JG SUMMITPetrochemical Corporation

Polyethylene Laboratory Overview

Seadrift, Texas

1997

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ISO 9001: 2000

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Scope

• Service organization that provides process control testing of granular and pelleted resin, and product qualification testing.

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ISO 9001: 2000

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Basic Introduction to Polyethylene

• Polymerization– Ethylene + Catalyst = Polymer Chain

H H H H H H H H H H H H H

│ │ │ │ │ │ │ │ │ │ │ │ │

C = C —→ C – C – C – C – C – C – C – C – C – C – C –——│ │ │ │ │ │ │ │ │ │ │ │ │

H H CH3 H CH3 H CH3 H CH3H CH3 H CH3

Ethylene Molecule ↑

└ This unit is repeated “n” times.

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ISO 9001: 2000

A JG SummitCompany

Basic Introduction to Polyethylene

• Melt Index (MI)– Measurement of Molecular Weight

• Molecular Weight Relative to Chain Length

– Polymer Chains of Different Lengths• Longer Chains Make Extrusion More Difficult

– Measured In Melt Index Plastometer• Forced Through Small Orifice• Temperature & Weight Critical• Less Material (by weight) Yields Lower Melt Index

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ISO 9001: 2000

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Basic Introduction to Polyethylene

• Molecular Weight Distribution (MWD)– Frequency of Chains With Different Lengths

• Different Chain Lengths Yield Different Molecular Weights• Narrow MWD Has Small Range of Chain Lengths• Broad MWD Has Wide Range of Chain Lengths

– Variations of Chain Lengths Create Distribution• This Variation Measured By Melt Flow Ration (MFR)

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ISO 9001: 2000

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Basic Introduction to Polyethylene

• Melt Flow Property Terminology– Melt Index uses 2.16 kg weight (44 psi) (I2)

• 5 kg weight (100 psi) for low melt index products (I5)

– Melt Flow Index uses 21.6 kg of weight (440 psi) (I21)

• Melt Flow Index/Melt Index• Indicator of Molecular Weight Distribution (MWD)

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ISO 9001: 2000

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Basic Introduction to Polyethylene

Molecular Weight & Molecular Weight Distribution

• There are 3 basic types of curves that depict the distribution of molecular weight present in different resins.

Narrow MWD

Broad MWDMedium MWD

Molecular Weight

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ISO 9001: 2000

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Basic Introduction to Polyethylene

Molecular Weight & Molecular Weight DistributionAs MWD Broadens

These Properties Increase, These Properties Decrease,

Moldability Tear Strength

Warpage Impact Strength

Shrinkage Gloss

Haze

  The molecular weight distribution of a given resin has a pronounced affect on the fabricating behavior of the resin. The development or selection of a product for a particular application, involves a compromise of all these parameters to achieve the best balance of properties for that application.

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ISO 9001: 2000

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Basic Introduction to Polyethylene

• MWD & Product Applications– Narrow Molecular Weight Distribution

• Application (LLDPE, HDPE)– Film Extrusion– Blow Molding– Injection Molding– Rotomolding

– Medium Molecular Weight Distribution• Application (HPDE, LDPE, LLDPE, MDPE)

– Film Extrusion– Blow Molding– Pipe, Hose, & Tubing

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ISO 9001: 2000

A JG SummitCompany

Basic Introduction to Polyethylene

• MWD & Product Applications– Broad Molecular Weight Distribution

• Application (HDPE, HMW-HDPE, MDPE)– Film– Blow Molding– Pipe, Hose, & Tubing

– Molecular Weight Distribution Classification• Class MFR

Very Narrow 20-32

Narrow 32-50

Medium 50-80

Broad 80-130

Very Broad >130

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ISO 9001: 2000

A JG SummitCompany

Basic Introduction to Polyethylene

• Crystallinity & Density– Density is a measure of the crystallinity of polyethylene.– The higher the density, the higher the level of

crystallinity.– Density is a guide primarily to the level of mechanical

properties.• 0.910 – 0.925 Considered Low Density• 0.926 – 0.940 Considered Medium Density• 0.941 – 0.960 Considered High Density

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ISO 9001: 2000

A JG SummitCompany

Basic Introduction to Polyethylene

• Crystallinity & Density– Crystallinity is a measure of the ability of the molecules in

the resin mass to orient themselves in ordered arrangements.

– When resin is fluxed or melted, the molecules lie in a somewhat tangled state with very little orderliness.

Amorphous State

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ISO 9001: 2000

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Basic Introduction to Polyethylene

• Crystallinity & Density– As the resin cools, the molecules align themselves into

ordered arrangements.– The stronger the attraction between the molecules, the

greater the degree of crystallinity.– Density is the resin property used to indicate the degree

of crystallinity in polyethylene.

crystalline

amorphouscrystalline

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ISO 9001: 2000

A JG SummitCompany

Basic Introduction to Polyethylene

• Crystallinity & DensityRigidity

Melting Point

Shrinkage

Warpage

Hardness

Abrasion Resistance

Tensile Yield Strength

Haze

Chemical Resistance

Increasing DensityProperties that increase as density goes up

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ISO 9001: 2000

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Basic Introduction to Polyethylene• Crystallinity & Density

Tear Strength

Impact Strength

ESCR

Permeability

Elongation

Cycle TimeIncreasing Density

Properties that decrease as density goes up

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ISO 9001: 2000

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Additives

• Stabilization Objectives– Control Changes In Melt Properties– Discoloration Resistance– Corrosion Protection– Gel Prevention– In-Service Performance– Cost Effective Stabilization

• Process Degradation Can Take Place During:Melt Extrusion

– Storage– Service Life

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ISO 9001: 2000

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Additives

• Polymer Degradation Can Consist Of:– Chain Scission and Cross-link Reactions– Incompletely Deactivated Catalyst Residuals– Environmental Conditions Such As Temperature,

Oxygen, and High Shear

• Poor Stabilization Can Result In:– Poor MD Tear Strength– Poor Color– Poor Impact Strength– Hazy Melt– Increased Die Swell

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ISO 9001: 2000

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Additives

• Classes of Stabilizers & Their Affects On PE– Anti-oxidants

• Can improve melt property retention

– Neutralizers• Work against corrosion• Reduce gel formation• Can improve color

– Slip Agents• Used for coefficient of friction (how well two layers of film slide

against surface of each other)

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ISO 9001: 2000

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Additives

• Classes of Stabilizers & Their Affects On PE– Anti-block agents

• Prevents layers of film from sticking to each other.• The load required to separate two layers of film.

– Processing Aids• Used to reduce melt fracture.• Used to lower shear stress during extrusion.• Can improve taste in some cases.

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ISO 9001: 2000

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Commercial Applications

• Film Extrusion Materials– HDPE Film (UCAT®-B, UCAT®-G Catalyst)

• Grocery Bags• Sack Liners• Shopping Bags

– LLDPE Blown Film (UCAT®-A, UCAT®-J Catalyst)• Food Bags• Grocery Sacks• Food Packaging

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ISO 9001: 2000

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Commercial Applications

• High Strength Film Resins– LLDPE Blown Film (UCAT®-A, UCAT®-J Catalyst)

• Trash Bags• Grocery Sacks• Stretch Wrap• Can Liners

– LLDPE Slot Cast Film (UCAT®-A Catalyst)• Diaper Film• Bread Bags• Stretch Wrap

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ISO 9001: 2000

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Commercial Applications

• Blow Molding Resins– HMW-HDPE (UCAT®-B, UCAT®-G Catalyst)

• Drums• Shipping Containers• Large Parts

– UNIVAL® Polyethylene Resins (UCAT®-B Catalyst)• Chemical Bottles• Dairy, Juice, & Water Bottles• Oil Bottles

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ISO 9001: 2000

A JG SummitCompany

Commercial Applications

• Injection Molding Resins– HDPE (UCAT®-A, UCAT®-J Catalyst)

• Housewares• Crates• Food Containers• Drink Cups

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ISO 9001: 2000

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Commercial Applications

• Pipe, Hose, & Tubing– LLDPE (UCAT®-B Catalyst)

• Drip Irrigation• Flexible Pipe, Hose• Flex Hose

– MDPE (UCAT®-B, UCAT®-G Catalyst)• Small Diameter Water Pipe• Municipal Gas Pipe

– HDPE (UCAT®-B, UCAT®-G Catalyst)• Large Diameter Gas, Water, & Industrial Pipe• Small Diameter Water Pipe

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ISO 9001: 2000

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Laboratory Testing

• Melt Flow Properties• Density• Ash• Bulk Density• Contamination• Pellet Uniformity• Extractables (Hexane/Cyclohexane)• Color (Hunterlab)• Additive Content by UV/Infrared & X-ray

Flourescence Spectroscopy

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ISO 9001: 2000

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Laboratory Testing

• Film Appearance Rating (FAR)• Tape Rating• APS (Average Particle Size)• Odor• Environmental Stress Crack Resistance (ESCR)• Bottle Weight• Residual Volatile Hydrocarbon• Mechanical Testing

– Tensile Yield– Tensile Strength– Ultimate Elongation

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ISO 9001: 2000

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Laboratory Testing

• Principle Structural Properties of Polyethylene For Reactor Control

Property Control Test

Molecular Weight Melt Index (MI) &

Melt Flow Index (MFI)

Crystallinity Density

• UNIPOL PE Technology Manual– Analytical & Contract Product Information– Volume V, Book 2

• Methods Identified With “PEG” No’s.• Equipment Identified with “E” No’s.• Includes Optional As Well As Required Equipment• Usually Referenced By known Vendor & Equipment Model No’s.

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ISO 9001: 2000

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Physical Test Descriptions

• Melt Index/MFI = PEG 302, 304, 305– Measure of the rate of extrusion of a thermoplastic

through an orifice of specified length and diameter under specified conditions of temperature and pressure.

– This is an indicator of Molecular Weight.

• Melt Flow Ration = PEG 304, 305– This is a calculated value. It is the Melt Flow Index

divided by the Melt Index.– This is an indicator of the Molecular Weight Distribution.

• Density = PEG-300– Measured by the weight per unit volume of the polymer

(g/cc or kg/m3).– Measure of the degree of crystallinity in the polymer

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ISO 9001: 2000

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Physical Test Descriptions

• Ash = PEG-306– Determines the inorganic ash content of polyethylene by

burning off the polymer portion.– Used as an indicator of catalyst productivity.

• Bulk Density = PEG-301– The measure of weight per unit volume (lb./cubic ft or

kg/m3). This property can change with particle size and type of catalyst

– Bed fluidization and conveying is affected by this variable

• Contamination = PEG-504– Measure of contaminants caused by oxidized resin,

external contamination, dirt, metal etc.. Determined by size and number of the contaminants.

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ISO 9001: 2000

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Physical Test Descriptions

• Pellet Uniformity = PEG-505– A visual inspection to check that the pellets are

reasonably uniform in size to minimize problems in extrusion at the customer’s location.

• Hexane Extractable = PEG-801– Measure of low molecular weight polyethylene

(oligomers), in resin used for food applications. Required for compliance with the FDA. Extractable limits apply to base resins without any additives.

• Color = PEG-502– A measure of what is “physically acceptable” to the

customer.– Can be dependent upon the level of catalyst residue in

granular resin.

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ISO 9001: 2000

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Physical Test Descriptions

• Additive Content = PEG-400-411– Measure the amount of resin modifiers being added to

the resin. Additives are added to prevent oxidation, act as UV stabilizers, or can be used as processing aids, or property enhancers.

• FAR = PEG-510, 511– Film Appearance Rating – subjective visual inspection for

gels and imperfections. It is done to predict its fabrication and its aesthetic value. Gels can either be polymeric (high molecular weight polymers), or silica (residual catalyst).

• Tape Rating = PEG-508– Visual inspection for gels (imperfections), 0.031”

(0.79mm) or larger

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ISO 9001: 2000

A JG SummitCompany

Physical Test Descriptions

• APS = PEG-507– Measure of the particle size of the resin. Bed fluidization

is affected by this variable

• Odor = PEG-503– Test to evaluate the odor of polyethylene in pellet form.

Odor can be defined as burnt, waxy, or acetic.

• Environmental Stress Crack Resistance = PEG-316– Test to determine endurance of plastic under the

expected environmental extremes. For ESCR testing, the specimen is immersed in a strong detergent solution (Igepal) to accelerate the stress cracking phenomena.

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ISO 9001: 2000

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Physical Test Descriptions

• Bottle Weight = PEG-315– Test to obtain swell characteristics of a test resin against

a standard resin.

• Residual Volatile Hydrocarbon = PEG-308– Test to determine the amount of residual hydrocarbons in

polyethylene resin.

• Mechanical Properties = PEG-317– Tensile yield– Tensile strength– Ultimate elongation

• Associated with the reaction that results when a force or load (stress) is applied to a material

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ISO 9001: 2000

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Test Time Requirements

• Test Analytical Time Technician Time

• Melt Index 15 minutes 5 Minutes• Melt Flow Ratio 15 Minutes 5 Minutes• Density 60 Minutes• Ash 45 Minutes 5 Minutes• Color 20 Minutes 5 Minutes• Bulk Density 15 Minutes 2 Minutes• Particle Size 15 Minutes 8 Minutes• Contamination 5 Minutes 5

Minutes

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ISO 9001: 2000

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Test Time Requirements

• Test Analytical Time Technician Time

• Antioxidant 25-60 Minutes 5-10 Minutes• Film Rating 40 Minutes 15 Minutes• N-Hex. Extr. 3 Hours 10 Minutes• Cycl. Extr. 4.5 Hours 30 Minutes• Tape Gel Rating 20 Minutes 5 Minutes• Bottle Weight 100 Minutes 30 Minutes• ESCR Days 20 Minutes• Tensile Prop. Days 25 Minutes

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ISO 9001: 2000

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Quality Control

• Calibration & Control Charting– Calibration are performed on all equipment.– Reference standards are used for calibration verification.– Control charts are used to track equipment performance.

• Half-Blind Sampling– Used as tool for checking the ability of technicians to reproduce their

analytical skills.– Technician is informed of what kind of sample, but not given

previous results.

• Round-Robin Sampling– Sampling technique used for determining how well two or more

laboratories are able to reproduce analytical testing.– Can also compare equipment performance between laboratories

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ISO 9001: 2000

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Staffing & Responsibilities

• Chemist (1):– Unit Technical Support and Problem Solving– Analytical Method Development and Commissioning– Analytical Method Trouble-Shooting– Interface With R&D Programs

• Supervisor (1):– Day to Day Operation of the Lab– Personnel Administration– Interface With Production (Sample Priorities, reruns,

Etc.)– Quantity and Quality of QC Data– Budget Responsibility– Technician Training

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ISO 9001: 2000

A JG SummitCompany

Staffing & Responsibilities

• Technician (4 Shifts, 1 per shift, & 2 Day):– Quality Control Testing (Determine & Report)– Calibrate Lab Equipment– Note: Based on 2 Reactor / 2 Extruder System

• Quality Coordinator:– Production Representative To R&D as it relates to

Product Specifications, Quality Studies, Special Programs.

– Makes decisions of product disposition.– Has final authority on rating product quality– Receives Customer Complaints and coordinates

resolution.– Inputs on production and catalyst run plans.

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ISO 9001: 2000

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Laboratory Equipment

• X-Ray Flourescence Spectrometer– Used for additive determination in polyethylene, as well

as residual metals analyses.

• Melt Index Plastometer– Used for determining melt flow properties.– Can perform melt index both by the manual-cut-and-

weigh and automatically timed.

• Fume Hood for Ash Analysis– A 20 gram sample is weighed into a platinum crucible,

and placed on a bunsen burner to burn off the polymer portion. The residues remaining in the cubicle are catalyst residuals.

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ISO 9001: 2000

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Laboratory Equipment

• Density Gradient Apparatus– Polyethylene specimens are compression molded and

then cut into small shapes and dropped into a gradient filled with a solution of water and isopropanol. The specimen is then plotted against calibrated density floats already in the gradient solution.

• Low Boy Film Extruder– Polyethylene resin, is placed into the hopper and

extruded at prescribed conditions as specified for either low or high density material. After the sample is allowed to extrude for approximately 15 minutes, a “sample resin” is taken, and a numerical rating is assigned to the sample based on a set of Film Appearance Standards.

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ISO 9001: 2000

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Laboratory Equipment

• Tape Extruder– Used to analyze polyethylene samples for gel

determination. A tape, approximately 3.05 m long, 0.51 mm thick, and 38.1 mm wide, is collected and inspected for gels that are 0.80 mm or larger in size. A numerical rating is assigned and reported.

• Bulk Density Apparatus– Used to measure the apparent bulk density of

polyethylene in kg/m3.

• Impco Blow Molding Machine (Bottles)– A parison is extruded into a set of molds, injected with

air, cooled and formed into a bottle, ejected, then weighed and inspected for gel content.

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ISO 9001: 2000

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Laboratory Equipment

• UV Spectrophotometer– Used for the determination of Irganox 1010, Irganox

1076, or BHT in polyethylene resin. An appropriate calibration curve of absorbance vs. additive content is used to determine the level of additive being added.

• Hunterlab Colorimeter– A compression molded specimen is placed over the

sample port and analyzed for a numerical value, based on CIE Color System Tri-stimulus Values X, Y, & Z, to the Union Carbide Corporation Color Rating.

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ISO 9001: 2000

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Laboratory Equipment

• G. C. Head-Space Analyzer– Used to determine residual hydrocarbons in

polyethylene. It is based on ASTM D4526, modified to correct for hydrocarbons dissolved in the resin, according to Henry’s Law.

• Inston Mechanical Tester– Used to determine tensile strength, elongation, and yield

strength of polyolefins and other semi-rigid materials.

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ISO 9001: 2000

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Glossary of Terms• Amorphous

– Refers to molecules that lie in a tangled state, or with very little order.

• Branching– Side chains attached to the main chain of the polymer.

• Brittleness– Refers to the test temperature at which plastics and elastomers

rupture by impact under certain conditions.

• Catalyst– A chemical substance added that speeds up the polymerization of a

compound.

• Compression Molding– A technique in which the molding compound is placed in an open

mold cavity, the mold is closed, and heat and pressure are applied until the material has cured or cooled.

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ISO 9001: 2000

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Glossary of Terms

• Cross-linking– The tying together of adjacent polymer chains.

• Crystallinity– The measure of the ability of the molecules in the resin mass to

orient themselves into ordered three dimensional arrays or arrangements.

• Elongation– The distance that it takes to break a molded specimen (in %).

• Extrudate– The product deliver by an extruder.

• FDA– Federal Drug Administration

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ISO 9001: 2000

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Glossary of Terms

• Fluorescence– A property of a substance that causes it to produce light while it is

being acted on by radiant energy, such as ultraviolet light or x-rays.

• Gloss– The measure of “shininess” of a plastic surface. 

• Hardness– The resistance of a material to compression, indention, and

scratching. 

• Haze– The cloudy appearance of an otherwise transparent sample, caused

by scattered light from within the sample or from its surface.

• Hoppercar– Container for transporting resin

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ISO 9001: 2000

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Glossary of Terms

• Impact Strength– The measure of the energy needed, or absorbed, in breaking a

specimen.

• Injection Molding– A molding procedure in which a heat-softened plastics is formed

from a cylinder into a relatively cool cavity which gives the item the desired shape.

• Linear– Refers to a long straight-chain molecule.

• Melting Point – The point at which a solid melts

• Molecular Weight– The sum of the atomic numbers of a molecule.

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ISO 9001: 2000

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Glossary of Terms

• Molecular Weight Distribution– Used to describe the number of different sizes of polyethylene

molecules in resin.

• Moldability– The ability for molten polyethylene to form to a mold.

• Permeability– The ability of a material to leak or pass through the wall made of

resin.

• Polymerization– The process of growing large molecules from smaller ones.

• Relative Density– The density of a given substance divided by the density of water.

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ISO 9001: 2000

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Glossary of Terms

• Shrinkage– The ability of a plastic to shrink around an object.

• Stabilizer– An ingredient used in the formulation of plastics to assist in holding

the physical and chemical properties of the compounded materials at their initial values throughout the processing and service life of the material.

• Stiffness– The capacity of a material to resist a bending force.

• Strain– The amount of deformation caused by stress.

• Stress– The amount of pulling force applied to a material until it breaks.

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ISO 9001: 2000

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Glossary of Terms• Swell

– Refers to the bottle weight

• Tear Strength– The force to initiate tearing or the force to propagate a tear.

• Tensile Strength– Refers to the pulling force required to break a molded polyethylene

specimen.

• Toughness– The energy required to break a material, equal to the area under the

stress-strain curve.

• Viscosity– A measure of the internal friction resulting when one layer of fluid is

caused to move in relationship to another.

• Warpage– The distortion of a flat surface, such as molding lids and boxes

immediately after molding.