Polymer

Appearance of real linear polymer chains as recorded using an atomic force microscope on a surface, under liquid medium. Chain contour length for this polymer is ~204 nm; thickness is ~0.4 nm.
Cartoon schematic of polymer molecules
Structure of a styrene-butadiene chain, from a molecular simulation.
Some memorable milestones in the history of polymers
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Microstructure of part of a DNA double helix biopolymer
Branch point in a polymer
A polyethylene sample that has necked under tension.
Thermal transitions in (A) amorphous and (B) semicrystalline polymers, represented as traces from differential scanning calorimetry. As the temperature increases, both amorphous and semicrystalline polymers go through the glass transition (Tg). Amorphous polymers (A) do not exhibit other phase transitions, though semicrystalline polymers (B) undergo crystallization and melting (at temperatures Tc and Tm, respectively).
Phase diagram of the typical mixing behavior of weakly interacting polymer solutions, showing spinodal curves and binodal coexistence curves.
A plastic item with thirty years of exposure to heat and cold, brake fluid, and sunlight. Notice the discoloration, swelling, and crazing of the material
Chlorine attack of acetal resin plumbing joint
Ozone-induced cracking in natural rubber tubing

A polymer ( Greek poly-, "many" + -mer, "part")

- Polymer

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Repeat unit

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In polymer chemistry, a repeat unit or repeating unit is a part of a polymer whose repetition would produce the complete polymer chain (except for the end-groups) by linking the repeat units together successively along the chain, like the beads of a necklace.

Natural rubber

Pieces of natural vulcanized rubber at Hutchinson's Research and Innovation Center in France.
Latex being collected from a tapped rubber tree, Cameroon
Rubber tree plantation in Thailand
Rubber latex
Rubber latex elasticity
Chemical structure of cis-polyisoprene, the main constituent of natural rubber. Synthetic cis-polyisoprene and natural cis-polyisoprene are derived from distinct precursors, isopentenyl pyrophosphate and isoprene.
Rubber is generally cultivated in large plantations. The image shows a coconut shell used in collecting latex, in plantations in Kerala, India.
Sheets of natural rubber
Vintage tobacco card, Tapping a Rubber Tree, India, Products of the World series, Player's Cigarettes, 1909
A woman in Sri Lanka harvesting rubber, c. 1920
Mixed field coagula.
Cup lump rubber coagula in a Myanmar road stall.
Removing coagulum from coagulating troughs.
Torn latex rubber dry suit wrist seal
Compression molded (cured) rubber boots before the flashes are removed
Compression molding machine for rubber parts

Rubber, also called India rubber, latex, Amazonian rubber, caucho, or caoutchouc, as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds.

Latex

Tapping of latex from a tree, for use in rubber production
Rubber tapping latex
Opium poppy exuding fresh latex from a cut

Latex is a stable dispersion (emulsion) of polymer microparticles in water.

Polymer chemistry

Portion of backbone of nylon 6,6.
Structures of some electrically conductive polymers: polyacetylene; polyphenylene vinylene; polypyrrole (X = NH) and polythiophene (X = S); and polyaniline (X = NH/N) and polyphenylene sulfide (X = S).
Structure of polydimethylsiloxane, illustrating a polymer with an inorganic backbone.
The viscosity of polymer solutions is a valued parameter. Viscometers such as this are employed in such measurements.
Segments of polypropylene, showing the slightly different structures of isotactic (above) and syndiotactic (below) polymers.
Composites are formed by combining polymeric materials to form an overall structure with properties that differ from the sum of the individual components.
A strand of cellulose showing the hydrogen bonds (dashed) within and between the chains.
Hermann Staudinger, father of polymer chemistry
Wallace Carothers, inventor of nylon.
Stephanie Kwolek, inventor of Kevlar.

Polymer chemistry is a sub-discipline of chemistry that focuses on the chemical synthesis, structure, and chemical and physical properties of polymers and macromolecules.

Material

Substance or mixture of substances that constitutes an object.

Hydrogen's purple glow in its plasma state, the most abundant in the universe

Polymers: materials based on long carbon or silicon chains

Viscoelasticity

Property of materials that exhibit both viscous and elastic characteristics when undergoing deformation.

Stress–strain curves for a purely elastic material (a) and a viscoelastic material (b). The red area is a hysteresis loop and shows the amount of energy lost (as heat) in a loading and unloading cycle. It is equal to  is strain.
Comparison of creep and stress relaxation for three and four element models
Maxwell model
Schematic representation of Kelvin–Voigt model.
Schematic of Maxwell-Wiechert Model
Temperature dependence of modulus
a) Applied stress and b) induced strain as functions of time over a short period for a viscoelastic material.
Schematic of the SER extensional rheometer. The sample (brown) is held to two cylinders (grey) which are then counterrotated at varying strain rates. The torque required to strain the sample at these rates is calculated via a set of torque transducers present in the instrument. These torque values are then converted to stress values, and the stresses and strain rates are then used to determine the viscosity of the sample.

When a stress is applied to a viscoelastic material such as a polymer, parts of the long polymer chain change positions.

Chemical substance

Form of matter having constant chemical composition and characteristic properties.

Steam and liquid water are two different forms of the same chemical (pure) substance: water.
Colors of a single chemical (Nile red) in different solvents, under visible and UV light, showing how the chemical interacts dynamically with its solvent environment.
Native sulfur crystals. Sulfur occurs naturally as elemental sulfur, in sulfide and sulfate minerals and in hydrogen sulfide.
Potassium ferricyanide is a compound of potassium, iron, carbon and nitrogen; although it contains cyanide anions, it does not release them and is nontoxic.
Cranberry glass, while appearing homogeneous, is a mixture consisting of glass and gold colloidal particles of about 40nm in diameter, giving it a red color.
Chemicals in graduated cylinders and beaker.

Polymers almost always appear as mixtures of molecules of multiple molar masses, each of which could be considered a separate chemical substance.

Nucleic acid

Nucleic acids are biopolymers, macromolecules, essential to all known forms of life.

Nucleic acids RNA (left) and DNA (right).
The Swiss scientist Friedrich Miescher discovered nucleic acid first naming it as nuclein, in 1868. Later, he raised the idea that it could be involved in heredity.

If the sugar is ribose, the polymer is RNA; if the sugar is the ribose derivative deoxyribose, the polymer is DNA.

Polypropylene

Micrograph of polypropylene
Effect of UV exposure on polypropylene rope
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A ball-and-stick model of syndiotactic polypropylene.
Polypropylene lid of a Tic Tac box, with a living hinge and the resin identification code under its flap
A polypropylene chair
Polypropylene items for laboratory use, blue and orange closures are not made of polypropylene.
Various polypropylene yarns and textiles
FKP 1 polypropylene (PP) film capacitor for pulse applications with metal foil manufactured by WIMA.
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Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications.

Polyethylene

Most common plastic in use today.

The repeating unit within polyethylene in the most stable staggered conformation
A pill box presented to a technician at ICI in 1936 made from the first pound of polyethylene
Stainless steel and ultra high molecular weight polyethylene hip replacement
HDPE pipe on site during installation in outback Western Australia. The white outer layer is co-extruded to provide a reduction of thermal heating, known as Acu-Therm.
A recyclable bag manufactured from polyethylene.
Say no to polythene. Sign. Nako, Himachal Pradesh, India.
Shown are the peroxide, the silane and irradiation crosslinking

It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bottles, etc.).