Spunbonding studies with polypropylene polymers

Spunbonding is a continuous process to produce polymer laid nonwovens for various applications. Polypropylene is the major polymer used in this process. Metallocene polypropylene (mPP) manufactured using the single site catalyst technology has been of interest for this industry and some research has been done for the past few years. This polymer seems to be different compared to the conventional Ziegler-Natta catalyzed polypropylene (znPP). This research was conducted to investigate the structure and properties of the filaments and fabrics produced with a metallocene catalyzed propylene polymer and to determine the optimum process conditions to produce good quality fabrics. A comparison is also made between the filaments and the fabrics produced from both types of polymers i.e., mPP and znPP. An investigation of the processing behavior of mPP polymer was conducted using the Reicofil spunbonding pilot line at the University of Tennessee, Knoxville. The filaments at three different throughput rates were studied for tensile properties and other structural features such as birefringence, x-ray diffraction and thermal responses. The fabrics bonded at different process conditions were tested for various mechanical properties. The structure and properties of the two types of spunbond filaments and fabrics were compared. The failure mechanism of the fabrics at different bonding temperatures was studied using scanning electron microscope. The results showed that mPP filaments have lower melting temperature than znPP filaments. They also have higher strengths and lower elongation than znPP filaments. The mPP fabrics also have shown higher strength and elongation properties than the comparable znPP fabrics. The rupture mechanism of the mPP fabrics was found to be different than that of the znPP fabrics. Also higher strength and elongation were observed in mPP fabrics that were bonded at relatively lower temperatures. For spunbonding process mPP was found to be much better than the znPP polymer