Polyamide flexural modulus

PBT will absorb very little water (0.08 %), and its mechanical properties are not affected in the short term. Polyamides, on the other hand, may absorb up to 12% of water. In nylon resins, the water acts as a plasticizer it lowers the Tg, decreases the flexural modulus, and may cause part growth. Based on these criteria alone, polyesters are often a better choice than nylons for many applications (less variation of properties). 

Figure 6.8 plots the reinforcement ratios for short glass fibre reinforced polyamide (PA-GF) versus neat polyamide for six important characteristics calculated versus density and material cost. These characteristics are tensile strength, tensile and flexural modulus, impact strength, HDT A and B. 

Hyperion Catalysis International markets its nanombes under the name Fibril . Adding 5% to polycarbonate transforms its volume resistivity from lO to 10 ohm-cm and, unlike some particulate additives, only reduces the tensile strength by 11%, while increasing the flexural modulus by 18%. One important application is the polyamide fuel lines in vehicles, and another is the production of the conductive thermoplastic fenders used for in-line electrostatic painting. In the case of fuel lines, the compounding system must produce highly homogeneous compositions to rule out local static build up. Less than one per cent of nanotubes is sufficient. 

DuPont s Fusabond AEB-560D is a modified ethylene-acrylate copolymer for use in polyamides. It is claimed to be a cost-effective toughener, more effective than maleic anhydride terpolymers and usable at low temperatures, while improving mould flow, with less of an adverse effect on the flexural modulus. 

The effect of moisture level on flexural modulus for polyamide-66-based composites (Fig. 12.20) is a dictating factor influencing long-term stiffness of... 

Base Polymer Type—Because of the influence of moisture, the polypropylene-based composites exhibit much greater stiffness than the hydroscopic polyamide resins that were preconditioned at 50% RH before testing of flexural modulus. 

Figure 1 Cost-related (specific) flexural strength of major thermoplastics, versus cost-related (specific) thermal tolerance. The unit cost is the market price in US cents (1992) of 1 cm plastics. The thermal tolerance is the temperature difference (AT) over room temperature (AT — T - room T), by which temperature (7 ) the flexural modulus is equal to 1 GPa. Designations, abbreviations WFRP-S, wood fiber reinforced PP (S type) of AECL, Canada (See Table 1) PMMA, polymethylmethacrylate PVC, pol)winyl chloride PS, polystyrene PP, polypropylene UP, unsaturated polyesters PA-GF, glass fiber (35%) reinforced polyamide PHR, phenolic resin EP, epoxy resin ABS, acrylonitrile/butadiene/styrene copolymer UF, urea/formaldehyde LDPE, low density polyethylene PC, polycarbonate POM, polyoxymethylene CAB, cellulose acetate butyrate LCP, liquid crystal polymers PEEK, polyether-etherketone PTFE, polytetrafluorethylene.

Reinforced polymers that combine high tensile strength with high flexural modulus include polybutylene terephthalate, polyether ether ketone, polyamide-imide, and polyethylene terephthalate (see Table 3.3). 

The incorporation of glass fiber info polyamide 6 increases the tensile strength from 40 to 145 GPa (Table 3.1), accompanied by an increase in flexural modulus (Table 3.2) from 1.0 to 1.6 MPa and hardly any change in elongation at break (Table 3.4). 

The corporation of glass fiber has little effect on the tensile strength of polyamide-imide from 185 to 195 MPa (Table 3.1) and the flexural modulus from 4.6 to 11.1 GPa (Table 3.2), while the elongation of break decreases from 12% to 5% (Table 3.4). 

The incorporation of 10%-30% carbon fiber into polyamides produces distinct improvements in tensile strength and flexural modulus, as shown for some polyamides in Table 3.8. 

With unreinforced RTM 65, the bis-maleimide flexural modulus falls from 27.1 to 0 GPa for zero exposure to gamma radiation after a radiation dose of 250 kGy. Under the same conditions, the flexural modulus of fiberglass-reinforced polyamide 3 increases from 19.9 to 25.3 GPa upon exposure to 250 kGy gamma radiation. 

Muscovite mica improves flexural modulus/ heat distortion resistance and dimensional stability of thermoplastic and thermoset composites. Applications are established in polyolefin, polyamide, polyester and polyurethane/polyurea polymers. 

Kojima et al. [ 122] report that the polyamide-6/montmorillonite compound (nanocomposite or hybrid) has superior modulus, tensile strength, flexural modulus, and impact strength compared to neat polyamide-6, as well as higher heat distortion temperature. Indeed, with 4.7 wt% montmorillonite, the heat distortion temperature was increased 87 °C over neat polyamide-6 to 152 °C. 

The polyamide 66 composites exhibit sinular property trends and more evidence of fiber degradation. Injection molded specimens could not be tested due to too much degradation. The flexural properties of polyamide 66 conposites are shown in Table 4. Conqjared to neat polyamide 66 there is a drop in flexural strength and an increase in flexural modulus. The flexural moduli of polyamide 6 and 66 composites are similar whereas the strengths of the polyamide 66 composites are lower. These trends are consistent with the lower quality of the polyamide 66 composites. 

Fig. 4.41 Modulus of elasticity in flexure in dependence on test temperature for polyacetale, polysulfone, polycarbonate, poly (butylene terephthalate), transparent polyamide and high temperature resistant acrylonitrile-butadiene-styrene [08Els].

Fig. 4.161 Flexural-creep modulus of glass fiber reinforced polyamide and polyphthal amide at 23 °C [12Els].

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