Question

If moisture regain of polyester and cotton is 0.4 % and 8.5 %, respectively, then moisture regain (%) of 70:30 polyester-cotton blend (correct up to 2 decimal places) is ________________.

Hint:

For calculating the moisture regain of a blend, multiply the moisture regain of each component by its fraction in the blend and then add the results.

Answer 1

Correct Answer: 2.66

The moisture regain of the blend is calculated as the weighted average of the moisture regain of polyester and cotton: \[ \text{Moisture regain of blend} = (0.7 \times \text{Moisture regain of polyester}) + (0.3 \times \text{Moisture regain of cotton}). \] Substitute the given values: \[ \text{Moisture regain of blend} = (0.7 \times 0.4) + (0.3 \times 8.5) = 0.28 + 2.55 = 2.83 \, %. \] Final Answer: \[ \boxed{2.83}. \]