Glazing types, generic

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 well as a susceptibility to bacteria and fungi.

The commercially available films and their characteristics can vary widely as well as their aging properties (see Boye, et al 2011). In recent years, the options available for the films include heat control (IR blocking), as well as reflectivity options that ensure visibility from the outside is blocked for security (often termed 'privacy'). As these optical characteristics for these options are related, they often come together. As noted by Boye, et al (2011) the adhesive on the film can be problematic and limit its useful lifetime. Thus, manufacturers have recently started offering 'static' cling films that do not have adhesives. One caution is that, thus far, these films are made from vinyl.

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 with 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.

Film composition	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); can be made to cling statically, thus no adhesive is required	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;
Clear Ceramic	Blocks 99% of UV rays, offers excellent heat rejection, and does not alter the window's appearance. Will not interfere with radio or cell signals.	Generally more expensive.	Applications	Brand names
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
Metallized	The metallic particles reflect sunlight, significantly reducing heat and glare. Provide reflectivity often termed 'privacy'. Is available for many polymeric options	Can cause signal interference with phones and GPS. Creates a reflective, "mirror-like" look on the exterior.	Applications	Brand names
High-Performance Dyed	A budget friendly option that offers decent UV protection and some solar energy absorption to reduce heat	Less effective at rejecting heat than ceramic or metalized films. No cell interference	Applications	Brand names Can cause signal interference with phones and GPS. Creates a reflective, "mirror-like" look on the exterior.

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

• Colleen Boye, Frank Preusser, Terry Schaeffer, 'Aging Properties of Select UV-Blocking Window Films' WAAC Newsletter, Vol 33(1), 2011 Link
• 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]