Deepak R. Parikh

A new class of ethylene-propylene-diene terpolymers produced from constrained geometry metallocene catalysts

Abstract Until recently, ethylene/propylene/diene (EPDM) terpolymers have been manufactured exclusively using vanadium based Ziegler—Natta catalyst systems. The vanadium based catalysts are known to have both product and process limitations. These limitations are due to a complex combination of factors including monomer reactivity, catalyst activity, reactor temperatures and pressures. Single-site metallocene constrained geometry catalyst (CGC) technology enables the manufacture of EPDM terpolymers at higher reactor temperature and catalyst efficiency than standard Ziegler—Natta catalyst systems. The unique combination of monomer, catalyst and process technology enables the manufacture of highly crystalline EPDMs having ethylene contents over 90 wt %. This study investigated these new highly crystalline EPDM terpolymers and their differentiation from commercially available EPDMs. The results indicated that these new EPDMs had very high green strength and barrier properties, yet could be cured by conventio...

Comparative Analysis of Thick Gauge Blended and Coextruded Polyethylene Films

Linear and branched polyethylene resins are extensively used in film production for packaging. Branched polyethylenes, such as low density polyethylene (LDPE), are unique due to their high melt strength and good optical properties; while linear polyethylenes, such as linear low density polyethylene (LLDPE), exhibit excellent physical properties and drawdown capabilities The combination of both resins via blends or coextrusion provides a mix of film properties very difficult to achieve with pure materials. This paper evaluates the performance of thick blown films made from blends of LLDPE (1.0 melt index, 0.926 density) with high pressure LDPE (0.2 melt index, 0.920 density), versus three-layer coextruded films made of the same materials at the same resin ratios. A major market for these films is in pack aging free-flowing granular products. The objective is to answer which fabrication method yields superior mechanical properties, as well as outline the fundamental reasoning to understand the differences through structural and morphological analyses