Evaluating the Performance of a Semiaromatic/Aliphatic Polyamide Blend: The Case for Polyphthalamide (PPA) and Polyamide 4,10 (PA410)

This paper studies the structure–property–processing relationship of polyphthalamide (PPA) PPA/polyamide 4,10 (PA410) blends, via co-relating their thermal-mechanical properties with their morphology, crystallization, and viscoelastic properties. When compared to neat PPA, the blends show improved processability with a lower processing temperature (20 °C lower than neat PPA) along with a higher modulus/strength and heat deflection temperature (HDT). The maximum tensile modulus is that of the 25PPA/75PA410 blend, ~3 GPa, 25% higher than neat PPA (~2.4 GPa). 25PPA/75PA410 also exhibits the highest HDT (136 °C) among all the blends, being 11% more than PPA (122 °C). The increase in the thermo-mechanical properties of the blends is explained by the partial miscibility between the two polymers. The blends improve the processing performance of PPA and broaden its applicability.

Reaction Mechanism and Mechanical Property Improvement of Poly(Lactic Acid) Reactive Blending with Epoxy Resin

Polylactic acid (PLA) was melt-blended with epoxy resin to study the effects of the reaction on the mechanical and thermal properties of the PLA. The addition of 0.5% (wt/wt) epoxy to PLA increased the maximum tensile strength of PLA (57.5 MPa) to 67 MPa, whereas the 20% epoxy improved the elongation at break to 12%, due to crosslinking caused by the epoxy reaction. The morphology of the PLA/epoxy blends showed epoxy nanoparticle dispersion in the PLA matrix that presented a smooth fracture surface with a high epoxy content. The glass transition temperature of PLA decreased with an increasing epoxy content owing to the partial miscibility between PLA and the epoxy resin. The Vicat softening temperature of the PLA was 59 °C and increased to 64.6 °C for 0.5% epoxy. NMR confirmed the reaction between the -COOH groups of PLA and the epoxy groups of the epoxy resin. This reaction, and partial miscibility of the PLA/epoxy blend, improved the interfacial crosslinking, morphology, thermal properties, and mechanical properties of the blends.

Quantitative insights into the phase behaviour and miscibility of a photovoltaic active layer from the perspective of neutron spectroscopy

We present a neutron spectroscopy based method to study quantitatively the partial miscibility and phase behaviour of photovoltaic active layer made of conjugated polymer:small molecule blends, presently illustrated with the...

Isothermal Crystallization Kinetics and Morphology of Double Crystalline PCL/PBS Blends Mixed with a Polycarbonate/MWCNTs Masterbatch

In this work, the 70/30 and 30/70 w/w polycaprolactone (PCL)/polybutylene succinate (PBS) blends and their corresponding PCL/PBS/(polycarbonate (PC)/multiwalled carbon nanotubes (MWCNTs) masterbatch) nanocomposites were prepared in a twin-screw extruder. The nanocomposites contained 1.0 and 4.0 wt% MWCNTs. The blends showed a sea-island morphology typical of immiscible blends. For the nanocomposites, three phases were formed: (i) The matrix (either PCL- or PBS-rich phase depending on the composition), (ii) dispersed polymer droplets of small size (either PCL- or PBS-rich phase depending on the composition), and (iii) dispersed aggregates of tens of micron sizes identified as PC/MWCNTs masterbatch. Atomic force microscopy (AFM) results showed that although most MWCNTs were located in the PC dispersed phase, some of them migrated to the polymer matrix. This is due to the partial miscibility and intimate contact at the interfaces between blend components. Non-isothermal differential scanning calorimetry (DSC) scans for the PCL/PBS blends showed an increase in the crystallization temperature (Tc) of the PCL-rich phase indicating a nucleation effect caused by the PBS-rich phase. For the nanocomposites, there was a decrease in Tc values. This was attributed to a competition between two effects: (1) The partial miscibility of the PC-rich and the PCL-rich and PBS-rich phases, and (2) the nucleation effect of the MWCNTs. The decrease in Tc values indicated that miscibility was the dominating effect. Isothermal crystallization results showed that the nanocomposites crystallized slower than the neat blends and the homopolymers. The introduction of the masterbatch generally increased the thermal conductivity of the blend nanocomposites and affected the mechanical properties.

Development of partial miscibility in polycarbonate/polypropylene blends via annealing

The morphology, dynamic mechanical properties and infrared spectra of polycarbonate (PC)/polypropylene (PP) blends were investigated. As expected, PC and PP were immiscible when blended together; however partial miscibility developed following annealing. The miscibility of one polymer in the other was examined using the modified Fox equation and the values of the Flory-Huggins polymer-polymer interaction parameter (χ12) were also calculated following the Kim and Burns approach. Moreover, the possible causes for partial miscibility in the annealed PC/PP blends were explored by infrared spectroscopy. It was concluded that annealing caused degradation of PP, leading to the formation of polar groups which were then able to interact with PC generating regions of partial miscibility.