8. Impact strength
Fig. 7 illustrates the impact strength of PHBV and its hybrid composite. The impact strength of PHBV decreased from 25 J/mt to 19 J/mt on addition of 20 wt.% talc and wood fiber each. In our previous publications it is described that the impact strength of PHBV decreases by 29%on addition of 40 wt.%woodorbamboofiber [31]. The decrease in this case was 24% suggesting that talc does not lead to any additional drop in impact strength of the composite but rather it is a generic phenomenon due to the addition of fillers. More over the decrease was due to the reduced interfacial interaction between
the wood fiber and PHBV in presence of talc which is visible in SEM micrographs. Due to the low fiber–matrix interfacial interaction fiber pull out used up less energy resulting in lower impact strength.