Evolution of the Microstructure of PP-LDHs Nanocomposites during Melt Compounding: A Simulation Approach

In the context of polymer-based nanocomposites containing layered nanofillers, the achievement of good extents of dispersion and distribution of the embedded nanoparticles and, even more, the obtainment of intercalated and/or exfoliated structures through melt compounding still represents a persistent challenge, especially in the case of anionic layered double hydroxides (LDHs)-containing systems and non-polar polymeric matrices. In this work, a simulation approach is proposed to evaluate the influence of the processing conditions on the morphology of polypropylene (PP)-based nanocomposites containing organomodified LDHs. In particular, the effect of the screw rotation speed and the feed rate on the final microstructure of the materials formulated through melt compounding in a twin-screw extruder was assessed. The rheological and morphological characterizations demonstrated that a more homogeneous morphology was achieved when high levels of both exploited processing parameters are selected. The results coming from the simulation of the processing were used to establish some relationships between the flow parameters and the microstructure of the nanocomposites, demonstrating that low residence times coupled with high local shear rates are required to ensure the achievement of homogenous morphologies, likely involving the occurrence of intercalation phenomena.

Modeling the yield strength of polymer nanocomposites based upon nanoparticle agglomeration and polymer-filler interphase

In this paper, some models for yield strength of polymer nanocomposites are developed to determine the properties of interphase and agglomerated nanoparticles. In this regard, "Bagg" parameter is defined assuming the agglomerates size (Dagg) and interphase properties. Additionally, the influences of "Bagg" and "Dagg" on the thickness and strength of interphase are evaluated by the developed equations. The agglomeration of nanoparticles causes contradictory effects on interphase properties in samples with different levels of interfacial bonding. Also, "Bagg" more depends to interphase properties compared to "Dagg". It is found that upon increasing in "Bagg" and "Dagg", the strength of interphase improves and reaches the most level at the highest values of "Bagg" and "Dagg". Therefore, controlling the levels of "Bagg" and "Dagg" is crucial to obtain a strong interphase.

Morphology-dependent performance of Mg3Al–CO3layered double hydroxide as a nanofiller for polypropylene nanocomposites

In this contribution, the morphology-dependent performance of Mg₃Al–CO₃layered double hydroxide (LDH) as a nanofiller for polypropylene (PP) was evaluated for the first time.