Properties of some thermoplastic materials[32][33]

name

Symbol

Density
[g/cm3]

Tensile strength
[MPa]

Flexural strength
[MPa]

Elastic modulus
[GPa]

Elongation at rupture
[%]

Thermal stability
[°C]

Expansion at 20°C
[10−6/°C]

 

High Density Polyethylene

HDPE

0.95

31

40

1.86

100

120

126

[32]

Low Density Polyethylene

LDPE

0.92

17

14

0.29

500

90

160

Polyvinyl Chloride

PVC

1.44

47

91

3.32

60

80

75

Polypropylene

PP

0.91

37

49

1.36

350

150

90

Polyethylene terephthalate

PET

1.35

61

105

1.35

170

120

70

Polymethylmethacrylate

PMMA

1.19

61

103

2.77

4

100

65

Polycarbonate

PC

1.2

68

95

2.3

130

120

66

Acrylonitrile butadiene styrene

ABS

1.05

45

70

2.45

33

70

90

Polyamide

Nylon 6

1.13

60

91

2.95

60

110

66

Polyimide

PI

1.38

96

143

3.1

7

380

43

Polysulfone

PSF

1.25

68

115

2.61

75

160

56

Polyamide-imide, electrical grade

PAI

1.41

138

193

4.1

12

260

30

Polyamide-imide, bearing grade

PAI

1.46

103

159

5.5

6

260

25

Polytetrafluoroethylene

PTFE

2.17

24

33

0.49

300

260

95

Polyetherimide

PEI

1.27

105

151

2.9

60

210

31

[33]

Polyether ether ketone

PEEK

1.32

100

3.6

50

343

Polyaryletherketone (strong)

PEAK

1.46

136

213

12.4

2.1

267

Polyaryletherketone (tough)

PEAK

1.29

87

124

3

40

190

Self-reinforcedpolyphenylene

SRP

1.19

152

234

5.52

10

151

Polyamide-imide

PAI

1.42

152

241

4.9

15

278

 

 

 

 

 

Engineering Resins

These resins offer exceptional strength and durability in demanding lab applications. For specific uses, they are superior to the polyolefins. Typical products are centrifuge ware, filterware and safety shields.

Among Engineering Resins, design advantages are:

  • Excellent mechanical properties over temperatures from below -40°C (-40°F) to above 148°C (300°F)
  • Self-extinguishing, non-dripping characteristics
  • Excellent dimensional stability and low water absorption
  • Resistance to aqueous chemical environments
  • Excellent impact strength

Acetal (ACL) , or polyoxymethylene, is a tough, strong material with excellent physical and mechanical properties. It is produced by polymerisation of formaldehyde. Acetal retains its dimensions and other properties at elevated temperatures. It offers excellent resistance to most organic solvents and fair to good resistance to strong acids and bases. Naturally opaque. Reinforced with glass fibres for increased stiffness when moulded into test tube racks.

Nylon (NYL) polyamide is a group of linear polymers with repeating amide linkages along the backbone. These are produced by an amidation of diamines with dibasic acids, or polymerisation of amino acids. Nylon is strong and tough. It resists abrasion, fatigue and impact. Nylon offers excellent chemical resistance with negligence permeation rates when used with organic solvents. However, it has poor resistance to strong mineral acids, oxidizing agents and certain salts.

Polycarbonate (PC) is window-clear, amazingly strong, and rigid. It is autoclavable, non-toxic and the toughest of all thermo-plastics. PC is a special type of polyester in which dihydric phenols are joined through carbonate linkages. These linkages are subject to chemical reaction with bases and concentrated acids, hydrolytic attack at elevated temperatures (e.g., during autoclaving), and make PC soluble in various organic solvents. For many applications, the transparency and unusual strength of PC offset these limitations. Its strength and dimensional stability make it ideal for high-speed centrifuge ware. Spectrophotometric analysis shows that the polycarbonate used in NALGENE safety products is essentially opaque to ultraviolet light from 200 to 380 nanometers (nm): 0% transmittance from 200-300 nm, 0.2% transmittance up to 380 nm. This covers the wavelengths emitted for germicidal applications such as laminar flow hoods (254 nm) and for fluorescence detection of dyes in electrophoresis or chromatography developing (350-360 nm).

Polyethylene Terephthalate G Copolymer (PETG) is similar to many other engineering resins. However, its glass-like clarity, toughness and excellent gas-barrier properties make it an outstanding choice for storing biologicals. Tests have shown PETG to be biologically equivalent to, or better than Type 1 borosilicate glass bottles for cell culture applications. In tests using a wide variety of cell lines, PETG was determined to be non-cytotoxic, and media stored in PETG bottles demonstrated proliferative and morphological characteristics comparable to control media. In fact, the PETG bottles allowed growth of good monolayers directly on the surface of the bottle. PETG can be sterilized with radiation or compatible chemicals but cannot be autoclaved. Chemical resistance is fair.

Polyketone (PK) is a new and unique family of aliphatic polymers composed of carbon monoxide, ethylene and minor amounts of other alpha olefins. This family of semi-crystalline resins exhibit many of the properties of engineering resins while processing similarly to polyolefins. The resins exhibit excellent creep resistance and stiffness coupled with broad chemical resistance to acids, bases and aliphatic and aromatic hydrocarbons.

Polymethylpentene (PMP or TPX) is similar to polypropylene, but it has an isobutyl group instead of a methyl group attached to each monomer group of the chain. Its chemical resistance is close to that of PP. It is more easily softened by some hydrocarbons and chlorinated solvents. PMP is slightly more susceptible than PP to attack by oxidizing agents. Its excellent transparency, rigidity, and resistance to chemicals and high temperatures make PMP a superior material for labware. PMP withstands repeated autoclaving, even at 150°C. It can withstand intermittent exposure to temperatures as high as 175°C. Products made of polymethylpentene are brittle at ambient temperature and may crack or break if dropped from benchtop height.

Polyphenylene Oxides (PPO) . General Electric uses a process for oxidative coupling of phenolic monomers in formulating Noryl phenylene oxide-based thermoplastic resins. The basic phenylene oxide structure is shown below. This family of engineering materials is characterized by outstanding dimensional stability at elevated temperatures, broad temperature-use range, outstanding hydrolytic stability, and excellent dielectric properties over a wide range of frequencies and temperatures.

Polysulfone (PSF) . Like polycarbonate, PSF is clear, strong, non-toxic and extremely tough. PSF is less subject than PC to hydrolytic attack during autoclaving and has a natural straw-coloured cast. PSF is resistant to acids, bases, aqueous solutions, aliphatic hydrocarbons and alcohols. PSF is composed of phenylene units linked by three different chemical groups-isopropylidene, ether and sulfone. Each of the three linkages imparts specific properties to the polymer, such as chemical resistance, temperature resistance and impact strength.

Polyurethane (PUR) belongs to the class of thermosetting polymers and contains the characteristic urethane (O-CO-NH) group formed in the typical condensation polymerisation. PUR is useful in different types of products as for example elastomers. Polyurethane elastomers have extremely good abrasion resistance and hardness, combined with good elasticity and resistance to greases, oils and solvents.

Thermanox™ (TMX) is a thermoplast and has in general a high gloss surface finish and good dielectric properties. It has a high impact strength and superior long term wear resistance. The p-phenylene group in the polymer chain leads to a fairly high melting point of the polymer. Its chemical and solvent resistance is good.


Fluorocarbons

Typical fluorocarbons are TEFLON tetrafluoroethylene (TFE) and TEFLON fluorinated ethylene propylene (FEP). Both have remarkable chemical resistance.

Halar ECTFE is an alternating copolymer of ethylene and chlorotrifluoroethylene. This fluoropolymer withstands continuous exposure to extreme temperatures and maintains excellent mechanical properties across this entire range (from cryogenic temperatures to 180°C). It has excellent electrical properties and chemical resistance, having no known solvent at 121°C. It is also non-burning and radiation-resistant. Its ease of processing affords a wide range of products.

Polyvinylidene Fluoride (PVDF, best known as Kynar) is a fluoropolymer with alternating CH 2 and CF 2 groups. PVDF is an opaque white resin. Extremely pure, it is superior for non-contaminating applications. Mechanical strength and abrasion resistance are high, similar to ECTFE. It resists UV radiation. The maximum service temperature for rotationally moulded PVDF tanks is 100°C. Up to this temperature, PVDF has excellent chemical resistance to weak bases and salts, strong acids, liquid halogens, strong oxidizing agents and aromatic, halogenated and aliphatic solvents. However, organic bases and short chain ketones, esters and oxygenated solvents will severely attack PVDF at room temperature. Fuming nitric acid and concentrated sulfuric acid will cause softening. At temperatures approaching the service limit, strong caustic solutions will cause partial dissolution. Autoclavable if tanks are empty and externally supported.

TEFLON FEP is translucent, flexible and feels heavy because of its high density. It resists all known chemicals except molten alkali metals, elemental fluorine and fluorine precursors at elevated temperatures. It should not be used with concentrated perchloric acid. FEP withstands temperatures from -270°C to 205°C, and may be sterilized repeatedly by all known chemical and thermal methods. It can even be boiled in nitric acid.

TEFLON PFA is translucent and slightly flexible. It has the widest temperature range of the fluoropolymers-from -270°C to 250°C – with superior chemical resistance across the entire range. Compared to TFE at 277°C, it has better strength, stiffness and creep resistance. PFA also has a low coefficient of friction, outstanding antistick properties and is flame-resistant.

TEFLON TFE is opaque, white and has the lowest coefficient of friction of any solid. It makes superior stopcock and separatory funnel plugs.

Tefzel ETFE is white, translucent and slightly flexible. It is a close analogue of TEFLON fluorocarbons, an ethylene tetrafluoroethylene copolymer. ETFE shares the remarkable chemical and temperature resistance of TEFLON TFE and FEP, and has even greater mechanical strength and impact resistance.


General Purpose Resins

Polymethylmethacrylate (PMMA) belongs to the group of acrylic resins. It is a rigid amorphous polymer with excellent clarity and the polymer is widely used in optical applications. PMMA is resistant to most inorganic aqueous solutions but prolonged contact with concentrated alcohols, aromatic and chlorinated hydrocarbons may soften or dissolve the polymer.

Polystyrene (PS) is rigid and non-toxic, with excellent dimensional stability and good chemical resistance to aqueous solutions but limited resistance to solvents. This glass-clear material is commonly used for disposable laboratory products. Products made of polystyrene are brittle at ambient temperature and may crack or break if dropped from benchtop height.

Polyvinyl Chloride (PVC) is similar in structure to polyethylene, but each unit contains a chlorine atom. The chlorine atom renders it vulnerable to some solvents, but also makes it more resistant in many applications. PVC has extremely good resistance to oils (except essential oils) and very low permeability to most gases. Polyvinyl chloride is transparent and has a slight bluish tint. Narrow-mouth bottles made of this material are relatively thin-walled and can be flexed slightly. When blended with phthalate ester plasticisers, PVC becomes soft and pliable, providing the useful tubing to be found in every well-equipped laboratory.


Polyolefins

Polyolefins are high molecular weight hydrocarbons. They include: low-density; linear low-density and high-density polyethylene; polypropylene copolymer; polypropylene; and polymethylpentene. All are break-resistant, non-toxic, and non-contaminating. These are the only plastics lighter than water. They easily withstand exposure to nearly all chemicals at room temperature for up to 24 hours. Strong oxidizing agents eventually cause embrittlement. All polyolefins can be damaged by long exposure to light.

Polyethylene . The polymerisation of ethylene 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.

Like other polyolefins, the polyethylenes are chemically inert. Strong oxidizing agents will eventually cause oxidation and embrittlement. They have no known solvent at room temperature. Aggressive solvents will cause softening or swelling, but these effects are normally reversible.

Low-density polyethylene (LDPE) has more extensive branching, resulting in a less compact molecular structure.

High-density polyethylene (HDPE) has minimal branching, which makes it more rigid and less permeable than LDPE.

Linear low-density polyethylene (LLDPE) combines the toughness of low-density polyethylene with the rigidity of high-density polyethylene.

Cross-linked high-density polyethylene (XLPE) is a form of high-density polyethylene wherein the individual molecular chains are bonded to each other (using heat, plus chemicals or radiation) to form a three-dimensional polymer of extremely high molecular weight. This structure provides superior stress-crack resistance and somewhat improves the toughness, stiffness and chemical resistance of HDPE. XLPE is a superior material for moulding very large storage tanks.

Polypropylene (PP) is similar to polyethylene, but each unit of the chain has a methyl group attached. It is translucent, autoclavable, and has no known solvent at room temperature. It is slightly more susceptible than polyethylene to strong oxidizing agents. It offers the best stress-crack resistance of the polyolefins. Products made of polypropylene are brittle at 0°C and may crack or break if dropped from benchtop height.

Polypropylene copolymer (PPCO) replaces polyallomer (PA) and is an essentially linear copolymer with repeated sequences of ethylene and propylene. It combines some of the advantages of both polymers. PPCO is autoclavable, and offers much of the high temperature performance of polypropylene. It also provides some of the low-temperature strength and flexibility of polyethylene.

Thermoplastic elastomer (TPE) is a type of polyolefin, which, due to structure, molecular weight and chemistry, can be moulded into autoclavable parts, which are rubber-like in application and performance. It is used for several small caps and plugs on filtration and ultracentrifuge ware products.