Engineering properties of compatibilized polypropylene/liquid crystalline polymer blends

Abstract

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.

Thermal degradation of polymer systems having liquid crystalline oligoester segment

“…The thermal behavior of liquid-crystalline polyesters (LCPs) has been subject of some papers due to their unique technological properties, such as low melting viscosity, self reinforcing mechanical properties, and high flame resistance [1][2][3][4] , which is verified by extensive char formation. The improvement of the mechanical properties of commodity and engineering thermoplastics upon addition of a small amount of liquid-crystalline polyester has been reported, even in the absence of miscibility in most of those systems [5,6] .…”

Morphology, mechanical, and rheological properties of poly(lactic acid)/ethylene acrylic acid copolymer blends processing via vane extruder

“…Ethylene acrylic acid copolymer (EAA) is commonly used as packing material, powder coat, adhesive, hot melt glue . In addition, EAA was proposed as compatibilizer for some binary immiscible blends, such as, polypropylene (PP)/thermotropic liquid crystalline polymer, low density polyethylene/polyamide 6, and poly(butylene terephthalate)/ethylene vinyl acetate copolymer blends . EAA was also blended with other polymers and fillers .…”

Misturas de poliestireno e poliéster líquido-cristalino.

“…Existe na literatura estudos sobre misturas de LCP com poliestireno (PS) [1][2][3]5,[30][31][32], polietileno (PE) [6,8], polipropileno (PP) [33][34][35][36], elastômero termoplástico poli(éter-ester) (TPEE) [37], poliamidas (PA) [9,[39][40][41][42], policarbonatos (PC) [10,[43][44][45][46], polieterimida (PEI) [41,47], polissulfona (PSU) [48][49][50], poli(tereftalato de etileno) (PET) e poli(tereftalato de butileno) (PBT) [51][52][53][54], polímero fluorado [55], poli(éter-éter-cetona) (PEEK) [50,56,57], poliimida (PI) [58] e copolímero de estireno e vinil fenol (PVPh) [59], e muitas pesquisas sobre materiais poliméricos estão focadas nesse assunto.…”

“…Os LCPs são conhecidos por formar fibras de reforço quando misturados com polímeros líquido-cristalinos [3,30,36,42,60]. No entanto, quando há imiscibilidade entre esses materiais as propriedades mecânicas desejadas não são alcançadas, de acordo com a lei das misturas [1], pois no caso de blendas poliméricas, as propriedades mecânicas estão fortemente relacionadas com a compatibilidade de seus componentes.…”

“…Diversos trabalhos [30,36,65,66] com blendas poliméricas apresentam estudos de morfologia através de microscopia eletrônica de varredura. Esse tipo de análise é muito útil para verificar a miscibilidade de blendas.…”