Low density polyethylene LDPE

Polyethylene is often categorized by its density, a measure of the mass per unit volume (e.g., g/cm or Ib/in ). When any type of polymer cools from the melt state, some of the chains may organize into highly ordered, more dense crystalline regions (Fig. 1.2). This 

The emission and consumption data shown in Table 3. 9 represent the emission and consumption levels from 27 plants that reported their data. The average age of these plants is 25 years and their average capacity in 1999 was 166 kt per year. 

The data for VOC emissions contain point sources as well as fugitive emissions which are calculated according to US EPA-21 method [48, EPA, 1989], Other calculation standards, like from VDI, will lead to different results, and are therefore not comparable. 

LDPE benchmark 1999 European average Average top 50 % Average 3rd quartile Average 4th quartile 

Redrawn from Tecnon Orbichem. Copyright Tecnon Orbichem 

LLDPE resins are ideal for downgauged lids and a variety of parts such as industrial containers, rubbish bins, automotive parts, closures, and similar items. LLDPE resins exhibit high gloss and low odour and most are suitable for packaging applications under US Food and Drug Administration (FDA) regulations. 

The disadvantages of LDPE are its low strength, stiffness, and maximum operating temperature, flammahility, poor UV resistance, high gas permeability (particularly CO ), and susceptibility to environmental stress cracking. 

it has almost totally been replaced by LLDPE. The main market for LDPE is in high-clarity products, which includes produce bags, bakery film, and textile and paper overwrap. Overall film use is declining by 0.4% per year. With the exception of extrusion coatings and adhesives and sealants, LDPE s other application segments are declining 2-3% annually, largely as a result of displacement by LLDPE. 

HDPE resins provide toughness (temperature toughness to -60 C), rigidity, and strength for blow-moulding applications, extruded and film products, and injection moulded items. They offer an excellent combination of stiffness and ESCR, and have many applications in personal care, household, industrial container, and bottle products. 

---

Low-density polyethylene (LDPE) Poly(phenyl sulfone)... 

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. 

Fig. 14. Shear viscosity, Tj, and extensional viscosity, Tj as a function of deformation rate of a low density polyethylene (LDPE) at 150°C (111). To convert...

Fig. 21. Dynamic viscoelastic properties of a low density polyethylene (LDPE) at 150°C complex dynamic viscosity Tj, storage modulus G and loss modulus G" vs angular velocity, CO. To convert Pa-s to P, multiply by 10 to convert Pa to dyn/cm, multiply by 10.

Fig. 5. Effect of surfactant type on surface resistivity, (a) Concentration of surface-active compound in low density polyethylene (LDPE) requked to achieve 10 Q/sq surface resistivity and (b) effect on surface resistivity of an acrylic polymer. Concentration of surface-active compound is 0.3%.

High pressure (60—350 MPa) free-radical polymerization using oxygen, peroxide, or other strong oxidizers as initiators at temperatures of up to 350°C to produce low density polyethylene (LDPE), a highly branched polymer, with densities from 0.91 to 0.94 g/cm. ... 

Resins and plastics such as low-density polyethylene (LDPE), high-density polyethylene (HOPE), linear low-density polyethylene (LLDPE), polypropylene, polystyrene, and polyvinyl chloride (PVC) ... 

Polyethylene is the simplest of so-called high polymers. The reaction for low density polyethylene (LDPE) follows the classical free radical polymerization steps of initiator decomposition, initiation, propagation, and termination. The reaction is... 

Low density polyethylene (LDPE). This is one of the most widely used plastics. It is characterised by a density in the range 918-935 kg/m and is very tough and flexible. Its major application is in packaging him although its outstanding dielectric properties means it is also widely used as an electrical insulator. Other applications include domestic ware, tubing, squeeze bottles and cold water tanks. 

High-pressure polymerization of ethylene was introduced in the 1930s. The discovery of a new titanium catalyst hy Karl Ziegler in 1953 revolutionized the production of linear unhranched polyethylene at lower pressures. The two most widely used grades of polyethylene are low-density polyethylene (LDPE) and high-density polyethylene (HDPE). Currently,... 

Low-density polyethylene (LDPE) is produced under high pressure in the presence of a free radical initiator. As with many free radical chain addition polymerizations, the polymer is highly branched. It has a lower crystallinity compared to HDPE due to its lower capability of packing. 

Note that, apart from the filler particle shape and size, the molecular mass of the base polymer may also have a marked effect on the viscosity of molten composites [182,183]. The higher the MM of the matrix the less apparent are the variations of relative viscosity with varying filler content. In Fig. 2, borrowed from [183], one can see that the effect of the matrix MM on the viscosity of filled systems decreases with the increasing filler activity. In the quoted reference it has also been shown that the lg r 0 — lg (MM)W relationships for filled and unfilled systems may intersect. The more branches the polymer has, the stronger is the filler effect on its viscosity. The data for filled high- (HDPE) and low-density polyethylene (LDPE) [164,182] may serve as an example the decrease of the molecular mass of LDPE causes a more rapid increase of the relative viscosity of filled systems than in case of HDPE. When the values (MM)W and (MM)W (MM) 1 are close, the increased degree of branching results in increase of the relative viscosity of filled system [184]. 

The presence of long chain branches in low density polyethylene (LDPE) accounts for the difference in properties e.g. higher melt strength, greater toughness for the same average molecular weight) between LDPE and linear low density polyethylene (LLDPE, made by coordination polymerization). 

E-plastomers, particularly the high- and medium-density materials, have found extensive use in films [17]. They are valued for their excellent seal character which allows the formation of mechanically strong seals at relatively low temperatures compared to traditional low-density polyethylene (LDPE). In addition, these E-plastomers can be obtained in a range of crystallinities and softness. These higher-density materials are typically made in the blown-film process and are used for protective film covers and disposable bags. 

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

Polyetiiylene (PE) is one of the lowest-cost polymers. There are various types of polyethylene denoted by their molecular weight. This ranges from low-density polyethylene (LDPE) through uTtrahigh-molecular-weight (UHMW) polyethylene. Physical properties, processability, and other characteristics of the polyethylene vary greatly with the molecular weight. 

Chimassorb 944 Determination in Polypropylene, High Density Polyethylene (HDPE) and Low Density Polyethylene (LDPE) by the Total Nitrogen Content Analytical Method, Code No. KC65/1, Ciba-Geigy, Basel (1980). 

Materials. Low density polyethylene (LDPE) was obtained from Dow Chemical Co., PE 510. High density polyethylene (HDPE) was obtained from Phillips Chemical, Marlex 6001. Polypropylene (PP) was obtained from Exxon Corp., Exxon PP 8216. Di-t.-butylperoxide, 99%, (DtBP) was obtained from Polysciences. Gaseous hexafluoroacetone vras obtained from Nippon Mektron Ltd., Japan. 

The plastic bottle and dispensing tip is made of low-density polyethylene (LDPE) resin, which provides the necessary flexibility and inertness. Because these components are in contact with the product during its shelf life, they must be carefully chosen and tested for their suitability for ophthalmic use. In addition to stability studies on the product in the container over a range of normal and accelerated temperatures, the plastic resins must pass the USP biological and chemical tests for... 

---