The Impact Of Containing Hydroxyl Substance On The Crystallization,Melting And Performance Of Polyoxymethylene

Polyoxymethylene (POM) was modified via melt blending method by addition of containing hydroxyl substance including 4,4’-Thiobis Phenol (TDP),4,4’-Biphenol (DHP), Poly(butylene succinate-co-butylene adipate) (PBSA) and Poly propylene carbonate (PPC), respectively. Intermolecular interactions, miscibility, melting and crystallization behavior and spherulitic morphologies of blends were studied using FTIR, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), polarized light microscope (PLM) and XRD. Mechanical properties of the blends were also tested.Intermolecular hydrogen bonds formed between the end hydroxyl and ether groups of POM and hydroxyl groups of TDP and DHP, which resulted in less compact crystal structure, decreased melting point and crystallization temperature. The introduction of TDP and DHP decreased the crystallization rate in isothermal crystallization process, but did not modify the crystal structure of POM. Meanwhile, TDP only had contributed to tensile properties of POM.For POM/PBSA, intermolecular hydrogen bonding was found between carbonyl groups of PBSA and hydroxyl groups of POM, which was beneficial to the miscibility between PBSA and POM. And the melting and crystallization temperatures of POM decreased with the incorporation of PBSA. Meanwhile, lower content of POM showed significant nucleating effect on the crystallization of PBSA and promoted its crystallization, resulting in more compact crystal structure. In addition, the miscibility between POM and PBSA was dependent on the PBSA content. Miscibility of POM/PBSA alloys was improved with increasing PBSA content. But the addition of PBSA did not change the crystal structure of POM. Moreover, in terms of mechanical properties, the tensile properties and notched impact strength of POM increased with the increasing content of PBSA. The flexural strength and tensile strength of PBSA increased with the increasing content of POM.The melting temperatures and the crystallization temperatures, heat of fusion (AHm), heat of crystallization (△Hc) and the crystallinity of POM decreased with the addition of PPC. In addition, the miscibility between POM and PPC depended on the PPC content. Miscibility of POM/PPC alloys was improved with increasing PPC content. For mechanical properties, the elongation at break of alloys increased from 64% to 569% when the weight fraction of PPC reached up to 50 wt%, which was nearly 8.4 times of that for pure POM. Only the plasticity of POM have been greatly improved. In addition, the addtion of 50 wt% POM improved the elongation at break of PPC by 116% and also contributed to strength and notched impact strength of PPC.