Rigid profiles

Thermoplastic Foam Extrusion. Foamed plastics find applications as rigid profiles, pipe, sheet, packaging material, and thermal insulation. Polystyrene (PS) finds the widest application in foamed products while poly(vinyl chloride) PVC, low-density polyethylene (LDPE), and acrylonitrile-butadiene-styrene (ABS) (21) are also used in large quantities. All common thermoplastics can be foamed by various techniques as described hereafter. 

Addition of some grades of emulsion polymer (e.g., Vestolit E 7037) improves properties of rigid profiles produced from suspension PVC. In calendering, this addition (10-30%) improves transparency and reduces blocking of semirigid and soft films. 

Rigid profile for outdoor use. [Data from Mark 2289. Technical data sheet. Crompton.]... 

Rigid profile. [Data from Sorbacid 911. Hydrotalcite as costabilizer for PVC. Sued-Chemie AG]... 

Chem. Descrip. Modified complex lead sulfophthalate salt Uses Heat stabilizer for PVC wire and cable (105°), high temp, wire and cable coatings, flexible and rigid profiles, CPE, CPVC, plastisols Features Economical... 

Carstab DLTDP Carstab DSTDP StaUlizer, heat flexiUe/rigid profiles... 

Reinforcing filaments saturated with thermosetting resin are pulled through an orifice in a heated die. Polymerization of the resin occurs as the wet bundle passes through the die, forming a continuous, rigid profile corresponding to the orifice shape. 

Like most other plastics, PVC extruded or calendered sheet used in making blisters and clamshells is generally not collected in postconsumer streams. On the other hand there is a robust market for in-process sheet scrap derived from package off-cuts. This material is chopped and sold into various applications including packaging sheet and sea wall and wall and rigid profile substrates. 

Since most rigid profile extrusion products have a long in-service lifetime, most of those products ever produced are still in service. When pipe, siding, and windows are removed from service, however, they are recyclable but in addition to low volume face many of the same barriers that other postconsumer plastics face. 

Clear rigid profiles for outdoor use are very similar. For general purpose rather than outdoor use, pigmented opaque sheet is similar except that low-odor tin lOTG stabilizers are used. The levels of impact modifier, processing aids, and lubricants vary with the extent of filler and pigment usage. 

Another PVC siding is an extmded product of an internally ribbed, dual-wall profile. A conventional screw extmder, with a vacuum sizer cooled with water and air, forms a product about 20 cm wide with 160 mm walls and 80 mm ribs on 25 cm centers. The total thickness is about 0.64 cm. The ribs provide rigidity and strength and the dual-wall constmction adds thermal insulation. No backing or core is used. 

Door and Window Frames and Sashes. The first successflil application of rigid PVC for windows was as a cladding over a wood core to avoid the need for painting and repainting the sash and the exterior of the frame. Since then, extmded profiles of rigid PVC have been developed to allow... 

Fig. 28.10. Successive cohtact profiles of a brittle sheet movihg agaihst a rigid structure. At ohy ihstoht, cohtact is ohiy made at discrete places.

The storage facilities at the end of the profile production line depend on the type of product (see Fig. 4.19). If it is rigid then the cooled extrudate may be cut to size on a guillotine for stacking. If the extrudate is flexible then it can be stored on drums. 

FIG. 12 Segment density profile as function of the distance from the wall Z for flexible (empty symbols) and semi-rigid (full symbols) living polymer chains at T = 0.4 [28]. The fractional occupancy of lattice sites by polymer segments is shown for the layers in the left half of the box. Dashed lines are guides for the eyes. 

The simulations to investigate electro-osmosis were carried out using the molecular dynamics method of Murad and Powles [22] described earher. For nonionic polar fluids the solvent molecule was modeled as a rigid homo-nuclear diatomic with charges q and —q on the two active LJ sites. The solute molecules were modeled as spherical LJ particles [26], as were the molecules that constituted the single molecular layer membrane. The effect of uniform external fields with directions either perpendicular to the membrane or along the diagonal direction (i.e. Ex = Ey = E ) was monitored. The simulation system is shown in Fig. 2. The density profiles, mean squared displacement, and movement of the solvent molecules across the membrane were examined, with and without an external held, to establish whether electro-osmosis can take place in polar systems. The results clearly estab-hshed that electro-osmosis can indeed take place in such solutions. 

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