Chapter 4
`
`Detailed accounts of thermoplastic resins
`
`BOREALIS EXHIBIT 1064
`
`Page 1 of 498
`
`

`
`Thermoplastics and Thermoplastic Composites
`
`For easier reading, certain elements of earlier chapters are repeated in the opening remarks
`on each material family and in the sections on ‘Applications’. However, for the latter, the
`reader should refer to Chapter 2 for the most complete and up-to-date information.
`Unless otherwise specified, the units used in the property tables at the end of each account are:
`
`Specific mass or density
`Shrinkage
`Absorption of water
`Tensile strength
`Elongation at break
`Tensile modulus
`Flexural strength
`Flexural modulus
`Compression strength
`Notched impact strength ASTM D256
`HDT B (0.46 MPa)
`HDT A (1.8 MPa)
`Continuous use temperature (unstressed)
`Glass transition temperature
`Brittle point
`Thermal conductivity
`Specific heat
`Coefficient of thermal expansion
`Volume resistivity
`Loss factor
`Dielectric strength
`Arc resistance
`
`g/cm3
`%
`% after 24 h of immersion
`MPa
`%
`GPa
`MPa
`GPa
`MPa
`J/m
`°C
`°C
`°C
`°C
`°C
`W/m.K
`cal/g/°C [1 cal ⫽ 4.19 J]
`10⫺5/°C
`ohm.cm
`10⫺4
`kV/mm
`s
`
`The data are examples that cannot be generalized and cannot be used for design purposes.
`
`4.1 Polyethylene or polythene (PE)
`Albeit having a simple chemical formula, —(CH2—CH2)n—, polyethylene is a broad family
`with versatile properties that depend on which of the three main polymerization processes
`is used:
`• Free radical vinyl polymerization, the oldest process, leads to branched low density
`polyethylene (LDPE). Macromolecules have numerous short branches, which reduce
`the melting point, tensile strength and crystallinity. Polymers are relatively flexible
`because of the high volume of the branched molecule and the low crystallinity.
`• Ziegler-Natta polymerization leads to linear unbranched polyethylene, the so-called
`high density polyethylene (HDPE), which is denser, tougher and more crystalline. By
`copolymerization with other alkenes it is possible to obtain linear low density polyethyl-
`ene (LLDPE) with better mechanical properties than LDPE. Blends of LLDPE and
`LDPE are used to combine the good final mechanical properties of LLDPE and the
`strength of LDPE in the molten state.
`• Metallocene catalysis polymerization is the most recent technique, growing fast to pro-
`duce a consistent, uniform distribution of molecular weight resulting in enhanced tough-
`ness, impact and puncture strengths, better cold behaviour and optical properties.
`These advantages allow the downgauging or enhancement of performances for the
`same weight of polymer. Metallocene catalysis allows the production of all densities,
`from ultra-low density to ultra-high molecular weight polyethylenes (UHMWPE).
`
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`Detailed accounts of thermoplastic resins
`
`In addition to their structural diversity, polyethylenes can be crosslinked.
`Polyethylenes can be classified versus density and molecular weight:
`• ultra-low and very low density, ULDPE and VLDPE
`• low density, LDPE and LLDPE
`• medium density, MDPE
`• high density, HDPE
`• high molecular weight, HMWPE
`• ultra-high molecular weight, UHMWPE.
`Regardless of molecular weight, polyethylene can be classified into five density categories:
`• 0.890 to 0.909 or 0.915
`• 0.910 to 0.925
`• 0.926 to 0.940
`• 0.941 to 0.959
`• 0.960 and higher.
`Regardless of density, polyethylenes have molecular weights of the order of:
`• LDPE & HDPE: from a few thousands to 300 000 depending on the end use
`• high molecular weight, HMWPE: approximately 200 000 to 500 000
`• ultra-high molecular weight, UHMWPE: approximately 3 000 000 and higher.
`Considering the versatility of polyethylenes, each polyethylene subfamily has, of course,
`its favoured application sectors:
`• HDPE is used for 86% of all polyethylene goods having applications that are struc-
`tural to a greater or lesser degree
`• LDPE and LLDPE are used for 86% of all polyethylene films.
`Expressed in another way:
`• 75% of HDPE is converted into parts having a structural function to a greater or lesser
`degree
`• 75% to 80% of LDPE and LLDPE are converted into films.
`For films, Table 4.1 proposes an arbitrary classification of the polyethylene subfamilies
`(where m indicates metallocene catalysis).
`
`Table 4.1 Films: arbitrary classification of the polyethylene subfamilies
`
`Function
`
`Mechanical
`
`Optical
`
`Organo-leptic
`
`Vapour barrier
`
`Sealability
`
`Processability
`
`mVLDPE
`mLLDPE
`LLDPE
`LDPE
`HDPE
`
`1
`1
`2
`3
`3
`
`1
`2
`2
`2
`3
`
`1
`1
`2
`1
`2
`
`1 – generally the best adapted to the function
`2 – intermediate behaviour
`3 – generally less adapted to the function
`
`2
`2
`2
`2
`1
`
`1
`2
`2
`2
`3
`
`3
`3
`3
`1
`2
`
`The same basic monomer generates a lot of common properties and, unless otherwise speci-
`fied, we will not make a distinction between the various subfamilies. Only the foams will be
`given special attention as they present particular properties due to their morphology:
`• decreased mechanical properties due to the low quantity of polymer and the high pro-
`portion of gas
`• weaker chemical resistance due to the highly divided state of the polymer.The thin cell
`walls immediately absorb liquids and gases.
`
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`Thermoplastics and Thermoplastic Composites
`
`4.1.1 General properties
`Advantages
`General advantages are low price, attractive price/property ratios, easy transformation,
`chemical inertness, impact resistance, low absorption of water, low density (HDPE included),
`good electrical insulator, low coefficient of friction, suitability for food contact, ease of
`welding, good machinability for rigid grades; good resistance against high-energy radiation,
`physiological inertness, versatility of processing methods except for UHMWPE.
`• LDPE: good mechanical properties, flexibility, impact resistance at ambient tempera-
`ture; good insulating material even in a wet medium; chemically inert.
`• HDPE: same properties as LDPE but more rigid; better thermal and creep behaviour;
`lower coefficient of friction and higher pressure strength, allowing antifriction applica-
`tions with higher PV (pressure*velocity) factor; more transparent.
`• UHMWPE: better mechanical properties, lower coefficient of friction and higher pres-
`sure strength allowing antifriction applications with higher PV factor.
`• Linear PE: same properties as the equivalent branched PE with an improvement in the
`mechanical properties, thermal and creep behaviour, and resistance to stress cracking.
`• Metallocene: enhanced toughness, impact and puncture strengths, better cold behav-
`iour and optical properties.
`• Crosslinked PE: more resistant to temperature, creep and cracking.
`
`Drawbacks
`General drawbacks are the innate sensitivity to heat, UV, light and weathering (but stabil-
`ized grades are marketed), stress cracking, and creep; low rigidity, significant shrinkage, lim-
`ited transparency. Due to the surface tension, gluing, painting and printing are difficult
`without surface treatments. Composed only of carbon and hydrogen, polyethylenes are nat-
`urally flammable but FR grades are marketed.
`Processing is difficult for UHMWPE due to the high molecular weight.
`Polyethylene is sensitive to pro-oxidant metals such as copper, manganese or cobalt,
`which must be avoided as inserts.
`
`Special grades
`They can be classified according to the type of processing, specific properties, targeted
`applications:
`• Extrusion, injection, compression, blown film, blow moulding, rotational moulding,
`foam, coating, powdering, co-extrusion, for thin or thick parts, for crosslinking, electro-
`welding . . .
`• Stabilized against heat, UV, light or weathering; antistatic, conductive, reinforced, food
`contact, physiologically inert, fireproofed, transparent, resistant to stress cracking, low
`warpage, high fluidity . . .
`• For films, sheets, tubes, wire and cable coatings, fibres, mass production of household
`requisites, bottle racks, bins, containers, pallets, tubes, prostheses, antifriction parts . . .
`
`Costs
`The costs, as for all plastics, fluctuate greatly with the crude oil price, and are only given to
`provide a rough idea. They are generally of the order of €1 per kilogram.
`
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`Detailed accounts of thermoplastic resins
`
`Processing
`All molten-state processing methods are usable: extrusion, injection, compression, blown
`film, blow moulding, rotational moulding, thermoforming, foam, coating, powdering,
`co-extrusion, fluidized bed, machining for high hardness grades, welding. Special grades can
`be crosslinked after shaping.
`
`Applications
`(See Chapter 2 for further information.)
`Although varying according to country, consumption is approximately divided into:
`• 40–45% HDPE
`• 30–35% LLDPE
`• 20–25% LDPE.
`Applications vary according to the polyethylene type.
`LDPE and LLDPE are mainly used for:
`• films for packaging: food, non-food, shrink, stretch . . .
`• films for other applications
`• sheets
`• extrusion coating
`• injection moulding
`• blow moulding
`• pipes and conduits.
`HDPE is mainly used for:
`• blow moulding of:
`䊊 household chemical bottles
`industrial drums
`liquid food bottles
`䊊 drugs, cosmetics and toiletries
`• injection moulding of:
`crates and totes
`food and beverage containers
`䊊 housewares
`industrial and shipping pails
`• films for food packaging and retail bags
`• sheets
`• pipes and conduits
`• rotomoulding.
`Among other applications, let us quote, for example:
`• films for agricultural, industrial or general-purpose uses
`• fuel tanks for the automotive industry
`• moulded basins, bottles, stoppers, toys, hollow parts, small electric equipment, pallets,
`street furniture, seats
`• large-sized objects: cisterns, tanks, septic tanks, hulls of boats, canoes, buoys, sailboards,
`barrels, drums . . .
`• gas, water or sewer pipes, sheaths
`• crosslinked foams, extruded and moulded parts
`• UHMWPE: gears, bearings, antifriction parts for light loads, prostheses
`
`䊊
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`221
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`䊊
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`䊊
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`䊊
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`Page 5 of 498
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`Thermoplastics and Thermoplastic Composites
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`• foams: densities from 25 kg/m3 up to 330 kg/m3, semi-rigid to flexible, with insulating
`and damping properties for packaging, building insulation, panels and sandwich struc-
`tures, multi-layer composites for damping (helmets, for example).
`
`4.1.2 Thermal behaviour
`The continuous use temperatures in an unstressed state are generally estimated from 90°C
`for LDPE up to 110–120°C for HDPE and 130°C for crosslinked polyethylenes if the soft-
`ening or melting temperatures are higher. For example, the sealing temperature of a given
`grade of VLDPE is 83°C.
`Service temperatures are lower under loading because of modulus decay, strain, creep,
`relaxation . . . They can be of the order of:
`• 50–90°C for LDPE
`• 50–120°C for HDPE.
`As examples:
`• for a given grade of LDPE, the short-term modulus retention at 80°C is 40% of the
`value at 20°C. For two grades of HDPE (see Figure 4.1), the short-term retention of
`stress at yield is in the range of 35% to 42% at 80°C
`• HDTs under 1.8 MPa are:
`from 30–40°C for LDPE
`to 45–60°C for HDPE.
`
`䊊
`
`䊊
`
`%
`
`120
`
`100
`
`80
`
`60
`
`40
`
`20
`
`0
`
`0
`
`20
`
`40
`
`60
`
`80
`
`100
`
`120
`
`140
`
`°C
`Figure 4.1. HDPE examples of stress at yield retention (%) versus temperature (°C)
`
`For long-term heat ageing, property retention depends on the property and grades con-
`sidered, notably the heat stabilizers used. For a heat-sensitive characteristic such as elonga-
`tion at break, the values for a given polyethylene after ageing at 120°C are roughly:
`• 60% after 10 days and 40% after 17 days for a grade without a stabilizer
`• 80–100% after 10 days and 60–90% after 17 days for several grades with various sta-
`bilizers, versus 120–160% initial elongation at break with or without a stabilizer.
`The UL temperature indices of specific grades can be 50°C for electrical and mechanical
`properties including impact.
`At low temperatures, the behaviour can be acceptable down to ⫺60°C or even less, down
`to ⫺110°C according to grades and the mechanical constraints experienced. Figure 4.2 dis-
`plays examples of stress at yield retention for polyethylenes at subzero temperatures.
`Despite a high increase in rigidity UHMWPE can be used down to ⫺269°C.
`
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`
`Detailed accounts of thermoplastic resins
`
`HDPE
`UHMWPE
`
`350
`
`300
`
`250
`
`200
`
`150
`
`100
`
`50
`
`%
`
`0
`⫺120 ⫺100
`
`⫺80
`
`⫺60
`
`⫺40
`°C
`Figure 4.2. HDPE & UHMWPE examples of stress at yield retention (%) versus sub-zero temperatures (°C)
`
`⫺20
`
`0
`
`20
`
`40
`
`The brittle points are generally of the order of ⫺70°C.
`The glass transition temperature of PE by DSC measurements is ⫺110°C. The glass tran-
`sition temperatures by DMTA measurements can be higher, depending on the frequency.
`These results relate to some grades only and cannot be generalized.
`
`4.1.3 Optical properties
`Polyethylenes are whitish and translucent to opaque according to the density and grade.
`The refractive index varies with the density and type of polyethylene, for example:
`• 1.51 for an LDPE
`• 1.52 for an MDPE
`• 1.54 for an HDPE.
`For films, haze can be 5–6% for specific grades.
`These results relate to some grades only and cannot be generalized.
`
`4.1.4 Mechanical properties
`The mechanical properties are generally fair with high elongations at break but much more
`limited strains at yield. Moduli and hardnesses are rather weak and impact strength is high
`to excellent. The abrasion resistance of polyethylene depends on the roughness, type and
`morphology of the antagonist sliding surface. Wear resistance is sufficient for antifriction
`applications under moderate pressure and low PV.
`Some grades can have weaker characteristics.
`Crystallinity and molecular orientation improve the mechanical properties but are harm-
`ful to notched impact resistance.
`
`Friction
`High density and UHMW polyethylenes are used to make antifriction parts. The coeffi-
`cients of friction are low but the moduli, hardnesses and softening temperatures are weak,
`which limits the loads and PV factors.
`
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`Thermoplastics and Thermoplastic Composites
`
`Table 4.2 gives some PV examples ranging from 0.04 up to 0.07 MPa.m/s. All these values
`are weak but certain sources quote very different data.
`These results relate to a few grades only and cannot be generalized.
`
`Table 4.2 UHMWPE: examples of tribological properties
`
`PV (MPa.m/s)
`
`Pressure, P (MPa)
`
`Velocity, V (m/s)
`
`Coefficient of friction
`
`0.07
`0.07
`0.07
`0.07
`0.06
`0.05
`0.04
`
`0.9
`0.7
`0.23
`0.14
`0.08
`0.05
`0.025
`
`0.08
`0.1
`0.3
`0.5
`0.8
`1
`1.7
`
`0.1–0.2
`0.1–0.2
`0.1–0.2
`0.2–0.3
`0.2–0.3
`0.2–0.3
`⬎0.2
`
`Dimensional stability
`Shrinkage, coefficient of thermal expansion, crystallinity and creep are rather high, but
`alterations through moisture exposure are slight.
`
`Poisson’s ratio
`Poisson’s ratio depends on numerous parameters concerning the grade used and its pro-
`cessing, the temperature, the possible reinforcements, the direction of testing with regard to
`the molecular or reinforcement orientation. For a given HDPE sample it is evaluated at
`0.46, but this is an example only that cannot be generalized.
`
`Creep
`Neat thermoplastic polyethylenes have low moduli that involve high strains for moderate
`loading. Consequently, creep moduli are also low, the more so as the temperature rises, as
`we can see in Figures 4.3 ((a) and (b)) where creep moduli are displayed as a function of
`time, load and temperature.
`In Figure 4.3(a) we can see a broad difference between two grades tested under a light
`load (2–3 MPa). The third grade tested under 8.75 MPa is probably more creep resistant.
`Figure 4.3(b) displays the fast decrease of creep moduli when the temperature rises mod-
`erately. Designers must be vigilant when computing the wall thickness of a part to be used
`at ambient temperatures (40°C) during warm weather.
`Finally, Figure 4.3(c) shows that glass fibre reinforcement is an efficient means to attain
`more suitable creep moduli.
`These results relate to a few grades only and cannot be generalized.
`
`Relaxation
`Figure 4.4 ((a) and (b)) displays the same relaxation data, first against a linear time scale,
`showing the fast drop in stress at the start of test, and second against a logarithmic time
`scale showing a regular decrease of stress.
`These results relate to a few grades only and cannot be generalized.
`
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`Detailed accounts of thermoplastic resins
`
`100
`
`h
`
`100
`
`h
`
`2 to 3 MPa
`2 to 3 MPa
`8.75 MPa
`
`23°C
`40°C
`60°C
`80°C
`
`30% GF
`20% GF
`Neat
`
`1
`
`GPa
`
`0
`
`(a)
`
`1
`
`1
`
`GPa
`
`0
`
`(b)
`
`1
`
`012345
`
`GPa
`
`(c)
`
`1
`
`100
`
`h
`(a) HDPE & UHMWPE examples of creep modulus (GPa) versus time (h) for various loading (MPa);
`Figure 4.3.
`(b) HDPE & UHMWPE examples of creep modulus (GPa) versus time (h) for various temperatures (°C); (c) HDPE
`examples of creep modulus (GPa) versus time (h) for various reinforcements
`
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`Thermoplastics and Thermoplastic Composites
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`100
`
`%
`
`50
`
`0
`
`0
`
`(a)
`
`100
`
`%
`
`50
`
`0
`
`1
`
`(b)
`
`500
`h
`
`1000
`
`10
`
`100
`
`1000
`
`h
`
`Figure 4.4. Stress relaxation of HDPE, examples of stress retention (%) versus time (h) under 2% strain at 20°C
`
`4.1.5 Ageing
`Dynamic fatigue
`The dynamic fatigue can be fair or good for certain grades if care is taken to limit the strains
`by restricting the stresses to values in keeping with the low modulus.
`For a given grade of HDPE, Figure 4.5 displays an example of an SN or Wöhler’s curve
`concerning flexural tests with maximum stress of ⫾σ and average stress of 0.
`
`Weathering
`Polyethylene resists hydrolysis well but is naturally sensitive to light and UV. It must be pro-
`tected by addition of anti-UV and other protective agents or by 2–3% of an adequate car-
`bon black. In such cases, after weathering of test bars for several years in various climates,
`the retention of tensile strength is generally good but the elongation at break retention can
`be as low as 10%. These results are examples only and they cannot be generalized.
`
`High-energy radiation
`In the absence of oxygen, polyethylene is crosslinked by exposure to high-energy ionizing
`radiation. The degree of reticulation depends only on the radiation dose. The reticulation
`brings in particular a better resistance to stress cracking but too high a dose involves a
`
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`Detailed accounts of thermoplastic resins
`
`50
`
`25
`
`MPa
`
`0
`1.0E⫹05
`
`1.0E⫹06
`N
`Figure 4.5. SN curve of HDPE, examples of maximum stress (MPa) versus number of cycles at rupture (N)
`
`1.0E⫹07
`
`reduction in elongation at break and impact resistance. For a dose greater than 100 kJ/kg
`(10 Mrad), the variations become measurable; 1 MJ/kg reduces elongation at break to a few
`percent of its initial value, but the stress at yield remains practically unchanged.
`In the presence of oxygen, for example in air, there are simultaneous crosslinking and
`degradation reactions.The action of the high-energy radiation depends in a complex way on
`the power, dose and wall thickness of the polyethylene. A short-duration irradiation to a
`strong dose on a broad wall thickness has the same effect as an irradiation in the absence of
`oxygen that does not have sufficient time to diffuse in depth. On the other hand, a long-
`duration irradiation (months or years) to a low dose involves a considerable reduction in
`the impact resistance because oxygen has a long enough time to diffuse in depth. Thus, a
`dose of 10–20 kJ/kg (1–2 mRad) per mm thickness reduces elongation at break to 10% of its
`initial value. These results are examples only and cannot be generalized.
`
`Behaviour at high frequencies
`Polyethylenes have very weak loss factors, about 1–10 ⫻ 10⫺4 and do not heat up under
`high-frequency current. They cannot be welded by this technique.
`
`Chemicals
`Polyethylenes absorb little water and are not very sensitive to it but have some propensity
`to stress cracking in the presence of soaps, alcohols, detergents . . .
`Suitable grades are usable in contact with food and are used for food packaging, milk bottles
`for example.
`Chemical resistance is generally good up to 60°C but polyethylenes are attacked by oxi-
`dizing acids, chlorinated solvents, certain oxidants, aromatic hydrocarbons.
`Copper, manganese and cobalt are oxidation catalysts and must be avoided, in particular
`for inserts.
`Crystallinity increases the impermeability and, consequently, chemical resistance.
`Generally, HDPE is slightly more resistant than LDPE.
`
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`Thermoplastics and Thermoplastic Composites
`
`Table 4.3 displays some results concerning general assessments of behaviour after pro-
`longed immersion in a range of chemicals at ambient temperature for given grades, which
`are not necessarily representative of all the polyethylenes. These general indications should
`be verified by consultation with the producer of the selected grades and by tests under
`operating conditions.
`
`Table 4.3 Polyethylene: examples of chemical behaviour at room temperature
`
`Chemical
`
`Concentration Estimated
`(%)
`behaviour
`
`Chemical
`
`Concentration Estimated
`(%)
`behaviour
`
`HDPE LDPE
`
`HDPE LDPE
`
`Acetic acid
`Acetic acid
`Acetic aldehyde
`Acetic anhydride
`Acetone
`Acetonitrile
`Acetophenone
`Acetyl chloride
`Adipic acid
`Allylic alcohol
`Alum
`Aluminium chloride
`Aluminium fluoride
`Aluminium sulfate
`Ammonia gas
`Ammonia liquid
`Ammonium chloride
`Ammonium fluoride
`Ammonium hydroxide
`Ammonium hydroxide
`Ammonium nitrate
`Ammonium sulfate
`Ammonium sulfide
`Amyl acetate
`Amyl alcohol
`Aniline
`Antimony chloride
`Aqua regia
`Aromatic hydrocarbons
`Arsenic acid
`ASTM1 oil
`ASTM2 oil
`ASTM3 oil
`Barium carbonate
`Barium chloride
`Barium hydroxide
`Barium sulfate
`Beer
`Benzaldehyde
`Benzene
`Benzoic acid
`Benzyl chloride
`Benzyl alcohol
`Borax
`
`228
`
`10–60
`⬎96
`100
`100
`100
`100
`100
`100
`Saturated
`96
`Solution
`Solution
`Saturated
`Unknown
`100
`100
`Solution
`Solution
`30
`Dilute
`Unknown
`50
`Solution
`100
`100
`100
`10–90
`Unknown
`100
`Unknown
`100
`100
`100
`Saturated
`Saturated
`Saturated
`Saturated
`Unknown
`100
`100
`Saturated
`100
`100
`Saturated
`
`S
`S
`S
`S
`l
`l
`S
`l
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`n
`n
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`l
`S
`l
`S
`S
`
`S
`l
`l
`l
`l
`l
`l
`l
`S
`l
`S
`S
`S
`S
`S
`l
`S
`S
`S
`S
`S
`S
`S
`n
`l
`n
`S
`n
`n
`S
`S
`S
`l
`S
`S
`S
`S
`S
`l
`n
`S
`l
`S
`S
`
`Boric acid
`Bromine (dry gas)
`Bromine (liquid)
`Bromine water
`Butanol
`Butanone
`Butyl acetate
`Butylamine
`Butylchloride
`Butyric acid
`Butyric acid
`Calcium chloride
`Calcium hydroxide
`Calcium hypochlorite
`Carbon sulfide
`Carbon tetrachloride
`Castor oil
`Cellosolve
`Cellosolve acetate
`Chlorinated hydrocarbons
`Chlorinated solvents
`Chlorine (dry gas)
`Chlorine dioxide
`Chlorine water
`Chloroacetic acid
`Chlorobenzene
`Chlorobenzene mono
`Chloroform
`Chlorosulfonic acid
`Chromic acid
`Citric acid
`Copper sulfate
`Cresol
`Cyclohexane
`Cyclohexanol
`Cyclohexanone
`Decaline
`Dextrin
`Dichloroethane
`Dichloroethylene
`Diethylamine
`Diethyleneglycol
`Diethylether
`Dimethylamine
`
`S
`Unknown
`n
`100
`n
`100
`n
`Solution
`S
`100
`S
`100
`S
`100
`n
`Unknown
`n
`100
`S
`100
`S
`Unknown
`S
`Unknown
`S
`Saturated
`S
`Solution
`l
`100
`l
`100
`S
`100
`n
`100
`n
`100
`n
`100
`n
`100
`l
`100
`l
`Unknown
`l
`Unknown
`l
`Unknown
`l
`100
`l
`100
`n
`100
`n
`Unknown
`S
`Unknown
`10 to saturated S
`Unknown
`S
`100
`S
`100
`S
`100
`S
`100
`S
`100
`S
`Solution
`S
`100
`l
`100
`l to n
`100
`l
`100
`S
`100
`l
`100
`l
`
`S
`n
`n
`n
`S
`l
`l
`l
`n
`l
`S
`S
`S
`S
`n
`n
`S
`l
`l
`n
`n
`n
`l
`n
`n
`l
`n
`n
`n
`S
`S
`S
`l
`l
`l
`l
`l
`S
`n
`l
`l
`S
`n
`n
`
`Page 12 of 498
`
`

`
`Table 4.3 (Continued)
`
`Chemical
`
`Dimethylformamide
`Dimethylhydrazine
`Dioctylphthalate
`Dioxan
`Ethanol
`Ethanol
`Ethanol
`Ethylacetate
`Ethylchloride
`Ethylene glycol
`Ethylenebromide
`Ethylhexanol
`Fluorine
`Fluosilicic acid
`Formaldehyde
`Formic acid
`Freon 113
`Freon 13b1
`Freon 22
`Freon 32
`Furfural
`Furfuryl alcohol
`Glucose
`Glycerol
`Glycollic acid
`Heptane
`Hexane
`Hydrazine
`Hydrobromic acid
`Hydrochloric acid
`Hydrofluoric acid
`Hydrogen
`Hydrogen peroxide
`Hydrogen sulfide
`Hydrogen sulfide gas
`Iron(III) chloride
`Iron sulfate
`Isobutanol
`Isooctane (Fuel A)
`Isopropanol
`Kerosene
`Lactic acid
`Lead acetate
`Linseed oil
`Liquid paraffin
`Magnesium carbonate
`Magnesium chloride
`Magnesium hydroxide
`Maleic acid
`Manganese sulfate
`Mercury
`
`Detailed accounts of thermoplastic resins
`
`Concentration Estimated
`(%)
`behaviour
`
`Chemical
`
`Concentration Estimated
`(%)
`behaviour
`
`HDPE LDPE
`
`HDPE LDPE
`
`100
`100
`100
`100
`40
`96
`Unknown
`100
`100
`100
`100
`100
`100
`Unknown
`35
`10–100
`100
`100
`100
`100
`100
`100
`Dilute
`100
`33
`100
`100
`100
`48–100
`10–36
`4–60
`100
`30–90
`Unknown
`Unknown
`Unknown
`Saturated
`100
`100
`100
`100
`90
`10
`100
`100
`Saturated
`Unknown
`Unknown
`Saturated
`Unknown
`100
`
`S
`S
`S
`S
`S
`S
`S
`S
`l
`S
`n
`S
`n
`S
`S
`S
`l
`S
`S
`S
`S
`S
`S
`S
`S
`S
`l
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`l to S
`S
`S
`S
`S
`S
`S
`
`l
`S
`l
`l
`S
`l
`S
`l
`l
`S
`l
`S
`l
`S
`S
`S
`l
`S
`S
`S
`S
`l
`S
`S
`S
`n
`l
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`l
`S
`l
`S
`S
`S
`l
`S
`S
`S
`S
`S
`S
`
`Mercury chloride
`Mercury(II) nitrate
`Methane chloride
`Methanol
`Methylbromide
`Methylchloride
`Methylene chloride
`Methylethylketone
`Methylglycol
`Milk
`Mineral oil
`Molasses
`Monoethanolamine
`Monoethyleneglycol
`Naphtha
`Nickel chloride
`Nickel nitrate
`Nitric acid
`Nitric acid
`Nitric acid
`Nitric acid
`Nitrobenzene
`Nonanol
`Oleic acid
`Oleic acid
`Olive oil
`Oxalic acid
`Ozone
`Pentanol
`Pentylacetate
`Perchloroethylene
`Petrol aliphatic
`Petroleum
`Phenol
`Phenol
`Phosphoric acid
`Picric acid
`Potassium bromate
`Potassium carbonate
`Potassium chlorate
`Potassium chromate
`Potassium cyanide
`Potassium dichromate
`Potassium ferrocyanide
`Potassium fluoride
`Potassium hydroxide
`Potassium hypochlorite
`Potassium nitrate
`Potassium perchlorate
`Potassium permanganate
`Potassium persulfate
`
`Unknown
`Solution
`100
`100
`100
`100
`100
`100
`Unknown
`100
`100
`Unknown
`Unknown
`100
`Unknown
`Unknown
`Saturated
`10–25
`50
`75
`100
`100
`100
`100
`Unknown
`100
`Saturated
`Unknown
`100
`100
`100
`100
`100
`Unknown
`Solution
`50–95
`Solution
`Unknown
`Saturated
`Saturated
`Saturated
`Unknown
`Saturated
`Saturated
`Unknown
`10–45
`Solution
`Saturated
`10
`20
`10
`
`S
`S
`l
`S
`l
`l
`l
`S
`S
`S
`S
`S
`l
`S
`S
`S
`S
`S
`l
`n
`n
`l
`S
`S
`S
`S
`S
`l
`S
`S
`l
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`
`S
`S
`l
`S
`n
`l
`n
`l
`S
`S
`l
`S
`l
`S
`l
`S
`S
`S
`l
`l
`n
`l
`S
`l
`S
`S
`S
`n
`l
`n
`n
`l
`l
`S
`l
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`
`(Continued)
`
`229
`
`Page 13 of 498
`
`

`
`Thermoplastics and Thermoplastic Composites
`
`Table 4.3 (Continued)
`
`Chemical
`
`Concentration Estimated
`(%)
`behaviour
`
`Chemical
`
`Concentration Estimated
`(%)
`behaviour
`
`HDPE LDPE
`
`HDPE LDPE
`
`Solution
`Potassium sulfide
`Unknown
`Potassium sulfate
`100
`Propanol
`100
`Propionic acid
`100
`Propylene oxide
`Unknown
`Pyridine
`Saturated
`Salicylic acid
`100
`Sea water
`100
`Silicone oil
`Saturated
`Silver acetate
`Saturated
`Silver cyanide
`Saturated
`Silver nitrate
`Unknown
`Sodium borate
`10–50
`Sodium carbonate
`Saturated
`Sodium chlorate
`25
`Sodium chloride
`Unknown
`Sodium cyanide
`Saturated
`Sodium fluoride
`10–55
`Sodium hydroxide
`20
`Sodium hypochlorite
`Solution
`Sodium nitrate
`100
`Sulfuric anhydride
`Solution
`Sulfurous acid
`Sulfurous anhydride (gas) Unknown
`Sulfur dioxide (dry)
`100
`Sulfur dioxide (gas)
`Unknown
`Sulfuric acid
`2–70
`Sulfuric acid
`96
`Sulfuric acid
`Fuming
`
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`n
`S
`S
`S
`S
`S
`S
`n
`
`S: satisfactory; l: limited; n: not satisfactory
`
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`S
`n
`S
`S
`S
`S
`S
`S to l
`n
`
`Tannic acid
`Tartaric acid
`Tetrachloroethane
`Tetrachloroethylene
`Tetrahydrofuran
`Thionyl chloride
`Tin chloride
`Titanium tetrachloride
`Toluene
`Transformer oil
`Trichloroacetic acid
`Trichloroethane
`Trichloroethylene
`Tricresylphosphate
`Triethanolamine
`Triethylamine
`Turpentine oil
`Urea
`Urine
`Vegetable oil
`Vinegar
`Vinyl chloride
`Vinyl acetate
`Water
`White spirit
`Wine
`Xylene
`Yeast
`Zinc chloride
`
`Solution
`Solution
`100
`100
`100
`100
`Unknown
`Unknown
`100
`100
`Unknown
`100
`100
`Unknown
`Unknown
`Unknown
`100
`Solution
`Unknown
`100
`Unknown
`Unknown
`100
`100
`100
`Unknown
`100
`Solution
`Unknown
`
`S
`S
`l
`l
`l
`n
`S
`S
`l
`S
`S
`n
`l
`S
`S
`l
`l
`S
`S
`S
`S
`n
`S
`S
`l
`S
`l
`S
`S
`
`S
`S
`l
`n
`l
`n
`S
`S
`n
`S
`S
`n
`l
`S
`S
`l
`l
`S
`S
`S
`S
`n
`l
`S
`l
`S
`n
`S
`S
`
`Permeability
`For films, in several series of experiments concerning various thicknesses of various poly-
`mers, permeability coefficients have been calculated for a reference thickness of 40 µm.
`Units differ for the various gases but are comparable for the different polymers tested with
`the same gas. The following data (without units) are only given to provide a general idea
`and cannot be used for designing any parts or goods.
`• Water vapour: polyethylene has a low permeability, evaluated from 0.9 up to 2.5 com-
`pared to the full range of 0.05 up to 400 for all tested plastics.
`• Gases: polyethylene has a rather high permeability, evaluated at:
`air: 750 to 2750 versus a full range of 3 up to 2750 for all tested plastics
`carbon dioxide: 7000 to 25 000 versus a full range of 30 up to 59 000 for all tested
`plastics
`䊊 nitrogen: 500 to 1700 versus a full range of 1 up to 3500 for all tested plastics
`䊊 oxygen: 1900 to 5000 versus a full range of ⬍1 up to 11 000 for all tested plastics
`䊊 hydrogen: 6000 to 20 000 versus a full range of 400 up to 20 000 for all tested plastics.
`
`䊊
`
`䊊
`
`230
`
`Page 14 of 498
`
`

`
`Detailed accounts of thermoplastic resins
`
`Fire resistance
`Fire resistance is naturally weak. Standard grades burn easily generating flames, even after
`the ignition source is removed. Moreover, polyethylene drips while burning.
`Oxygen indices are roughly 17 with a poor UL94 rating.
`Special formulations make it possible to improve this behaviour, sometimes to the detri-
`ment of other properties. UL94 V0 rating can be reached for some FR grades.
`
`4.1.6 Electrical properties
`Polyethylenes are good insulators even in wet environments, with high dielectric resistivities
`and rigidities, and low loss factors. Special grades are marketed for electrical applications
`such as the insulation of wires and cables.
`
`4.1.7 Joining, decoration
`Welding is easy using thermal processes, possible with ultrasound methods but impossible
`with the high-frequency technique.
`Gluing is difficult, needing pre-treatments such as, for example, chemical etching (sulfo-
`chromic acid etching), flame oxidation or hot-air (500°C) treatment, corona discharge,
`plasma or UV treatments. The exposure must be brief and superficial and the original and
`aged properties must be tested.
`All precautions must be taken concerning health and safety according to local laws and
`regulations.
`Polyethylene can generally be decorated after the same pre-treatments by painting, print-
`ing, metallization. Service conditions must be light.
`
`4.1.8 Crosslinked polyethylene
`Specific grades of polyethylene can be cured before use to improve some performances.The
`main processing methods involve:
`• heating to promote chemical reaction of curing agents such as silanes or peroxides
`leading to crosslinking.
`• irradiation to promote direct crosslinking.
`Heating can be achieved by discontinuous processes, such as heated moulds, ovens, or by
`continuous processes such as hot tubes for wire curing or hot tunnels.
`Irradiation can be achieved by discontinuous processes such as the cobalt bomb, which is
`more convenient for thick parts, but slow or continuous processes such as the electron beam
`are more suitable and speedier for thinner parts.
`Crosslinking improves resistance to heat, stress cracking and abrasion, and also reduces
`permanent set after loading, residual monomers and/or oligomers and VOCs (volatile
`organic compounds). Irradiation is a ‘cold’ sterilization process.
`Of course, there are also some drawbacks, notably the overspend for an additional
`processing step and the corresponding investments or subcontracting. Irradiation can also
`damage polyethylene.
`Crosslinking creates an irreversible 3D network and makes polyethylene more difficult to
`recycle.
`
`231
`
`Page 15 of 498
`
`

`
`Thermoplastics and Thermoplastic Composites
`
`4.1.9 Foams
`Unlike industrial solid polymers, which are processed as carefully as possible to avoid the
`formation of bubbles, vacuoles etc., alveolar materials result from the desire to introduce, in
`a controlled way, a certain proportion of voids with the aim of:
`• increasing flexibility: very soft seals
`• improving the thermal or phonic insulating character: foams for building, automotive . . .
`• making damping parts: foams for packaging, automotive and transport safety parts.
`The alveolar materials consist of a polymer skeleton surrounding the cells, which may be
`closed or partially or completely open to neighbouring cells or the outside.
`The intrinsic properties come from those of the polyethylene with:
`• a reduction in the mechanical properties due to the small quantity of material and the
`high proportion of gas.
`• a reduction in the chemical behaviour due to the highly divided nature of the material.
`The thin cell walls immediately absorb liquids and gases and are rapidly damaged.
`Generally, the properties of polyethylene foams are:
`• densities from 25 kg/m3 up to 330 kg/m3.
`• semi-rigid to flexible
`• closed cells
`• crosslinked or linear. Often, crosslinking improves the mechanical properties and
`chemical resistance.
`Polyethylene foams (see Table 4.4) have:
`• insulating properties
`• damping properties
`• fair mechanical characteristics according to their density: Figure 4.6 displays an example
`of tensile strength versus density
`• a low absorption and permeability to water or moisture and excellent hydrolysis
`behaviour
`• a naturally low fire resistance that can be improved by a suitable formulation.
`
`Table 4.4 Example