Name and synonyms for LLDPE:
IUPAC-Name (International Union of Pure and Applied Chemistry) for polyethylene:
Poly(ethene) Synonyms: PE-LLD, LLD-PE, linear high pressure polyethylene
(Synonyms for polyethylene: Poly(methylene), Polythene)
German: Lineares Hochdruck-Polyethylen (LLD-PE)
Spanish: polietileno lineal de baja densidad (PELBD)
French: polyéthylène à basse densité linéaire (PE-BDL)
Italian: polietilene lineare a bassa densità (PE a.d.)
Russian: Линейный полиэтилен высокого давления
Arabic: البولي إثيلين الخطي منخفض الكثافة
Chinese: 線性低密度聚乙烯
Japanese: 直鎖状低密度ポリエチレン
Basic information on LLDPE:
Chemical formula: (CH2=CH2)n (general polyethylene)
CAS-Nr.: 9002-88-4 (general polyethylene)
ESIS entry: -- (no EINECS or ELINCS registration)
LLDPE is a semi-crystalline thermoplastic polymer, which belongs to the polyolefin group and is manufactured through the copolymerization of ethylene with the help of catalysts and with long-chain olefins, like butane, hexene, or octane. LLDPE is a versatile plastic that combines the strength of high density polyethylene (HDPE) with the flexibility of low density polyethylene (LDPE). Approximately XX million tons of LLDPE were sold worldwide in 2007.
Both elastic and rigid products are manufactured from LLDPE, and mixtures with LDPE or HDPE are often utilized. Among other things, thin films can be produced from this material. In addition, LLDPE is processed into packaging made up of several layers. It is relatively transparent, extremely ductile, and rigid. These characteristics are also advantageous for the production of larger products, such as lids and containers.
LLDPE is a byproduct of the invention of HDPE. Since it was first introduced to the market in the 1970's, LLDPE has seen the fastest growth rate of the three largest polyethylene grades. Manufacturers around the world continue to work on new types of LLDPE for a wide range of applications.
Information on manufacturing and processing methods, as well as catalysts can be found in Market Study Polyethylene - LLDPE, available soon from Ceresana Research.
Important characteristics of LLDPE:
Parameter: LLDPE:
Density (g/cm³) ~ 0.925 - 0.940
Melting point (°C) between 112 and 124
Service temperature (°C) 90 to 110 (maximum continuous use temperature)
Tensile strength (N/mm²) 0,0276 to 50
Tensile strength at break (N/mm²) 13 to 27
Chemical resistance Affected by strong acids; stable in alcohols, alkaline and saline solutions; not affected by weak organic or inorganic acids. Soluble at high temperatures in certain aromatic compounds, aliphatic and aromatic hydrocarbons.
LLDPE only contains short-chain branches, which are not evenly distributed across the molecular weight. This lack of long-chain branches produces a crystalline polymer with a high melting point and little clarity. LLDPE is very flexible and has better elastic characteristics than LDPE. It has greater tensile strength than LDPE, and it also exhibits superior impact and puncture resistance. LLDPE can be processed into films of lower density - which helps to save resources. LLDPE has a better resistance to environmental stress cracking than LDPE, however, it is not easy to process, has very little gloss, and has a narrow range for heat sealing.
An overview of LLDPE's most important characteristics, as well as detailed information on additives and fillers used in this plastic are provided in Market Study Polyethylene - LLDPE, available soon from Ceresana Research.
Hazard indications for LLDPE:
No mandatory danger symbols (R/S statements) are required to label LLDPE. The plastic is considered to be safe and non-toxic, and is used in applications that come into contact with foods, drinking water, and medications. Health concerns and provisions for LLDPE only relate to the use of pigments and other additives which can migrate from the material. LLDPE is easily recyclable. Particulate matter can accumulate during transportation, which is why the risk of dust explosions must be taken into consideration.
Additional information on environmental discussions on plastics, legal issues, work safety, and various recycling methods can be found in Market Study Polyethylene - LLDPE, available soon from Ceresana Research.
LLDPE Manufacturing Methods:
LLDPE is a linear polymer with a vast number of short branches, and is manufactured with the same low-pressure, catalytic polymerization method as HDPE. However, its density is reduced by the incorporation of longer alpha-olefins as comonomers (principally butene, hexane, and octane). Copolymerization produces an LLDPE polymer with a narrower molecular weight distribution than traditional LDPE and different rheological properties. Today, all low-pressure polymerization methods (suspension, solution, and the most commonly used vapor phase processes) utilize high mileage catalysts. The remains of these catalysts can remain in the polymers. LLDPE, manufactured using metallocene catalysts, is referred to as mLLDPE.
Detailed information on LLDPE production, Ziegler-Natta and metallocene catalysts, as well as LLDPE processing is provided in Market Study Polyethylene - LLDPE, available soon from Ceresana Research.
Application examples for LLDPE:
LLDPE covers almost all traditional markets for polyethylene: It is used for plastic sacks and sheets (where narrower thickness is allowed than that provided by LDPE), for plastic packaging, stretch-wrap packaging, bags, lids, pipes, buckets and containers, cable insulation, geomembranes and flexible tubes. Its flexibility and elasticity make LLDPE the preferred choice for applications where a product, such as a children's toy, is exposed to frequent impacts.
For the most part, LLDPE is applied to film applications, where it has commonly displaced LDPE due to its superior strength characteristics, downgauging potential, and cost benefits. Today, trash bags, shopping bags, stretch films, and food packaging films are predominantly manufactured from LLDPE or LLDPE-rich composites, on account of its tensile strength, as well as impact and tear characteristics. In these respects, LLDPE is also superior to HDPE. On the other hand, traditional LLDPE cannot be applied to shrink-wrap.
The second-largest application area for LLDPE is that of injection molded products, such as garbage cans, buckets, food containers, lids and caps, sporting goods, and medical equipment. LLDPE has advantages over LDPE, with regard to mechanical characteristics: better resistance to environmental stress cracks, reduced warping and shrinking, rigid at low temperatures. Use of LLDPE with a high melt flow index allows for accelerated production and cost reductions. LLDPE is also preferred over polypropylene for low-temperature applications. In comparison to conventional LLDPE, metallocene catalyst resins offer improved impact resistance, less brittleness among high melt flow indices, as well as less odor and taste transfer.
Metallocene catalyzed LLDPE is processed using rotational molding, primarily because of shorter cycle times, lower energy consumption, a broader processing window, and greater impact resistance in comparison to traditional LLDPE. Rotational molding is most commonly applied to the manufacture of very large goods that are usually produced in relatively small amounts, such as children's toys, lawn furniture, and traffic bollards.
LLDPE is not used in plastic pipes as often as HDPE. Typical applications include irrigation pipes and flexible tubes with small dimensions. LLDPE has better bursting strength, as well as resistance to heat and environmental stress cracking than LDPE. Plastomer grades can substitute PVC in medical-purpose tubes.
Market Study Polyethylene - LLDPE, available soon from Ceresana Research, offers comprehensive information on consumption amounts within individual application areas and divides them among the different world regions.
LLDPE manufacturers:
(->for more info see Market Study Polyethylene - LLDPE, available soon from Ceresana Research)
Last revision: 19.01.09
