Polyesters glass reinforced, comparative

Aliphatic organofunctional silanes recommended as coupling agents for glass-reinforced polyesters, epoxies, or phenolics have heat stabilities of typical aliphatic organic chemicals and are not at all comparable to the methyl or phenyl silicones found in silicone polymers and resins. 

Mechanical rubber goods include hoses, power transmission (PT) belts, and conveyor belts. Aramids compete with nylon, polyester, glass, and steel in these applications. Steel dominates the rubber hydraulic hose market and polyester is the reinforcement of choice in lower pressure thermoplastic hoses. Advantages of aramid vs. other textiles in hose applications include higher strength, which can lead to constructions with fewer plies and less weight, and better thermal stability, dimensional stability, and chemical resistance. When compared with steel, aramid will not corrode and can be fabricated into lower weight, more flexible hoses. 

Impurities in the water have a great effect on the water resistance of the joints. The maximal strength decrease of glass-reinforced plastics is caused by distilled water. The strength of steel joints cemented with adhesive based on the Epoxy-1000 resin decreased by 44% when subjected for 60 days to rainwater, by 21% with river water, and by 18% with sea water. Adhesives based on PN polyester resin form comparatively water-resistant joints with glass-reinforced plastics [211], while steel joints cemented by these adhesives are not water-resistant. When subjected to warm (60°C) water for 400 h and to boiling water for 120 h, the strength of steel joints bonded by polyester adhesives decreased 3—4 times. 

The glass-reinforced thermoplastic polyester resins are nnusual in that they are the first thermoplastic that can compare with, or are better than, thermosets in electrical, mechanical, dimensional, and aeep properties at elevated temperatures (approximately 150°C), while having superior impact properties. The glass fiber concentration usually ranges from 10 to 30 percent in commercially available grades. In molded parts, the glass fibers remain slightly below the surface so that finished items have a very smooth surface finish as well as an excellent appearance. 

The stiffness of common plastics materials is very low compared with steel (flexural modulus of most common thermoplastics 2 GN m 2, modulus of steel 200 GM m"2). Glass reinforcement greatly increases the stiffness of plastics, both thermosetting and thermoplastic - see Philips glass-coupled polypropylene washing machine tank. Chapter 9. For example, the flexural modulus of cast unsaturated polyester resin 3.5 GN m 2, flexural modulus of GRP (glass reinforced polyester resin) SGM m"2. 

Glass-Reinforced Composites. These composites are prepared from SMC and by liquid injection molding, (LIM). Phenolic resins are usually not amenable to LIM because of the volatiles generated. However, a resin suitable to LIM has been prepared (107). The properties of the 60% glass-mat-reinforced product obtained from this resin were compared to conventional isophthalic polyester and vinyl ester sheet-molding compounds at equivalent glass loading the mechanical... 

The separator is a vertical cylindrical vessel made from Werkstoff 4505 (comparable to STST316L but containing 2% Cu, 1.5% Nb and higher in H than 316L) or constructed of polyester resin reinforced with glass fibre. This is protected on the inside by a 3 mm layer of PVC, chemically bonded to the glass fibre. Although the latter separators are cheaper than the Werkstoff type, special skills would be needed to repair them if tMs became necessary. 

Water absorption of thermoplastic resins is lowered with glass reinforcements as indicated in Table 3-1. Exceptionally low water absorption is found in glass-reinforced (GR) fluoropolymers, PVC, polyethylene, polypropylene, modified polyphenylene oxide, polyphenylene sulfide, polycarbonates, and polyesters. The poorest systems are the nylons 6, 6/6, 6/10 and acetals. Other nylons such as nylons 11,12, and 6/12 are comparable to... 

Fig. 3-20 compares the flexural modulus versus temperatures for four 30% GRTP s. Because modulus is a frequently appearing property in mechanical design equations, creep data often are plotted as apparent or creep modulus. These data are shown in Table 3-6 for GRTP s. As can be seen, the apparent creep modulus improves with glass reinforcement. Generally, the creep modulus of the reinforced thermoplastics decreases as stress and temperature are increased. However, the creep modulus data for reinforced nylon, acetal, polyester, polysulfone, and polyvinyl chloride appear to be less dependent on stress under the conditions of this particular test. When creep modulus data at different stresses coincide—a phenomenon known as the Boltzman superposition—there is an obvious reduction in the amount of testing required. However, such a relationship is both temperature and stress dependent and must be confirmed at the conditions of interest for the specific material involved. Other techniques, such as time-temperature superposition and other empirical correlations, also have been devised to simplify the time-dependent response of plastics ... 

Undoubtedly the idea of adding the fillers is to achieve reduction in cost. However, there are some special type of fillers which are used purely on a functional basis with an accepted trade-off in the cost reduction, for example, some fiber glass reinforcements for polyesters, barium ferrite as a magnetizable filler, metallic powders for electrical and thermal conductivity improvement. In fact all these specialty fillers are more expensive than general purpose fillers and in some cases even more expensive than the polymer which they fill. In any case, the cost-effectiveness of the filler ought to be determined. The objective should be to compare the full cost of the completed product with and without the filler. 

Test specimens can also be used to simulate some degree of warpage. Figure 5-8 compares unreinforced and reinforced glass fiber-TS polyester flexural-type specimens at different temperatures in a droop test (with a center support), sag test (end supports), and an expansion test (bolted at three points). The study for this particular test is conducted at various temperatures. 

Our study is outlined in five parts, (a) Two polystyrene plastics were reinforced at different fiber contents alternately with polyester, asbestos, and glass fibers, (b) The mechanical/physical properties of the resultant monofiber-reinforced plastics were determined and compared, (c) Combinations of fibers were then used to fabricate multifiber-rein-forced structures to exploit simultaneously the particular advantages of the different reinforcements, (d) The effect of each fabrication stage on the molecular weight and molecular weight distribution of the matrix plastics was established and (e) a linear mathematical model was formulated to predict the properties of multifiber structures and forecasted values compared with corresponding values experimentally obtained from (c) above. 

Comparison with Asbestos and Glass. Tables III, IV, V, and VI catalog the properties obtained when the two polystyrenes were reinforced with asbestos and glass. Table VII compares the reinforcing effects of the several fibers studied at 30 wt %. The data show that particular fibers improve particular properties. The tensile modulus and tensile strength are most improved by glass the heat deflection is most improved by asbestos, and the impact strength is most improved by polyester. 

In this respect, (thermoset) plastics composites with discontinuous fibre products are already mostly used in the car body applications, where polyester/E-glass is predominating (mostly because of polyesters, economy, ease of processability and reasonable mechanical properties provided), followed by use of phenolics (when fire retardance is required, in friction linings and engine compartments), and epoxies. Replacement by carbon or aramid fibre reinforcements can reduce body mass by 40% (compared to steel) and with more added strength, but the cost is unfavourable at the moment, as mentioned previously [12, 13]. 

---