Solid shear extrusion

Bilgili, E., Arastoopour, H., and Bernstein, B., Analysis of rubber particles produced by the solid state shear extrusion pulverization process. Rubber Chem. Technol., 73, 340, 2000. 

The physical state of starch during extrusion can be considered to change from a partially crystalline polymer to a polymer melt which is homogenized by shear. Extrusion may also decrease the molecular size of starch components, which is observed from decreased melt viscosity (Lai and Kokini 1991), and obviously a decreased molecular size results in a decreased glass transition temperature of the extmdate. The dramatic decrease of pressure that occurs as a viscous, plasticized melt exits the die may allow an extremely rapid loss of water, expansion of the melt and cooling to an amorphous solid state. 

In addition, surface forces [240] and shear fields [%, 188, 241-243] have successfully been employed in orienting the LCPs. Solid state extrusion [10, 188] and mdt-spinning [96] produce fibers, with nearly perfect aligoonent of the director axes 0.9). This is demonstrated in Fig. 30. The H NMR spectra Ctop row) refer to melt-spun fibers of LCP 4 (a-CD ) and five different orientations of fiber axis and magnetic field. Drastical lineshape chan are observed when the sample is rotated. A detailed analysis, based on spectral simulations (bottom row), provides the parameters of micro- and macroorder, summarized in Table 9 [96]. 

SMMA Styrene-methyl methacrylate block copolymer sPS Syndiotactic polystyrene S-S Simha and Somcynsky cell-hole theory SSE Single-screw extmder SSSE Solid-state shear extrusion TD Transverse direction TEM Transmission electron microscopy Tg Glass transition temperature THE Tetrahydrofuran TIBA fr -Isobutyl aluminum (°C) Melting temperature TMA fr -Methyl aluminum TMS Trimethylsilyl... 

Northwestern University has developed a process they refer to as solid-state shear extrusion pulverization. In this process, a twin-screw extruder is used to convert mixed plastics and scrap rubber into a imi-form fine powder, which can then be used in a variety of products. 

For low density, flexible high resilient and rigid PU foam post-consumer wastes, a modified solid state shear extrusion (SSSE) technique was applied for their pulverisation. The fine powder obtained can be nsed as a filler and/or reinforcing material for polymers and mineral products with improved mechanical properties [257]. 

Prom a historical point of view, the development of SRPMs started with the in situ production of 1-D-reinforced variants. This occurred mostly with solid phase extrusion forming, and techniques exploiting melt shearing in the solidifying melts [7]. 

Liquid shearing, such as high pressure homogenization, solid shear, such as bead milling and the extrusion of frozen cells are the most common mechanical methods for cell disruption (D souza and Killedar, 2008 Hatti-Kaul and Mattiasson, 2003). These methods are mainly based on the use of mechanical force to disrupt the cell. Some of these techniques, such as bead milling, have already found applications on a large scale (Prasad, 2010). 

Kliait, K. (1995) "Recycling of unsorted plastic waste by new solid-state shear extrusion... 

Shutov F, Arastoopour H and Ivanov G (1993) Recycling of pol5Uirethane waste foams using new pulverisation principle Solid State Shear Extrusion (SSSE), Cellular Polymers 2" Int Conf, Edinburgh, Paper 18. 

The double integral represents the nonzero terms of the dissipation rate tensor as adapted by Middleman [61] and Bernhardt and McKelvey for adiabatic extrusion [62]. The nontensorial approach was adopted by Tadmor and Klein in their classical text on extrusion [9]. In essence these are the nonzero terms of the dissipation rate tensor when it is applied to the boundary of the fluid at the solid-fluid interface. In the following development this historic analysis was adopted for energy dissipation for a rotating screw. In this case the velocities Ui are evaluated at the screw surface s and calculated in relation to screw rotation theory. The work in the flight clearance was previously described in the literature [9]. The shear... 

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