Editorial Feature

Polymethylmethacrylate - Acrylic - PMMA General Purpose

A transparent thermoplastic, Polymethylmethacrylate (PMMA) is a possible lightweight, shatter-resistent substitute for glass. Often referred to as acrylic glass, PMMA is a synthetic polymer of the organic compound methyl methacrylate (MMA). It is seen as a cheap alternative to polycarbonate when high strength is not necessarily a stringent requirement for the given application.

PMMA in its unmodified form can be brittle with particularly poor impact toughness and has a lower hardness than conventional glass rendering it prone to scratches. However, when modified, both of these properties can be significantly improved.

Polymer Type

Thermoplastic

Advantages

There are a number of advantages to using PMMA:

  • Outstanding weathering and resistance to UV radiation

  • Transparent

  • High gloss and hardness (when modified)

  • Good rigidity

  • Dimensionally stable

  • Good abrasion resistance - surface scratches can be polished out (when modified)

Disadvantages

  • Not a tough material in comparison with engineering plastics - notch sensitive and generally brittle

  • Although not attacked by alcohol alone, alcohol with carbon tetrachloride and ether will cause swelling

  • Dissolved by most aromatic and chlorinated hydrocarbons

  • Water absorption is low but can have a considerable effect on dimensions and a lesser one on mechanical properties

Typical Properties

Property

Value

Density (g/cm3)

1.18

Surface Hardness

RM92

Tensile Strength (MPa)

70

Flexural Modulus (GPa)

2.9

Notched Izod (kJ/m)

0.02

Linear expansion (/°C x 10-5)

7

Elongation at Break (%)

2.5

Strain at Yield (%)

N/A

Max. Operating Temp. (°C)

50

Water Absorption (%)

0.3

Oxygen Index (%)

19

Flammability UL94

HB

Volume Resistivity (log ohm.cm)

15

Dielectric Strength (MV/m)

25

Dissipation Factor 1kHz

0.03

Dielectric const. 1kHz

3.3

HDT @ 0.45 MPa (°C)

103

HDT @ 1.80 MPa (°C)

95

Material. Drying hrs @ (°C)

2 @ 75

Melting Temp. Range (°C)

220 - 240

Mould Shrinkage (%)

0.6

Mould Temp. Range (°C)

60 - 80

Applications

  • Sinks, baths, knobs and batons

  • Displays and signs

  • Aircraft glazing, technical models, tap tops and accessories

  • Automotive rear light housings, automotive components such as badges, steering wheel insignia and fascia panels

Source : Abstracted from Plascams

For more information on Plascams please visit RAPRA Technology Ltd.

Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Submit