Relationship between interchain spacing of amorphous polymers and blend miscibility as determined by wide‐angle X‐ray scattering

摘要

AbstractThe average molecular interchain spacing (〈R〉) in Angstroms for amorphous polymers was calculated from the strong maximum in the wide‐angle X‐ray scattering (WAXS) diffraction scan using established equations. The half‐width (HW) of the maximum was used to qualitatively describe the distribution of 〈R〉. 〈R〉 and HW for immiscible blends corresponded to the weighted average of 〈R〉 and HW of the homopolymers in the blend. 〈R〉 for a miscible blend (natural rubber and high‐vinyl PBd) was much larger than the weighted average of 〈R〉 of the component homopolymers, indicating that a new amorphous molecular structure had developed. The larger 〈R〉 for the miscible blend indicates that the molecular chains are spread further apart, resulting in an increase in free volume to accommodate the new packing order. The singleTgof this blend was lower than predi