Effect of antiblock and slip additives on the properties of tubular quenched polypropylene film

In the present investigation, silica and talc were used as antiblock additives with slip additive to investigate their effects on tubular quenched polypropylene (TQPP) film properties. Polypropylene (PP) powder was compounded with additives in twin-screw extruder and subsequently processed through TQPP machine to prepare the films. Tear and tensile properties [in machine direction (MD) and transverse direction (TD)] and surface properties of the produced TQPP films were investigated in terms of optics and coefficient of friction (CoF). The effect of conditioning time on CoF was also studied. Addition of slip agent alone to PP did not show any significant change in tear strength, CoF and tensile properties, whereas CoF reduced drastically by adding both slip and antiblock agents in combination. Reduction in CoF values were found to be more pronounced in the presence of silica-based antiblock compared to talc-based antiblock. Film surface morphology was further examined by field-emission scanning electron microscopy. The tear strength and the gloss of TQPP film decreased slightly in presence of only antiblock agents, but the tensile strength was found to increase. It was also found that tensile properties of TQPP films were superior in silica-based formulation, whereas tear strength was better in talc-based formulation in MD and TD.

Study on corrosion resistance of superhydrophobic surface on aluminum alloy

Anti-corrosion of aluminum alloys with different roughness were researched in this study. To further verify the relationship between anti-corrosion and surface roughness, surface with micro structure alloy was successfully fabricated via anode oxidation on aluminum. The water contact angle of aluminum alloy surface after coating polypropylene film was 154° and sliding angle was 3°. The micro-nano structure was constructed by adding nano-SiO2. The contacts angle of surface was 165° and the sliding angle was 1.8°. The superhydrophobic samples were used to test corrosion resistance. Compared with aluminum coated with unmodified film, the corrosion potential for modified superhydrophobic aluminum alloy increased by about 0.05 V. When nano-SiO2 particles were added, the corrosion resistance for the sample was also improved.

Comparison of angular-selective metasurfaces as tools for sub-THz single-frequency sensing

We demonstrate and numerically characterize a set of single-layer metasurfaces based on capacitively-coupled bent metal strips deposited on a thin polypropylene film operating as band-stop filters at 139.1 GHz. Due to a high inter-digital coupling capacitance between neighboring inclusions formed by the strips, the resonance of the metasurface becomes highly sensitive to the incidence angle of a plane wave. At the same time, a narrow-band resonance is achieved by reducing the conductor length along the vertical polarization direction of the incident wave. We propose to use both properties for designing a sensor, which analyses the thickness of a thin slab of a known substance deposited over the structure by tracking the angle at which the minimum of transmission can be measured at a single frequency. We compare three versions of the proposed geometry by numerical calculation of the transmission coefficient depending on both the incidence angle and analyte slab’s thickness. We select the most suitable structure for sensing.

Preparation of Polypropylene/silver nanoparticles Nanocomposite films and Evaluation of its Barrier and Antimicrobial Properties for Packaging Applications

Polymeric films which can be used in packaging industries were prepared by blown film method with polypropylene chips and silver nanoparticles. The nanocomposite films were characterized concerning its potential use. Oxygen Transmission rate (OTR) measurements was done in order to ascertain permeability of oxygen through the polymeric films. It was found that the permeability of oxygen through nanocomposite film is higher than that of virgin polypropylene film due to incompatibility between polypropylene matrix and silver nanoparticles. The water vapour transmission rate (WVTR) test of the polymeric nanocomposite films was calculated in order to know the information about mass transfer mechanisms and solute-polymer interactions in the food packaging film. It has been found that, there is a significant decreased water vapour transmission rate through nanocomposite films compared to that of virgin polypropylene film. With increasing the concentration of silver nanoparticles, this effect was reduced. The explanation for this could be that with higher concentration of silver nanoparticles agglomeration in the polymer film could the possibility which create narrow pathway for water molecules to travel. The effect of various silver nanoparticles content in the polymer nanocomposites with respect to its antimicrobial efficacy against the Gram positive bacteria Escherichia coli and Gram positive bacteria Staphylococcus aureus were studied. However, Escherichia coli was most effectively retarded by silver nanoparticles than Staphylococcus aureus, which is related to the difference in the cell wall of the gram positive and gram negative bacteria.

Investigation on Charge Transport in Polypropylene Film under High Electric Field by Experiments and Simulation

The charge transport in polypropylene was studied under DC electric fields at different temperatures. By the experimental measurement and simulation of the BCT model, we studied conduction currents, breakdown strength, and space charge distribution. In particular, the conduction characteristics under high temperature and high field, especially the conduction characteristics before the breakdown, were studied by systematic experiments, and the conduction characteristics and the breakdown mechanism were further studied by simulation. The results show that in the process of measuring conduction currents until breakdown, both high temperature and high electric field will promote charge transport. However, the free volume will increase at high temperature, which will easily lead to faster charge transport and breakdown. In the breakdown process at different temperatures, there are different breakdown mechanisms. At 20–60 °C, the electric breakdown process has mainly occurred in polypropylene film, and the breakdown strength is almost unchanged. At 80 °C, electric breakdown and thermal breakdown act together, and the charge transport is faster, and the breakdown field becomes smaller. Finally, we conclude that thermal stress plays a very important role in charge transport. In a high-temperature environment, the volume expansion of polypropylene will promote charge transport, and the insulation of polypropylene capacitor films will be damaged.