Thermal effects in the necking of thermoplastics

Cross, Andrew; Hall, M. G.; Haward, R. N.

doi:10.1038/253340a0

Cited by 15 publications

(3 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This can be explained by the thermal effects in the necked region due to high strain rate generated by stretching and crystallisation occurring at high temperatures. [30][31][32] Second, the variation observed for linear crystallinity at high temperatures is rather smaller than that in the foregoing case, due to the formation of relatively homogeneous thickness distribution of lamellar stacks caused by stretching. It is important to note that the initial volume fraction crystallinity is larger than the global crystallinity estimated from DSC melting curves, which could be associated with the existence of distances between laterally adjacent lamellae.…”

Section: Resultsmentioning

confidence: 75%

Morphological and structural evolution of tensile deformed high density polyethylene during melting:in situsynchrotron small-angle X-ray scattering study

Jiang

Tang

Men

2010

Plastics, Rubber and Composites

View full text Add to dashboard Cite

The morphological and structural evolution of quenched high density polyethylene specimens subjected to different strains during the heating process was explored via synchrotron smallangle X-ray scattering technique. On the basis of one-dimensional scattering intensity distribution profile analysis, a general scheme for the melting of polyethylene was proposed that surface melting occurs below the crystallisation temperature, followed by melting and recrystallisation and/or lamellar thickening process via sequential melting and stack melting at the ultimate stages of melting. It was shown that in the case of undeformed specimen, the crystallisation process has finished at the temperature of y90uC during quenching, while the crystallisation temperature is equivalent to 70uC for the highly oriented sample, which was attributed to the thermal effects in the necked region due to high strain rate. A qualitative argument that the isotropic material possesses a wide distribution of lamellar (or amorphous domain) thicknesses with respect to the highly oriented one can be made in terms of the temperature dependent one-dimensional correlation function. In addition, it could be evidenced that moderate deformation ratio does not affect the intrinsic property of existing stacks of lamellar crystals by a direct comparison of the evolution of structural parameters of their lamellar structure during heating.

show abstract

Section: Resultsmentioning

confidence: 75%

Morphological and structural evolution of tensile deformed high density polyethylene during melting:in situsynchrotron small-angle X-ray scattering study

Jiang

Tang

Men

2010

Plastics, Rubber and Composites

View full text Add to dashboard Cite

show abstract

“…The generation of heat during the necking of semicrystalline polymers was noted at least as far back as 1960 [28], while Haward et al [29][30][31] and Roseen [32] first applied infrared thermography to the deformation of semicrystalline polymers in the mid 1970s. With that said, the use of this technique to study the plastic deformation of amorphous polymers has received much less attention, and we believe this to be the first attempt to quantify the thermomechanical behavior of filled polymers and of nanocomposites in particular.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Thermomechanical Assessment of Plastic Deformation in Model Amorphous Polyamide/Clay Nanocomposites

Tulsyan

Toshniwal

Dorairaju

et al. 2010

Journal of Nanomaterials

View full text Add to dashboard Cite

In an effort to isolate the role of nanofiller independent of changes in polymer microstructure, we report the processing and characterization of model amorphous polyamide/clay nanocomposites. Analyses confirm fully amorphous character, no change inTgor thermal stability, and a partially exfoliated structure. The tensile modulus, yield stress, and failure stress increase with the clay content, both in dried and conditioned samples. In contrast, failure strain decreases with increasing clay content in conditioned samples but is independent of clay content in dried samples. Concurrently, the conversion of mechanical work to heat during plastic deformation was studied using infrared thermography, with the heat of deformation estimated based on these results and compared to the work of deformation. These results allow us to quantify changes in deformation mechanism and to conclude that the presence of clay enhances the conversion of mechanical energy to heat in these materials.

show abstract

“…In contrast, Liao et al determined the maximum temperature for the cold-drawing of fibers of PET with infrared thermography to be about 85 °C for a crosshead speed of 750 mm/min [8]. Most authors used thermography systems to determine the temperature evolution, with one of the first reported instances found from Cross et al [11] A dependence of the phenomena on the deformation rate is widely acknowledged. Bazhenov found for PET films a dependence of the engineering stress during neck propagation on the crosshead speed [7].…”

Section: Introductionmentioning

confidence: 99%

Thermomechanical Characterization and Modeling of Cold-Drawing of Poly(ethylene Terephthalate)

2019

View full text Add to dashboard Cite

The tensile testing of amorphous polyethylene terephthalate is observed until failure by IR thermography and optical strain measurement. The deformation can be subdivided in six deformation phases: elastic deformation, neck formation with a localized sharp temperature rise, neck propagation, which is also known as cold-drawing, with heat generation in a transition zone, crack initialization with local heating, crack growth, and rupture. These deformation phases are showing different mechanical and thermal reactions to the deformation. The initial and drawn samples are studied with differential scanning calorimetry. Alongside heating due to the dissipation of mechanical energy, latent heat due to strain-induced crystallization was detected. While the material is cold-drawn, a high dependence on the crosshead speed is found for the heat generation as well as the draw ratio, mechanical response, and morphological changes due to orientation and crystallization. For cold-drawing, a thermomechanical model is introduced, which is based on the first law of thermodynamics and reproduces the temperature distribution along the sample.

show abstract

Thermal effects in the necking of thermoplastics

Cited by 15 publications

References 2 publications

Morphological and structural evolution of tensile deformed high density polyethylene during melting:in situsynchrotron small-angle X-ray scattering study

Morphological and structural evolution of tensile deformed high density polyethylene during melting:in situsynchrotron small-angle X-ray scattering study

Thermomechanical Assessment of Plastic Deformation in Model Amorphous Polyamide/Clay Nanocomposites

Thermomechanical Characterization and Modeling of Cold-Drawing of Poly(ethylene Terephthalate)

Contact Info

Product

Resources

About