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cross-linking polymers

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Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 August 2013
DOI: 10.31399/asm.tb.ems.t53730099
EISBN: 978-1-62708-283-9
... Abstract This chapter discusses the structural classifications, molecular configuration, degradation, properties, and uses of polymers. It describes thermoplastic and thermosetting polymers, degree of polymerization, branching, cross-linking, and copolymers. It also discusses glass transition...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 November 2012
DOI: 10.31399/asm.tb.ffub.t53610327
EISBN: 978-1-62708-303-4
... plasticizers, changing the polymer from one that is hard, stiff, and brittle to one which is softer, more flexible, and tougher. Often these chemicals can dissolve the polymer if they are present in large enough quantity and if the polymer is not cross linked. Other chemicals can induce environmental stress...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780146
EISBN: 978-1-62708-281-5
.... , American Chemical Society , 1992 Chemical reaction kinetics of polymers are similar to those of small molecules, in spite of the enhanced resistance of crystalline, cross-linked, and stiffened polymers. A polymer is a giant molecule that differs from conventional, small molecules, such as ethane...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780003
EISBN: 978-1-62708-281-5
... structure polymer cross linking AN ENGINEERING PLASTIC may be defined as a synthetic polymer with mechanical properties that enable its use in the form of a load-bearing shape. Polymers, which constitute the major portion of an engineering plastic, are made up of extremely large molecules formed from...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780267
EISBN: 978-1-62708-281-5
... for tribological applications. The problem encountered with such polymers is their tendency to fail in a catastrophic manner when the glass transition temperature is reached. Examples of this class of polymer are PMMA, PS, and polycarbonate. Cross-linked polymer PEEK also behaves in a way similar...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780343
EISBN: 978-1-62708-281-5
... processing operation. Fig. 2 Basic elements of engineering polymers. See Table 1 for explanation. Table 1 Basic elements of engineering polymers Location Characteristics Examples 1 Flexible and crystallizable chains PE PP PVC PA 2 Cross-linked amorphous networks of...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 30 April 2020
DOI: 10.31399/asm.tb.bpapp.t59290035
EISBN: 978-1-62708-319-5
... properties can be reversed if the material is once again heated. Candle wax is a prime example. In contrast, a thermosetting polymer, such as epoxy, undergoes irreversible cross linking. After the first heating cycle, the polymer backbone chains bond to each other, making the structure rigid. When this...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 October 2012
DOI: 10.31399/asm.tb.lmub.t53550385
EISBN: 978-1-62708-307-2
..., such as the 0°, +45°, –45°, and 90° directions. A micrograph of a cross-plied continuous carbon-fiber/epoxy laminate is shown in Fig. 8.14 . A balanced laminate with equal numbers of plies in the 0°, +45°, –45°, and 90° directions is called a quasi-isotropic laminate ( Fig. 8.12b ) because it will...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780329
EISBN: 978-1-62708-281-5
... stresses all combine to produce changes in the chemical composition of the material. These changes may take the form of polymer molecular weight reduction due to main-chain cleavage, the formation of cross links, or the formation of oxidized and other functional groups. As the chemical composition of the...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780295
EISBN: 978-1-62708-281-5
... ). This work has been extended to include cross-linked ( Ref 37 , 39 ) and filled ( Ref 37 , 40 ) polymers. It is speculated that aging occurs above the T g in crystalline polymers because of the pinning action of crystalline components, which retard mobility ( Ref 19 ). Aging is also known to occur...
Series: ASM Technical Books
Publisher: ASM International
Published: 30 April 2021
DOI: 10.31399/asm.tb.tpsfwea.t59300301
EISBN: 978-1-62708-323-2
... Abstract This chapter covers the friction and wear behaviors of plastics and elastomers. It begins by describing the molecular differences between the two types of polymers and their typical uses. It then discusses the important attributes of engineering plastics and their suitability for...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.tb.scm.t52870063
EISBN: 978-1-62708-314-0
... the specimens are subsequently loaded to failure, the toughened systems have a larger cross-sectional area of undamaged material to help support the compression load. Fig. 3.18 Damage comparison during low-velocity impact To impart greater toughness to the crosslinked thermoset polymers...
Series: ASM Technical Books
Publisher: ASM International
Published: 30 April 2020
DOI: 10.31399/asm.tb.bpapp.9781627083195
EISBN: 978-1-62708-319-5
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780404
EISBN: 978-1-62708-281-5
... elongations in tension (2 to 4%). These include PS, PMMA, and rigid (unplasticized) PVC. Crazing is the dominant mechanism of failure in such polymers. Highly cross-linked polymers, such as epoxies and unsaturated polyesters, are also brittle, yet their fracture involves a microcracking mechanism. On the...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780115
EISBN: 978-1-62708-281-5
... behavior for cross-linked systems). This region of behavior above the transition is called the rubbery plateau, in reference to the high degree of molecular motion possible at these temperatures. Fig. 1 Temperature dependence of the modulus, E , of polymers. Examples of idealized behaviors...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 October 2012
DOI: 10.31399/asm.tb.lmub.t53550457
EISBN: 978-1-62708-307-2
... conductivity of the MMC is much higher than the cast iron liner, decreasing operating temperature and resulting in extended engine life. Fig. 9.2 Cutaway section of the Honda Prelude 2000 cm 3 cast aluminum engine block with integral metal-matrix composite (MMC) piston liners. A cross section of the...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 October 2012
DOI: 10.31399/asm.tb.lmub.t53550621
EISBN: 978-1-62708-307-2
... 295 12.12 Cross N. , Engineering Design Methods , 2nd ed. , John Wiley & Sons, Inc. , 1994 12.13 Dieter G.E. , Engineering Design: A Materials and Processing Approach , 2nd ed. , McGraw-Hill , 1991 12.14 Souder W.E. , Management Decision Methods for...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780238
EISBN: 978-1-62708-281-5
... in engineering polymers. Polymers are sensitive to a number of molecular variables, including molecular weight, molecular weight distribution, crystallinity, chain entanglement density, and cross-linking ( Ref 3 , 5 , 20 , 21 ). In general, as the molecular weight of the polymer is increased...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.cfap.t69780359
EISBN: 978-1-62708-281-5
..., evaporation, crystallization, solidification, cross linking, chemical reactions, and decomposition. A typical DSC result is presented in Fig. 5 . Differential scanning calorimetry uses the temperature difference between a sample material and a reference as the raw data. In the application, the...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.tb.scm.t52870449
EISBN: 978-1-62708-314-0
... insufficient edge distance and width or an insufficient number of cross-plies, for example ± 45° and 90°. Fastener pull-through : Fastener pull-through can occur when the countersink is too deep or when a shear head fastener is used. Fastener failure : The fastener itself can fail if it is too small...