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Comprehensive List of Transparent Polymers

SpecialChem – Oct 25, 2017

Comprehensive List of Transparent PolymersFrom baby bottles to optical lenses to television or mobile phones… the applications list is never ending for transparent plastics. Today, we are surrounded by several clear or transparent plastic materials that make product more attractive as well as portable to use over traditional glass.

Nowadays, several manufacturers are taking advantage of the inherent quality and consistency of transparent plastic materials by incorporating them in several applications to:

  • Manufacture lightweight, durable and shatter-resistant products
  • Lower production costs
  • Produce complex geometry and uniquely shaped components
  • Achieve visible light transmission and/or optical refractive power comparable to glass
  • And many more… 

Some of the popular applications benefiting from above mentioned advantages are:

  1. Packaging (food, cosmetics…)
  2. Consumer products (Food processing jars, data storage products, lenses…)
  3. Glazing for buildings (aquarium, security shields…)
  4. Automotive & electrical components (LEDs, headlamp covers…)
  5. Healthcare (syringes, …)
  6. Agricultural films

However, this range of applications is very broad, it is remarkable that only a few polymer types meet the demanding material specifications.

Let’s take a look at this ‘sparkling’ category of plastics and discuss some of the transparent polymers (PC, PMMA, PET, SMMA, COC…and more) for their features and popular applications!

Polycarbonate


Polycarbonate (PC) is a high-performance tough, amorphous and transparent thermoplastic polymer offering unique combination of properties such as high impact strength, dimensional stability, good mechanical properties, etc. It can transmit over 90% light and block ultraviolet radiation and provide 100% protection from the sun's harmful UV rays.
Polycarbonate Applications in Electrical & Electronics Market

Polycarbonate is used in a large variety of everyday applications:

  • Electrical and electronics (LED lights, Connectors, cell phones…)
  • Automotive (Headlight bezels, door handles, radiator grills and inner lenses)
  • Agriculture (Greenhouse covering materials)
  • Consumer goods (eyewear, appliances, food contact…)
  • Medical (surgical instruments, devices…)

Transparent sheets made up of PC are up to 200 times stronger than its equivalent thickness in glass on impact tests and easy to cut.


PMMA or Acrylic


PMMA is a rigid, transparent thermoplastic material widely used as a “shatter-resistant” alternative to glass. Over other clear plastics (PC, PS), this polymer has several technical advantages such as:
PMMA Sheets Used to Build Aquariums
  • High resistance to UV light and weathering,
  • Upto 92% Light transmission & optical properties
  • Unlimited coloring options

These benefits make PMMA sheets suitable for architecture and construction to build greenhouses, marine centers; car windows, light covers, lamps, electronic equipment display, designer furniture and many more.


Polyethylene Terephthalate (PET)


PET is a general-purpose, clear thermoplastic polymer known for its excellent combination of properties such as mechanical-, thermal-, chemical resistance as well as dimensional stability. PET may appear opaque, white and transparent depending on its crystalline and amorphous structure.

The desirable properties of PET (clear, lightweight, high strength, stiffness high chemical resistance, barrier properties and low price) make it the material of choice for:

  • Water bottles
  • Carbonated soft drinks containers
  • Fibers
  • Films
PET Packaging for Water, Carbonate Drinks...

Due to low cost, better aesthetic appearance, and better handling, PET is being preferred over polycarbonate (PC).


Amorphous Copolyester (PETG)


Copolyester forms when modifications are made to polyesters, which are combinations of diacids and diols. Amorphous copolyesters such as PETG offer versatility to meet a wide range of applications. Amorphous copolyester combines excellent clarity and toughness with outstanding heat and chemical resistance.

PETG can be a drop-in replacement for PC, PMMA, and PC/Polyester with minor or no modifications.

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Transparency


Polyvinyl Chloride (PVC)


PVC is an amorphous thermoplastic with good transparency. Clear PVC sheets combine excellent mechanical properties and impact strength with water-clear clarity & excellent resistance to chemicals and fire resistance.

PVC is an Amorphous Thermoplastic with Good Transparency While, transparent PVC pipes are specifically formulated to block damaging UV light. These pipes are widely recommended for outdoor applications which are exposed to sunlight and where transparency is required.

Optical characteristics of clear PVC products range from high light transmission to high clarity, anti-glare surface to high impact strength and hence, making them suitable for external applications. Main application of transparent PVC sheets, tubes and clear films include:

  • Construction – day lighting, safety glazing, greenhouses…
  • Packaging – Blister Packs, cling films, clear wraps…
  • Medical – Bags, tubing, drips, connectors, valves…


Liquid Silicone Rubber (LSR)


Liquid silicone rubber is a low viscosity, transparent thermoset elastomer compound which offers:

  • Excellent Optical Clarity (94% transmission)
  • Durability (High temperature resistance upto 150°C)
  • Excellent processability
  • Design Freedom
Applications of Liquid Silicone Rubber

It is a lightweight materials which has successfully replaced glass and other thermoplastics in various applications such as high power LED lighting, electronics, automotive lighting, consumer goods, healthcare and many others where high transparency, heat / UV-light resistance, and long-term durability are key requirements.


Cyclic Olefin Copolymers


Cyclic Olefin Copolymer (COC) is an amorphous, transparent thermoplastic produced by chain copolymerization of cyclic monomers with ethane. It is a relatively new class of polymers as compared to commodities such as polypropylene and polyethylene and known for its excellent optical clarity, good mechanical properties and moisture barrier properties.

Medical Applications of COC
  • High stiffness and strength
  • Excellent moisture and aroma barrier
  • High transparency and gloss
  • Compliant for food and healthcare applications

Outstanding optical properties of COC make it ideal for food packaging films, optical data discs, high precision lenses, optical films etc. Also, being resistant to moisture, solvents and sterilization, Cyclic Olefin Copolymer finds good use in medical and life science applications such as blister packs, medical trays etc.


Polyethylene (PE)


Plastic Pouches Made from LDPEPolyethylene is a very durable thermoplastic widely used to produce films, tubes, plastic parts, laminates, etc. in several markets (packaging, automotive, electrical, etc.). It is the most produce plastic in the world and you use it almost daily in your life.

LDPE is flexible, tough & has good transparency and is widely used in applications ranging from plastic bags, clear films, laboratory equipment etc.


Ionomer Resin


Ionomers is a polymer class which has ethylene as the major component, but which contains both covalent and ionic bonds and are known for its outstanding clarity, toughness, and light weight. Ionomer resins are widely used to produce luxury decorative effects, transparency and scratch resistance in cosmetics and perfume packaging.
Ionomer Resin

The transparent polymer provide design freedom to designers and manufacturers to produce new shapes and use colors for the inner and outer containers separately as well as develop new material combinations for improved barrier properties and chemical resistance. Food packaging, medical devices, golf ball covers, overmolded bottles etc. are among popular applications for ionomer resins.


Transparent Polypropylene (PP)


Polypropylene is an excellent resin thanks to its good physical properties, cost-effectiveness and recyclability but due to its crystalline nature, it was difficult to obtain transparent PP sheets. But today, clear polypropylene (PP) has made significant progresses thanks to new efficient clarifying additives, also called clarifiers as these polymers provide design flexibility, easier processing ability, better colorability / decoration, and offer cost savings via light-weighting.

Transparent Polypropylene Also, a combination of quick quenching and suitable heat treatment can improve the transparency of polypropylene extrusion sheets. Other benefits which make transparent PP a viable substitution for higher cost clear materials such as glass and clear plastics (PS, PC, PETG) include:

  • Good stiffness / impact balance
  • Good moisture / vapor barrier

These performance advantages and its low density make transparent PP an ideal packaging material choice for:

  1. Food packaging and storage (Cups, Trays, bottles, jugs, jars…)
  2. Personal care products packaging
  3. Storage boxes


Fluorinated Ethylene Propylene (FEP)


Fluorinated ethylene propylene (FEP) is chemically a copolymer of hexafluoropropylene and tetrafluoroethylene. This polymer transmits a high percentage of ultraviolet and visible light. The solar transmission of FEP in thin-film form is approximately 96%. FEP films transmit more UV, visible and infrared radiation than ordinary glass. Other benefits of FEP:

  • Most chemically inert in all plastics
  • Outstanding weathering resistance
  • Excellent optical characteristics


Styrene Methyl Methacrylate (SMMA)


SMMA or Styrene Methyl Methacrylate (SMMA) is a high clarity styrene-acrylic copolymer with superior glossy surface. It combines excellent processing advantages & cost-attractiveness of styrene polymers and high brilliance & transparency of polyacetal. Other benefits of SMMA are:

  • Excellent thermal stability 
  • Better alcohol resistance than acrylic
  • Better mechanical properties than GPPS
  • Scratch resistant
  • FDA-complaint

SMMA or Styrene Methyl Methacrylate

As compared to PMMA, PC, and PET, SMMA is cheaper and demonstrates similar surface quality.

SMMA is suitable for applications demanding a strong, stiff, water clear such as household products, tumblers, glassware, cosmetic packaging, medical devices, personal hygiene products etc.


Styrene Acrylonitrile Resin (SAN)


SAN, or Styrene-acrylonitrile resin, is a copolymer plastic made up of styrene and acrylonitrile monomers. It is a durable, break-resistant transparent plastic widely used to make kitchenware (glassware, tumblers…) thanks to its attractiveness and resistance to fats, oils and cleaning agent. Other applications of SAN include appliances, furniture, automotive parts etc.

SAN, or Styrene-acrylonitrile Resin

It combines the clarity and rigidity of polystyrene with the hardness, strength, and heat and solvent resistance of polyacrylonitrile. As compared to polystyrene, it has a higher glass transition temperature and better impact strength but it is more expensive and less transparency.


Polystyrene (General Purpose – GPPS)


General Purpose Polystyrene (GPPS), also known as crystal-clear polystyrene, is a clear polymer which exhibits:

  • High stiffness
  • Good dimensional stability
  • Low specific gravity, and
  • Excellent heat resistance
  • Good electrical insulation properties

Polystyrene (General Purpose – GPPS)

Thanks to its amorphous nature, it offers several benefits over other polymers because of its clarity, low cost and ease of processing. Some of the applications of GPPS are toys, CD cases, hangers, vegetable boxes for refrigerators, showers enclosure panels, IT equipment, clear jewellery box, refrigerator shelves and drawers and plastic cups. It is also used for the manufacturing of disposable medical products such as test tubes, test kits housing, diagnostic products, Petri-dishes, etc.

Few disadvantages of polystyrene include low resistance to cracking and scratching.


MABS (Transparent ABS)


ABS is an impact-resistant engineering thermoplastic made up of three monomers: acrylonitrile, butadiene and styrene. The styrene-acrylonitrile copolymer provides stiffness while butadiene provides impact resistance.

Manufacturers incorporated methyl methacrylate monomer into the SAN phase leading to highly transparent ABS resin called as MABS (Methyl Methacrylate Acrylonitrile Butadiene Styrene). Properties offered by MABS are:

Transparent ABS for Consumer Applications
  • High light transmittance
  • Low haze
  • Consistent and stable color
  • Improved flow characteristics

Transparent ABS can outperform polystyrene, SAN and PMMA for impact resistance and offers good processability. MABS grades with improved flow characteristics can be used as an interesting alternative to polycarbonate (PC). Clear ABS is used in consumer appliances, medical applications, sports goods, medical devices and more.


Optical Properties of Transparent Polymers


  Transmission [%] Refractive Index Haze [%]
PC 86-91 1.584-1.586 0.2-2.7
PMMA 89-92 1.49 0.10-2.6
PET 87-92.1 1.575 0.20-5.1
PETG 92 1.55 0.7
Clear PVC Upto 97% 1.381 2.5
LSR 94 1.41 <1
COC 91 1.53 3
LDPE 4.4-94 1.476 3-12
Ionomer Resin 93.4 1.49 2.7-4.2
Transparent PP - 1.347 -
FEP 92 1.55 0.7
SMMA 89-92.8 1.59 0.3-1.0
SAN 86.2-89.3 1.57 0.4-2.8
GPPS 88-90 1.6 0.3-1.1
Transparent ABS 86 1.52 3



6 Comments on "Comprehensive List of Transparent Polymers"
Kirill K Sep 13, 2018
Looks like PVC has better chances as optical material than PMMA or PC! Congrats! P.S. SBC and MBS are missing.
Sibabrata D Dec 17, 2017
in the SMMA section it is mentioned "styrene polymers and high brilliance & transparency of polyacetal" I guess it will be PMMA
Marcos K Dec 6, 2017
There is also the amorphous PAs Grilamid TR.
Marcos K Dec 6, 2017
You algo forgot PMP (polymethylpentene), know as TPX.
Manuel H Nov 9, 2017
you forgot a major polymer, PVC ! http://www.pvc.org/en/p/transparency
Wayne A Nov 8, 2017
Where does the Eastman Tritan Co-Polyester fit within the above table ?

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