Editing Glass fiber (section)

==Properties==

===Thermal===

Fabrics of woven glass fibers are useful thermal insulators because of their high ratio of surface area to weight. However, the increased surface area makes them much more susceptible to chemical attack. By trapping air within them, blocks of glass fiber make good [[thermal insulation]], with a [[thermal conductivity]] of the order of 0.05 [[Watt|W]]/(m·[[Kelvin|K]]).<ref>
{{cite book
 |first1= Frank P.
 |last1= Incropera
 |first2= David P.
 |last2= De Witt
 |title= Fundamentals of Heat and Mass Transfer
 |url= https://archive.org/details/fundamentalsofhe00incr
 |url-access= registration
 |pages= A11
 |edition= 3rd
 |publisher= [[John Wiley & Sons]]
 |year= 1990
 |isbn= 978-0-471-51729-0
}}
</ref>

===Selected properties===

{| class="wikitable" style="text-align:center"
|-
! Fiber type !! [[Tensile strength]] <br/>(MPa)<ref>{{cite book|author1=Frederick T. Wallenberger|author2=Paul A. Bingham|title=Fiberglass and Glass Technology: Energy-Friendly Compositions and Applications|url=https://books.google.com/books?id=REYTVy3OCWgC&pg=PA211|access-date=29 April 2011|date=October 2009|publisher=Springer|isbn=978-1-4419-0735-6|pages=211–}}</ref>!![[Compressive strength]] <br/>(MPa)<!-- Potentially misleading. See talk page -->
!Young's Modulus, E
(GPa)<ref name=":0">{{Citation|title=Fibres and matrices|date=1996|url=https://www.cambridge.org/core/books/an-introduction-to-composite-materials/fibres-and-matrices/062E64AB1E04EC499473B26EDA5A3C27|work=An Introduction to Composite Materials|pages=15|editor-last=Hull|editor-first=D.|series=Cambridge Solid State Science Series|edition=2|place=Cambridge|publisher=Cambridge University Press|doi=10.1017/cbo9781139170130.004|isbn=978-1-139-17013-0|access-date=2020-11-07|editor2-last=Clyne|editor2-first=T. W.}}</ref>
! Density <br/>(g/cm<sup>3</sup>)!!Thermal expansion<br/>(μm/m·°C)!!Softening T<br/>(°C)!!Price<br/>($/kg)
|-
| E-glass || 3445 ||1080 
|76.0||2.58||5||846||~2
|-
|C-glass<ref name=":0" />
|3300
| --
|69.0
|2.49
|7.2
| --
| --
|-
| S-2 glass || 4890 ||1600 
|85.5|| 2.46||2.9||1056||~20
|}

=== Mechanical properties ===
The strength of glass is usually tested and reported for "virgin" or pristine fibers—those that have just been manufactured. The freshest, thinnest fibers are the strongest because the thinner fibers are more ductile. The more the surface is scratched, the less the resulting [[wiktionary:tenacity|tenacity]].<ref name="Volf" /> Because glass has an [[amorphous]] structure, its properties are the same along the fiber and across the fiber.<ref name="Gupta"/> [[Humidity]] is an important factor in the tensile strength. Moisture is easily [[adsorption|adsorbed]] and can worsen microscopic cracks and surface defects, and lessen tenacity.

In contrast to [[carbon fiber]], glass can undergo more elongation before it breaks.<ref name="Gupta"/> Thinner filaments can bend further before they break.<ref>Hillermeier KH, Melliand Textilberichte 1/1969, Dortmund-Mengede, pp. 26–28, "Glass fiber—its properties related to the filament fiber diameter".</ref> The viscosity of the molten glass is very important for manufacturing success. During drawing, the process where the hot glass is pulled to reduce the diameter of the fiber, the viscosity must be relatively low. If it is too high, the fiber will break during drawing. However, if it is too low, the glass will form droplets instead of being drawn out into a fiber.