Glazing types, generic
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Description
Any optically transparent thermoplastic sheet that may be used as a replacement for window glass. In general, the polymers are stronger than glass, block more UV light, and are lighter weight and easier to install. Additionally, most plastic brands have numerous options to provide optimum strength, impact resistance, clarity and transparency that are produced using various additives and or coatings. The current most common polymer types include acrylics, polycarbonates, and polyesters. Drawbacks for the using polymers can include aging characteristics (yellowing or brittleness), poor resistance to scratching and cleaners, as will as a susceptibility to bacteria and fungi.
Glass is recycled at a rate of 76%, while the average rate for plastics is 41%. This is not solely based on glazing as the recycling for both products is highest for containers. For glazing, tempered and laminated glass are never recycled. In the environment, however, glass and its degradation products are non-toxic while plastics break down to micro-plastics that easily spread.
Some more recent developments in transparent polymers include the following materials (not included in the tables below). For more information see Omnexus list of transparent polymers
- Liquid silicone rubber (LSR): a thermoset elastomer with high clarity
- Cyclic Olefin Copolymers (COC): has the best properties of polyethylene and polypropylene
- Ionomer resin: an ethylene polymer that high clarity, scratch resistance and chemical resistance
- Fluorinated ethylene propylene (FEP): chemically inert with high transmission of UV, visible and infrared radiation
- Styrene methyl methacrylate (SMMA): a high clarity, glossy copolymer with excellent processing and mechanical properties
- Styrene-acrylonitrile resin (SAN): a clear rigid polymer with better impact strength
- Polystyrene (general purpose - GPPS): a crystal clear polymer that is inexpensive and easy to process; commonly used for plastic cups.
| Polymer | Advantages/Strengths | Limitations | Applications | Brand names |
|---|---|---|---|---|
| Acrylic (PMMA) | Optically clear; lightweight; good dimensional stability; available in many sizes and shapes; forming does not affect clarity; resistant to UV light and weathering; good moldability; not recyclable (symbol #7) | Shelves can sag/crack under weight; can be broken, scratched, shattered; not resistant to aromatic HCs | Display cases, light fixtures, transparent shelves for lightweight materials, indoor and outdoor signage; UV grades available | Acrylite; Altuglas; Duraplex; Lucite; Optium; Optix; Plexiglas; PMMA Brands |
| Polycarbonate (PC) | High strength and stiffness; lightweight; easy to machine; impact resistant; heat resistant to 135C; flame retardant; abrasion resistant; can accept printing temps to 260-300C; not recyclable (symbol #7) | Attacked by hydrocarbons, oils, and bases; hot water immersion reduces physical properties; UV stabilizers needed to minimize UV degradation; poor stress cracking performance | Bullet proof windows, doors, and windshields; headlamps; safety helmets, visors in sporting gear, signage; UV grade signs for outdoor use | Lexan; Tuffak (formerly Makrolon); Palsun; Sunlite; Trizod; PC brands |
| Polyethylene terephthalate (PET) | Low gas permeability; strong; lightweight; doesn’t break or fracture; safe for foods and beverages; excellent resistance to alcohols, oils, and acids; most often used for 3D printing; fire resistant; recyclable (symbol #1) | Low impact strength, low moldability; easily degrades in UV light | Films and sheets; fibers; food and beverage containers; geotextiles, electronics | Mylar; Melinex; PET Brands |
| Polyethylene (LDPE) | Very lightweight; flexible; good transparency; high impact strength; resistant to acids and bases; good weathering resistance; very low water absorption; special recycle (symbol #4) | Low strength, stiffness; susceptible to stress cracking; high gas permeability; highly flammable; cannot be welded using high frequency | Films, bags, bottles, tubing, laminates, extrusion molding | Volara; Tyvek; Tupperware; Plastazote; Correx; Polythene; PE brands |
| Polyethylene (HDPE) | Excellent chemical resistance; high tensile strength; semi-flexible; good weathering resistance, low water absorption; excellent moisture barrier; recyclable (symbol #2) | Translucent to opaque; susceptible to stress cracking; high mold shrinkage; cannot be welded using high frequency | Hollow plastic products, pipes; crates; ice boxes, trash cans, wiring and cables ; ropes and nets | Volara; Tyvek; Tupperware; Plastazote; Correx; Polythene; Sanalite; PE brands |
| Transparent Polypropylene (PP) | Inexpensive but difficult to obtain transparent sheets unless clarifying additives are used; good stiffness and barrier properties; durable; resistant to stress cracking; recyclable (symbol #5) | Highly flammable; sensitive to UV and microbes; poor resistance to impact and scratches; poor paint adhesion; adversely affected by contact with metals | Packaging, storage boxes; textiles, pipes, automobiles; | PP Brands |
| Rigid PVC (Clear), unplasticized | Lightweight; 'water clear' clarity; optional high-impact and UV resistance with additives; formable; abrasion resistant; high fire rating; not recyclable (symbol #3) | Not easy to recycle; only flexible when plasticized; poor heat stability; releases chlorine with degradation; difficult to melt | Window frames, house siding; pipes, laminates car seats, backs credit cards, traffic signs | Geon; Dural; Komacel; Komatex; Forex; sintra; PALIGHT; PVC brands |
| Transparent ABS (MABS) | High rigidity and dimensional stability; good weldability; high impact and abrasion resistance; good insulating properties; often used in 3d printing; special recycle (symbol #9) | Poor weathering resistant; burns easily; poor solvent resistance; low continuous service temperature; often blended with other polymers | Usually reinforced with fibers or minerals or blended with other polymers; used in autos, appliances, household goods, and electronics | Abson; Cycolac; Primeco; ABS brands |
| Glass | Advantages/Strengths | Limitations | Applications | Brand names |
| Soda-lime glass | Most common and least expensive; high light transmission; chemically stable; resistant to chemicals, abrasion and electrical current; durable; fire resistant; excellent volatile barrier; recyclable | Brittle; will shatter when hit; twice as heavy as polymers; requires strong support frames | Standard material for windows and glassware; | |
| Laminated Glass | Crystal clear with almost no reflections; abrasion and shatter resistant; anti-reflective, 99% UV protection; durable; fire resistant; excellent volatile barrier | Glass will break unless held in place with polymer layer; twice as heavy as polymers; requires strong support frames; cannot be recycled | Usually two layers of glass with interior polymer layer and a polymer coating on both exterior sides | UltraVue laminated glass |
Physical and Chemical Properties
| Polymer | Melt Temperature C | Extrusion Temperature C | Density g/ml | RI | Visible light transmission (%) | Haze (%) | Shrinkage % | Water absorption % | Hardness Shore D | Flex. Mod. Gpa (Bending stiffness) | Tensile strength Mpa | Izod impact J/m | Thermal Expansion X10-5/C | Fire Resistance (LOI) % | Link |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Acrylic (PMMA) | 200-250 | 180-250 | 1.17 | 1.49 | 80-93 | 0.1-2.6 | 0.2-0.8 | 0.29-0.42 | 90-99 | 2.5-3.5 | 38-70 | 10-25 | 5-9 | 19-20 | PMMA Properties |
| Polycarbonate (PC) | 230-260 | 260-300 | 1.2 | 1.585 | 86-91 | 0.2-2.7 | 0.7-1.0 | 0.1-0.2 | 90-95 | 2.2-2.5 | 55-77 | 80-650 | 7-9 | 24-25 | PC Properties |
| Polyester Terephalate (PET) | 280-310 | 279-290 | 1.3-1.4 | 1.575 | 70-92 | 0.20-5.1 | 0.2-3.0 | 0.1-0.2 | 85-95 | 2.8-3.5 | 45-70 | 140 | 6-8 | 23-25 | PET Properties |
| Polyethylene (LDPE) | 105-115 | 0.92-0.94 | 1.476 | 4.4-94 | 1.3-27.5 | 2-4 | 0.005-0.015 | 40-50 | 0.245-0.335 | 10-20 | no break | 10-20 | 17-18 | PE Properties | |
| Polyethylene (HDPE) | 120-140 | 0.94-0.97 | 80 | 6 | 1.5-4 | 0.005-0.01 | 60-70 | 0.75-1.575 | 25-45 | 20-220 | 6-11 | 17-18 | PE Properties | ||
| Tr.Polyprop (PP) | 160-165 | 200-300 | 0.9 | 1.347 | 85-90 | 11 | 1-3 | 0.01-0.1 | 70-83 | 1.2-1.6 | 20-40 | 27-107 | 6-17 | 17-18 | PP Properties |
| Rigid PVC (Clear), unplasticized | 170-210 | 1.35-1.5 | 1.381 | 80-87 | 2.5 | 0.1-0.6 | 0.03-0.4 | 65-90 | 2.1-3.5 | 35-60 | 20-110 | 5-18 | 40-45 | PVC Properties | |
| Tr. ABS (MABS) | 210-270 | 210-240 | 1.02-1.21 | 1.52 | 86 | 3 | 0.7-1.6 | 0.5-1.8 | 100 | 1.6-2.4 | 30-48 | 20-160 | 7-15 | 19 | ABS Properties |
| Glass | Melt Temperature C | Extrusion Temperature C | Density g/ml | RI | Visible light transmission (%) | Haze (%) | Shrinkage % | Water absorption % | Hardness Shore D | Flex. Mod. Gpa (Bending stiffness) | Tensile strength Mpa | Izod impact J/m | Thermal Expansion X10-5/C | Fire Resistance (LOI) % | Link |
| Soda-lime glass | 1040 | <600 (working pt) | 3.4-2.5 | 1.513-1.523 | 99 | variable | slight expansion until >500C | 0.001 | 6-7 | 72 | 7-90 | Izod impact J/m | 0.3-0.6 | Non-flammable | Physical properties of glass |
Resources and Citations
- Omnexus Materials Selection: List of Transparent Polymers
- Abrisa Technologies: [www.abrisatechnologies.com Soda-lime glass]
- Wikipedia: Properties of Glass
- Kopp Glass: Glass Thermal Properties
- R. Razouk and A. Salem, 'The Adsorption of Water Vapor on Glass ' J. Phys. Chem. 1948, 52, 7, 1208–1227 [J. Phys. Chem. 1948, 52, 7, 1208–1227 Link]