Extrusion blow molding of long fiber reinforced polyolefins

Abstract

A 58% (by weight) long glass fiber reinforced (LGF)‐HDPE master batch was blended with a typical blow molding HDPE grade. HDPE composites having between 5% and 20% (by weight) long fiber content were extruded at different processing conditions (extrusion speed, die gap, hang time). The parison swell (diameter and thickness) decreased with increasing fiber content. Although the HDPE exhibited significant shear rate dependence, the LGF/HDPE composites were shear rate insensitive. Both the diameter and weight swell results also indicated very different sagging behavior. The LGF/HDPE parisons did sag as a solid‐body (equal speed at different axial locations) governed by the orientation caused by the flow in the die. Samples taken from blown bottles showed that fiber lengths decreased to 1‐3 mm, from the original 11 mm fiber length fed to the extruder. No significant difference in fiber length distribution was found when samples for different regions of the bottle were analyzed. SEM micrographs corroborate the absence of fiber segregation and clustering or the occurrence of fiber bundles (homogeneous spatial fiber distribution) as well as a preferential fiber orientation with the direction of flow. The blowing step did not change the orientation of the fibers. Five‐percent (5%) and 10% LGF/HDPE composites could be blown with very slight variations to the neat HDPE inflation conditions. However, 20% LGF/HDPE composites could not be consistently inflated. Problems related to blowouts and incomplete weldlines were the major source of problems.

Continuous extrusion and tensile strength of self-reinforced HDPE/UHMWPE sheet

“…Generally, diversified fibers and other fillers were incorporated into polymer materials to achieve this goal by using the reinforcing effect of fillers (Garcia-Rejon et al, 2002;Kitano et al, 2000;Zhou et al, 2004;Zhu et al, 2002;Robin and Breton, 2001). Aside from this method, self-reinforcement has been proved to be an effective way to improve the mechanical properties of polymer materials, taking advantage of molecular orientation during processing.…”

Shear and elongational flow properties of peroxide‐modified wood/low‐density polyethylene composite melts

“…Su et al [10] studied the elongational properties of long‐chain branched polypropylene (PP)/nanoclay composites and found that the melt strength and elongational viscosity decreased with increasing nanoclay content up to 6 phr, at higher filler concentration, however, the melt strength and elongational viscosity slightly increased. Garcia‐Rejon et al [11] measured the elongational viscosity of long glass fiber–reinforced high‐density polyethylene (HDPE) using the convergent flow technique, finding that the elongational viscosity increased with increasing fiber content. Férec et al [12] showed that the elongational viscosity of glass fiber‐filled PP increased with increasing fiber content and the elongational viscosity was even higher if the fibers are initially oriented in the stretching direction.…”

“…Elongational flow has a great importance when the polymer is stretched or forced to flow through contractions. The investigation of elongational flow properties for polymer composites has recently received considerable attention [8][9][10][11][12][13][14]. Strain hardening is defined as the deviation of the transient elongational viscosity from the linear viscoelastic start-up curve towards higher viscosities.…”

DD ArtPix

“…Elongational flow has a great importance when the polymer is stretched or forced to flow through contractions. The investigation of elongational flow properties for polymer composites has recently received considerable attention [8–14]. Strain hardening is defined as the deviation of the transient elongational viscosity from the linear viscoelastic start‐up curve towards higher viscosities.…”