Study on in-situ fiber forming properties of different LLDPE systems

Abstract

In this article, we use a co-rotating tri-screw extruder by changing the extruder speed, processing temperature, and reinforcing phase content. The ability of fibers generation under various processing parameters was researched. The influence of fibers on the toughness and strength was also explored. The experimental results of fiber morphology indicate that the content of reinforcing phase has a more significant impact on the formation of fibers than changing process parameters, and the linear low-density polyethylene/poly(butylene terephthalate) (LLDPE/PBT) system clearly reflects the phenomenon. The fibers generated by 30% content of PBT was uniform thickness and clear orientation and the 20% content of PBT no fibers are visible almost, as the content of reinforcing phase increased, fibers generated easier for the reinforcing phase to interact with the matrix. The cross-sectional scanning electron microscopy (SEM) scanning experiment shows that the compatibility of two phases and difference melting point has a significant impact on fiber formation. The LLDPE/PP system can illustrate this conclusion. Frequency scanning experiments shown that the linear low-density polyethylene/ polypropylene (LLDPE/PP), LLDPE/PBT, and the linear low density polyethylene/ polytetrafluroethylene (LLDPE/PTFE) composites exhibit shear thinning behavior, meaning that the complex viscosity increased with frequency increasing. We also found that as the extrusion temperature and screw speed increase, the peak loss factor increases, and the effect of temperature on the peak value is greater than that of screw speed.