Structure and Properties of Polypropylene/Polyolefin Elastomer/Organic Montmorillonite Nanocomposites

Investigation of the Effect of Hybrid Nanofiller on the Mechanical Performance and Surface Properties of Bio-Based Polylactic Acid/Polyolefin Elastomer (PLA/POE) Blend

Polylactic acid has stood out among bio-based polymers for its usage in the food packaging industry and biomedical fields. Through the melt mixing process, the toughened poly(lactic) acid (PLA) was prepared with polyolefin elastomer (POE), incorporated via various ratios of nanoclay and a fixed amount of nanosilver particles (AgNPs). The correlation between the compatibility and morphology, mechanical properties, and surface roughness of samples with nanoclay was studied. The calculated surface tension and melt rheology confirmed the interfacial interaction demonstrated by droplet size, impact strength, and elongation at break. Each blend sample exhibited matrix-dispersed droplets, and the size of POE droplets steadily dropped with increasing nanoclay content, corresponding to the enhanced thermodynamic affinity between PLA and POE. Scanning electron microscopy (SEM) acknowledged that the inclusion of nanoclay in the PLA/POE blend ameliorated the mechanical performance by preferable localization in the interface of used components. The optimum value of elongation at break was acquired at about 32.44%, where the incorporation of 1 wt.% nanoclay led, respectively, to 171.4% and 24% enhancement rather than the PLA/POE blend with the composition of 80/20 and the virgin PLA. Similarly, the impact strength reached 3.46 ± 0.18 kJ m^-1 as the highest obtained amount, showing the proximity of 23% progress to the unfilled PLA/POE blend. Surface analysis indicated that adding nanoclay caused the augment of surface roughness from 23.78 ± 5.80 µm in the unfilled PLA/POE blend to 57.65 ± 18.2 µm in PLA/POE contained 3 wt.% nanoclay. Rheological measurements implied that organoclay resulted in the strengthening of melt viscosity as well as the rheological parameters such as storage modulus and loss modulus. Han plot further showed that the storage modulus is always higher than the loss modulus in all prepared PLA/POE nanocomposite samples, corresponding to the restriction of polymer chains mobility induced by the formation of strong molecular interaction between nanofillers and polymer chains.

Preparation and Characterization of Polypropylene/Sepiolite Nanocomposites for Potential Application in Automotive Lightweight Materials

Polypropylene (PP)/sepiolite nanocomposites were prepared using the melt blending technique. The effects of nano-sepiolite content on the mechanical property, thermal property, crystallinity, morphology and rheological property of PP/sepiolite nanocomposites were investigated. The organic modified sepiolites (OSep) were dispersed evenly in PP matrix after surface treatment. The addition of OSep improved the storage modulus and thermal stability, showing a strong interaction between OSep and PP matrix. With the increase of OSep content, the fluidity of PP/OSep composites first increased due to the lubrication of surface modifiers and then decreased due to the interaction between OSep and PP. The size of the toughening agent elastomer first increased and then decreased, and the impact notched strength of PP/Osep composites first decreased and then increased. The loading of OSep also reduced the crystallinity and shrinkage rate of PP. PP/OSep nanocomposites have potential applications in high-performance automotive lightweight materials.

Structure and Properties of Polyoxymethylene/Silver/Maleic Anhydride-Grafted Polyolefin Elastomer Ternary Nanocomposites

In the present study, silver (Ag) nanoparticles and maleic anhydride-grafted polyolefin elastomer (MAH-g-POE) were used as enhancement additives to improve the performance of the polyoxymethylene (POM) homopolymer. Specifically, the POM/Ag/MAH-g-POE ternary nanocomposites with varying Ag nanoparticles and MAH-g-POE contents were prepared by a melt mixing method. The effects of the additives on the microstructure, thermal stability, crystallization behavior, mechanical properties, and dynamic mechanical thermal properties of the ternary nanocomposites were studied. It was found that the MAH-g-POE played a role in the bridging of the Ag nanoparticles and POM matrix and improved the interfacial adhesion between the Ag nanoparticles and POM matrix, owing to the good compatibility between Ag/MAH-g-POE and the POM matrix. Moreover, it was found that the combined addition of Ag nanoparticles and MAH-g-POE significantly enhanced the thermal stability, crystallization properties, and mechanical properties of the POM/Ag/MAH-g-POE ternary nanocomposites. When the Ag/MAH-g-POE content was 1 wt.%, the tensile strength reached the maximum value of 54.78 MPa. In addition, when the Ag/MAH-g-POE content increased to 15wt.%, the elongation at break reached the maximum value of 64.02%. However, when the Ag/MAH-g-POE content further increased to 20 wt.%, the elongation at break decreased again, which could be attributed to the aggregation of excessive Ag nanoparticles forming local defects in the POM/Ag/MAH-g-POE ternary nanocomposites. Furthermore, when the Ag/MAH-g-POE content was 20 wt.%, the maximum decomposition temperature of POM/Ag/MAH-g-POE ternary nanocomposites was 398.22 °C, which was 71.39 °C higher than that of pure POM. However, compared with POM, the storage modulus of POM/Ag/MAH-g-POE ternary nanocomposites decreased with the Ag/MAH-g-POE content, because the MAH-g-POE elastomer could reduce the rigidity of POM.

Effect of Silver Nanoparticles on the Microstructure, Non-Isothermal Crystallization Behavior and Antibacterial Activity of Polyoxymethylene

Silver (Ag) nanoparticles were synthesized by a facile route in the presence of oleic acid and n-propylamine. It was shown that the average primary size of the as-synthesized Ag nanoparticles was approximately 10 nm and the surface of as-synthesized Ag nanoparticles was capped with monolayer surfactants with the content of 19.6%. Based on as-synthesized Ag nanoparticles, polyoxymethylene (POM)/Ag nanocomposites were prepared. The influence of Ag nanoparticles on non-isothermal crystallization behavior of POM was investigated by differential scanning calorimetry (DSC). The Jeziorny, Jeziorny-modified Avrami, Ozawa, Liu and Mo, Ziabicki and Kissinger models were applied to analyze the non-isothermal melt crystallization data of POM/Ag nanocomposites. Results of half time (t_1/2), crystallization rate parameter (CRP), crystallization rate function (K(T)), kinetic parameter (F(T)), the kinetic crystallizability at unit cooling rate (G_Z) and the crystallization activation energy (∆E) were determined. Small amounts of Ag nanoparticles dispersed into POM matrix were shown to act as heterogeneous nuclei, which could enhance the crystallization rate of POM, increase the number of POM spherulites and reduce POM spherulites size. However, the higher loading of Ag nanoparticles were easily aggregated, which restrained POM crystallization to some degree. Furthermore, the POM/Ag nanocomposites showed robust antibacterial activity against Escherichia coli and Staphylococcus aureus.