Glass transition in nylons

Gordon, Gerald A.

doi:10.1002/pol.1971.160090911

Cited by 66 publications

(36 citation statements)

References 9 publications

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“…A working rule of thumb (44) is that the beta transition must be related to either localized movement in the main chain or very large side chain movement to sufficiently absorb enough energy. The relationship of large side chain movement and toughness has been extensively studied in polycarbonate by Yee (45) as well as in many other tough glassy polymers (46).…”

Section: Sub-t G Transitionsmentioning

confidence: 99%

Dynamic Mechanical Analysis in the Analysis of Polymers and Rubbers

Menard

2015

Encyclopedia of Polymer Science and Technology

105

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DYNAMIC MECHANICAL ANALYSISsixties when commercial instruments became more user-friendly. About 1966, Gillham developed the TBA (10) and started the modern period of DMA. In 1971, Starita and Macosko (11) built a DMA that measured normal forces and from this came the Rheometrics Corporation. In 1976, Bohlin also developed a commercial DMA and started Bohlin Rheologia. Both instruments used torsional geometry. The early instruments were, regardless of manufacturer, difficult to use, slow, and limited in their ability to process data. In the late seventies, Murayani (12) and Read and Brown (13) wrote books on the uses of DMA for material characterization. Several thermal and rheological instrument companies introduced DMA's in the same time period, and currently most thermal and rheological vendors offer some type of DMA. Polymer Labs offered a dynamic mechanical thermal analyzer (DMTA using an axial geometry in the early 1980s. This was soon followed by an instrument from Du Pont. Perkin-Elmer developed a controlled stress analyzer based on their thermomechanical analyzer (TMA) technology, which was designed for increased low-end sensitivity. Triton Technologies, acquired by Mettler Toledo in 2010, developed a very easy to use design that formalized both immersion and humidity methods. On the high force end of applications, Mettler Toledo also makes an instrument capable of 40 N loads and both Gabo and MetaVib work exclusively in high load instruments. Small vendors include Hitachi, Bosch, and others. The competition between vendors has led to easier to use, faster, and less expensive instruments. The revolution in computer technology, which has so affected the laboratory, changed the latter, and DMA of all types became more user-friendly as computers and software evolved. This movement to easier to use instruments has led to more use in quality control and the development of ASTM standards (14).

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Section: Sub-t G Transitionsmentioning

confidence: 99%

Dynamic Mechanical Analysis in the Analysis of Polymers and Rubbers

Menard

2015

Encyclopedia of Polymer Science and Technology

105

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“…A poorly resolved double melting endotherm is observed for the sample heattreated to 240°C. The melting behavior of PA66 has been studied extensively, [17][18][19] and the origins of multiple endotherms has been explained by two different crystal forms, differences in crystallite sizes, or melting and recrystallization during the scan. Crystallinity values were estimated from our DSC data via the heat of fusion values and are included in Table I, from which crystallinity Density IR DSC 25 25 31 31 40 40 31 30 44 80 31 31 40 120 30 28 41 160 33 31 40 200 38 32 43 240 48 42 43 150 25 35 35 44 40 35 34 80 35 39 120 35 35 160 35 33 200 38 38 240 49 42 200 25 45 42 40 45 42 80 46 43 120 46 45 160 47 49 200 46 44 240 49 44 Figure 1.…”

Section: Density and Dsc Measurementsmentioning

confidence: 99%

Infrared spectroscopic characterization of oriented polyamide 66: Band assignment and crystallinity measurement

Vasanthan

Salem

2000

J. Polym. Sci. B Polym. Phys.

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“…Results of this examination yield an endotherm typically of the type shown in the solid curve of Figure 1. The lower temperature region of this endotherm is of some interest in that the heat evolution commences at approximately the glass temperature, as noted many years ago by Gordon,6 and exhibits a maximum that ranges from a high of about 125°C to lower values between 60 and 8OoC, depending on the conditions of the filament extrusion. This region is followed by a high-tempera- ture endotherm reflecting the primary crystalline melting point.…”

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confidence: 77%

Studies of the development of fibrillar structure in nylon 6

Lim

George

Gupta

1987

J. Appl. Polym. Sci.

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The writers have been examining the production of trilobal nylon 6 filaments mimicking certain commercial production techniques in a laboratory setup. In the course of this work, we have observed some rather special fiber properties that appear to depend upon the quenching conditions to which the fiber is subjected after it emerges from the spinneret prior to its take-up preceding any drawing treatments. The quenching conditions that were introduced involve maintaining the temperature of the molten filament while it moves through the first 5 cm of filament line after emerging from the spinneret followed by quenching in enhanced turbulence, which, it is hoped, provided a rapid chill at the surfaces of the fiber. Subsequently, the as-produced filaments, which approximated a commercial carpet yarn, with an appropriate trilobal geometry were subjected to tensile testing and a tensile factor, or a figure of merit, determined for the tensile quality of the fiber in the form of an index, which was originally due to Rosenthal' and describes the tenacity-elongation exchange relationship. The factor we use is the product of the breaking tenacity and the square root of the numerical value of the elongation expressed as a percentage. Nominally, the commercial products and the process that we were studying produced values of the order of 35-38 in this index. The delayed quenching processes tended to produce filaments that gave tensile figures of merit in excess of 40 (42 in one particular quenching configuration). The yarn product with this higher property was subjected to a closer examination, and the work reported in this letter followed.Small lengths of the filaments were sectioned and examined longitudinally in a thermal microscope at heating rates of 10°C/min until very close to the terminal melting. After the disappearance of the primary birefringence of these filaments, lines of residual birefringence were observed in the tips of the lobes of the trilobal filament, which persisted for several degrees above the normal melting point; namely, 216220°C. Further, in nonpolarized light, optical examination of the melting sections revealed that the tips of the lobes tended to extend beyond the shrunken surfaces of the cut ends, suggesting a thermally more stable element in the tips than in the body of the trilobal yam. A similar kind of stability was observed earlier by one of the writers' in polyethylene filaments that had been extruded just above the conditions for melt fracture. When short sections of these filaments were examined near the melting point in a thermal microscope, the central portions of the filaments retained their original cut lengths but the body pulled back into a more GF less equilateral "glob" around the central spike, which persisted to relatively

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Glass transition in nylons

Cited by 66 publications

References 9 publications

Dynamic Mechanical Analysis in the Analysis of Polymers and Rubbers

Dynamic Mechanical Analysis in the Analysis of Polymers and Rubbers

Infrared spectroscopic characterization of oriented polyamide 66: Band assignment and crystallinity measurement

Studies of the development of fibrillar structure in nylon 6

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