Isothermal crystallization kinetics of polypropylene latex-based nanocomposites with organo-modified clay

Rapid Crystallization and Fluorescence of Poly(ethylene terephthalate) Using Graphene Quantum Dots as Nucleating Agents

In this study, graphene quantum dots (GQDs) with a diameter of ~3 nm were successfully synthesized and incorporated into a poly(ethylene terephthalate) (PET) matrix to fabricate PET/GQDs nanocomposites. The impact of GQDs on the crystallization and thermal stability of the PET/GQDs nanocomposites was investigated. It was observed that the addition of only 0.5 wt% GQDs into the nanocomposites resulted in a significant increase in the crystallization temperature (peak temperature) of PET, from 194.3 °C to 206.0 °C during the cooling scan process. This suggested that an optimal concentration of GQDs could function as a nucleating agent and effectively enhance the crystallization temperature of PET. The isothermal crystallization method was employed to analyze the crystallization kinetics of the PET/GQDs nanocomposites, and the data showed that 0.5 wt% GQDs significantly accelerated the crystallization rate. Furthermore, the incorporation of GQDs into the PET matrix imparted photoluminescent properties to the resulting PET/GQDs nanocomposites. The PET crystals with GQDs as crystal nuclei and the crazes caused by defects played a vital role in isolating and suppressing the concentration quenching of GQDs. This effect facilitated the detection of defects in PET.

Characterization of sustainable polyhydroxyls, produced from bio-based feedstock, and polyurethane and copolymer urethane-amide foams

This manuscript presents data related to the research article entitled "Synthesis and characterization of sustainable polyurethane foams based on polyhydroxyls with different terminal groups" (DOI: 10.1016/j.polymer.2018.06.077) [1]. We provide Supplementary data on the chemical properties, in terms of FTIR characterization, of polyhydroxyls produced starting from bio-based feedstock (biosuccinic acid and 1,4 butandiol) and thermal properties (glass transition temperature-Tg and thermal degradation behavior) of polyurethane and copolymer urethane-amide foams manufactured from the aforementioned polyhydroxyls. The FTIR characterization elucidates the chemical structure of polyhydroxyls and allows to make some hypothesis on their reaction routes with the isocyanate molecules. The thermal characterization revealed that the addition of bio-based polyhydroxyls to the sample formulations improves both the glass transition and degradation temperature of the foams. These foamed products exhibit potential performances to be applied as a substitute for conventional polyurethane foams.

Crystallization Kinetics for PP/EPDM/Nano-CaCO3 Composites – The Influence of Nanoparticles Distribution

The primary aim of this paper is to provide an insight on the effect of the distribution of calcium carbonate nanoparticles (nano-CaCO3) on the isothermal crystallization kinetics in Polypropylene (PP)/ethylene-propylene-diene terpolymer (EPDM)/nano-CaCO3 composites prepared by different compounding procedures. PP/EPDM/CaCO3 composites were prepared by two compounding procedures (direct compounding: mixed all three solid materials together; multistep compounding: the melted EPDM/CaCO3 master batch in a single screw extruder blended with melted PP in twin-screw extruder via injecting into the twin-screw extruder from a lateral port at the melting section of the twin-screw extruder). Morphological observation showed that abundant CaCO3 particles concentrated around EPDM dispersed phase in the multistep compounding composite, essentially different from the respectively dispersed morphology of CaCO3 particles and EPDM domains in the matrix for the direct compounding composite. Moreover, better dispersion of CaCO3 particles in the multistep compounding composite was observed comparing to the direct compounding composite. Futhermore, a pronounced improvement of the crystallization half time (t1/2), rate of crystallization (G) was achieved in the multistep compounding composite, which may originate from the better dispersion of CaCO3 particles providing larger nucleation density and the collaborative nucleation of EPDM and CaCO3 during the isothermal crystallization.

Influence of ferrite nanoparticle type and content on the crystallization kinetics and electroactive phase nucleation of poly(vinylidene fluoride)

This work reports on the nucleation of the β-phase of poly(vinylidene fluoride) (PVDF) by incorporating CoFe(2)O(4) and NiFe(2)O(4) nanoparticles, leading in this way to the preparation of magnetoelectric composites. The fraction of filler nanoparticles needed to produce the same β- to α-phase ratio in crystallized PVDF is 1 order of magnitude lower in the cobalt ferrite nanoparticles. The interaction between nanoparticles and PVDF chains induce the all-trans conformation in PVDF segments, and this structure then propagates in crystal growth. The nucleation kinetics is enhanced by the presence of nanoparticles, as corroborated by the increasing number of spherulites with increasing nanoparticle content and by the variations of the Avrami's exponent. Further, the decrease of the crystalline fraction of PVDF with increasing nanoparticle content indicates that an important fraction of polymer chains are confined in interphases with the filler particle.