Every term that matters in blow molding, injection molding, films and packaging chemistry - defined plainly, A to Z.
⏱ Reference page · updated October 2026
The vocabulary of plastics is the first barrier between a buyer and a good quotation. This glossary defines the terms our engineers use every day - from melt index to EVOH, parison to corona treatment - in plain language, with the packaging context that makes each one matter. Filter as you type, or jump to a letter.
Tough, rigid engineering thermoplastic (acrylonitrile butadiene styrene) used for machine housings, panels and durable rigid components.
Any chemical blended into resin to add properties - UV protection, color, slip, antistatic, clarification - typically dosed between 0.05% and a few percent.
Plastics with no ordered molecular structure - clear but softer when heated (PS, PC, PVC), as opposed to semi-crystalline resins.
Controlled slow heating and cooling of finished parts to release internal stresses and improve dimensional stability.
Surface treatment that stops water condensing as visible droplets on clear film - essential for fresh-produce packaging.
Silver-ion or similar system blended into plastic to inhibit bacterial growth on the pack surface.
Additive that stops polymer degrading during melt processing and long storage - phenolics and phosphites dosed at 0.05-0.3%.
Additive that dissipates static charge so dust does not cling to packaging - glycerol monostearate and ethoxylated amines are typical.
American Society for Testing and Materials - the body whose test methods define how plastic properties like impact and melt flow are measured.
Resistance applied to the screw during recovery in injection molding - controls melt mixing and temperature consistency.
Specialist layer in multi-layer packaging (EVOH, foil, PVDC) that blocks oxygen, moisture or aroma to extend shelf life.
Material designed to break down biologically - standards like EN 13432 define the conditions; not the same as compostable.
Pre-formed plastic cavity, usually PVC or PET, sealed to a backing card - standard for pharmaceuticals and small goods.
Process that inflates a hot plastic tube (parison) inside a mold to make hollow items - bottles, jerrycans and drums.
Ratio of bubble diameter to die diameter in film blowing - controls film width and orientation balance.
Biaxially oriented polyamide (nylon) film - extreme puncture resistance for retort pouches, vacuum packs and frozen food.
Biaxially oriented PET film - strong, clear, high-barrier web used in laminates and metallizing.
Biaxially oriented polypropylene film - crystal clear, stiff and printable; the workhorse of snack and label packaging.
PET resin with intrinsic viscosity 0.72-0.84 and controlled acetaldehyde - engineered specifically for stretch-blow bottles.
Pressure at which a container or film ruptures - a key safety metric for bags and flexible packaging.
The most common mineral filler - adds stiffness and reduces cost, dosed 5-40% depending on the grade.
Soft sealing element inside a cap (TPE, foam or linerless design) that creates the seal against the bottle finish.
Pigment and UV blocker for black plastics - also the masterbatch that hides light-sensitive contents.
Film produced by extruding onto a chilled roller - clear, calm and excellent for laminating.
The tonnage an injection machine applies to keep the mold shut against melt pressure - the sizing spec of every press.
Optical quality of a plastic - how clearly you can see through it; PET and BOPP lead, PP needs clarifiers.
Extruding multiple polymer layers through one die simultaneously - builds barrier structures layer by layer.
Adhesive pattern that seals to itself with pressure alone - used where product cannot take heat, like chocolate.
Pigment or dye system giving plastic its color - most commonly delivered as masterbatch dosed at 0.5-3%.
Second monomer polymerized into a resin to tune properties - comonomers make LLDPE flexible and PP copolymers tougher.
Plastic built from two monomers instead of one - PP random copolymers are clearer and tougher than homopolymer.
Electrical discharge treatment raising film surface energy to 38-42 dynes/cm so inks and adhesives can bond.
Cast polypropylene film - the heat-sealable companion layer to BOPP in laminates.
Creating chemical bonds between polymer chains - produces thermosets and irradiation-sterilized heat-proof parts.
The ordered fraction of a polymer's structure - higher crystallinity means stiffer, more opaque, better chemical resistance.
Total seconds to complete one molding cycle - the productivity heartbeat of every injection and blow plant.
Removing the thin excess plastic (flash) that squeezes out at the mold parting line - by hand, tumbling or cryogenics.
Moisture-absorbing sachet or blended additive keeping hygroscopic resins and pack contents dry.
The shaped metal exit through which melted plastic flows - it defines the parison, film or profile geometry.
The expansion of melted plastic as it exits the die and relaxes - parison programming must compensate for it.
A part's ability to hold its size through temperature, humidity and time - critical for caps on high-speed filling lines.
Reducing film or wall thickness while keeping performance - the main sustainability and cost lever in packaging.
How much the melt is stretched from die opening to final size - too high causes neck-in and weak spots.
Removing absorbed moisture from hygroscopic resins (PET, PA, PC) before molding - typically 4 hours at controlled temperature.
Extrusion blow molding - the continuous or intermittent parison process behind bottles, jerrycans and drums.
Environmental stress crack resistance - ability to survive contact with detergents and chemicals without cracking; the deciding spec for chemical packaging.
Ethylene-vinyl acetate - soft, flexible copolymer used for sealant layers and flexible bottle shoulders.
Ethylene-vinyl alcohol - the oxygen-barrier champion of multi-layer packaging, sandwiched between moisture-protecting layers.
The machine that melts, mixes and pumps plastic through a die - barrel, screw and heater zones working as one.
Continuous process pushing melted plastic through a die - parent process of film, sheet, pipe and parison production.
Mineral (calcium carbonate, talc) or glass blended into resin for stiffness and cost - 5-40% depending on grade.
Excess plastic that escapes the mold parting line - removed in deflashing.
Stiffness measured by bending - the number that decides whether a jerrycan wall bulges under load.
Resin certified compliant for touching food - EU 10/2011, FDA 21 CFR - always supplied with its documentation chain.
Integrated process where film is formed into a pack, filled and sealed on one machine - sachet economics at scale.
The height in film blowing where the bubble crystallizes from melt to solid - the process's most watched parameter.
Compliance documentation (EU 10/2011, FDA 21 CFR, BfR) proving a resin is safe for touching food - always supplied with its shipment.
In injection molds, the solidified layer where melt stops flowing - a sign of short shots and cold runners.
The narrow entry point where melted plastic enters the mold cavity - its design marks and scars every injection part.
The tiny bump left when an injection part is cut from its gate - minimized on cosmetic closures.
Film thickness, measured in microns - 'down to gauge' means thinning the film while holding performance.
Gel permeation chromatography - the lab test revealing a polymer's molecular weight distribution, the fingerprint behind its processing behavior.
The folded panel that lets a pouch or bag stand and expand - designed into the film, not formed after.
Hindered amine light stabilizers - the most durable UV protection family, dosed 0.2-2%, essential for outdoor plastics.
The percentage of light scattered by a clear material - low haze equals the crystal clarity water bottles demand.
High-density polyethylene - stiff, chemically resistant, moisture-proof; the resin of milk bottles, jerrycans and drums.
The unfilled gap between a pack's contents and its seal - controlled to manage vacuum and swelling.
Fusing two thermoplastic layers with heat and pressure - temperature, dwell time and pressure form the sealing triangle.
The innermost laminate film that performs the actual sealing - CPP, EVA or ionomer grades.
Heat deflection temperature - the heat a plastic survives under load before deforming; decides hot-fill suitability.
Thin PP section acting as an integral spring - a closure can open and close thousands of times without a separate hinge part.
Filling at 85-92C for shelf-stable products - requires heat-set PET or PP copolymer containers and panel designs that survive vacuum.
Moisture-absorbing resins (PET, PA, PC) that must be dried before molding - wet resin hydrolyzes and shows silver streaks.
The inside measurement of a bottle neck or tube - pairs with the cap's sealing geometry.
Energy a plastic absorbs before breaking - measured by Izod or falling dart, decisive for crates and thin parts.
Process where melted plastic is injected under pressure into a closed mold - closures, crates, preforms and precision parts.
Two-stage PET process: injection molds the preform, then it is stretched and blown into the bottle - the retail water bottle process.
The molecular weight measure of PET - 0.72-0.84 for bottles; higher IV means stronger bottles.
Tough sealant resin with excellent oil resistance - common in laminates for fatty foods.
International Organization for Standardization - ISO 9001 (quality), ISO 14001 (environment) anchor exporter credibility.
Rigid HDPE container, typically 5-25L, with a handle and DIN neck - UN-rated versions carry hazardous chemicals.
Styrene-butadiene copolymer - crystal clear and shatter-resistant for display packaging.
Multiple film layers bonded with adhesive - each layer contributes barrier, print or seal properties.
See Hinge (Living) - the integral PP flex joint of flip-top caps.
Linear low-density polyethylene - tough, puncture-resistant and stretchable; stretch film and pouches.
Machine direction - the direction film moves through the line; its strength differs from cross-direction by design.
Gravimetric dosing unit for masterbatch and additives - accuracy by weight loss, not volume.
Additive easing melt flow through the machine - reduces friction, shear and energy per kilo.
Concentrated pigment or additive carried in resin pellets, dosed at 1-4% - the clean way to color and fortify plastics.
Screen pack in the extruder catching contaminants before the die - protects the pump and the product.
Grams of polymer flowing through a standard die in 10 minutes - the single most-quoted processing number.
See MFI - higher index flows easier (thin walls, fast cycles); lower index gives strength and parison stability.
The actual temperature of the plastic inside the machine - setpoints are only a proxy for this real value.
Melt flow index - see Melt Index.
Additive or monomer moving from packaging into food - regulated to strict limits under EU 10/2011; the reason food-grade papers matter.
Rinse-fill-cap machine where all three operations run inside one frame - the core of a bottling line.
Layer or resin property blocking water vapor transmission - HDPE and foil lead; measured in WVTR.
Container or film built from stacked polymer layers - barrier, tie and structural layers each doing one job.
The machined steel cavity and core set that shapes the part - its cooling channels decide cycle time.
Unit circulating water or oil through mold channels at set temperature - stability for warp-free parts.
Packaging built from a single polymer family instead of laminates - the recyclability direction of the industry.
The precision-machined top of a bottle that receives the cap - defined by standards like 38mm 3-start for jerrycans and PCO 1881 for water bottles.
Additive that creates extra crystal formation sites - turns PP glass-clear and speeds molding cycles.
Fluorescent additive making white packaging look brighter - dosed at trace levels.
Stretching polymer chains into alignment while warm - biaxial orientation gives PET and PP their strength and clarity.
The hot hollow tube of plastic extruded in blow molding - inflated inside the mold to become the bottle.
Controlling parison wall thickness point-by-point as it extrudes - so a jerrycan gets thick corners and a light body.
Polycarbonate - virtually unbreakable and transparent; the food-grade standard for returnable 19-20L water jars.
Polyethylene terephthalate - crystal clear, strong and fully recyclable; the world's water and juice bottle resin.
Polymer degradation triggered by UV light plus oxygen - prevented by HALS and carbon black.
Additive that softens flexible PVC by spacing its chains - modern grades are phthalate-free (DOTP, citrates).
The injection-molded test-tube-shaped PET intermediate - stretched and blown into the final bottle at the filling plant.
The range of temperatures, pressures and times within which a machine makes good parts - wider windows mean forgiving production.
Running clean material through a machine to flush out the previous color or degraded resin - between every color change.
Polyvinylidene chloride - high oxygen and aroma barrier coating for films where EVOH cannot be used.
Clean production waste ground into pellets and blended back into virgin resin - managed at 10-25% to protect strength.
The raw polymer in pellet or powder form - the starting material of every molding and extrusion process.
Sterilization at 121C+ after filling - packaging that survives it needs BOPA and PP laminates or heat-set containers.
The science of how melted plastic flows - shear, viscosity and elasticity decide every process setting.
The channel network feeding melt from the injection nozzle to each gate - hot runners eliminate the waste cold runners create.
Frictional heating and stretching as melt flows - too much shear burns color and additives.
An incompletely filled part - caused by blocked vents, cold melt or insufficient pressure.
How much a part contracts as it cools - molders design the mold oversize by exactly this number.
Grams of plastic injected per cycle - the capacity spec matched to machine and part.
Full-body printed film label slid and shrunk over the container - 360-degree decoration.
Additive (erucamide, oleamide) lowering film friction for high-speed filling and easy roll separation.
Density relative to water - the quick test separating polyolefins (float, under 1.0) from PET and PVC (sink, over 1.0).
How far a preform is stretched axially and radially during PET blow molding - the ratio that builds strength and clarity.
Slow cracking under constant stress plus chemical contact - prevented by ESCR-rated HDPE grades.
Mineral filler adding stiffness and heat resistance - common in PP crates and industrial parts.
Force needed to propagate a tear in film - decisive for pouch opening features.
Shaping heated plastic sheet over a mold by vacuum or pressure - trays, cups and lids.
Adhesive polymer bonding incompatible layers in coextrusion - the glue of barrier structures.
Thermoplastic elastomer - rubber-soft, moldable like plastic; cap gaskets and soft-grip surfaces.
Thermoplastic polyurethane - the toughest elastomer family: abrasion, oil and temperature resistant.
Certification proving a jerrycan survives drop, stack and pressure tests for hazardous chemicals - required for dangerous goods transport.
Additive family (HALS, absorbers) protecting plastic from sunlight degradation - see HALS.
Thermoforming where vacuum draws heated sheet onto the mold - the economical tray process.
Micro-groove in the mold letting trapped air escape - blocked vents cause burn marks and short shots.
Never-processed polymer straight from the reactor - food-contact packaging requires it.
A melt's resistance to flow - the property melt index measures inversely.
Part distortion from uneven cooling stress - prevented by balanced mold cooling and holding profiles.
Water vapor transmission rate - grams of moisture passing through a square meter per day; the moisture-barrier scorecard.
The stress at which plastic permanently deforms - the design limit for structural containers.
The catalysis chemistry behind virtually all PE and PP production - its refinement created the modern resin grades every processor runs.
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