Several new commercial or experimental materials offer rotational molders higher stiffness, toughness, and processability in applications from toys to large storage tanks. The news includes both polyethylenes and engineering materials. Easy-runningMDPE & LDPE
Higher stiffness, toughness, and processability, as well as exceptional whiteness are the chief benefits cited by Nova Chemicals for two new experimental rotomolding resins in the Surpass line made with the new Advanced Sclairtech dual-reactor solution process and non-metallocene single-site catalysts.
Grade EX-RMs539 is an octene MDPE with a 5.2 MI for easy flow and a density of 0.939 g/cc. The resin is said to have low viscosity and an extremely broad processing window. Tensile yield strength is 2900 psi, and flexural modulus (1% secant) is 117,000 psi. ARM impact strength at -40 C for a 0.25-in. sample is 180 ft-lb. A companion product is super-rigid EX-RMs244, an octene HDPE with 1.7 MI and 0.944 density. Its broad processing window is said to allow for lower process temperatures as well as faster sintering. It has a flex modulus of 142,000 psi, tensile yield strength of 3400 psi, and ARM impact strength (0.25 in.) of 180 ft-lb.
Nylon 11 natural powder
Atofina Chemicals rolled out a new natural grade of nylon 11 powder for rotomolding. Rilsan Roto 11 complements a black grade previously available. Suitable for molding fuel, coolant, and hydraulic-fluid tanks in agricultural vehicles and lawn/garden or marine uses, this translucent grade makes the fill level visible. It is also pigmentable.
A new ABS rotomolding compound from Chroma Corp. is formulated for improved heat stability and particle coalescence. Grade AG-9000 NA is a natural-color compound with an MFR of 6 g/10 min, density of 1.04 g/cc, tensile strength of 3300 psi, and flex modulus of 110,000 psi.
Teknor Color has developed a new variation of its Tek Tuff CE HDPE compound for rotomolding that is 5% to 10% less expensive than earlier formulations. It offers a broad processing window and contains a uv stabilizer for outdoor weatherability. MI is 3.0 with a density of 0.948. The material has tensile strength of 2975 psi, ultimate elongation of 460%, and flex modulus of 130,500 psi. ARM impact at –40 F is 60 ft-lb. More concentrated special-effect colorants with loadings up to 50% are available from Jericho Plastic Industries. These cost-saving masterbatches can be formulated with high-flow LLDPE carriers.