HDPE containers, blow-molded

Figure 4 Commercially blow-molded HDPE containers. Elongation retention of blow-molded, high density polyethylene .05-in. wall container sections pigmented with phthalocyanine green, chrome yellow, and Ti02 (rutile) as a 6 function of UV exposure.

In South Africa, owing to the diversity and small production volume of specific motor car models, it is not economically feasible to blow-mold HDPE fuel tanks. The only cost-effective plastic tank manufacturing process used in South Africa is rotational molding, using LLDPE with a density of 0.939 g/cm3. Some selected properties of LLDPE before and after petrol exposure are compared to HDPE in Table 16.2. It is clear that owing to weaker mechanical properties, LLDPE is far less suitable than HDPE for petrol containment, mainly because of its lower crystallinity. 

The PA/PE grafted blend was offered commercially as a concentrate (Selar RB) to be melt blended with HDPE to a final PA/HDPE ratio = 15/85 for subsequent blow molding into containers such as gasoline tanks, solvent containers, etc. This laminar barrier blend of HDPE and PA was reported to provide up to 100 fold improvement in the barrier to permeation of such organic solvents as toluene, relative to pure HDPE, or a similar blend composition containing PA as a uniform spherical dispersion. 

Squeeze bottles, toys, housewares, lids, containers made from LDPE. Blow-molded HDPE used as containers for bleaches, liquid detergents, milk and other beverages, automobile and truck gas tanks, crates and pails... 

As technology developed to better handle this and other contamination issues, and as pressure to recycle plastics moimted, HDPE milk bottle recycHng expanded and many programs began to included nonmilk bottle HDPE containers. Now the majority of curbside and drop-off collection programs for recyclables include blow-molded HDPE bottles as one of the materials collected. The recychng rate for HDPE milk and water bottles in the United States in 1996 was 30.8% according to the U.S. 

Polyethylene, HDPE, MDPE. Applications injection molding for domestic parts and industrial parts blow molding for containers and sports goods extrasion for pressure pipes, pipes, electrical insulating material, bags, envelopes, and tissue. 

Blow-molded products represent the biggest use of HDPE resins, at around 40%. Packaging appHcations account for by far the greatest share of this market. These include such products as botties (especially for milk, juice, and soap), housewares, toys, pails, dmms, and tanks. Expected aimual average growth rates for these appHcations are about 5—6%. Injection-molding products are the second largest appHcation, with approximately 20% of the HDPE market. These products include housewares, toys, food containers, pails, crates, and cases. 

Low-density polyethylene (LDPE) film for food packaging, etc. High-density polyethylene (HDPE) blow molded into bottles and containers... 

Blow-molded containers, hot fill applications for, 20 50-52 Blow molded food packaging, 18 49-51 Blow-mold-fill-seal food packaging, 18 51 Blow molding, 10 179, 193-194 19 553-554 23 399 ABS, 1 427 HDPE, 20 171-172 LDPE, 20 237 LLDPE, 20 200... 

Typical HDPE—blow-molded products bottles, cans, trays, drums, tanks, and pails injection-molded products housewares, toys, food containers, cases, pails, and crates films, pipes, bags, conduit, wire and cable coating, foam, insulation for coaxial and communication cables... 

Packaging films (extruded, blown, and cast) are used in pressure-sensitive tapes and electrical applications and as replacements for cellophane and glassine films in liners for cereal boxes, wraps for snack foods, cigarettes, bread, and cheese. Blow-molded containers are used in applications where the higher use temperature of polypropene is needed (compared to HDPE), such as in packaging of syrups that are hot-filled. 

With a simple parison, the large-diameter sections of the bottle have a thin wall and the small-diameter sections have a thick wall. Certain modifications of the die can control the thickness of the parison wall along its length, which results in a botde with improved wall thickness distribution and better strength. High density polyethylene (HDPE) is the most common blow molding resin used to produce containers ranging in size from 30 cm3 to 200 L. 

HDPE is alinear polymer with the chemical composition ofpolymethylene, (CII2V Depending on application, HDPE molecules either have no branches at all. as in certain injection molding and blow molding grades, or contain a small number of branches which are introduced by copolymerizing ethylene with o-olefins, e g., ethyl branches in the case of 1-butene and -butyl branches in the case of 1-hexene. The number of branches in HDPE resins is low, at most 5 to 10 branches per 1000 carbon atoms in the chain. 

Blends of PET and HDPE have been suggested to exploit the availability of these clean recycled polymers. The blends could combine the inherent chemical resistance of HDPE with the processing characteristics of PET. Since the two polymers are mutually immiscible, about 5% compatibilizer must be added to the molten mixture (41). The properties of polymer blends containing 80—90% PET/20—10% HDPE have been reported (42). Use of 5—15% compatbilizer produces polymers more suitable for extmsion blow molding than pure PET. 

Other applications for THV are flexible liners (drop-in liners or bag liners), used in chemical process industries and other industries, and blow-molded containers, where it enhances the resistance to permeation when combined with a less expensive plastic (e.g., high-density polyethylene-HDPE), which provides the structural integrity.61 Optical clarity, excellent weatherability, and flexibility make THV suitable as a protection of solar cell surface in solar modules.63... 

Figure 3. Hydrocarbon (unleaded gasoline) permeability (weight loss, g) in blow molded containers from polyethylene (HDPE) and polyethylene/nylon blends. (Reprinted with permission from Ref. 1. Copyright 1984 Technical Association of Pulp and Paper Industry.)...

Sample Preparation. The experimental containers were 16 oz. cylindrical bottles prepared by extrusion blow molding of Rexene B54-25H grade HDPE resin from Soltex Corp. (0.954 g/cc density). 

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