New and Emerging Materials

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29 Νοε 2013 (πριν από 3 χρόνια και 10 μήνες)

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New and Emerging Materials

Dale Fenton


Plastic Structural Members

While current use of polymers is reduced to non
-
structural applications there are
advances with some high
-
density polymers that provide sufficient strength for use in
structural superstructures and eventually in highly plastic structural shapes.


Some of these plastics have the benefit of being fire
-
resistant, and nonreactive with
the environment once in place.


Some uses of high
-
density plastics can currently be seen in transmission towers and
lightweight bridges. Plastic formed “lumber” is also available and while it is only
currently available in standard sizes could be produced into more organic and fluid
forms for exterior applications where resistance to rotting is desired.

Plastic Structural Adhesives


Great advances are being made in the strength and durability of polymer adhesives.
While many are currently used for sealants and construction adhesives there is hope
that at some point these adhesives may be strong and versatile enough to essentially
“glue” disparate building modules together in strong, durable structurally sound
bonds so that mechanical fasteners could be avoided. Current structural adhesives
are based on epoxy, acrylic or polyurethane chemistry. In the future there may be
adhesives capable of providing structural bonds similar to welds between different
materials such as metals, plastics, wood, and glass.

High
-
Tech Concrete

There is significant research into new types of concrete with varying
properties. The most promising advancements are in ductile concrete
which has increased strength in compression compared to normal
concrete, but also can accept significant tensile stresses making it
appropriate for creating complex forms without the need to
incorporate reinforcing steel because the mixture uses small
aggregate and includes fiber reinforcing from carbon
-
fiber, glass fiber
or other high
-
tensile strength materials.

Smart Materials

Smart Materials include a broad category of newly developing substances and
composites with incredible properties. Some of these are:

Piezoelectric:
materials that produce a voltage when stress is applied

Shape memory materials:
can be deformed and returned to their original shape

Self
-
healing materials:
can repair damage to themselves

Other types of materials respond to changes in: magnetic fields, pH differences,
temperature, light, or other external stimuli.

Aerogel

An extremely lightweight, manufactured material derived from a gel where the liquid component is
replaced with gas through supercritical drying.


Impressive load bearing capabilities


Dendritic microstructure


spherical particles 2
-
5 nm fused together in clusters


99% air


Friable


current structures easily shattered with enough force


Good thermal insulators


nullifies convection, conduction, and radiation


Types of Aerogel


Silica


lowest density solid 1mg/cm3


absorbs solar radiation, traps heat


extremely low thermal conductivity 0.03 W/mk to 0.004 W/mk


currently used aboard Stardust spacecrafts to trap space dust


Carbon


can be electrically conductive, depending on density


absorbs infrared radiation







Alumina


SEAgel


made of agar, substance derived from kelp or red algae


currently used in time
-
release medical pills and sound damping for trains


Possible Uses in Architecture


Structure


good load
-
bearing capabilities

Insulation


Aerogel lattice traps air


poor conductor of heat


absorbs solar radiation

Windows







Carbon Nanotubes

A form of carbon with a cylindrical nanostructure.


Belongs to Fullerene structural family


Strong tensile strength


due to “covalent sp2 bonds between individual carbon atoms”


specific strength up to 48,000

kN∙m∙kg
−1



high
-
carbon steel 154

kN∙m∙kg
−1


Weak in compression


Low density solid


1.3 to 1.4

g∙cm
−3


Length to diameter ratio 132,000,000 : 1

1/50,000th width of human hair

up to 18 cm long


Efficient thermal conductor


Current applications


Carbon nanotubes currently used is fragmented masses


Used as composite fibers in polymers


Zyvex Performance Materials


bicycle components, lightweight boat 8,000 lbs


underwater sonar speakers
























Kevlar

A lightweight, synthetic fiber spun from liquid crystalline solution.


Manufactured by DuPont


High tensile strength, light weight


5x stronger than steel


Range of products


Pulp, fiber, paper, felt


Body armor, military uses


Storm shelter


DuPont Storm Shelter


anchored in ground with concrete


resists wind and gusts up to 250 mi/hr


integrated with house


includes wiring and plumbing











Spider Silk

“High performance
fibres

from natural or artificial proteins based on
the principles used by spiders and insects to create natural silk
fibres



6x stronger than steel

5x stronger than Kevlar


Manufactured by
Spinox


current devices produces silk 4x thicker (15 microns ) than natural
spider silk


High strength to weight ratio

Strong in tension


stretches 140% of length without breaking


Current applications


Sutures, tissue replacement, bone and joint repair


Currently difficult to mass produce


spiders squirt out thick gel solution, use body weight and gravity to
elongate into fibers


alignment of protein fibers give strength




Genetically engineered silkworms




Sources:

Transmaterial

: a catalog of materials that redefine our physical environment / edited by Blaine E. Brownell.

New York : Princeton Architectural Press, c2006


High
-
performance construction materials : science and applications / editors,
Caijun

Shi, Y.L. Mo.

Singapore ; Hackensack, NJ : World Scientific, 2008


Materials for the third millennium / editors, R.K. Ray ... [et al.]

Enfield, NH, USA : Science Publishers, c2001


Material architecture : emergent materials for innovative buildings and ecological construction / John
Fernandez

Boston : Architectural Press, c2006