Autoclave INDEX

All reactions were run in a Parr stirred autoclave (Model 4561) at 1000 psi H2 and 200°C for 6h. A weighed quantity (0.5 g dry basis) of the catalyst, Ru/C or Ni/Re/C, was introduced into the reactor and reduced at 250 C and 200 psi H2 (Ru/C) or at 280°C and 500 psi H2 (Ni/Re/C) for 13 hours. After cooling, 100ml of solution (l.OM GO and O.l-l.OM KOH) was added to the closed reactor. For reactions in solvent mixtures, entries 1-4 in Table 2, the water/solvent ratio was 1/9 (v/v). When the solvent was either t-BuOH or 1,4-dioxane, 1.5 g of water was added to the solution to facilitate dissolution of KOH, because of its low solubility these solvents. Once steady state was achieved following heatup, samples were taken at 30 minute intervals for the first hour, and then hourly, and analyzed via HPLC. The HPLC column was a BIORAD Aminex HPX-87H run at 65 C with 5mM H2SO4 as the mobile phase at a flow rate of 0.6mFmin, using both UV (210 nm) and refractive index (RI) detection. 

A 100-ml autoclave was charged with ethyl acetate (24 parts), 1,4-dioxene (20 parts), and t-bu ty 1 pcrox pi val ate (0.3 parts) and then treated with chlorotrifluoroethylene (31 parts) and polymerized at 55°C for 13 hours. The precipitated polymer was isolated and dissolved in 150 ml of tetrahydrofuran (THF) and then precipitated in methanol, the process being repeated twice. Thirty-five grams of product were isolated having a Tg of 154°C and an Mn of28,000 Da with a refractive index of 1.459. The material was soluble in most organic solvents and formed transparent films. 

Description A variety of polymers are produced on these large reactors for various applications. The melt index, polymer density and molecular weight distribution are controlled with temperature profile, pressure, initiator and comonomer concentration. Autoclave reactors can give narrow or broad molecular weight distribution depending on the selected reactor conditions, whereas tubular reac-... 

Thus, compliance with limits for temperature uniformity throughout empty autoclaves (heat distribution studies) is an index of the way in which the autoclaves are engineered. Compliance with limits for temperature uniformity within items loaded into the autoclaves (heat penetration) is an index of the way in which items are wrapped for sterilization (where applicable) and how they are loaded into the autoclaves in relation to the positions of steam inlets, drains, racks, trays, and thermal sensors. 

COMPRO, Virtual Autoclave simulation tool, http //www.convergeuLca/products/ index.html. Convergent Manufacturing Technologies, Vancouver, BC. 

Fig. 1. Long-chain branching in fractions with 200,000 from polyethylenes with melt index 1.7 and density 0.918-0.919 g/cm (a) autoclave product with 20 long branches (b) tubular product with 7 long branches. Short-chain branches are not shown.

Upon completion of the reaction, the autoclave is cautiously vented and coagulum is filtered off. The latex may be coagulated by the addition of a 5% aqueous solution of potassium aluminum sulfate. The coagulum is filtered off, washed with distilled water, and dried at reduced pressure at 60°C. The syndiotactic index of this latex is determined from the infrared absorptions at 635 and 692 cm" When prepared at 0°C, the resin has a syndiotacticity index of 2.1 and a glass transition temperature of 105°C. 

The ethylene polymerization of this catalyst was carried out in an autoclave reactor at 221°F in isopentane as the slurry solvent in the presence of triisobutylaluminum as cocatalyst and 50 psig of hydrogen and sufficient ethylene to achieve a total reactor pressure of 550 psig. The catalyst activity was 10,540 g of PE/g of catalyst/ hr, which corresponded to an activity of 146,000 g PE/g Ti/hr. The granular polyethylene product obtained was considered suitable for a particle-form slurry process such as the Phillips slurry process. The polyethylene sample displayed a Melt Index (I value of 0.70 and a High Load Melt Index ) value (HLMI) of 3 1 with a HLMI/MI ratio of 45, which indicates tfiat the polyethylene molecular weight distribution was of an intermediate value. 

The product mix of autoclave and tubular reactors are similar in terms of LDPE homopolymers (0.910-0.935 g/cc) and some specialty grades of polyethylene such as ethylene/vinyl acetate copolymers up to about 30 wt% vinyl acetate (VA). However, the autoclave process provides higher levels of vinyl acetate (40 wt%) in ethylene/VA copolymers and additional specialty grades of polyethylene such as ethylene/methyl acrylate, ethylene/acrylic acid and ethylene/n-butyl acrylate. Polyethylene molecular weight can be varied over a wide range with the high-pressure process, with Melt Index values (I ranging from 0.15 to 40. 

In 1982, Wild and coworkers [17] reported the short-chain branching distribution of LDPE produced in each type of reactor design by utilizing the temperature rising elution fractionation (TREF)analytical technique. The autoclave LDPE sample had a 0.924 g/cc density and a 3.0 Melt Index. The tubular LDPE sample had a 0.921 g/cc density and a 2.2 Melt Index. Ihe branching distribution data from each sample is summarized in Figure 5.7. 

As discussed above, it was clear that ethylene/1-butene copolymers possessed significantly improved mechanical properties compared to ethylene homopolymer products, so that a commercial particle-form reactor design was needed that could provide polyethylene copolymers over a range of Flow Index values with sustained operability over extended periods of time without reactor shut down. Adding 1 -butene to the polymerization process made the autoclave stirred tank reactor even more difficult to operate, as reactor wall fouling problems persisted and in some cases polymer particle morphology was reduced due to some polymer components becoming soluble in the n-pentane. 

Polymerization and analytical procedures Polymerization of propylene was conducted either in a 200 cm glass reactor or in a 100 cm stainless steel autoclave equipped with a magnetic stirrer. Polymerization was terminated by adding a dilute hydrochloric acid solution in methanol. The polymer produced was fractionated by extraction with boiling heptane for 10 h to determine the isotactic index (I.I.). The... 

Figure 93 Variation of wdght-aveiage molecular weig of LDPE versus melt flow index for autoclave and tubular grades of resin (O) A series ( ) B series, (A) C series, and ( ) T series. (From Ref. 3.)...

Figure 9.6 Relationship between melt flow index and weight average molecular weight using a conection factor, g (O, , A) autoclave grades and ( ) tubular grades. (FTom Ref. 3.)...

MFI, ,o Melt flow index for autoclave reactor polymer g per 10 min (9.3)... 

For instance, in Ex. 1, the starting monomer mixture contained 55 mole% of TFE and 45-mole% Et. The reaction mixture was heated up to 65°C while the pressure reached 2.8 MPa. After two hours the autoclave was cooled and the contents were removed. The copolymer (139 g) was washed with boiling water, filtered, and dried, and its properties were measured (Table 5.53). Melting point deereased with an inerease in TFE content while melt flow index inereased. Tensile strength of the copolymer deereased, indieating a reduction of the molecular weight at higher TFE eon-tent. Thermal stability was evaluated by the repeated... 

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