Thermoplastic matrices polycarbonate

Among the more common thermoplastics from ring opening polymerization of interest in composite processing are polylactams, polyethers, polyacetals, and polycycloolefins. It has also been shown that polycarbonates can be produced from cyclic carbonates [22], Anionic ring opening polymerization of caprolactam to nylon 6 is uniquely suited to form a thermoplastic matrix for fiber-reinforced composites, specifically by the reaction injection pultrusion process [23-25]. The fast reaction kinetics with no by-products and the crystalline... 

Thermoplastic matrix composites are generally employed where high-volume and economic considerations exist such as in the automotive and decorative paneling industries. Thermoplastic resin-based composites range from high-priced polyimide, polyethersul-fone, and polyetheretherketone to the more affordable nylon, acetal, and polycarbonate resins. Practically all thermoplastics are available in glass-reinforced grades. 

In semicrystalline thermoplastic matrix composites, the nucleation and growth of a transcrystalline interface around the reinforcing fiber is thought to have a critical influence on the improvement of the stiffness and tensile strength [63-65]. The rheological behavior of in situ microfibrillar HDPE/PET and HDPE/polycarbonate (PC) polymer blends was investigated in a recent study [66,67]. For both HDPE/PET and HDPE/PC microfibrillar blends, the viscosity increased with PET and PC microfibrils concentration. In another study, Xu et al [68] reported that the flexible microfibrils of PET reduced the melt elasticity and viscosity of HDPE/PET microfibrillar blends. 

The lower thermal stability of natural fibers, up to 230°C, the thermal stability is only small, which limits the number of thermoplastics to be considered as matrix materials for natural fiber composites. Only those thermoplastics whose processing temperature does not exceed 230°C are usable for natural fiber reinforced composites. These are, most of all, polyolefines, such as polyethylene and polypropylene. Technical thermoplastics, such as poyamides, polyesters, and polycarbonates, require... 

Fig. 6.8. Fracture toughness, K, of short glass fiber-thermoplastics injection molded composites as a function of weight fraction of fiber, fVr. (O) and (A) polyethylene terephthalate (PET) matrix ( ) and (A) polycarbonate (PC) matrix. Notches made transverse (O, ) and parallel (A, A) to the mold fill direction,...

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]. 

Reinforced plastics are composites in which a resin is combined with a reinforcing agent to improve one or more properties of the resin matrix. The resin may be either thermosetting or thermoplastic. Typical thermosetting resins used in RPs include unsaturated polyester, epoxy, phenolic, melamine, silicone, alkyd, and diallyl phthalate. In the field of reinforced thermoplastics (RTFs), virtually every type of thermoplastic material can be, and has been, reinforced and commercially molded. The more popular grades include nylon, polystyrene, polycarbonate, polyporpylene, polyethylene, acetal, PVC, ABS, styrene-acrylonitrile, polysulfone, polyphenylene sulfide, and thermoplastic polyesters. 

Among thermoplastic resins used as the matrix in reinforced plastics, the largest tonnage group is the polyolefins, followed by nylon, polystyrene, thermoplastic polyesters, acetal, polycarbonate, and polysulfone. The choice of any thermoplastic is dictated by the type of application, the service environment, and the cost. 

All TP or TS matrix property can be improved or changed to meet varying requirements by using reinforcements. Typical thermoplastics used include TP polyesters, polyethylenes (PEs), nylons (polyamides/ PAs), polycarbonates (PCs), TP polyurethanes (PURs), acrylics (PMMAs), acetals (polyoxymethylenes/POMs), polypropylenes (PPs), acrylonitrile butadienes (ABSs), and fluorinated ethylene propylenes (FEPs). The thermoset plastics include TS polyesters (unsaturated polyesters), epoxies (EPs), TS polyurethanes (PURs), diallyl phthalates (DAPs), phenolics (phenol formaldehydes/PFs), silicones (Sis), and melamine formaldehydes (MFs). RTSs predominate for the high performance applications with RTFs fabricating more products. The RTPs continue to expand in the electronic, automotive, aircraft, underground pipe, appliance, camera, and many other products. 

CNTs can be first synthesized by arc discharge, laser ablation, and chemical vapor decomposition. CNTs are dispersed in a polymer matrix by melt blending under a high temperature and high shear force, which is also compatible with current industrial practices (Moniruzzaman and Winey, 2006). Melt blending is simple and useful for thermoplastic polymers, such as, polyethylene, polypropylene, polycarbonate, poly(methyl methacrylate)... 

Plastics. Plastics denotes the matrix thermoplastic or thermoset materials in which additives are used to improve the performance of the total system. There are many different types of plastics that use large volumes of chemical additives including (in order of total additive consumption) polyvinyl chloride (PVC), the polyolefins [polyethylene (PE) and polypropylene (PP)], the styrenics —[polystyrene (PS) and acrylonitrile butadiene styrene (ABS)], and engineering resins such as polycarbonate and nylon. 

In thermoplastics, the organometallics appear mainly to provide a catalytic support bed for in situ re-polymerization of the polymer matrix, which reflects itself in improved processing. A test on a 40% polycarbonate/glass compound showed improvements in mechanical properties, together with significant improvements in productivity. 

A TEM thin section of an unstained LCP with 5% polycarbonate is shown as an example in Fig. 5.100, as prepared by Wood [273]. Ultramicrotomy of the blend shows the typical banded texture of the LCP with the dark submicrometer isotropic polycarbonate domains uniformly dispersed in the ordered matrix. It is worth noting that although there is extensive research going on in university laboratories today there are few major commercial products which are blends with LCPs. In most cases this is due to the mismatch in thermal and rheological properties which results in materials which have physical properties that resemble the thermoplastics rather than the liquid crystalline polymers. 

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