TpOs

To ensure that the motor does not stall or lock-up during pick-up under such a condition, it should have an adequately high pull-out torque (Tpo). 

In certain cases, for example in large motors where Tpf, is normally not very high, during a severe drop in voltage Tpo may fall to a value less than the load requirement and result in a stalling or even a locked rotor condition (see Figure 12.7). 

A manufacturer considering using a thermoplastic elastomer would probably first consider one of the thermoplastic polyolefin rubbers or TPOs, since these tend to have the lowest raw polymer price. These are mainly based on blends of polypropylene and an ethylene-propylene rubber (either EPM or EPDM) although some of the polypropylene may be replaeed by polyethylene. A wide range of blends are possible which may also contain some filler, oil and flame retardant in addition to the polymers. The blends are usually subject to dynamic vulcanisation as described in Section 11.9.1. 

Whilst approximately twice the raw material cost of TPO- and S-B-S-type polymers, thermoplastic polyurethane elastomers find applications where abrasion resistance and toughness are particular requirements. Uses include gears, timing and drive belts, footwear (including ski boots) and tyre chains. Polyether-based materials have also achieved a number of significant medical applications. There is also some minor use as hot melt adhesives, particularly for the footwear industry. 

If polypropylene is too hard for the purpose envisaged, then the user should consider, progressively, polyethylene, ethylene-vinyl acetate and plasticised PVC. If more rubberiness is required, then a vulcanising rubber such as natural rubber or SBR or a thermoplastic polyolefin elastomer may be considered. If the material requires to be rubbery and oil and/or heat resistant, vulcanising rubbers such as the polychloroprenes, nitrile rubbers, acrylic rubbers or hydrin rubbers or a thermoplastic elastomer such as a thermoplastic polyester elastomer, thermoplastic polyurethane elastomer or thermoplastic polyamide elastomer may be considered. Where it is important that the elastomer remain rubbery at very low temperatures, then NR, SBR, BR or TPO rubbers may be considered where oil resistance is not a consideration. If, however, oil resistance is important, a polypropylene oxide or hydrin rubber may be preferred. Where a wide temperature service range is paramount, a silicone rubber may be indicated. The selection of rubbery materials has been dealt with by the author elsewhere. ... 

Adhesion of paints and adhesives to TPOs is especially problematical due to the aliphatic nature of the substrate material. In Europe, plasma and corona treatment is employed to render these surfaces wettable and obtain strong adhesion by adhesives and paints in automotive manufacture. In the United States, however, primers based on solvent-borne chlorinated polyolefin oligomers (CPOs) have become the treatment of choice for these substrate materials. The VOC emissions from these primers are considerable (as in all solvent-borne adhesives), but the less... 

Similar to the primers developed for cyanoacrylate resins, the solvent carrier plays an important role in facilitating interdiffusion of the primer and the substrate. Fig. 12 shows a schematic view of the top few microns of an injection molded TPO surface. 

S4N4 as a source thionitxosyl-metal complexes is limited to a single example. The first selenonitrosyl-metal complex TpOs(NSe)Cl2 (Tp = hydrotris(l-pyrazolyl)borate) was prepared recently by method (a). ... 

The chassis is made from a 1/4 in. sheet of either ABS or TPO vacuum formed into a tub and reinforced with reinforced pultruded glass fiber-TS polyester plastic tubing. The hood and other products are being made from a 20 mm thick sandwich of thermo-formed PPO-alloy skins, glass fabric infused with thermosetting vinyl ester, and a urethane foam core. The bumper and front fascia is thermoformed from a polyolefin elastomer sheet with an UV-resistant cap layer of DuPont s Tediar PVF film. The dash and... 

Spartech Polycom Filled HDPE Filled and Reinforced PP Filled TPO... 

Thrombopoietic factors (no recombinant TPO product in clinical use at this time IL-11 [recombinant product oprelvekin] has marketing approval) stimulate the production of megakaryocyte precursors, megakaryocytes, and platelets [8]. Interleukin-11 has many effects on multiple tissues, and can interact with IL-3, TPO, and SCF. AMG 531, a recombinant peptibody in that binds to the thrombopoetin receptor Mpl and stimulates the production of platelets, is in phase 1 and 2 studies and has been shown to safely increase platelet counts in patients with immune thrombocytopenic purpura [9]. 

Several cytokines are in clinical use that support immune responses, such as IL-2, DFNs, or colony-stimulating factors. IL-2 supports the proliferation and effector ftmction of T-lymphocytes in immune compromised patients such as after prolonged dialysis or HIV infection. IFNs support antiviral responses or antitumoral activities of phagocytes, NK cells, and cytotoxic T-lymphocytes. Colony-stimulatory factors enforce the formation of mature blood cells from progenitor cells, e.g., after chemo- or radiotherapy (G-CSF to generate neutrophils, TPO to generate platelets, EPO to generate erythrocytes). 

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