ABSTRACT
Chitin whiskers are promising reinforcing filler for composites due to their mechanical properties, renewable nature and low cost. A new method for preparation of ß-chitin fibrils from squid pens in ascorbic acid aqueous solutions (AscA) was developed. Stirring of the solution with 2â¯g/l AscA for 2â¯h disperses the swollen chitin to individualized fibrils with an aspect ratioâ¯>â¯250. The optimal conditions of ß-chitin exfoliation in acrylic acid (AcrA) aqueous solution were found (0.75-2â¯g/l, 3-4â¯h). TEMPO-oxidized ß-chitin fibrils were chosen as a reference sample for comparison of different methods. 0.1% chitin suspensions exfoliated in AscA and AcrA solutions show similar gel-like behavior with a storage modulus (G') of 98⯱â¯23 and 34⯱â¯12â¯Pa, respectively, whereas G' of 0.1% dispersion of the TEMPO-oxidized ß-chitin fibrils was 0.015⯱â¯0.005â¯Pa only. Composites based on poly(acrylic acid) comprising 1-3â¯wt% of ß-chitin fibrils were fabricated by polymerization filling. Mechanical properties of the composites were investigated in dry state in the temperature range of 25-250⯰C and at controlled relative humidity in the range from 53.6% to 100%. It was revealed that the maximum reinforcing effect is achieved at high temperature (>120⯰C) and high relative humidity (≥75.3%RH).