General Description NTR-975 is another new chromium-based catalyst developed by Shanghai Nartrin Chemical Company.  It was designed specifically for medium-density applications requiring high melt strength and low sag performance, such as in geomembrane, sheeting and large-diameter pipe.  The catalyst offers superior melt index potential, and highly efficient incorporation of comonomer.  It performs equally well in both slurry and gas-phase polymerization processes, yielding high activity and good particle morphology for maximum production rates. NTR-975 is founded on a unique silica-titania support technology that produces a moderately broad molecular weight distribution, yielding high impact resistance and notched constant tensile load (NCTL) performance, as well as good environmental stress crack resistance (ESCR).  The pore structure of this support was constructed to allow efficient transport of comonomer through the catalyst matrix and to the active sites, thus making the catalyst excellent for medium to lower density applications.  The large pore diameter contributes a high melt index potential, for good operations during manufacturing.  And the pore structure also imparts a high level of long chain branching to the resin that produces easy extrusion (shear thinning) and delivers high melt elasticity.  That is, the resins exhibit superior melt strength and they resist sag during molding. NTR-975 is especially well-suited to slurry technologies, yielding high production rates because of:             1) Highly efficient incorporation of comonomer.            2) a high melt index potential so that comfortable reaction temperatures may be used and ethylene concentrations kept high.            3) good particle morphology that produces fast efficient settling and lower power consumption to maintain circulation.            4) the catalyst activity is naturally high so that costs are reduced and the polymer is clean.  These attributes are also useful in gas phase reactors.       Typical NTR-975 Characteristics            Cr (wt %, dry)                                                      1.0-1.2%            Ti (wt%, dry)                                                        1.0-1.5%            Surface Area, SA (BET, m2/gm)                           280-330            Pore Volume (N2 P/P0 0.993,  mL/g)                  1.5-1.7     Particle Size Distribution (Malvern)            D10 (10th Percentile – PS µm)                                55            D50 (50th Percentile – APS µm)                             105            D90 (90th Percentile – PH µm)                               185            Activity (kg PE/kg Catalyst/h)                            3000-5000  Recommended Applications As a consequence of its chemical composition and its microstructure, NTR-975 is especially well suited to the production of medium density polyethylene grades (0.932 to 0.945 g/mL) having low to moderate melt index (HLMI 5 to 30).  Such polymers are useful in geomembrane, pipe and sheet.  The unusual melt elasticity of NTR-975 derived polymers delivers excellent melt strength and sag resistance during molding, which is again advantageous for these same applications.  Of course these resins naturally exhibit superior impact resistance, and ESCR and NCTL performance, which are also necessary in these applications.