Polyethylene Plastic PE Films Glossary

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There are currently 56 glossary in this directory
ANTIBLOCK
Additive used to give surface of film a rougher texture at a microscopic level. Without additives, film has tacky texture similar to cling wrap. Prevents film from sticking together, or "blocking". Diatomaceous earth is the most common.
ANTISTAT
Plastic has a natural tendency to attract static electricity. Additives put in to dissipate static are referred to as antistats. There are many standardized tests, such as MIL B – 81705C to measure the effectiveness of antistatic agents. CLICK HERE to learn more about our anti-stat film.
BAREFOOT POLYETHYLENE
Resins which have no additives (slip or antiblock). PE films made with barefoot resins are always very slow slip / high COF (Coefficient of Friction)
BIODEGRADABLE PLASTIC
A degradable plastic in which the degradation results from the action of naturally occurring micro-organisms such as bacteria. There are a multitude of evolving standards. Visit our biodegradable plastic film page to learn more.
BUTENE
Can be used as a monomer in the formation of polymers, most commonly linear low density polyethylene, hence the name "butane LLDPE". For more in-depth information on LLDPE visit our blog.
CAMBER
As it applies to blown polyethylene film, camber is the tendency of any straight line to eventually curve. Also known as "dishing", any film which does not unroll perfectly straight will cause machinability issues in printing presses, bag machines, shrink tunnels and vertical form fill & seal VFFS machines.
CENTERFOLD
Film which is folded on one side and open on the other. Centerfold A Centerfold B
CLEAR CLARITY
see HAZE
COF (COEFFICIENT OF FRICTION) / ASTM D 1984
While COF is usually measured film-to-film which makes sense for applications such as beverage shrink wrap, the interface is usually between film and stainless steel in VFFS vertical form / fill / seal, HFFS horizontal form / fill / seal and bakery bread applications. Stainless steel has a high surface energy of around 75 dynes, so it is reasonable to expect different results vis-à-vis film-to-film.
What is high slip, medium slip and low slip? The Flexible Packaging Association defines the ranges of slip (high, mediuim and low) and the kinetic coefficient of friction, when tested, film-to-film, in accordance with ASTM D 1984, as follows:
Surface C.O.F.
Low Slip Greater than 0.5
Medium Slip 0.2 to 0.5
High Slip Less than 0.2
COMONOMER
A monomer which is combined with a different monomer to make a polymer. A common example is EVA (ethylene vinyl acetate) / PEVA.
DART DROP TEST / ASTM D 1709A
Determines resistance to puncturing of the film. Measured in grams.
DENSITY
Measure of how closely molecules are packed together. Called out as the number of grams per cubic centimeter. General purpose low density PE films are around .925 gm/cc. Density affects characteristics of film. Density ranges are as follows:
Low Density Under .929
Medium Density .930 to .940
High Density Over .940
DIFFERENTIAL SCANNING CALORIMETRY (DSC) MELTING POINT
Used to measure the melting point of plastics. Different test method that vicat softening point, so different values result.
DOUBLE WOUND SHEETING
Two plies of sheeting wound together.
Double Wound Sheeting
DYNE LEVEL
Measure of surface tension. Higher level of surface tension is achieved by passing an electrical charge across the film. The higher the value, the greater the amount of tension. Untreated film has a natural dyne level of about 33. For film to accept adhesive coatings and solvent-based ink for printing, it is necessary to treat film to 38 to 40 dynes. For water-based inks and laminations, a treat level of 45 dynes is required.
ELMENDORF TEAR TEST / ASTM D1922
Originally developed to measure tear resistance of paper, this test measures the resistance to tearing. Learn about the ASTM D1922 test method.
ETHYLENE C2H4
The basic monomer building block of polyethylene, extracted from either natural gas or naptha. Note: neither of these feedstocks is suitable for deriving gasoline.
EVA
Short for ethylene-vinyl acetate. Also vinyl acetate copolymerized with polyethylene. It is a copolymer that enhances sealability and clarity. The higher the VA percentage, the lower the melting point and stiffness. High percentage EVA's are popular choice for total batch inclusion bags which must melt often at temperatures less than 200°F. Very low density metallocenes have rendered EVA obsolete for applications requiring fast tack and low seal initiation temperature.
FDA Approval
The US Food and Drug Administration never actually approves a resin for prolonged and direct food contact. A resin can only be listed as compliant with CFR 212, section 177.1520, 175:30 (or 21 CFR 177.1630 sections h(1), (ii) ) for prolonged and/or direct contact for food packaging. Visit our blog to learn more about what FDA compliance really means.
FLAME RETARDANT(FR)
PE film with additives to retard the natural flammability of polyethylene. By definition it is tough. Polyethylene is long strings of ethylene natural gas.
FRACTIONAL MELT
Resin which has a melt index less than 1.0, as measured by ASTM D 1238 (see melt index below), hence the name "fractional" .
GAUGE
Thickness of film. In English units, gauge is measured in mils or 1/1000 of an inch. The metric unit of measure is microns. The symbol for microns is μm. Click here to visit our Polyethylene Film Weights and Measures page to learn more about mils and microns.
GELS
Unmelted particles of plastic that are not necessarily impurities. Click below to look at AEP/Berry Plastics specifications for gels. Click here!
GLOSS 45°
Measure of how much light is reflected by a film. Learn more about the ASTM D 2457 test method.
GUSSET
Folds, or "pleats" put into film as it is collapsed. ½ of the total gusset width is on each side. Visit our GUSSET page for more information.
HAZE
Measure of clarity of film. Expressed in percent. For example, a resin which has a haze of 5.5 allows 94.5% of light to pass through the film. Learn more about ASTM D 1003. Haze is crucially important for optimum product presentation at retail, especially when ink coverage is over 90 %
Ink Coverage
HEAT SEAL
HEXENE
Used as a monomer in the formation of polymers, usually LLDPE resin. Stronger film strength than butene. Visit our blog to learn more about the varieties of LLDPE.
HIGH DENSITY POLYETHYLENE ( HDPE )
Polyethylene resin with a density over .940 gm/cc. Much stiffer than low density polyethylene. Common examples of HDPE are milk jugs, motor oil bottles and plastic grocery sacks.
IONOMER
Copolymers of ethylene and acrylic acids that have been neutralized to some degree to form metal salts. The dramatic bond strength from the most commercial brand, Surlyn® from DuPont, results from an ion which shares orbits with adjacent molecules.
IQF Individually Quick-Frozen
Freezes bagged meat or vegetables rapidly by exposing it to blast of air at approximately -40° F. To avoid cracking at sub-freezing temperatures, either a very low density metallocene or some EVA should be a component of the PE blend. Visit our IQF page for more information.
J Sheet
Film which looks like the letter "J". Has a "short" and "long" side. Visit the J SHEET page for more information.
J Sheet A Wind J Sheet B Wind
Layflat Tubing
Flexible polyethylene tubing which has been pressed flat. Layflat Tubing
Layflat Tubing
Layflat Tubing
Visit our Lay Flat tubing page for more information.
LINEAR LOW DENSITY POLYETHYLENE ( LLDPE )
Polyethylene which has more crystallinity than LDPE. Can be produced with butene, hexene or octene comonomer for a wide variety of properties usually stronger than conventional LDPE. Visit our LDPE page for more information.
LOW DENSITY POLYETHYLENE ( LDPE )
Polyethylene having a density ranging from .915 to .929 grams/cc. Visit our LDPE page for more information.
MACHINE DIRECTION (MD)
Direction the film is being pulled through a machine much like the direction of woodgrain.
MEDIUM DENSITY POLYETHYLENE ( MDPE )
Polyethylene having a density ranging from .929 to .940 grams/cc. Learn more from our blog post What is Polyethylene?
MELT INDEX (MI)
a.k.a "melt flow index" or "melt flow rate". Measure of viscosity (resistance to flow) of a resin by ASTM D 1238. The amount of polymer which exits the die in ten minutes is measured in grams. In general terms, the lower melt index resin which has more viscosity will be stronger than a higher melt index and trade off clarity or haze. If the number of grams extruded is less than 1, the resin is referred to as a "fractional melt" (less than 1.0.)
METALLOCENE
Latest generation of resin technology utilizing a metallocene catalyst which is basically tiny particles of positively charged metal ions sandwiched between two rings of carbon atoms that have five atoms apiece. Metallocene is not a comonomer; it is a catalyst which imparts consistent molecules. Metallocenes are not necessarily stronger than LDPE or LLDPE.
MIL
One thousandths ( 1/ 1000 ) of an inch expressed as "001". Metric equivalent is 25.4 microns.
MONOMER
Small molecule ( ethylene, propylene, styrene, etc. ) that may become chemically bonded to other monomers to form a polymer.
OCTENE
Comonomer in production of usually linear low density ( LLD ) polyethylene.
OTR
Oxygen transmission rate as measured by ASTM D 3985. Measure of the amount of oxygen which passes across the film.
POLYETHYLENE
Polyethylene is comprised of long chains of the building block ethylene monomer. How these chains are put together determine the wide variety of resin properties. Polyethylene is the largest volume thermoplastic resin. As such, it has a wide variety of uses. Worldwide, there are probably hundreds of grades just for film alone.
PROPOSITION 65
Proposition 65, otherwise known as the Safe Drinking Water and Toxic Enforcement Act of 1986 or Prop 65 was a voter initiative passed into law to address public concern over exposure to unsafe and toxic chemicals in the State of California.
SEAL INITIATION TEMPERATURE
Measure of lowest temperature at which the required hot tack and seal strength levels are both achieved. Seal range is the temperature range over which hot tack and seal strength are greater than the acceptable minimum required levels. Maximum hot tack level indicates what maximum loading the sealing material can sustain during the packaging cycle.
SECANT MODULUS
Measure of stiffness. Higher the number, the stiffer the film. ASTM D 882
SINGLE WOUND SHEETING
Slip
Slip is added to polyethylene resin to make it slipperier as the name implies. Slip agent, most commonly an erucamide or oleamide, exhibits a "blooming" phenomenon. Slip exudes to the surface of the polyethylene film to create a lubricated effect on the finish, or coefficient of friction (COF). A common example of a very high slip film is a bread bag. The same parts per million of slip produces a higher slip / lower COF film as gauge is increased. This is explained by what is known as the reservoir effect. The same parts per million exuding to the surface area of a thicker film has a larger reservoir of slip which all wants to get to the surface. Two applications which should never have slip are medical applications involving gamma irradiation sterilization and tamper evident bags with a tape closure.
TRANSVERSE DIRECTION
Cross direction or sideways dimension 90° orientation to the machine direction.
TREAT
a.k.a. corona discharge treatment. Method of raising the surface energy and to some extent etching of films in order to accept adhesives and inks. Most commonly achieved by arcing of electricity across the film. "Corona" refers to the original method of flame treating.
ULDPE /VLDPE
Specialized form of linear low-density polyethylene having density between .86 and .90 grams/cc. Learn more from our What is Polyethylene? blog post.
UVI ULTRAVIOLET INHIBITOR
Retards the degrading effect of sunlight on polyethylene.
VLDPE
Specialized form of linear low-density polyethylene having density between .86 and .90 grams/cc. Learn more from our blog post What is Polyethylene?
Yield
Net weight per 1,000 lineal feet of film. We have Polyethylene Film Weights and Measures for calculating yields.
More Resources
PE Films Weights and Measures
Converting weight to area is easy.
Polyethylene Plastic
PE Films Glossary
We have compiled a list of PE film terms and definitions.
Certifications and
Regulatory Compliance
Brentwood Plastics film and materials meet several certifications.
PE Film
Data Sheets
Chances are we have a time-tested PE Film for tyour application.

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