High-density polyethylene Chemical Company

Plastic materials represent less than 10% by weight of all packagiag materials. They have a value of over 7 biUion including composite flexible packagiag about half is for film and half for botties, jars, cups, tubs, and trays. The principal materials used are high density polyethylene (HDPE) for botties, low density polyethylene for film, polypropylene (PP) for film, and polyester for both botties and films. Plastic resias are manufactured by petrochemical companies, eg. Union Carbide and Mobil Chemical for low density polyethylene (LDPE), Solvay for high density polyethylene, Himont for polypropylene, and Shell and Eastman for polyester. 

High-density polyethylene (HDPE) is a commodity chemical that is produced on a very large scale in one of two catalytic processes the Ziegler-Natta and the Phillips process. The latter accounts for about one third of all polyethylene. It uses a catalyst consisting of small amounts of chromium (0.2-1.0 wt% Cr) on a silica support, developed by Hogan and Banks at the Phillips Petroleum Company in the early 1950s [84,85]. 

Yury V. Kissin, Mobil Chemical Company. Edison. NJ. htlp/Acwu. csxonmobilchcmical.com/. Polyethylene (under Olefin Polymers) High Density Polyethylene (under Olefin Polymers) Linear Low Density Polyethylene (under Olefin Polymers) and Polymers of Higher Olefins (under Olefin Polymers)... 

A good AEM should fulfill stringent mechanical, thermal, and chemical properties as mentioned in Section 11.2. Historically, the first AEM material was developed by researchers from the Toknyama Soda Company. They introduced quaternary ammonium groups to the divinylbenzene-cross-linked polychloropropene polymer matrix via trimethylamine. Since then, several membrane-associated companies explored various kinds of AEMs and pushed them to commercial market most of them were based on cross-linked polystyrene, polyvinyl alcohol, low (or high)-density polyethylene, and other aliphatic polymers through irradiation-grafting method. The primary objective of developing these materials was for applications in the fields such as electrodialysis, desalination, selective electrode, and waste acid recovery. However, they showed performance in AEM fuel cells far below practical... 

Materials. The fillers utilized inelude a eommercially available eom stareh, Argo Stareh, distributed by ACH Food Companies, in blend preparation and a Nanocor Nanomer montmorillonite based elay in nanoeomposites. The matrix material used in blends was high-density polyethylene (HDPE) from Equistar Chemieals (Petrothene LM6007). For the nanoeomposites, PCL from Aldrich Chemical was the matrix. 

Three homopolymers and one diblock copolymer were used. A barefoot resin of high-density polyethylene (HOPE 3000) was supplied by Petromont. Polypropylene PP PD702 was supplied by Eased, while polystyrene PS 615APR was supplied by the Dow Chemical Company. SEE CAP4741, a 1,4-hydrogenated styrene-ethylene-butylene diblock copolymer, was supplied by Shell. The materials characteristics are listed in Table 1. 

The second type of solution polymerization concept uses mixtures of supercritical ethylene and molten PE as the medium for ethylene polymerization. Some reactors previously used for free-radical ethylene polymerization in supercritical ethylene at high pressure (see Olefin POLYMERS,LOW DENSITY polyethylene) were converted for the catalytic synthesis of LLDPE. Both stirred and tubular autoclaves operating at 30—200 MPa (4,500—30,000 psig) and 170—350°C can also be used for this purpose. Residence times in these reactors are short, from 1 to 5 minutes. Three types of catalysts are used in these processes. The first type includes pseudo-homogeneous Ziegler catalysts. In this case, all catalyst components are introduced into a reactor as hquids or solutions but form soHd catalysts when combined in the reactor. Examples of such catalysts include titanium tetrachloride as well as its mixtures with vanadium oxytrichloride and a trialkyl aluminum compound (53,54). The second type of catalysts are soHd Ziegler catalysts (55). Both of these catalysts produce compositionaHy nonuniform LLDPE resins. Exxon Chemical Company uses a third type of catalysts, metallocene catalysts, in a similar solution process to produce uniformly branched ethylene copolymers with 1-butene and 1-hexene called Exact resins (56). 

In 1989, the NDF Company opened a facility in Georgetown, South Carolina to produce low density polyethylene. Manufacturing of the polyethylene is done in two 50-ton reactors that are encased individually within their own 8-story-high process unit. The main raw materials for the manufacturing operations include ethylene, hexane, and hutene. The polymerization is completed in the presence of a catalyst. The hase chemicals for the catalyst are aluminum alkyl and isopentane. The reactor and catalyst preparation areas are on a distributed control system (DCS). A simplihed process flow diagram is attached. 

Another key limitation of Z-N catalysts is the inability to incorporate very high levels of alpha-olefin comonomer such as 1-butene, 1-hexene, or 1-octene to make the density less than about 0.885 g/cm. The lowest density Z-N catalyzed VLDPE resin commercially available today (FLEXOMER from The Dow Chemical Company) has a target density of 0.885 g/cm (approximately 20 wt% crystallinity). Due to this, Z-N catalyzed VLDPE resins cannot be used in applications requiring very low modulus, low shore A hardness (density less than 0.885 g/cm ). Note that logarithm of modulus of polyethylene resins is related to density (degree of crystallinity) ... 

It should also be noted that recently a new high-pressure autoclave process has been developed by Exxon Chemical Company to produce linear low-density polyethylene using metallocene catalyst technology. Because the metallocene catalyst is a single-site catalyst, the molecular-weight distribution of the resulting polyethylene is very low (M /M = 2.0). The polymerization is carried out in a staged autoclave reactor at 1000-2000 atm and 150-250°C with 30-120 sec of reactor residence time [13]. 

Low density polyethylene (LDPE), high-impact polystyrene (HIPS), acrylonitrile butadiene styrene (ABS), and linear low density polyethylene (LLDPE) resins were used for this study. All resins were manufactured by The Dow Chemical Company. The flow rates for these resins are shown by Table 1. Coefficients of dynamic friction, shear stresses at the interface, and melting fluxes were reported previously for similar resins, but the data were not as comprehensive as those reported here, and most did not extend to high temperatures [1,3,5,9,10-12]. 

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