Influence of compatibilizer on notched impact strength and fractography of HDPE–organoclay composites

Polypropylene (PP)-based polymer nanocomposites containing organically modified montmorillonite (OMMT) with and without maleic anhydride grafted PP, were compounded by twin-screw extrusion. The extrusion process was repeated various numbers of times to increase the extruder residence time (T R ) and, through that, the particle dispersion. Rheological measurements fitted to a modified Carreau-Yasuda model defining a melt yield stress were used to indicate changes in the particle dispersion with regard to T R . This analysis showed a monotonically increased dispersion of clay particles in the PP matrix with increasing extruder T R . The small-strain tensile properties were tested at both ambient (20 C) and elevated (90 C) tem-peratures, and no significant changes were observed in the tensile strength or modulus as a function of T R . Instrumented Izod impact tests showed that the nanocomposite impact strength (r i ) increased monotonically with increased T R by 70% from least dispersed to best dispersed, which was still 20% below the level for neat PP. Both the fracture initiation energy and propagation energy increased with T R , but the primary effect on r i came from the fracture propagation energy, which delivered 80% of the improvement. V C 2012Wiley Periodicals, Inc. J Appl Polym Sci 126: 620-630, 2012

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of multiple extrusions on the impact properties of polypropylene/clay nanocomposites

Klitkou

Jensen

Christiansen

2012

“…This point has been clearly illustrated in nylon systems, which are polar materials, and as a result, the clay is fully exfoliated 10–12. For nonpolar polyolefins such as PE, the level of improvement is much less and varies depending on the degree of dispersion 13–17. For this nonpolar system, it is difficult to disperse the organomodified clay homogeneously to the same level as can be obtained in the nylon system, so generally a modified polar polyolefin is used as a compatibilizer.…”

Section: Introductionmentioning

confidence: 99%

“…However, the literature on bulk PE–clay systems is rather inconsistent with regard to the mechanical properties and morphology for both high‐density13–17 and low‐density18–23 systems. There are reports of systems with improved elastic modulus and yield strength values13–17, 20–22 and also with lower tensile properties 18, 19, 23. All of this suggested that it was imperative to look at different PE materials and compatibilizer systems to obtain more insight into the relationship between the composite structure and mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Polyethylene composite fibers. I. Composite fibers of high‐density polyethylene

Rattanawijan

Amornsakchai

2011

Self Cite

Polymer matrix composites are generally studied in the form of bulk solids, and very few works have examined composite fibers. The research described here extended such bulk studies to fibers. The question is whether or not what has been reported for bulk polymers will be the same in fibers. In this article are reported studies of high-density polyethylene (HDPE), whereas those of linear low-density polyethylene are reported in part II of this article series. Two types of filler were used, that is, organically modified montmorillonite (OMMT), in which the nanosized filler particles had a high aspect ratio, and microsized calcium carbonate (CaCO 3 ), with an aspect ratio nearer to unity. Composite fibers of both as-spun and highly drawn forms were prepared, and their structures, morphology, and mechanical properties were studied. It was found that the microsized particles gave HDPE composite fibers with mechanical properties that were the same as those of the neat polymer. In the case of clay composite fibers, the clay interfered with the yield process, and the usual yield point could not be observed. The particle shape did not affect the mechanical properties. The fibers showed different deformation morphologies at low draw ratios. The CaCO 3 composite fibers showed cavities, which were indicative of low interaction between the polymer and the filler. The OMMT composite fibers showed platelets aligned along the fibers and good polymer-filler interaction.

Toughness of HDPE/CaCO₃ microcomposites prepared from masterbatch by melt blend method

Ali

Elleithy

2011

In this study, a series of high-density polyethylene and micro/nanocalcium carbonate polymer composites (HDPE/CaCO 3 nanocomposites) were prepared via melt blend technique using a twin screw extruder. Nanocomposite samples were prepared via injection molding for further testing. The effect of % loading of CaCO 3 on mechanical and fracture toughness of these composites has been investigated in details. The effect of precrack length variation on the fracture toughness of the composite samples was evaluated, and the morphology of the fractured samples was also observed using scanning electron microscopy (SEM). It was found that increasing the % of CaCO 3 and precrack length decreased the fracture toughness. Fracture surface examination by SEM indicated that the diminished fracture properties in the composites were caused by the aglomerization of CaCO 3 particles which acted as stress concentrators. A finite element analysis using ANSYS was also carried out to understand the effect of agglomeration size, interaction between the particles and crack tip length on the fracture properties of these composites. Finally, a schematic presentation of the envisioned fracture processes was proposed.