thermosetting

adj.

熱硬化性の

WordNet

having the property of becoming permanently hard and rigid when heated or cured; "the phenol resins and plastics were the original synthetic thermosetting materials" (同)thermoset
a material that hardens when heated and cannot be remolded (同)thermosetting resin

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熱硬化性の

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/07/30 13:48:11」(JST)

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A thermosetting polymer (or plastic), also known as a thermoset, is a prepolymer material that cures irreversibly. The cure may be induced by heat, generally above 200 °C (392 °F), through a chemical reaction, or suitable irradiation.

Thermoset materials are usually liquid or malleable prior to curing and designed to be molded into their final form, or used as adhesives. Others are solids like that of the molding compound used in semiconductors and integrated circuits (IC). Once hardened a thermoset resin cannot be reheated and melted to be shaped differently.

Thermosetting resin may be contrasted with thermoplastic polymers which are commonly produced in pellets and shaped into their final product form by melting and pressing or injection molding.

Definition

IUPAC defines a thermosetting resin as a prepolymer in a soft solid or viscous state that changes irreversibly into an infusible, insoluble polymer network by curing. Curing can be induced by the action of heat or suitable radiation, and/or both. There are various kinds of thermosetting plastics. A cured thermosetting resin is called a thermoset.^[1]

Process

The curing process transforms the resin into a plastic or rubber by a cross-linking process. Energy and/or catalysts are added that cause the molecular chains to react at chemically active sites (unsaturated or epoxy sites, for example), linking into a rigid, 3-D structure. The cross-linking process forms a molecule with a larger molecular weight, resulting in a material with a higher melting point. During the reaction, the molecular weight has increased to a point so that the melting point is higher than the surrounding ambient temperature, the material forms into a solid material.

Uncontrolled reheating of the material results in reaching the decomposition temperature before the melting point is obtained. Therefore, a thermoset material cannot be melted and re-shaped after it is cured. This implies that thermosets cannot be recycled, except as filler material.^[2]

Properties

Thermoset materials are generally stronger than thermoplastic materials due to this three-dimensional network of bonds (cross-linking), and are also better suited to high-temperature applications up to the decomposition temperature. However, they are more brittle. Since their shape is permanent, they tend not to be recyclable as a source for newly made plastic.

Examples

Polyester fibreglass systems: sheet molding compounds and bulk molding compounds
Polyurethanes: insulating foams, mattresses, coatings, adhesives, car parts, print rollers, shoe soles, flooring, synthetic fibers, etc. Polyurethane polymers are formed by combining two bi- or higher functional monomers/oligomers.
Vulcanized rubber
Bakelite, a phenol-formaldehyde resin used in electrical insulators and plasticware
Duroplast, light but strong material, similar to bakelite used for making car parts
Urea-formaldehyde foam used in plywood, particleboard and medium-density fiberboard
Melamine resin used on worktop surfaces^[3]
Diallyl-phthalate (DAP) used in high temperature and mil-spec electrical connectors and other components. Usually glass filled.
Epoxy resin used as the matrix component in many fiber reinforced plastics such as glass-reinforced plastic and graphite-reinforced plastic
Polyimides used in printed circuit boards and in body parts of modern aircraft
Cyanate esters or polycyanurates for electronics applications with need for dielectric properties and high glass temperature requirements in composites
Mold or mold runners (the black plastic part in integrated circuits or semiconductors)
Polyester resins

Some methods of molding thermosets are:

Reactive injection molding (used for objects such as milk bottle crates)
Extrusion molding (used for making pipes, threads of fabric and insulation for electrical cables)
Compression molding (used to shape most thermosetting plastics)
Spin casting (used for producing fishing lures and jigs, gaming miniatures, figurines, emblems as well as production and replacement parts)

References

^ http://old.iupac.org/goldbook/TT07168.pdf
^ The Open University (UK), 2000. T838 Design and Manufacture with Polymers: Introduction to Polymers, page 9. Milton Keynes: The Open University
^ Roberto C. Dante, Diego A. Santamaría and Jesús Martín Gil (2009). "Crosslinking and thermal stability of thermosets based on novolak and melamine". Journal of Applied Polymer Science 114 (6): 4059–4065. doi:10.1002/app.31114.

English Journal

Environmental and health hazard ranking and assessment of plastic polymers based on chemical composition.

Lithner D, Larsson A, Dave G.SourceDepartment of Plant and Environmental Sciences, University of Gothenburg, P.O. Box 461, 405 30 Göteborg, Sweden. delilah.lithner@gmail.com
The Science of the total environment.Sci Total Environ.2011 Aug 15;409(18):3309-24. Epub 2011 Jun 12.
Plastics constitute a large material group with a global annual production that has doubled in 15 years (245 million tonnes in 2008). Plastics are present everywhere in society and the environment, especially the marine environment, where large amounts of plastic waste accumulate. The knowledge of h
PMID 21663944

Impact of Structure and Functionality of Core Polyol in Highly Functional Biobased Epoxy Resins.

Pan X, Webster DC.SourceDepartment of Coatings and Polymeric Materials, North Dakota State University, Fargo, North Dakota 58108, USA.
Macromolecular rapid communications.Macromol Rapid Commun.2011 Jun 20. doi: 10.1002/marc.201100215. [Epub ahead of print]
Highly functional biobased epoxy resins were prepared using dipentaerythritol (DPE), tripentaerythritol (TPE), and sucrose as core polyols that were substituted with epoxidized soybean oil fatty acids, and the impact of structure and functionality of the core polyol on the properties of the macromol
PMID 21692121

Characterizing mesh size distributions (MSDs) in thermosetting materials using a high-pressure system.

Larché JF, Seynaeve JM, Voyard G, Bussière PO, Gardette JL.SourceLaboratoire de Photochimie Moléculaire et Macromoléculaire, Université Blaise Pascal, Clermont Université, Clermont-Ferrand, France.
The journal of physical chemistry. B.J Phys Chem B.2011 Apr 21;115(15):4273-8. Epub 2011 Mar 23.
The thermoporosimetry method was adapted to determine the mesh size distribution of an acrylate thermoset clearcoat. This goal was achieved by increasing the solvent rate transfer by increasing the pressure and temperature. A comparison of the results obtained using this approach with those obtained
PMID 21428423

Japanese Journal

ベンゾオキサジン樹脂とシアネートエステル樹脂からなる新規熱硬化性樹脂コンポジット

木村肇,大塚恵子,松本明博
強化プラスチックス 60(7), 278-284, 2014-07
NAID 40020170918

Surface texturing of natural 'urushi' thermosetting polymer thin films

Watanabe Hirohmi,Fujimoto Aya,Takahara Atsushi
Polymer journal 46(4), 216-219, 2014-04
NAID 40020031403

SANSおよびSAXSによるフェノール樹脂硬化物の構造解析 (特集中性子の産業利用)

和泉篤士,中尾俊夫,岩瀬裕希 [他]
波紋 : Neutron network news 24(1), 11-14, 2014-02
NAID 40019975476

リグニンのエポキシ化条件の最適化と熱硬化性樹脂への応用

内藤穂波,奥平浩之,高橋昭雄 [他]
ネットワークポリマー = Journal of network polymer, Japan 35(3), 110-117, 2014
NAID 40020105795

Related Pictures

[1] ttp://old.iupac.org/goldbook/TT07168.pdf

[2] The Open University (UK), 2000. T838 Design and Manufacture with Polymers: Introduction to Polymers, page 9. Milton Keynes: The Open University

[3] Roberto C. Dante, Diego A. Santamaría and Jesús Martín Gil (2009). "Crosslinking and thermal stability of thermosets based on novolak and melamine". Journal of Applied Polymer Science 114 (6): 4059–4065. doi:10.1002/app.31114.

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