Low Density Polyethylene (LDPE) Labware

The polymerization of polyethylene results in an essentially straight chain, high molecular weight hydrocarbon.  The polyethylenes are classified according to the relative degree of branching (side chain formation) in their molecular structures, which can be controlled with selective catalysts. LDPE has more side branching than HDPE resulting in a less-dense 3-D structure.  As a result, LDPE is naturally very flexible without the addition of plasticizers and melts at a relatively low temperature (85°C).

Like other polyolefins, LDPE is chemically inert.  Strong oxidizing agents will eventually cause oxidation and embrittlement.  LDPE has no solvent at room temperature.  Aggressive solvents will cause softening or swelling, but these effects are normally reversible. LDPE can be damaged by long-term exposure to UV light.   

Low density polyethylene is used to make Nalgene bottles, wash bottles, carboys, dropper bottles and other items where flexibility, impact strength and long-term chemical compatibility are key requirements. Nalgene LDPE resins have very low trace metal content making Nalgene LDPE bottles popular for use in trace metals analysis labs. 

The following table contains general use exposure ratings at 20°C.  The ability of plastic materials to resist chemical attack and damage is dependent also on temperature, length of exposure to the chemical and added stresses such as centrifugation.  For more detailed chemical resistance ratings for Nalgene products and materials, please consult the resources referenced at the bottom of this page.

*except for oxidizing acids: for oxidizing acids, see "Oxidizing agents, strong."

Plasticizer myth
It is a common myth that all lab plastics contain phthalate plasticizers in order make them pliable or flexible. Nalgene LDPE products are naturally flexible without the addition of any plasticizers, so there’s no need to worry about phthalate plasticizers leaching from Nalgene LDPE labware.

Material identification
LDPE is not autoclavable; it will melt into a puddle in your autoclave. Don’t mistake your LDPE carboy for a polypropylene one and accidentally autoclave it or the results will be catastrophic to the carboy and potentially damaging to your autoclave. You can identify the material your Nalgene bottle or carboy is made from by looking at the bottom of the container.  The resin code will be molded into the bottom (“LDPE” for example). It is best practice to always check the resin code on the bottom of a bottle or carboy before each autoclave cycle to confirm the material of construction and determine if it’s autoclavable.

Plastic aging
LDPE labware will age over time. If labware pieces are permanently discolored (yellow, brown, pink, etc.), if you see cracks or spiderweb-like “crazing” beginning to occur, it’s probably time to replace your old labware. A squeeze of your Nalgene LDPE bottle should feel soft and flexible; if you instead hear or feel crackling, immediately retire your bottle and replace it to prevent failure in use. To slow the aging process and prolong the life of your LDPE labware, store products in a cabinet out of direct exposure with UV light (including overhead indoor lighting), use only with compatible chemicals, and wash with a pH neutral detergent like Nalgene L900.

Recyclability
LDPE products are recyclable in most communities (recycle code 4).  Most Nalgene LDPE products are reusable and will last a long time under typical lab conditions if used appropriately, but you can recycle them at the end of their lifetime as long as they are thoroughly cleaned for safe handling. 

Footnotes:
[1]. Heat Deflection Temperature is the temperature at which an injection molded bar deflects 0.1” when placed under 66 psig (ASTM D648) of pressure.  Materials may be used above Heat Deflection Temperatures in non-stress applications; see Max. Use Temp.
[2]. Max. Use Temp. °C: this is related to the maximum continuous use temperature, ductile/brittle temperature and glass transition temperature and represents the highest temperature at which the polymer can be exposed for the matter of minutes to 2 hours where there is little or no loss of strength.
[3]. The brittleness temperature is the temperature at which an item made from the resin may break or cracked if dropped. This is not the lowest use temperature if care is exercised in use and handling.
[4]. STERILIZATION: Autoclaving (121° C, 15 psig for 20 minutes) -- Clean and rinse items with distilled before autoclaving. (Always completely disengage thread before autoclaving.) Certain chemicals which have no appreciable effect on resins at room temperature may cause deterioration at autoclaving temperatures unless removed with distilled water before hand.
     EtO Gas -- Ethylene Oxide: 100% EtO, EtO:Nitrogen mixture, EtO:HCFC mixture
     Dry Heat -- exposure to 160° C for 120 minutes without stress/load on the polymer parts
     Disinfectants -- Benzalkonium chloride, formalin/formaldehyde, hydrogen peroxide, ethanol, etc.
     Radiation -- gamma or beta irradiation at 25 kGy (2.5 MRad) with unstabilized plastic.
[6]. “Yes” indicates the resin has been determined to be non-cytotoxic, based on USP and ASTM biocompatibility testing standards utilizing an MEM elution technique with WI38 human diploid lung cell line.
[7]. Resins meet requirements of CFR21 section of Food Additives Amendment of the Federal Food and Drug Act. End users are responsible for validation of compliance for specific containers used in conjunction with their particular applications.
[8]. Acceptable for:
   - Nonacid, aqueous products; may contain salt, sugar or both (pH above 5.0)
   - Dairy products and modifications; oil-in-water emulsions, high or low fat
   - Moist bakery products with surface containing no free fat or oil
   - Dry solids with the surfaces containing no free fat or oil (no end-test required) and under all conditions as described in Table 2 of FDA Regulation 177.1520 except condition A - high temperature sterilization (e.g. over 100°C / 212°F)
[12]. Ratings based on 5-minute tests using 600 watts of power on exposed, empty labware. CAUTION: Do not exceed Max. Use Temp., or expose labware to chemicals which heating cause to attack the plastic or be rapidly absorbed.

For assistance choosing products appropriate for your application, plesae speak with a Nalgene Technical Support Representative team by phone at +1 585 586 8800 or (1 800 625 4327 US toll free), or email your request to technicalsupport@thermofisher.com.

In Austria, France, Germany, Ireland, Switzerland and the United Kingdom please contact technical support by phone at +800 1234 9696 (toll free) or +49 6184 90 6321, or email your request to techsupport.labproducts.eu@thermofisher.com.

Regulatory Support:  For regulatory documentation of product or material claims, please contact Nalgene Regulatory Support at RocRegSupport@thermofisher.com