low-density polyethylene

LDPE is defined by a density range of 917–930 kg/m³.{{Cite web |url= http://www.bpf.co.uk/plastipedia/polymers/LDPE.aspx |title= Polyethylene (Low Density) LDPE, LLDPE| last=BPF |website= www.bpf.co.uk |language=en |access-date= 2018-06-14}} At room temperature it is not reactive, except to strong oxidizers; some solvents cause it to swell. It can withstand temperatures of {{cvt|65|°C|F}} continuously and {{cvt|90|°C|F}} for a short time. Made in translucent and opaque variations, it is quite flexible and tough.

LDPE has more branching (on about 2% of the carbon atoms) than HDPE, so its intermolecular forces (instantaneous-dipole induced-dipole attraction) are weaker, its tensile strength is lower, and its resilience is higher. The side branches mean that its molecules are less tightly packed and less crystalline, and therefore its density is lower.

When exposed to consistent sunlight, the plastic produces significant amounts of two greenhouse gases: methane and ethylene. Because of its lower density (high branching), it breaks down more easily than other plastics; as this happens, the surface area increases. Production of these trace gases from virgin plastics increases with surface area and with time, so that LDPE emits greenhouse gases at a more unsustainable rate than other plastics. In a test at the end of 212 days' incubation, emissions recorded were 5.8 nmol g⁻¹ d⁻¹ of methane, 14.5 nmol g⁻¹ d⁻¹ of ethylene, 3.9 nmol g⁻¹ d⁻¹ of ethane, and 9.7 nmol g⁻¹ d⁻¹ of propylene. When incubated in air, LDPE emits methane and ethylene at rates about 2 times and about 76 times, respectively, more than in water.{{cite journal |last1=Karl |first1=David M. |last2=Wilson |first2=Samuel T. |last3=Ferrón |first3=Sara |last4=Royer |first4=Sarah-Jeanne |title=Production of methane and ethylene from plastic in the environment |journal=PLOS ONE |date=1 August 2018 |volume=13 |issue=8 |pages=e0200574 |doi=10.1371/journal.pone.0200574 |language=en |issn=1932-6203|pmc=6070199 |pmid=30067755 |bibcode=2018PLoSO..1300574R |doi-access=free }}{{cc-notice|cc=by4|author=Royer et al}}

• Excellent resistance (no attack/no chemical reaction) to dilute and concentrated acids, alcohols, bases, and esters
• Good resistance (minor attack/very low chemical reactivity) to aldehydes, ketones, and vegetable oils
• Limited resistance (moderate attack/significant chemical reaction, suitable for short-term use only) to aliphatic and aromatic hydrocarbons, mineral oils, and oxidizing agents
• Poor resistance, and not recommended for use with halogenated hydrocarbons.{{cite journal |last1=Qiu |first1=Xia-Wen |last2=Pei |first2=Jie |last3=Wu |first3=Chen-Chou |last4=Song |first4=Lin |last5=Bao |first5=Lian-Jun |last6=Zeng |first6=Eddy Y. |title=Determination of low-density polyethylene–water partition coefficients for novel halogenated flame retardants with the large volume model and co-solvent model |journal=Chemosphere |date=August 2021 |volume=277 |pages=130235 |doi=10.1016/j.chemosphere.2021.130235 |pmid=33794435 |bibcode=2021Chmsp.27730235Q |s2cid=232764239 }}{{cite web |title=LDPE Chemical Compatibility Chart |publisher=CP Lab Safety |url=http://www.calpaclab.com/ldpe-chemical-compatibility-chart/}}

File:Plastic_(LDPE)_bowl,_by_GEECO,_Made_in_England,_c1950.jpg

File:LDPE Foam.jpg made from LDPE]]

File:A Ziploc bag made from LDPE.jpg

File:Facial wash gel bottle made of LDPE.jpg

Polyolefins (LDPE, HDPE, PP) are a major type of thermoplastic.{{cite journal |last1=Achilias |first1=D.S. |last2=Roupakias |first2=C. |last3=Megalokonomos |first3=P. |last4=Lappas |first4=A.A. |last5=Antonakou |first5=Ε.V. |title=Chemical recycling of plastic wastes made from polyethylene (LDPE and HDPE) and polypropylene (PP) |journal=Journal of Hazardous Materials |date=November 2007 |volume=149 |issue=3 |pages=536–542 |doi=10.1016/j.jhazmat.2007.06.076 |pmid=17681427 |bibcode=2007JHzM..149..536A }} LDPE is widely used for manufacturing various containers, dispensing bottles, wash bottles, tubing, plastic parts for computer components, and various molded laboratory equipment. Its most common use is in plastic bags. Other products made from it include:

• Trays and general purpose containers
• Corrosion-resistant work surfaces
• Parts that need to be weldable and machinable
• Parts that require flexibility, for which it serves very well
• Very soft and pliable parts such as snap-on lids
• Six-pack rings
• Juice and milk cartons are made of liquid packaging board, a laminate of paperboard and LDPE (as the waterproof inner and outer layer), and often with of a layer of aluminum foil (thus becoming aseptic packaging).[http://www.exxonmobilchemical.com/Chem-English/productsservices/polymers-ldpe-products-applications.aspx LDPE products and applications]. Exxon Mobil Corporation[https://web.archive.org/web/20080101220903/http://www.ides.com/grades/ds/E7178.htm DOW LDPE 5004I]. IDES – The Plastics Web
• Packaging for computer hardware, such as hard disk drives, screen cards, and optical disc drives
• Playground slides
• Plastic wraps
• Plastic bags
• Plastic containers
• Pipes
• Housewares
• Battery cases
• Automotive parts
• Electrical components

• Film blowing machine
• High-density polyethylene (HDPE)
• Linear low-density polyethylene (LLDPE)
• Medium-density polyethylene (MDPE)
• Polyethylene terephthalate (PET/PETE)
• Stretch wrap
• Ultra-high-molecular-weight polyethylene (UHMWPE)

{{reflist}}

• {{Commons category-inline}}
• [http://www.epa.gov/osw/nonhaz/municipal/pubs/2010_MSW_Tables_and_Figures_508.pdf 2010_MSW_Tables_and_Figures_508.pdf]. epa.gov

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Category:Polyolefins

Category:Plastics

Category:Packaging materials

Category:British inventions

Category:Food packaging