Influence of processing conditions on the morphological and mechanical properties of compatibilized PP/LCP blends

Polypropylene was melt blended in a single screw extruder with thermo tropic Vectra B-950 liquid crystalline polymer (copolyester amide) in different proportions in presence of 2% of EAA ,ethylene-acrylic acid copolymer (based on PP) as a compatibilizer. The mechanical properties of such compatibilized blends were evaluated and compared in respect of their Young's Modulii, Ultimate tensile strength, percent elongation at break, and toughness to those of Pure PP. The Morphology was studied by using a polarizing light microscope (PLM) and Scanning electron microscope (SEM). The Thermal characterization of these blends were carried out by differential scanning calorimeter (DSC).The mechanical properties under dynamic conditions of such compatibilized blends and pure PP were studied by dynamic mechanical analyzer (DMA). Mechanical analysis (Tensile properties) of the compatibilized blends displayed improvements in Modulii and ultimate tensile strength (UTS) of PP matrix with the incorporation of 2-10% of LCP incorporation. The development of fine fibrillar morphology in the compatibilized PP/LCP blends had large influence on the mechanical properties. Differential scanning calorimeter (DSC) studies indicated no remarkable changes in the crystalline melting temperature of the blends with respect to that of pure PP. However, an increase in the softening range of the blends over that of PP was observed.

Section: Morphologymentioning

confidence: 54%

Section: Scanning Electron Microscopementioning

confidence: 94%

Studies on morphology, mechanical, thermal, and dynamic mechanical behavior of extrusion blended polypropylene and thermotropic liquid crystalline polymer in presence of compatibilizer

Mandal

Chakraborty

2008

“…The increase of the Young's modulus of our blend with compatibilizer C is also higher than the ones obtained in the past by other researchers with different compatibilizers. 18,30 We must point out, however, that the Young's modulus of blends compatibilized with 4 wt % of compatibilizer E (which is the optimum content of this compatibilizer for our blend, contrary to what happens to the optimum content of compatibilizer C, which is 2 wt %, as we have proved in another work 27 ) becomes slightly higher than the Young modulus of the blend with 2 wt % of compatibilizer C.…”

Section: Discussionmentioning

confidence: 69%

“…In earlier studies, 27,29 we have performed the optimization of the compatibilizer contents for compatibilizers C and E, those that presented (with a 2 wt % compatibilizer content) better mechanical properties. From this study, we concluded that the optimum compatibilizer content for compatibilizers C and E were 2 and 4 wt %, respectively.…”

Section: Mechanical Characterizationmentioning

confidence: 99%

“…One problem concerning this method is that, to avoid phase separation, homopolymers have to be short, crystallizable, and with an appropriate polydispersity, which turned impossible to use this method for our blends, since the synthesis of compatibilizers was just a continuation of a work that we had already started 20,26,27 and our matrix, as will be described in the Material section, was a isotatic polypropylene with a weight-average molecular weight (M w ) of 1200,000 g/mol.…”

Section: Introductionmentioning

confidence: 99%

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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).

Engineering properties of compatibilized polypropylene/liquid crystalline polymer blends

Mandal

Siddhanta²,

Chakraborty

2011

Polypropylene (PP) and Vectra A950, a thermotropic liquid crystalline polymer (LCP), blends were prepared in a single-screw extruder with the variation in Vectra A950 content in presence of fixed amount (2%, with respect to PP and LCP mixture as a whole) of ethylene-acrylic acid (EAA) copolymer as a compatibilizer. Mechanical analysis of the compatibilized blends within the range of LCP incorporations under study (2-10%) indicated pronounced improvement in the moduli, ultimate tensile strength (UTS), and hardness. Fourier transform infrared (FTIR) spectroscopy studies revealed the presence of strong interaction through H-bonding between the segments of Vectra A950 and the compatibilizer EAA. Morphological studies performed by scanning electron microscopy (SEM) manifested the development of fine fibrillar morphology in the compatibilized PP/ Vectra A950 blends, which had large influence on the mechanical properties. Differential scanning calorimetry studies showed an initial drop of the melting point of PP in the presence of EAA followed by enhancement of the same in presence of Vectra A950. TGA showed an increase in the thermal stability for all blends with respect to matrix polymer PP. Rheological studies showed that a very small quantity of Vectra A 950 was capable of reducing the melt viscosity of PP particularly in the lower shear rate region and hence facilitated processibility of the blends.