Effect of compatibilizers on mechanical properties and morphology of in‐situ composite film of thermotropic liquid crystalline polymer/polypropylene

Abstract

An in-situ composite f i l m of a thermotropic liquid crystalline polymer (LC3000)/ polypropylene (TLCP/PP) was produced using the extrusion cast f i l m technique.The compatibiljzing effect of thermoplastic elastomers, styrene-ethylene butylenestyrene (SEBS), maleic anhydride grafted SEBS (MA-SEBS). and maleic anhydride grafted polypropylene (MA-PP) on the mechanical properties and morphology of the TLCP/PP composite films was investigated. It was found that SEBS provided a higher value of tensile modulus than MA-SEBS, which in turn was higher than MA-PP, despite the expected stronger interaction between the MA chain and TLCP. The observation of the morphology under optical and scanning electron microscopes suggested that all three compatibilizers helped improve the dispersion of the TLCP fibers and increased the fiber aspect ratio to a different extent. The fractured surface of the specimens showed more fiber breakage than pull-out when a compatibih e r was added, which suggested the improvement of interfacial adhesion. The surface roughness of fibers with an added elastomeric compatibilizer may also provide mechanical interloclang at the interface. It is suggested that the increase in the viscosity ratio of TLCP/PP due to the added elastomeric compatibilizer, SEBS and MA-SEBS, compared with the thermoplastic compatibilizer, MA-PP, is more effective in improving the composite mechanical properties.

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

“…7(a)]. Although the increase in the Young's modulus obtained by the addition of compatibilizers A, B, and C are from the same order of those obtained in the past by other researchers, with different compatibilizers, 18,30 as can be seen in Table I, we should point out that the mechanical improvement (in what concerns the Young's modulus) of the blend with compatibilizer C can, under appropriate processing conditions, be increased from 27 to 38%, with respect to the noncompatibilized blend. 29 In fact, the application of a lower screw speed, 100 rpm, revealed to be beneficial for the fibrillation process, giving rise to blends with a higher Young's modulus, than those obtained for a screw speed of 150 rpm.…”

“…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.…”

“…4,18,22 A novel strategy has appeared recently, 25 in which the blends are prepared in such a way that a finely dispersed cocontinuous morphology is obtained for the blend. This is possible through reactive blending between the component with higher content, to which reactive groups along the backbone were added, and the component with lower content which presents end reactive chains.…”

“…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.…”

Melting behavior, nonisothermal crystallization kinetics, and morphology of PP/nylon 11/EPDM‐g‐MAH blends

“…Therefore, toughening of PP has still attracted numerous research interests. Compounding PP with elastomers [ethylene-propylenediene rubber (EPDM)], [1][2][3][4] ethylene-propylene rubber (EPR), [5][6][7] styrene-ethylene-butylene-styrene (SEBS), [8][9][10][11][12][13][14][15][16] etc), rigid polymer (PA6, [17][18][19][20][21][22][23][24][25] PA66, [26][27][28] LCP, 29 etc), and rigid particles (CaCO 3 , [30][31][32] SiO 2 33,34 ) were the three traditional approaches to improve the toughness of PP. However, the addition of elastomers often has negative effects on some properties of PP, such as the stiffness and hardness.…”