Polymethylmethacrylate (POL-ee-meth-uhl-meth-AK-rill-ate) is a clear thermoplastic resin used to make windshields, visors, coatings for baths, advertising signs, and contact lenses. It is also widely used in dentistry and medicine. A thermoplastic resin is one that becomes soft when heated and hard when cooled. It can be converted back and forth any number of times between the solid and liquid states by further heating and cooling.

1. Polymethyl
Methacrylate
(PMMA)

2. Historical uses of PMMA
 Du Pont first used PMMA primarily for cast
products (rods, tubes, and blocks)
 ICI and Röhm and Haas focused on
producing sheets of PMMA to be used as
safety glass.
 Rohm and Haas introduced Plexiglass to
market in 1936 and ICI followed with Perspex
later that same year.

3. INTRODUCTION
Acrylic plastic refers to a family of synthetic, or man-made,
plastic materials containing one or more derivatives of acrylic
acid. The most common acrylic plastic is polymethyl
methacrylate (PMMA), which is sold under the brand names
of
Plexiglas, Lucite, Perspex, and Crystallite.
PMMA is a tough, highly transparent material with excellent
resistance to ultraviolet radiation and weathering. It can be
colored, molded, cut, drilled, and formed. These properties
make it ideal for many applications including airplane
windshields, skylights, automobile tail lights, and outdoor
signs. One notable application is the ceiling of the Houston
Astrodome which is composed of hundreds of double-
insulating panels of PMMA acrylic plastic.

5. Manufacture of polymer
 Free Radical Polymerization

7. Raffinate-1 and Raffinate-2 can be regarded as stages in the processing of Crude
C4s streams. The first stage of the process is to remove, by solvent extraction, the
valuable butadiene which may be 40-45% of the stream. What is left is Raffinate-1.
It consists of Isobutylene, the two normal isomers, butene-1 and butene-2 and
small quantities of butanes and other compounds. Removal of the isobutylene,
usually by reaction with Methanol to produce MTBE, leaves Raffinate-2.
Raffinate-1 is a chemical building block used in the manufacture of methyl tertiary
butyl ether (MTBE) and isobutylene (IB).

8. Acrylic plastic polymers are formed by reacting a monomer, such as methyl
methacrylate, with a catalyst.
A typical catalyst would be an organic peroxide.
Acrylic plastics are available in three forms:
flat sheets,
elongated shapes (rods and tubes),
molding powder.
Molding powders are sometimes made by a process known as suspension
polymerization in which the reaction takes place between tiny droplets of the
monomer suspended in a solution of water and catalyst. This results in grains
of polymer with tightly controlled molecular weight suitable for molding or
extrusion.

9. Acrylic plastic sheets are formed by a process known as bulk polymerization.
In this process, the monomer and catalyst are poured into a mold where the
reaction takes place.
Two methods of bulk polymerization may be used:
batch cell
continuous.
Batch cell is the most common because it is simple and is easily adapted for
making acrylic sheets in thicknesses from 0.06 to 6.0 inches (0.16-15 cm) and
widths from 3 feet (0.9 m) up to several hundred feet.
The batch cell method may also be used to form rods and tubes.
The continuous method is quicker and involves less labor. It is used to make
sheets of thinner thicknesses and smaller widths than those produced by the
batch cell method.

11. Properties of PMMA
 Lighter than glass (density is about half that of glass)
 Shatter proof
 Softer and easier to scratch than glass (scratch resistant
coatings may be applied)
 Transmits more light than glass (92% of visible light)
 Does not filter UV light (may be coated with UV film)
 More transparent than glass, so windows can be made
thicker.

12. Young's modulus 1800 - 3100 MPa
Tensile strength 48 - 76 MPa
Elongation 2 - 10 %
Compressive strength 83 - 124 MPa
Impact strength 0.16 - 0.27 J/cm
Quantity Value Unit
Glass temperature 105 - 105 °C
Service temperature -40 - 90 °C
Density 1170 - 1200 kg/m3
Friction coefficient 0.54 - 0.54
Refraction index 1.492 - 1.492
Shrinkage 0.3 - 0.8 %
Water absorption 0.3 - 0.4 %

13. Current uses for PMMA
 Include many uses similar to those for
which it was first developed but include
many things never imagined by the
inventors! A partial list of the uses for
PMMA includes:

14.  Safety glass such as Plexiglass and Lucite – uses
range from windows for aquariums and under-
water restaurants to safety shields at hockey
rinks to skylights in your home to simple
paperweights

15. Medical Uses
 Used as bone cement for use in
arthroplastic procedures of the hip, knee,
and other joints for the fixation of polymer
or metallic prosthetic implants to living
bone.
 Used in Pacemakers

16. Dentures!

17.  Artificial eye lenses used for cataract
surgery
 Suspended in collagen and implanted to
reduce wrinkles in cosmetic procedures

18. Acrylic Paints
 Acrylic “latex paints” often contain PMMA
suspended in water

19. Blacklight Tattoo Ink
 Made of 97.5% PMMA and 2.5%
microspheres of fluorescent dye suspended
in UV sterilized, distilled water with no
preservatives or other additives.

21. Breakdown of PMMA
 Autoignites at 445° C (833° F)
 Burns cleanly to produce H2O and CO2
 Virtually smokeless combustion
 Has superior recyclability
 Can be reground and reused
 Can be depolymerized back to monomer,
purged of impurities, and reploymerized back
to PMMA

22. Potential Toxicity
 PMMA is an essentially non-toxic material
 No workplace exposure limits
 MMA
 Respiratory effects may result from chronic
low level exposure or from short term acute
exposure
 Exposure primarily occupational (production
of monomer and its polymers, doctors,
nurses, dentists, and dental technicians)