Transparent thermoplastic sheet materials: the smart alternative to glass. 

Why polycarbonate, PMMA, PETG and other thermoplastics often perform better than glass. Lighter, more impact-resistant and more energy-efficient.

When considering transparent materials for glazing or protection, glass is often the first choice. However, transparent thermoplastic sheets offer clear advantages in many applications. 

At Zweko Optics, we work with high-quality plastics such as polycarbonate (PC), polymethyl methacrylate (PMMA), PETG, SAN and APET on a daily basis to create solutions for visors, protective screens and optical components. 

But which material is best suited to your application? We compare the properties of glass and thermoplastics for you. Discover why plastics are often a smarter alternative.

Is glass or plastic better for my application?

Glass is known for its hardness, scratch resistance and chemical stability, making it a good choice for architecture and outdoor applications. What is the disadvantage of glass? It is heavy, fragile and difficult to work with. Thermoplastics, on the other hand, are lighter, more impact-resistant and easier to shape or process. 

Figure 1. Stress/strain curves for glass (left) and polycarbonate (right).

Polycarbonate (PC) is known for its unrivalled impact resistance and is often used in safety glazing and visors. PMMA, better known as acrylic (or under the brand name Plexiglas®), excels in clarity and gloss, making it ideal for applications where optical quality is paramount. PETG combines clarity with chemical resistance and is often chosen in medical or industrial environments where regular cleaning and disinfection are required. Materials such as SAN and APET also have specific advantages, from lightweight industrial windows to moisture-resistant solutions for refrigerated display cases.

What are the advantages of SAN in sectional doors?

Styrene Acrylonitrile, better known as SAN, is a thermoplastic that stands out for its high rigidity combined with low weight. These properties make it particularly suitable for windows in sectional doors. 

Thanks to its transparency, SAN creates a sleek, modern look. Its light weight also means that the door construction is subjected to less stress than with glass, resulting in less wear and tear on the motor and hinges and increasing the service life of the system. 

In addition, SAN is highly resistant to temperature fluctuations and retains its dimensional stability, which contributes to the durability of sectional door applications. This makes it a smart alternative to glass that offers both aesthetic and practical advantages.  

What is the best material for visors?

One of the most frequently asked questions is: ‘What is the best material for visors or protective goggles?’

1 | Polycarbonate for personal protective equipment

Polycarbonate (PC) is the number one choice for visors thanks to its extremely high impact resistance. It can absorb hard impacts without breaking, making it ideal for helmets, face protection and safety glasses.

2 | Acrylic for optical quality

PMMA (acrylic) offers the highest light transmission and a luxurious shine, but is less impact resistant. It is often chosen for applications where optical quality is more important than impact resistance.

3 | PETG for chemical resistance

PETG is strong, clear and chemically resistant. It is also easy to mould, which is useful in medical or industrial environments where regular cleaning is required.

Why choose thermoplastics over glass?

Those who prioritise safety, weight and flexibility usually opt for thermoplastics. They are about half the weight of glass and can be processed at much lower temperatures, which makes production easier and more energy efficient.

Glass is simply not an option for visors: it would be too heavy and too fragile to guarantee comfort and safety. Plastics such as polycarbonate, on the other hand, offer the necessary protection and comfort of use. 

At Zweko Optics, we can further improve these materials with our in-house coatings that provide scratch resistance, UV protection and extra durability.

How do you choose the right material?

The choice of the right thermoplastic sheet material depends on three important selection criteria: density, toughness and processing temperature. Glass has a density of approximately 2.5 g/cm³, more than twice as heavy as most thermoplastics, which are around 1.2 g/cm³. 

For applications where weight is a factor, such as in vehicles, cabins or portable protective equipment, plastic is therefore often the better choice. Thermoplastics also score better in terms of toughness. Polycarbonate can withstand much higher impacts than glass, which means it can even be used for burglar-proof or bullet-proof applications. 

Finally, processing temperature plays a role. Glass requires temperatures above 500°C to be formed, while thermoplastics can be processed at much lower temperatures. This saves energy and makes production more efficient and flexible.

Figure 2. Values of standard transparent thermoplastic materials

Source: Vegt, van der, A. K., & Govaert, L. E. (2003). Polymers: from chain to plastic
* Chemical resistance on pure material, without coating and compared to glass on acids, alkalis and organic solvents.
** Outdoor resistance on pure material, without coating or co-extruded cover layers and compared to glass
1) Extruded sheet of PMMA
2) Cast sheet of PMMA
Young’s modulus, tensile strength and elongation at break measured according to ISO 527
Notch impact measured according to ISO 180/1A
LOI = oxygen limit index according to ASTM D2863
Pencil hardness measured according to ASTM D3363

How does Zweko enhance the performance of thermoplastics?

In addition to the basic performance of the material, at Zweko Optics we can further improve its properties by applying in-house ViewTec coatings. These coatings increase scratch resistance, improve chemical resistance and offer UV protection. As a result, transparent thermoplastic sheets last longer and perform even better in demanding conditions, such as outdoor use or intensive cleaning.

Costs and the environment: are thermoplastics a more sustainable alternative?

At first glance, glass appears to be cheaper per kilogram than plastics, but when you look at the total life cycle, thermoplastics are often more cost-efficient. Their lower weight allows for lighter constructions and easier installation. Production is more energy-efficient thanks to lower processing temperatures. 

Due to their higher impact resistance and longer service life, thermoplastics need to be replaced less often. In addition, recycling plastics requires less energy than recycling glass, which reduces the environmental impact.

Conclusion: which material is right for your project?

Transparent thermoplastic sheets such as polycarbonate, PMMA and PETG are versatile and cost-effective alternatives to glass. Their light weight, impact resistance and ease of processing make them the ideal choice for visors, safety glazing and optical applications.

If you are wondering, ‘Which material is best for my visor or protective application?’, the answer is clear: thermoplastics combine safety, performance and flexibility in a way that glass can never match.

With Zweko Optics’ expertise in coatings and processing, we go one step further and create materials that really make a difference.

Curious about which material best suits your project? Contact our specialists; we are happy to help you find the right solution.