essential role. A new and exciting field of research represent the composites based on liquidcrystallinepolymers or reinforcements
Authors:Ting Hu, Huanling Kong, Lie Chen, Yiwang Chen, Fan Li, and Daijun Zha
, W , Wendorff , JH , Hopmeier , M , Feldmann , J . Polarized photoluminescence of liquidcrystallinepolymers with isolated arylenevinylene segments in the main chain . Adv Mater . 1995 ; 7 : 923 – 925 . 10.1002/adma.19950071112
electrical and luminescence behaviors of polyacetylenes can be greatly tuned by changing their molecular structures. Generally, the mono- and disubstituted type exert great on the properties of liquidcrystallinepolymers, such as polynorbornene derivatives