Polyurethane, thermoplastic composites

Short fiber reinforcement of TPEs has recently opened up a new era in the field of polymer technology. Vajrasthira et al. [22] studied the fiber-matrix interactions in short aramid fiber-reinforced thermoplastic polyurethane (TPU) composites. Campbell and Goettler [23] reported the reinforcement of TPE matrix by Santoweb fibers, whereas Akhtar et al. [24] reported the reinforcement of a TPE matrix by short silk fiber. The reinforcement of thermoplastic co-polyester and TPU by short aramid fiber was reported by Watson and Prances [25]. Roy and coworkers [26-28] studied the rheological, hysteresis, mechanical, and dynamic mechanical behavior of short carbon fiber-filled styrene-isoprene-styrene (SIS) block copolymers and TPEs derived from NR and high-density polyethylene (HOPE) blends. 

Recendy, storm doors have been constmcted of advanced thermoplastic composites. Stampable, glass-mat reinforced polypropylene sheet is used to create a high strength outer skin. These compression molded skins are welded together using a friction or ultrasonic process then injection molded with a polyurethane foam core to produce an insulated structure. New technology for window frames incorporate the pultrusion of frame channels to produce a thermoset composite channel that can be filled with fiber glass for further insulation enhancement (12,31,33,34,48,49,54—56,60—67). 

The foregoing mastication pattern is characteristic of the several fully formed thermoplastic polyurethane elastomer compositions we have examined. An obvious question the pattern raises is why mastication reduces already formed polymer to such essentially constant low viscosity level under a given set of shear/temperature/time conditions while the same conditions raise the viscosity of the same composition of forming polymer to a much higher and growing or constant viscosity level, (e.g., Polymer 5, Figure 3). 

A biodegradable thermoplastic composition comprising polyvinyl alcohols, polyurethanes or polyacrylates, cellulose fibers, and chitosan is disclosed in U.S. Pat. No. 5,306,550 [125]. 

A large mrmber of polymeric materials are involved in a web coating. These include poly-virtylchloride, polyurethanes (thermoplastic and thermoset solvent-based and water-based), natural, nitrile, chloroprene, and ethylene-propylene rabbers, silicones, polyethylene (chlorinated and chlorositifonated), polyamide, polyester, acrylic resins, polyvinylal-cohol, polytetrafluroethylene, and ethylene-vinyl acetate copolymer as the main matrix polymers of coating compositions. Most of these polymers are not plasticized or seldom... 

Dow, using Fulcrum thermoplastic composites technology and Isoplast thermoplastic polyurethanes, have developed a new thermoplastic pultrusion process. 

Polyurethane adhesives currently used to bond most thermosets, including glass fibre reinforced plastics (GRP), sheet moulding compound (SMC), glass fibre reinforced epoxy (GRE), and thermoplastic composites including ABS, PVC, acrylics, polycarbonates, etc., are pre sented in Table 20. 

Handlin D.L. et al., Methods for producing mixed polyol thermoplastic polyurethane compositions, US Patent 6323299, 2001. 

Brink, A. E. and Owens, J. T., Thermoplastic polyurethane additives for improved polymer matrix composites and methods of making and using therefor, US Patent 6 043 313, 2000. 

Polyurethanes are obtained by the reaction between polyols and isocyanates. They are of diverse chemical natures and applications. Most are thermosets (see Thermosets and Composites, M. Biron, Elsevier Ltd (2004) ISBN 1856174115) but others are thermoplastics (TPU), ranging from elastomer flexibility to polyethylene rigidity. 

The most common advanced composites are made of thermosetting resins, such as epoxy polymers (the most popular singlematrix material), polyesters, vinyl esters, polyurethanes, polyimids, cianamids, bismaleimides, silicones, and melamine. Some of the most widely used thermoplastic polymers are polyvinyl chloride (PVC), PPE (poly[phenylene ether]), polypropylene, PEEK (poly [etheretherketone]), and ABS (acrylonitrile-butadiene-styrene). The precise matrix selected for any given product depends primarily on the physical properties desired for that product. Each type of resin has its own characteristic thermal properties (such as melting point... 

Among the various associations involving organomodified clays, the use with components of intumescent compositions, such as APP, was widely reported for various host polymers or blends, in which the role of the carbon source is played by a polymer (PA6, EVA, thermoplastic polyurethanes). 

Polyurethanes show particularly good results when used for bonding plasticized poly(vinyl chloride) compositions and good results also with other plastics and rubbers, such as the thermoplastic styrene-butadiene-styrene ( SBS ) copolymers. 

Soft blocks are composed of linear, dihydroxy poly ethers or polyesters with molecular weights between 600 and 3000. In a typical polymerization of a thermoplastic polyurethane elastomer, the macroglycol is end capped with the full amount of aromatic diisocyanate required in the final composition. Subsequently, the end-capped prepolymer and excess diisocyanate mixture reacts further with the required stoichiometric amount of monomeric diol to complete the reaction. The diol links the prepolymer segments together while excess diol and diisocyanate form short hard-block sements, leading to the (AB)n structure illustrated in Figure 1. Block lengths in (AB)n polymers are frequently much shorter than those in anionically synthesized ABA block copolymers. 

Research on the pyrolysis of thermoset plastics is less common than thermoplastic pyrolysis research. Thermosets are most often used in composite materials which contain many different components, mainly fibre reinforcement, fillers and the thermoset or polymer, which is the matrix or continuous phase. There has been interest in the application of the technology of pyrolysis to recycle composite plastics [25, 26]. Product yields of gas, oil/wax and char are complicated and misleading because of the wide variety of formulations used in the production of the composite. For example, a high amount of filler and fibre reinforcement results in a high solid residue and inevitably a reduced gas and oiFwax yield. Similarly, in many cases, the polymeric resin is a mixture of different thermosets and thermoplastics and for real-world samples, the formulation is proprietary information. Table 11.4 shows the product yield for the pyrolysis of polyurethane, polyester, polyamide and polycarbonate in a fluidized-bed pyrolysis reactor [9]. 

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