Effect of solid particle erosion on fracture strength of low density polyethylene film

In this study,the infuence of solid particle erosion on the fracture strength of low density polyethylene(LDPE)film under con-trolled conditions is investigated through impact experiments.The variations in the residual fracture stress as well as the residual fracture strain of the LDPE flm after solid particle impact against the impact angle(α),impact velocity(νp)and impact duration(t)are analysed.The study revealed that the fracture stress and the fracture strain of the LDPE film decrease with an increase in the impact duration,and the degradation rate increases with the impact velocity and impact angle.Furthermore,the fracture stress and the fracture strain of LDPE film decrease exponentially against the impact energy under the same particle impact angle condition,and the reductions of fracture stress and fracture strain increase quasi-linearly with the sine-squared impact angle under the same impact energy.The study proposes empirical models to predict the attenuation of the fracture stress and the fracture strain of LDPE films due to the finite particle impact energy.

Surface Grafting of Phenolic Resole onto LDPE Films

Low density polyethylene film surface-grafted phenolic resole was prepared by a sequential processes. Firstly, acrylic acid was grafted to the surface of low density polyethylene by photo-grafting. Secondly, the carboxylic groups in poly（acrylic acid） chains were transferred to sulfonic groups by the reaction of carboxylic groups with sulfanilic acid. Finally, a thin layer of phenolic resole was cured onto the surface of low density polyethylene. The grafting process was characterized by FTIR-ATR and gravimetric analysis. A possible model was proposed to interpret the experimental results.

Development of a Novel Extrusion Process for Preparing Rice Straw/LLDPE Composites

Straw utilization is a key issue related to agricultural production and air pollution control.In this study,a novel extrusion process was proposed to improve the physical and mechanical properties of the straw-reinforced linear low-density polyethylene(LLDPE)composite.Instead of crushing the straw and mixing it with plastic matrix,the new method mixes straw with plastic matrix in its original form.The intact long rice straws were parallelly spread on the LLDPE film and then rolled up together into a prefabricated roll.The rolls experienced three extrusion processes as follows:(1)twin-screw melting,cooling and crushing,single-screw extruding;(2)twin-screw melting and single-screw extruding;(3)directly single-screw extruding.The testing results showed that the straw/LLDPE composite(with a ratio of 6:4)prepared by Method(2)exhibited optimized properties.Characterization by scanning electron microscopy indicated that the damage to rice straw fibers was relatively minor,the orientation of long fibers was good,and the binding of fibers with the LLDPE matrix was excellent in this case.The results of dynamic mechanical testing(DMA),differential scanning calorimetry(DSC)and thermogravimetric(TG)analysis demonstrated that composites prepared by the new process exhibited significantly improved thermal stability and energy storage modulus,compared with those prepared by conventional processes(e.g.,extruded straw particles/LLDPE composite).The new proposed method yielded significantly enhanced mechanical properties while reducing dust pollution.