Polystyrene: Versatility & Limitations in Thermoplastics

Introduction

Polystyrene (PS) is a widely used thermoplastic with a fascinating history and numerous applications. This blog explores polystyrene's characteristics, uses, advantages, and disadvantages, shedding light on its environmental impact and alternative possibilities. Let's delve into the world of polystyrene and discover what makes it so popular yet controversial.

What is Polystyrene?

Polystyrene, a clear, hard, and rather brittle thermoplastic, has a long history dating back to 1839, when it was discovered by Eduard Simon. It then evolved over the years. After about 80 years later, macromolecules were discovered when styrol was heated via a chain reaction thanks to German organic chemist Hermann Staudinger. Eventually, this led to the substance receiving its present name, polystyrene.

Dow Chemical Company then invented a proprietary process to make their trademarked and well-known PS foam product, “styrofoam,” in 1941. Throughout the years, though, the thermoplastic has not been the most favorable in environmental organizations (due to its slow degrading process). It is not hard to deny this fact, as almost anyone can walk outside and see some form of polystyrene trash on the ground.

To make polystyrene, hydrocarbon fuels are distilled to create lighter groups called “fractions.” Some of which are combined with other catalysts to produce plastics. As a result, the polymerization process creates the PS we all know today. However, it does come in many forms. Much like other plastics, such as PETG and TPU, it also has a whole range of uses.

Extruded Polystyrene Foam

Extruded polystyrene foam (XPS) consists of closed cells, most commonly seen in crafts and model building.

Common Characteristics

Generally, Polystyrene (PS) is an amorphous, glassy polymer that is generally rigid and relatively inexpensive. Unfilled polystyrene has a sparkle appearance and is often referred to as crystal PS or general-purpose polystyrene (GPPS). High-impact polystyrene grades (HIPS) are produced by adding rubber or butadiene copolymer. Therefore, this increases the toughness and impact strength of the polymer. Other qualities include:

• High surface qualities
• Generally non-toxic and odorless
• Good electric insulator
• Flammable
• Shock-resistance
• Good pressing results
• Ideal for thermoforming
• Polished or mat surface
• Approved for food contact (although some studies have reported “potential health impacts from polystyrene foam food packaging associated with its production)

Advantages and Disadvantages

Polystyrene boasts numerous advantages, such as being inexpensive, readily available, and easy to work with for sanding, gluing, cutting, and painting. On the flip side, its flammability, poor solvent resistance, and brittleness are some of the downsides. Understanding its characteristics helps evaluate its suitability for specific applications.

Pros

• Inexpensive
• Readily available
• White in color
• Easy to sand, glue cut, and paint

Cons

• Flammable but retarded grades are available.
• Inert (i.e., doesn’t react particularly well with either acidic or basic solutions)
• Poor solvent resistance, attacked by many chemicals
• Homopolymers are brittle
• Subject to stress and environmental cracking
• Poor thermal stability

Extruding and 3D Printing

We over at 3devo decided to try out extruding some polystyrene, thanks to the Composer 450 filament maker.

Top Left: PS granules used. Top Right: The PS granules in the hopper. Bottom Left: PS filament being extruded with the Composer 450. Bottom Right: The finished filament!