Polyphenylene oxide mechanical

Modified-polyphenylene oxide (or ether) is a blend of high impact polystyrene (PS) and polyphenylene oxide (PPO), plus thermal stabilizers and a triarylphosphate flame retardant. Studies of the mechanism of the flame retardant in modified-polyphenylene oxide have shown some evidence for both solid phase and vapor phase inhibition (4). Indeed, one is always interested to know whether flame retardant action is on the solid or vapor phase. 

Several flexible polymers, such as natural rubber (NR) synthetic rubber (SR) polyalkyl acrylates copolymers of acrylonitrile, butadiene, and styrene, (ABS) and polyvinyl alkyl ethers, have been used to improve the impact resistance of PS and PVC. PS and copolymers of ethylene and propylene have been used to increase the ductility of polyphenylene oxide (PPO) and nylon 66, respectively. The mechanical properties of several other engineering plastics have been improved by blending them with thermoplastics. 

Polyphenylene oxide (PPO) or Polyphenylene ether (PPE) is an amorphous polymer with a softening temperature of about 210 °C. To improve its processability it is mostly blended with PS (modified PPE, e.g. Noryl ), which is at the cost of its heat distortion temperature. The properties are excellent the applications are mainly in fine-mechanical construction, in automotive parts, in household equipment etc. 

Kambour et al. performed extensive studies on the mechanisms of plasticization [18-25]. The correlation observed between the critical strain to craze and the extent of the glass-transition temperature (Tg) depression speaks strongly in favor of a mechanism of easier chain motion and hence easier void formation. In various studies on polycarbonate [19,24], polyphenylene oxide [20], polysulfone [21], polystyrene [22], and polyetherimide [25], Kambour and coauthors showed that the absorption of solvent and accompanying reduction in the polymer s glass-transition temperature could be correlated with a propensity for stress cracking. The experiments, performed over a wide range of polymer-solvent systems, allowed Kambour to observe that the critical strain to craze or crack was least in those systems where the polymer and the solvent had similar solubility values. The Hildebrand solubility parameter S [26] is defined as... 

Spin relaxation in dilute solution has been employed to characterize local chain motion in several polymers with aromatic backbone units. The two general types examined so far are polyphenylene oxides (1-2) and aromatic polycarbonates (3-5) and these two types are the most common high impact resistant engineering plastics. The polymer considered in this report is an aromatic polyformal (see Figure 1) where the aromatic unit is identical to that of one of the polycarbonates. This polymer has a similar dynamic mechanical spectrum to the impact resistant polycarbonates (6 ) and is therefore an interesting system for comparison of chain dynamics. 

Wei Wei, G. X., Sue, H.-J. Fracture mechanisms in preformed polyphenylene oxide particle-modified bismaleimide resins. J. Appl. Polym. Sci. 74 (1999) 2539-2545. 

Composition profiles generated by interdiffusion in the concentrated regime between polyphenylene oxide-polystyrene blend pairs were experimentally determined by two techniques. Three-point bending moment measurements over a convenient temperature range (dynamic mechanical analysis (DMA)) were used to determine interphase composition profiles. Confocal micro-Raman spectroscopy was also used to measure local compositions along a direction which was perpendicular to the original interface. The study included some limiting cases to test accuracy, precision and flexibility of the DMA method. 4 refs. 

The halogen groups can be incorporated directly in the backbone of the PPE. Consequently, tribro-mophenols have been condensed to get brominated polyphenylene oxide [72]. Obviously, the mechanism of polymer formation is different from that of oxidative coupling. The condensation takes place in the presence of NaOH, initially below room temperature. After condensation, a decolorization treatment is necessary. Hydrazine is used for decolorization. 

The effect of moisture on the p relaxations in amorphous phenylene polymers is well documented (93-95) for many of the systems cited previously. For example, Allen and co-workers (93) determined that both the dielectric and mechanical P relaxations in polysulfone, polycarbonate, polyphenylene oxide, and polyether sulfone were dependent on the water content of the samples. In addition, the amount of water absorbed depended on the polarity of the molecule. The effect of moisture on the dielectric p process in these polymers appears to be greater than for the mechanical loss process, as illustrated in Figures 41 and 42 (93). 

A modified epoxy matrix for Kevlar FRP composites was produced from ep>oxy/polyphenylene oxide (PPO) blends cured with multifunctional cyanate ester resin [94]. The effects of the PPO content on the cme behavior in the cyanate ester-cmed epoxy were investigated with FTIR. The cme reaction in the ep>oxy/PPO blends was faster than that of the neat epoxy system. FTIR analysis revealed that the cyanate fimctional group reactions were accelerated by adding PPO and that several co-reactions had occurred. Thermal mechanical analysis showed that the thermal stability of the epoxy/PPO matrix is improved by adding PPO. In the respective compursites, the ISS values between Kevlar fiber and the epoxy/PPO blends are almost the same as those between Kevlar fiber and neat epoxy. The ILSS in the respective laminates increases with the PPO content, which was attributed to an increase in the composites ductility. 

Property data for GRTP s are presented in two major breakouts. In the first breakout, the basic resins—styrene acrylonitrile (SAN), polycarbonate, polysulfone, polyacetal, polypropylene, polyphenylene oxide (PPG), nylon, modified PPG, and polyvinyl chloride—are treated as the independent variables and the physical, mechanical, electrical, thermal, chemical, and weathering characteristics are treated as the dependent variables. In the second breakout, the functional relationships are reversed, te., the properties are the independent variable and the resins are the dependent variable. ASTM test methods by which the physical values were determined are listed. The. physical data versus resins are presented in both tabular and graphic form. 

TABLE 3-83. PHYSICAL AND MECHANICAL PROPERTIES OF MODIFIED POLYPHENYLENE OXIDE... 

Physical and Mechanical Properties ofModified Polyphenylene Oxide. 3-229... 

Exterior door handles are another application that has turned to plastics to balance chemical resistance and mechanical properties. Many filled thermoplastics such as blends of PC and polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and nylon have been tried or used in this application, with nylon as the clear wirmer. Exterior mirror housings likewise use many thermoplastic solutions such as ABS, PC/ABS, blends of polyphenylene oxide (PPO) and polystyrene (PS), nylon, blends of PP and ethylene propylene diene monomer (EPDM), and weatherable ABS. Again, nylon clearly dominates this application in terms of volume. Many other exterior parts continue to adopt thermoplastic solutions. Figure 14 shows an impingement shield constructed from LGF PP. 

Polyphenylene oxide (PPO) thermoplastic polymer with good electrical and mechanical properties and excellent dimensional stability over a wide range of temperatures. Uses include medical equipment, electronic components, hot water controls, etc. 

---