LDPE, additives Carbon-black

Elongation was better retained also by the addition of 5% soot to LDPE. The material underwent a rapid erosslinking at 50-60 kGy whieh improved its elongation by a faetor of 4. At the same time, its tensile strength was decreased by 30%." Polyethylene eontaining earbon blaek was found to be resistant to ionizing radiation. The impact strength of carbon black filled HDPE and HDPE/EPDM was improved after exposure to Y-radiation. ... 

Figure 16.9 compares the effect of carbon black concentration on PS, LDPE, and their blends. The polymer blends have better conductivity than individual polymers. A rapid decrease in conductivity by small additions of carbon black can be obtained in segregated blends, but mechanical properties of such blends are infe-... 

The outdoor stability of EVA resins is superior to that of LDPE by virtue of their greater flexibility. Addition of UV stabilizers can extend the outdoor life of clear compounds to three to five years, depending on the degree of exposure. Outdoor life expectancy is also enhanced by the addition of carbon black. 

The HDPE, LDPE, and LLDPE can be stabilized by UV absorbers of type benzophenone or benzotriazole and also combination of HALS and UV-absorbers. Usually pipes used in irrigation are pigmented with white titanium dioxide or carbon black. Titanium dioxide may be used up to an additional level of 0.5 wt%. Each of the HALS and UV absorber may be added up to 0.05 wt% [50-53]. 

Fig. 18.21 (a) Effects of addition of Irganox B225 (1 1 blend of Irganox 101 and Irgafos 168) on repetitively extruded (up to five times) HDPE. The stabilizer was added in the amount of 0, 0.05, and 0.20 wt% (After Herbst et al. 1997). (b) Stabilization effects of HALS on a virgin and recycled LLDPE/LDPE blends with and without carbon black (CB) (After Herbst et al. 1997)... 

Low amounts of stabilizer are necessary for improving the stability of polymers [06C1]. The most used polymer, polyethylene, needs antioxidants in its product formulation, even though it is saturate polymer and the oxidation in any conditions starts more slowly than in many other polymer materials. A comparative study on the effect of two additives (hydrolysis-conditioned phosphate and IRGANOX 1076) on the thermal stability of medium density polyethylene (MDPE) and low density polyethylene (LDPE) (Fig. 71) illustrates the performances of material modified with carbon black (CB) and dicumyl peroxide (DCP), respectively [02F1]. This figure demonstrates that the same antioxidants promote differently thermal protection in the direct relation with material formulation. 

Figure 2.16 shows the TG separation of an LDPE formulation containing a lubricant, carbon-black and inert filler using an optimised stepwise analysis mode. The percentage lubricant, polymer, carbon, and inert filler can quantitatively be determined [272]. Lever et al. [273] have shown that HRTGA gives a much cleaner resolution of mass losses than conventional TG of a polymeric derivative used as an oil additive. Also the high resolution TG analysis of DOP in vinyl plastics has been reported [229]. 

Masterbatches are concentrated mixtures of colours and/or additives incorporated into suitable carrier materials. This enables easy incorporation of the selected masterbatch formulation into the production process. Often, masterbatches are used to improve the downtime when changing colour and materials, which improves production efficiency. It is more expensive to buy a masterbatch than an additive. However, the advantages, especially in cases where nmnerous colour changes are required, can quickly repay the cost. For example, carbon black pigment is very fine and incredibly difficult to remove from feed hoppers and mixers (and the production workers ), whereas a black masterbatch containing perhaps 20% black pigment in a carrier material such as low-density polyethylene (LDPE) can be added to the mixture at 1-5%, leaving the hoppers and mixers easy to clean, ready for the next blend. 

Largely as for LDPE UV stabilized by 2-3% carbon black addition low heat resistance, limited use to 65°C electrical properties inferior to LDPE attacked by strong acids, chlorinated and aromatic hydrocarbons and ketones. 

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