PMMA characteristics, processes, applications and recycling systems

PMMA, or Polymethylmethacrylate, is a thermoplastic resin belonging to the group of technopolymers, obtained from the polymerization of methacrylate (MMA).

It is commonly considered an acrylic glass, as it boasts a better transparency than traditional glass, so much so that in many applications it has been replaced by PMMA.

The history of PMMA began in 1938 when in Germany, by Otto Rohm, the first product called plexiglass was placed on the market.

As we said, it has the evident characteristic of transparency, but it can maintain, unlike glass, also an excellent mechanical resistance, which is achieved thanks to different polymeric compounds, so much so that it is also used for the production of safety glass.

What are the characteristics of PMMA

• density: 1.18 - 1.19 gr / cm3

• melting temperature Tm: 105-160 ° C

• glass transition temperature Tg: 80-105 ° C

• good rigidity

• mechanical strength

• high impact resistance and hardness.

• good tensile strength

• good compression and bending values

• high UV stability

• excellent resistance to aging

• sensitivity to scratches and abrasions

• good weather resistance

• excellent optical properties, clarity and transparency

• excellent electrical properties

• good thermal resistance

• chemical resistance to salts

• resistance to aliphatic hydrocarbons

• does not resist chlorinated hydrocarbons, concentrated acids, nitro and paints

How PMMA works

Polymethylmethacrylate can be processed through extrusion and thermoforming, which represent two processing systems for traditional plastics.

There is a third one, called by pouring, which is normally used for the production of PMMA sheets, using an acrylic paste, called "syrup", obtained pre -polymerizing the MMA monomer in a reactor by stirring.

PMMA Applications

Polymethylmethacrylate has a very wide range of applications, in different sectors and with countless products that we could summarize below:

 Construction

 sheets for doors and windows

 unbreakable windows

 skylights

 bathtubs

 shower trays

 shower enclosures

 cabins for medical use in general

 elements of pools

 sinks

 honeycomb sheets for greenhouses

 Lighting

 outdoor luminous signs

 traffic signs

 advertising plates

 bright letters

 illuminated plaques for instructions

 Transport sector

 car lights

 reflectors

 speedometer discs

 warning triangles

 flashing lights

 windshield for aircraft and space uses

 Medical sector

 filters

 parts of dialysis equipment

 containers for blood

 orthopedic applications

 dental prostheses

 cosmetic packaging

 lenses

 Electrical and electronics industry

 switches

 command buttons

 optical memorizers

 CD and DVD

 displays for mobile

 fiber optic elements

How to recycle PMMA

The recycling of Polymethylmethacrylate begins with the collection and selection of end-of-life products or scraps of industrial processes, differentiating them according to the color so to create homogeneous sources between them.

At this point there are two recycling systems: the mechanical one, like a normal polyolefin, and the chemical one, which aims at the depolymerization of PMMA.

Using mechanical recycling, the material to be recycled is ground into suitable dimensions for subsequent use and reintroduced into production, for example slabs, through the thermal process induced by an extruder.

Using chemical recycling, the PMMA waste will undergo a depolymerization process, which consists in the dissociation of the molecules of the material to be recycled.

After appropriate purification, MMA is generated, which, through a polymerization reaction, gives life to the new 99% pure rPMMA polymer.

The cycle is completely zero impact, as the process is carried out in a closed circuit and all the by-products of this chemical process are reused within the production cycle .

The disadvantage of chemical recycling is that at the end of the process there will be a less translucent rPMMA, having a high recycling cost and an important energy consumption.

Common trade names for PMMA

Acridite

ACRYLITE

Acryvill

Altuglas

Amanite

Cyrolite

Green Cast

LuciteOptix

Oroglas

Perspex

Plexiglas

R-Cast

Setacryl

Crylux

TrespexZylar

Automatic translation. We apologize for any inaccuracies. Original article in Italian.