Fibres from polypropylene and liquid crystal polymer blends using compatibilizing agents: 3. Assessment of graft side chain liquid crystalline compatibilizers based upon acrylic acid-functionalized polypropylene

An immiscible blend of poly(propylene) (PP) with a thermotropic liquid-crystalline polymer (TLCP, trade name Rodrun LC5000), a copolyester of 80/20 mol ratio of p-hydroxy benzoic acid and polyethylene terephthalate was prepared in a twin-screw extruder. The blend extrudate was fabricated as monofilament by using a single-screw extruder equipped with a fiber line. The as-spun filament was drawn at 120°C to enhance molecular orientation. Morphology, thermal, tensile, and dynamic mechanical properties of both as-spun and drawn monofilaments were investigated. Almost continuously long TLCP fibers dispersed in PP matrix were obtained in the composite as-spun monofilaments. The maximum modulus was found in 15 wt % TLCP/PP composite as-spun filament, an increase of about 2.4 times that of the as-spun neat PP. For the drawn filaments, the 10 wt % TLCP/PP composite showed a maximum modulus, an increase of about 1.5 times that of the drawn neat PP. The increase in the moduli was attributed not only to the reinforcement by TLCP fibrils with very high aspect ratio but also to the increases in PP crystallinity and molecular orientation through the drawing process. A remarkable improvement in the dynamic mechanical properties of the composite monofilaments was observed, especially in the high-temperature region.

Section: Tensile Propertiesmentioning

confidence: 90%

Section: Tensile Propertiesmentioning

confidence: 99%

Section: Tensile Propertiesmentioning

confidence: 99%

See 1 more Smart Citation

In situ modulus enhancement of polypropylene monofilament through blending with a liquid‐crystalline copolyester

Sukananta

Bualek-Limcharoen

2003

“…For this reason, compatibilization by different methods is often used to improve the interfacial interactions, mostly using ethylene copolymers with acrylic. [18][19][20][21][22] Analogous compatibilizer was used in this work.…”

Section: Introductionmentioning

confidence: 99%

Molecular orientation of extruded PET/LCP blend films. II. X‐ray pole figures

Branciforti

Silva

Machado

et al. 2007

ABSTRACT:The crystalline uniaxial molecular orientation of two liquid crystalline polymers (LCPs), Vectra 1 A950, and Rodrun 1 LC5000, blended with poly(ethylene terephthalate) (PET) was obtained from wide angle X-ray pole figures. The blends films were produced by extrusion using a twin screw extruder with a slit die. The molecular orientation was evaluated along the transverse section of the films and as a function of the blends composition. The influence of a compatibilizer agent on the LCPs orientation was also analyzed. It was found that the orientation of both LCPs in the pure LCP films was high, highest in the draw direction but variable along the transverse section of the extruded films; in this last case, it was higher at the position where the shear rate was maximum. However, a drastic orientation decrease in both LCP's phases was observed in the films made of PET/LCPs blends. The maximum orientation effects were observed for the blend with 5 wt % of LCP content and also at the position where the shear rate was the highest. The Vectra 1 A950 LCP, as a pure material and in the blend with PET, orient more effectively than the Rodrun 1 LC5000 LCP in the films produced at the same processing conditions. The results showed that the use of a compatibilizer agent decreased the LCP orientation and were in accordance with previous studies using polarized infrared spectroscopy.

“…The addition of compatibilizers that promote a decrease of the interfacial tension between the matrix and the dispersed phase, and a better dispersion of the LCP in the matrix, is a strategy to partially overcome this problem. [5][6][7]12,15,16,18,19,24 The compatibilization is usually achieved by physical or chemical interactions between the components of the blend and the compatibilizer, which are performed by adding small amounts of functionalized graft or block copolymers to the LCP/thermoplastic blends. [5][6][7]15,16 In principle, the degree of adhesion can be improved by using compatibilizers with chemical structures consisting of segments similar to those of the LCP and the thermoplastic blends, which will migrate to the interface, and thus, reduce the interfacial tension between the two components.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of compatibilizers and characterization of the compatibilized and noncompatibilized blends of PP/Rodrun LC3000

Cidade

Filipe

Duarte

et al. 2007

The addition of a liquid crystalline polymer (LCP) to a matrix of a flexible thermoplastic (TP) has been used in the last two decades as an in situ reinforcement of the matrix. Owing to the immiscibility of the two phases and the high degree of orientation typical of LCPs, the dispersed phase is, after processing, essentially constituted by fibrillar structures, which are responsible for the reinforcement of the matrix and the decrease of viscosity with respect to the matrix. The low degree of adhesion typical of LCP/TP blends often requires the use of compatibilizers, which will act reducing the interfacial tension between the two components. In this work, we present the synthesis of three different compatibilizers, as well as the mechanical characterization of the corresponding compatibilized blends. Some scanning electron microphotographs will be also presented to better explain the mechanical results. The mechanical properties of these blends were compared with the noncompatibilized blend, as well as with the ones presented by blends obtained with two commercial compatibilizers, leading to the conclusion that, considering our compatibilizer C, the one that leads to the higher enhancement of the Young's modulus, when compared with the noncompatibilized blend, we obtain a Young's modulus 27% higher than the one presented by the noncompatibilized blend. Comparing this result with those presented by the blends compatibilized with the two commercial compatibilizers, D and E, we conclude that this enhancement is higher than those presented by those blends (increase in Young's modulus of 16% for both compatibilizers).