In situ composites: effect of elongational flow velocity on thermotropic liquid crystalline co-polyester fibrillation in thermoplastic/TLCP systems

Thangamathesvaran, P. M.; Hu, Xiao; Tam, Kam Chiu; Yue, Chee Yoon

doi:10.1016/s0266-3538(00)00189-5

Cited by 15 publications

(11 citation statements)

References 8 publications

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“…The polymer with lower T m is used as matrix and is reinforced by fibrils of the other polymer with higher T m (dispersed phase), which are generated in situ during processing. Typically, thermoplastic liquid‐crystal polymers (TLCP) are used as the dispersion phase to prepare the MFCs and can strengthen the thermoplastic polymer (TP) because the rodlike TLCP molecules can be oriented, and the reinforcement is achieved in situ in the TP matrix . However, the TLCPs are restricted in general engineering applications because of their high price and high processing temperature, so researchers have focused on other polymers, especially engineering polymers like polyamide (PA), poly(ethylene terephthalate) (PET), and so on.…”

Section: Introductionmentioning

confidence: 99%

In situ fibrillation of poly(trimethylene terephthalate) in polyolefin elastomer through multistage stretching extrusion

Jian

Sun

et al. 2016

J of Applied Polymer Sci

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Polyolefin elastomer (POE)/poly(trimethylene terephthalate) (PTT) microfibrillar composites (MFCs) were successfully fabricated by multistage stretching extrusion with an assembly of laminating‐multiplying elements (LMEs). The morphologies of these novel materials were greatly influenced by the compositions. The number of microfibrils increased with increasing PTT concentration, as revealed by scanning electron microscopy. The tensile strength was the highest along the extrusion direction at the weight ratio of 85/15. Moreover, dynamic rheological results showed that the storage modulus, loss modulus, and complex viscosity were the highest while the tan δ was the lowest for MFCs prepared at the weight ratio 85/15 compared with the neat POE, especially at low frequency (ω < 1 rad/s). In addition, the PTT microfibrils had more effect on the rheological properties compared to the PTT particles. However, the differences became negligible at high frequency (ω > 100 rad/s). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43797.

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Section: Introductionmentioning

confidence: 99%

In situ fibrillation of poly(trimethylene terephthalate) in polyolefin elastomer through multistage stretching extrusion

Jian

Sun

et al. 2016

J of Applied Polymer Sci

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“…Therefore, blending LCPs with conventional polymers has attracted much attention over the last decade. [3][4][5][6][7][8][9][10][11][12][13][14] Recently, it was proved that the two-stage processing, which involves extrusion and injection moulding of LCP blends at the matrix processing temperature, i.e. below the melting temperature (T m ) of the LCP component in the blend, results in a much better product for overall performance than the product obtained from singlestage direct injection moulding.…”

Section: Introductionmentioning

confidence: 99%

“…In general, LCP fibrillation and hence the mechanical performance of the resultant product will be better with an increase in draw ratio. [10][11][12][13][14] However, the draw ratio depends on many factors like processing temperature, screw speed, die diameter, L/D ratio and material feedrate. In addition, most of the incompatible systems show a variation in extrudate diameter and hence a large variation in draw ratio.…”

Section: Introductionmentioning

confidence: 99%

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Manufacturing and characterisation of microfibrillar reinforced composites from liquid crystalline polymers and poly(phenylene ether)

Evstatiev¹,

Fakirov²,

Friedrich³

2004

Plastics, Rubber and Composites

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The purpose of the present study was to investigate the fibrillisation process of liquid crystalline polymers (LCPs) in an amorphous poly(phenylene ether) (PPE) matrix during melt blending and a subsequent drawing operation, as well as to analyse the relationship between morphology and mechanical properties of the fibrillar reinforced LCP/PPE blends. In order to understand the effect of the compatibility between the blend partners, an additional set of LCP/PEE blends, containing different amounts of a compatibiliser, was studied too. The processing steps included: (i) melt extrusion and continuous hot stretching for fibrillisation of the LCP component in the different LCP/ PPE blends, and (ii) compression (CM) or injection moulding (IM) of the drawn blends at temperatures below the melting temperature (T m ) of the LCPs. Samples from each processing stage were characterised by means of scanning electron microscopy (SEM), wide and small angle X-ray scattering (WAXS and SAXS), and mechanical testing. SEM and WAXS showed that the as extruded blends were isotropic, but after hot stretching the LCP components became highly oriented, with a high aspect ratio and a diameter of the fibrils between 0 . 4 and 3 mm. The fibrillated structure of the LCPs in the blends could be preserved after the compression and injection moulding only at temperatures below T m of the LCPs. Addition of a compatibiliser to the LCP/PPE blend did not remarkably improve the adhesion between the components, as a result of the large difference between the coefficients of thermal expansion of the blend partners, which leads to different shrinkage conditions of the LCP fibrils and the PPE matrix. The flexural modulus (E) of all IM blends increased stepwise with an increase in the weight (wt) fraction of the LCP. At the same time, the highest values for the flexural strength (s) were obtained for the LCP/PPE blends containing 5 wt-% LCP.

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“…One major shortcoming of this criterion is that it has no consideration for the effect of LCP concentration in the blend on fiber formation. Following Taylor's work on the breakup of a single Newtonian drop in a simple shear, researchers combined the capillary number (the ratio of viscous force to interfacial force) 8,9 C a ϭ ␥ m D 2…”

Section: Introductionmentioning

confidence: 99%

Energy‐based predictive criterion for LCP fibrillation in LCP/thermoplastic polymer blends under shear

Joshi

Lam

Yue

et al. 2003

J of Applied Polymer Sci

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This article relates the fibrillation of liquid crystalline polymer (LCP) under shear in its blend with a thermoplastic polymer (TP) to the relative rate of energy utilization in the LCP and TP phases. The development of a criterion based on the energy relationship for predicting LCP fibrillation in the blend is discussed. The formation of LCP fibers in the blends of LCP with polycarbonate (PC), polyethylene naphthalate (PEN), high-density polyethylene (HDPE), polypropylene (PP), and silica-filled polypropylene (PP) was studied to validate the criterion and to demonstrate its applicability. For all the blends, viscosity data were obtained by using a capillary rheometer, which was subsequently used to estimate the rate of energy utilization in the LCP and the matrix phases. The predictions based on the proposed criterion were verified through the morphological investigations carried out on the extrudates obtained from the same capillary experiments. The energy-based criterion was easy to implement, could account for the effect of variable LCP concentration and fillers in the blend, and could provide reliable predictions for a variety of LCP/TP blends.

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In situ composites: effect of elongational flow velocity on thermotropic liquid crystalline co-polyester fibrillation in thermoplastic/TLCP systems

Cited by 15 publications

References 8 publications

In situ fibrillation of poly(trimethylene terephthalate) in polyolefin elastomer through multistage stretching extrusion

In situ fibrillation of poly(trimethylene terephthalate) in polyolefin elastomer through multistage stretching extrusion

Manufacturing and characterisation of microfibrillar reinforced composites from liquid crystalline polymers and poly(phenylene ether)

Energy‐based predictive criterion for LCP fibrillation in LCP/thermoplastic polymer blends under shear

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