Strength izod impact

The Izod impact strengths for virgin and glass fibre reinforced engineering polymers are shown in Table 2.12. 

Polymer Unreinforced polymer Glass fibre reinforced polymer  

The incorporation of carbon fibre produces hardly any change in Izod impact strength of polyacetal (0.04 kj/m), compared to that of the base polymer (0.06 kj/m). Various other additives hardly affect Izod impact strength as shown in Table 2.13. 

Polymer Impact strength of virgin Impact strength of the polymer 

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Izod impact strength, J /m of notch ASTM D256 21.35-53.38... 

Typical products have a specific gravity of 1.3-1.4, a tensile strength of 50 MPa and a flexural modulus of 2500 MPa. ASTM Izod impact strengths range from 1 to 25 ft Ibf/in of notch according to formulation whilst melt flow may also be varied 100-fold in a similar manner. 

The brittleness of isotactic polystyrenes has hindered their commercial development. Quoted Izod impact strengths are only 20% that of conventional amorphous polymer. Impact strength double that of the amorphous material has, however, been claimed when isotactic polymer is blended with a synthetic rubber or a polyolefin. 

Non-self-extinguishing grades with a heat distortion temperature in the range 110-160°C and with a notched Izod impact strength of 200-500 J/m. 

Notched Izod impact strength (3.2 mm bar) Impact strength in tension... 

Trade literature can provide a wealth of information. Users should, however, bear in mind that suppliers will naturally wish to emphasise data in the best possible light. For example, if the Izod impact strength increases sharply with decrease in sample thickness, then results may be quoted for thinner section test pieces. Whilst the facts may be stated, the underlying significance may not be fully appreciated by the casual reader. 

The study on commercial HDPE samples could not provide a correlation of the izod impact test with the field performance test, i.e., drop impact resistance on moulded products [113]. It was found that the sample of highest density and lowest izod impact strength passed the drop impact test, but other samples of lower density and higher izod impact strength could not withstand shock loading by drop impact and failed in brittle manner. This may be due to the fact that velocities and modes of loading vary widely in different impact tests. It has been reported that even the qualitative agreement between the different impact tests is poor because the test bars and moulded products often have different orientation characteristics, particularly near the surface [115]. 

Elliot [38] has reported that interfacial adhesion in the NR-PP blend can be enhanced by the addition of small amounts of HOPE. Addition of HDPE does give some improvement in the notched Izod impact strength of NR-PP blend (Fig. 7). The effect of HDPE on the impact modification of NR-PP is associated with the improved crystallinity of PP, enhanced by HDPE. During the mill mixing of NR and PP, chain scission may occur to give polymeric radicals that, on reaction with... 

Figure 7 Effect of addition of HOPE on Izod impact strength of NR-PP blend. (O) 20 80 NR-PP homopolymer, (V) 20 67 13 NR-PP-homopolymer-HDPE, ( ) 15 85 NR-PP copolymer grade, and (x) 15 75 10 NR-PP-copo-lymer-HDPE.

The importance of the morphological aspects of the HIPS on their Izod impact strength and gloss has been... 

Rubber particle size (/i.m) Large particles in blends (%) Rubber phase volume fraction Notched Izod impact strength ft. Ibs/in. Gloss... 

Particle diameter (urn) izod Impact Strength (J/m) Gloss (arbitrary unit) (ABS=80)... 

Heterogeneous compatible blends of preformed elastomers and brittle plastics are also an important route for the development of blends of enhanced performance with respect to crack or impact resistance. Polycarbonate blends with preformed rubber particles of different sizes have been used to provide an insight into the impact properties and the fracture modes of these toughened materials. Izod impact strength of the blends having 5-7.5 wt% of rubber particles exhibits best overall product performance over a wide range temperature (RT to -40°C) [151-154]. 

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