Filled thermoplastics

Although it would be desirable to recycle laminate scrap, this has been difficult because of its thermoset nature. However, a 1993 patent (18) suggested a means whereby scrap consisting of cellulose, thermoset resins, and partially reacted resins can be ground to a powder which is used as a filler in a thermoplastic resin. The filled thermoplastic resin is then used for mol ding of various articles. 

The processing of discontinuous fiber-filled thermoplastics owes much to the rheology of the system. Shear thinning and adiabatic heating associated with the broad... 

For filled thermoplastics (30-40% by mass of chalk, ash or asbestos), complex shear may, as reported in [235], provide an increase of apparatus productivity by 40-80%, or if the flow rate is to be constant, the pressure in the molding instrument may be reduced by at least 20-30%. It is to be noted that while some extra power is required to create the complex shear conditions, the total power consumption of the apparatus as a whole may be reduced, on the power per unit of product basis, due to the high extrusion rates [233]. 

In [332] it was noted that the strength of samples cut out at different locations of an article made from filled thermoplastics by pressure molding may differ widely — which is due to the non uniform orientation of the polymer at different locations of the mold. The very high strength parameters of composites with PMF in molded specimens are obviously also due to orientation effects, while for standard mixed samples of similar composition (that is, a matrix which, apart from the filler, contains some superhigh molecular polyethylene imitating the PMF coats) the... 

Table 18. Effect of molding method on mechanical properties of mica-filled thermoplastics (Vf = 0.5) [375]...

DSM Engineering Plastics, nylon, PBT, Polycarbonate Thermoplastic Elastomer PC/ABS Conductive Resins Thermoplastics Reinforced and Filled Thermoplastics Lubricated... 

Hornsby, P.t Rheology, Compoundind and Processing of Filled Thermoplastics. VoL 139, pp. 155-216,... 

Portions of the sun visor arms used in automobiles can be manufactured from glass-filled thermoplastic polymers. Several visor arms contained visible blemishes on the surface. Typically, the steel insert of the visor arm is overmolded with the glass-filled thermoplastic polymer. Manufacturers sometimes utilize striations on the steel insert to provide a mechanical interlock with the over-molded thermoplastic polymer. However, in an improperly controlled environment, the mechanical process that produces the striations can also be the source of contamination and cause surface blemishes in the final product. 

H.J. Barraza, F. Pompeo, E.A. O Rear, and D.E. Resasco, SWNT-filled thermoplastic and elastomeric composites prepared by miniemulsion polymerization. Nano Lett. 2, 797-802 (2002). 

Montsinger, L. V., Apparatus and method for forming fiber filled thermoplastic composite materials, US Patent 5 176 775, 1993. 

INCREASING THE DIMENSIONAL STABILITY OF PRODUCTS MADE FROM FOAMED AND FILLED THERMOPLASTICS BY THE USE OF GAS COUNTERPRESSURE INJECTION MOULDING Piperov N L... 

Binary combinations, i.e. filled thermoplastics or blends of two polymers, exhibit either increased stiffness or enhanced fracture resistance [17,18]. High fill-... 

In particulate-filled thermoplastics, the matrix is the load-bearing component and all deformation processes take place in the matrix. Particulate fillers are, in most cases, not capable of carrying any substantial portion of the load due to the absence of interfacial friction as the means of stress transfer. This is evidenced by the lack of broken particles on the surfaces of fractured filled thermoplastics. Hence, it seems appropriate to start this volume with a brief overview of the basic structural levels and manifestation of these levels in governing the mechanical properties of semicrystaUine thermoplastics used in compounding. 

Thus, a brief survey of the current understanding of the molecular and super-molecular structures of common thermoplastics is presented first. This review starts with a brief description of the current state-of-the-art knowledge of the constitution, configuration, conformation and supermolecular structure of common glassy and semicrystalline thermoplastics. Later in this chapter, specific features of the structure-property relationships are discussed in greater detail for the most frequently filled thermoplastics. Effects of fillers on the structural variables in polypropylene, considered the most commercially important matrix, are especially emphasized. 

Hancock M Filled Thermoplastics. In Rothon R (ed) Particulate filled polymer composites. Longman Scientific Technical, Harlow (UK), p 279... 

Lutz JT Jr (1989) Thermoplastic polymer additives. Marcel Dekker, New York Miyata S, Imahashi T, Anabuk H (1980) J Appl Polym Sci 25 415 Hancock M (1995) Filled thermoplastics. In Rothon RN (ed) Particulate-fiUed polymer composites. Longman, Harlow, p281... 

Han [17] has shown that the effect of silane coupling agents on the viscosity of filled thermoplastics is not consistent. Melt viscosity may be decreased or increased depending on the chemical structure of the treatment and the nature of the polymer/filler combination under consideration. These observations probably reflect the effectiveness of the coupling agent in promoting bonding between filler and polymer, and hence the extent of polymer immobilization. 

Various investigations have considered the effects of titanate treatments on melt rheology of filled thermoplastics [17,41]. Figure 10, for example, shows that with polypropylene filled with 50% by weight of calcium carbonate, the inclusion of isopropyl triisostearoyl titanate dispersion aid decreases melt viscosity but increases first normal stress difference. This suggests that the shear flow of the polymer is promoted by the presence of titanate treatment, and is consistent with the view that these additives provide ineffective coupling between filler particles and polymer matrix [42]. 

It has been suggested that the three-dimensional network structures discussed above, which are believed to occur from particle interactions at high filler loadings, may, in the case of plate-like particles, lead to anisotropic shear yield values [35]. Although this effect has not been substantiated experimentally, further theoretical interpretation of shear yield phenomena in talc- and mica-filled thermoplastics has been attempted [31,35]. 

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