Journal of Plastic Film & Sheeting

Nanocomposite sheets based on high density polyethylene and containing organically modified fluoromica and three different compatibilizers (ethylene vinyl acetate copolymer and two maleic anhydride grafted high density polyethylene (HDPE-g-MA) grades with different melt flow indices) were prepared by melt mixing processing in an internal mixer. In order to evaluate the direct relationship between different properties of compression molded sheets and their microstructures, mechanical and barrier properties of the final nanocomposites were examined. Fluoromica content, compatibilizer type, and compatibilizer to clay ratio were changed to study the effects of different material variables on the final nanocomposite properties. A second-order polynomial function fitted well on experimental results and showed that the compatibilizer molecular weight played an important role in the morphology and consequently, the nanocomposite properties. Reducing the compatibilizer molecular weight resulted in better delamination and subsequent enhancement in mechanical and barrier properties. Optimization of various properties was done over the 16 designed experiments and 42% improvement in Young’s modulus and 30% reduction of permeability, compared to pristine high density polyethylene, were obtained for the optimal sample.

Excessive pressure and temperature during hot bar sealing of flexible packaging films can result in seal failure due to squeezing out of the sealant from the seal area. A model is developed that shows the amount of squeeze-out increases with increasing seal bar pressure, seal temperature (by lowering the viscosity of the sealant), sealing dwell time, film thickness, and decreasing seal bar width. Validation experiments qualitatively agree with the model predictions. Both the model and experimental results show that the rheology of the sealant plays a significant role in preventing squeeze-out; high viscosity at low shear rates favor less squeeze-out. The work shows that under normal sealing conditions, squeeze-out is not substantial. Avoiding excessive temperature or pressure is critical to minimizing squeeze out to ensure good sealing performance.

In this study, novel nanocomposite films of chitosan with fructose modified multi-walled carbon nanotube were prepared by solution casting technique. The fructose modified multi-walled carbon nanotube and the resulting bionanocomposite films were characterized using thermogravimetric analysis, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, atomic force microscopy and transmission electron microscopy. The transmission electron microscopy showed that the presence of the functional moieties helped to improve the dispersion and compatibility of the multi-walled carbon nanotubes in the chitosan matrix. The tensile strength of bionanocomposite films was increased from 32 MPa for the pure chitosan film up to 62.96 MPa for the nanocomposite with 7 wt% addition of fructose modified multi-walled carbon nanotube.

We have modeled an incompressible, non-isothermal flow of a magnetohydrodynamic (MHD) viscoplastic fluid when it passes through the tapered area between two co-rotating rolls. The basic conservation equations like mass, momentum, and energy based on the lubrication approximation theory (LAT) are developed, non-dimensionalized, and solved exactly for the velocity-, pressure gradient-, and temperature-distribution. The value of λ, where the sheet leaves the rolls, is calculated using Simpson’s 1/3 formula for numerical integration along with the modify regula-falsi method. Moreover, quantities of engineering interest such as extreme pressure, the roll separation force and the power transferred to the fluid by the rolls are also computed. The results show that the inclusion of the viscoplastic parameter affects the velocity field, pressure gradient-, and temperature-distribution substantially. It is found that the magnetic field provides a mechanism to control power transmission, separation force, and distance between attachment and detachment points, which are very useful for the calendering process.

The aim of this work concerned the performances and limitations of uses of two commercial biocides, namely 2-hydroxypropyl-3-piperazinyl-quinoline carboxylic acid methacrylate and N²-tert-butyl-N⁴-ethyl-6-methylthio-1,3,5-triazine-2,4-diamine (Terbutryn), in low-density polyethylene mulching film for agricultural application. The effects of type and algaecide concentration as well as aging deterioration of low-density polyethylene film surfaces were studied in relation to the mechanical, physical, and antialgal properties of the low-density polyethylene films. For antialgal evaluation, disk diffusion test and chlorophyll-a measurement technique were carried out on Chlorella vulgaris, a single-cell green algae, and Phormidium angustissimum, a blue-green algae. The results suggested that adding 2-hydroxypropyl-3-piperazinyl-quinoline carboxylic acid methacrylate or Terbutryn tended to slightly increase the lightness value (L*) of specimens, but did not affect the film mechanical properties. The disk diffusion test indicated that only Terbutryn at 600–1000 ppm resulted in clear zone development against C. vulgaris for low-density polyethylene film specimens. Regarding the quantitative study by chlorophyll-a measurement technique, the antialgal activities of low-density polyethylene films gradually improved with increasing algaecide concentrations. Terbutryn appeared to show more effective antialgal efficacy than 2-hydroxypropyl-3-piperazinyl-quinoline carboxylic acid methacrylate. Under aging deterioration, Terbutryn-low-density polyethylene films showed less degradation of mechanical properties than neat low-density polyethylene films. However, the antialgal activity of Terbutryn-low-density polyethylene films at various algaecide concentrations was reduced under both accelerated UV weathering and natural outdoor exposure.