Equal-channel angular extrusion of polymers

Abstract

International audienceOne of the priority lines of development of physics of polymers and material science is the development of the principles of structure modification of polymeric materials and the study of the relation between the structure and the properties, aimed to their control. Nowadays, great attention is paid to investigation of severe plastic deformation (SPD) effect on the structure modification of polymers and polymeric composites as well as to the development of the simple shear based methods of formation of orientation order. The main difference between SPD and traditional methods of pressure shaping such as die extrusion, rolling, drawing is the ability to accumulate essential plastic deformation in the processed materials. At the same time, the billet form and size are maintained and there is a possibility of development of varied deformation routes in order to generate different forms of molecular orientation. The most widely used SPD methods applied to polymeric materials are equal-channel angular extrusion (ECAE) and its modified version, so-called equal-channel multiple angular extrusion (ECMAE). The investigations carried out in research centers of USA, Japan, China, France and Ukraine showed perspectives of the use of these methods for improvement of the set of the existing physical and mechanical properties and the formation of functional properties previously unknown. In particular, in the case of semi-crystalline polymers, SPD results in increase in rigidity and strength at conserved high level of plasticity. For polymeric composites, SPD facilitates homogeneous distribution and better dispersion of the filler particles within the polymeric matrix, orientation of transition layers and polymeric matrix etc. As a result, physical and mechanical characteristics higher of those of polymeric composites without SPD were achieved

Effects of orientation ordering of low‐density polyethylene—multi‐walled carbon nanotubes composites determined by severe plastic deformation

“…Now a great attention is paid to the processes of severe plastic deformation (SPD) realized by simple shear under high pressure . This group of methods includes equal‐channel angular extrusion (ECAE) and modified variant that is equal‐channel multiple‐angular extrusion (ECMAE).…”

“…Simple shear deformation does not result in shape and size modification of the billet. On the other hand, controlled molecular orientation is achieved by a change of the shear plane position . Although SPD process such as ECAE is found to improve dispersion of the nanofiller within the polymeric matrix as well as modified aspect ratio, another innovative method such as ECMAE appears even more effective.…”

Specific features of plastic flow of biaxially oriented flexible-chain semicrystalline polymers

“…1) had significantly higher microhardness anisotropy (ΔH = 0.28), and the linear strain continuously decreased with increasing temperature (Fig. 3, curve 2), which is evidence of the formation of predominantly uniaxially oriented struc ture [12]. The highest microhardness anisotropy (ΔH = 0.60) and the largest decrease in linear strain with increasing temperature (Fig.…”

“…In the first case, the specimens were characterized by low microhardness anisotropy (ΔH = 0.04) and a small change in linear strain (Δl/l 0 ) values on heating (Fig. 3, curve 1), which is typical of a biaxially oriented structure [12,13]. The specimens corresponding to point В (Fig.…”

Effects of Material Rheology and Die Walls Translational Motions on the Dynamics of Viscous Flow during Equal Channel Angular Extrusion through a Segal 2θ-Die: CFD 2D Solution of a Curl Transfer Equation

“…Today rheologically complex problems of pressureinduced polymer dynamics during SPD by ECAE attract the attention of such researchers as Aour et al (2009) [1], Beloshenko et al (2013) [2], [3], Creasy and Kang (2004) [4], Han et al (2008) [5], Li et al (2012) [7], Minakowski (2014) [8], Perig et al (2010 [9,13,14,17,19,20], Qiu et al (2012) [21], Seo and Weon (2013) [22], Sue et al (1999) [23], Weon et al (2005) [24], Xia et al (2000) [26], [27], and others. Research efforts of these scientists have been focused on physicalmechanical investigations into the engineering problems of polymer materials local flow in angular domains during SPD ECAE material pressure forming.…”