•The dispersion of CaCO3 nanoparticles into the PET matrix was homogeneous.•CaCO3 nanoparticles act as nucleating agent of PET crystallization process.•CaCO3 nanoparticles could increase the thermal stability of PET.A series of poly(ethylene terephthalate) (PET) nanocomposites were prepared by in situ polymerization containing different amounts of surface treated calcium carbonate (CaCO3). As verified by SEM micrographs, the dispersion of CaCO3 nanoparticles into the PET matrix was homogeneous when the content of CaCO3 was below 5 wt.%, however, some aggregates existed at higher filler content. DSC study results showed that the crystallization became faster, and there was, also, a shifting of temperature of the crystallization peak to higher value by the addition of CaCO3 till 5 wt.%, this being evidence that CaCO3 can act as nucleating agent. From TG curves it was concluded that PET and the samples with different content of CaCO3 nanoparticles presented good thermal stabilities, since no remarkable mass loss occurred up to 360 °C (< 0.5%). Moreover, from the variations of the activation energies, calculated from the TG curves, it was clear that nanocomposites containing CaCO3 had a higher activation energy compared to the pure PET, indicating that the addition of the nanoparticles could slightly increased the thermal stability of the matrix.Nanocomposites containing CaCO3 had a higher activation energy compared to the pure PET, indicating that the addition of the CaCO3 nanoparticles could slightly increase the thermal stability of the PET matrix.

A recyclable technology was proposed for preparation of silica powder using rice hull ash and NH4F. The silica in rice hull ash was dissolved into NH4F solution to produce (NH4)2SiF6 and NH3. The silica powder was precipitated when (NH4)2SiF6 solution was added to NH3·H2O. The microstructure and morphology analysis of the precipitated silica powders were characterized using transmission electron microscopy (TEM). The preparation conditions and the recyclable process were explored experimentally. The yield of silica reached up to 94.6% and the particles were spherical with the diameter of 50–60 nm. Most importantly, all the reactants and byproducts were recyclable in this process.In this paper, we proposed a recyclable technique for the formation of silica powder. All the reactants and byproducts were recyclable in this process, and none pollutants were discharged to environment. The preparation conditions were determined and the recyclability of the process was confirmed experimentally. This technique over the conventional ones for producing silica powders includes inexpensive starting materials, environmental benign and its potential to realize scale production.Highlights► The synthetic procedure is inexpensive, sustainable and environment-friendly. ► The wastewater and the NH3 generated in the process of preparation have been collected and reutilized. ► The raw is the waste product.

Calcium carbonate (CaCO3) nanoparticles were successfully prepared via a carbonization route with polyethylene glycol phosphate 1000 (PGP) as the modifying agent to improve the dispersion and increase the compatibility between nanoparticles and poly(ethylene terephthalate) (PET) matrix. PET/CaCO3 nanocomposites were prepared by further in situ polymerization with 5 wt.% CaCO3 nanoparticles. The microstructure and dispersion of CaCO3 nanoparticles in the nanocomposites were investigated. It was found that well dispersion was obtained up to 5 wt.% of the surface treated CaCO3 loading for PET/CaCO3 nanocomposites. Compared to the nanocomposites filled with the blank CaCO3, a significant improvement in thermal stability and crystallinity properties was observed with the addition of 5 wt.% of the surface treated CaCO3.Graphical abstractIn this paper, CaCO3 nanoparticles were successfully prepared via a carbonization route with polyethylene glycol phosphate 1000 (PGP) as the modifying agent to improve the dispersion and increase the compatibility between nanoparticles and poly(ethylene terephthalate) (PET) matrix. PET/CaCO3 nanocomposites were prepared by further in situ polymerization with 5 wt.% CaCO3 nanoparticles. It was found that well dispersion was obtained up to 5 wt.% of the surface treated CaCO3 loading for PET/CaCO3 nanocomposites. Compared to the nanocomposites filled with the blank CaCO3, a significant improvement in thermal stability and crystallinity properties was observed with the addition of the surface treated CaCO3.Highlights► Surface modification of CaCO3 nanoparticles with PGP. ► The surface modified CaCO3 exhibits a better dispersion in PET than the blank CaCO3. ► The dispersion state of CaCO3 in PET influences the performance of PET.

Hydrophobic BaSO4 nanoparticles were successfully prepared by one-step precipitation reaction in aqueous solution of Na2SO4 and BaCl2 with stearic acid (SA) as the modifying agent. BaSO4/poly(ethylene terephthalate) (PET) nanocomposites were prepared by further in situ polymerization of purified terephthalic acid (PTA), ethylene glycol (EG) and BaSO4 nanoparticles. The surface modification of BaSO4, the microstructure and the properties of nanocomposites were investigated by relative contact angle, TEM, FTIR, XRD, SEM, TGA and DSC. Measurements of relative contact angle indicated that BaSO4 samples were hydrophobic. Compared to the nanocomposites filled with the blank BaSO4, the resulting nanocomposites filled with the modified BaSO4 exhibit a better dispersion of the nanoparticles, a superior crystallinity properties and a better thermal stability. The experimental results also suggested that the properties of nanocomposites were correlated with the dispersion of BaSO4 in PET and the interfacial interactions between BaSO4 and PET matrix.Graphical abstractIn this paper, hydrophobic BaSO4 nanoparticles were successfully prepared by one-step precipitation reaction in aqueous solution of Na2SO4 and BaCl2 with stearic acid (SA) as the modifying agent. BaSO4/poly(ethylene terephthalate) (PET) nanocomposites were prepared by further in situ polymerization of purified terephthalic acid (PTA), ethylene glycol (EG) and BaSO4 nanoparticles. Compared to the nanocomposites filled with the blank BaSO4, the resulting nanocomposites filled with the modified BaSO4 exhibit a better dispersion of the nanoparticles, a superior crystallinity properties and a better thermal stability.Highlights► Stearic acid induces a change on BaSO4 surface from hydrophilicity to hydrophobicity. ► The surface modified BaSO4 exhibits a better dispersion in PET than the blank BaSO4. ► The dispersion state of BaSO4 in PET influences the thermal properties of PET.