Structure and properties of polyformaldehyde composite modified by cyclodextrin coating
Using cyclodextrin and PEG-PPG-PEG triblock copolymer(PEG-PPG-PEG)as raw materials,the modifier(DA)coated PEG-PPG-PEG with cyclodextrin was prepared by drip reaction.And polyformaldehyde(POM)composite modified with DA was prepared by melt blending and extrusion.The structure and mechanical properties of the mod-ified composites were characterized by differential scanning calorimeter,polarizing microscope,scan-ning electron microscope,universal material testing machine and impact testing machine.The results showed that when the mass fraction of DA was 3.0%,the DA in the modified composite was dispersed in the POM matrix in the form of small particles,simi-lar to the island structure.Compared with the un-modified POM resin,at the same crystallization temperature,the time of nucleation of the modified composite was shorten,the number of nucleation and spherulite were increased,and the spherulite size was decreased.The crystallinity of the modified composites was improved,but there was little differ-ence between the modified composites after adding different mass fractions of DA.When the mass frac-tion of DA was 0.5%and 1.0%and 3.0%,the ten-sile strength,bending modulus and notched impact strength of simple supported beam of the modified composite increased correspondingly.
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