Quantifying tie-chain content in semicrystalline polyolefins with vapor-flow small-angle neutron scattering

A long-standing fundamental concept in our understanding of the mechanical properties of semicrystalline polymers is that of tie chains—molecules which form part of two adjacent crystalline lamellae and function as crosslinks between them. Although characterization methods targeting crystalline regions are well established, quantifying the properties of the interlamellar amorphous region remains challenging. This technique establishes a crucial link between semicrystalline polymer mechanical properties and calculations of tie-chain content based on molecular architecture. Here, we compare both notch test results and a primary structural parameter [1] with tie-chain content calculated by applying equilibrium swelling theory to vapor-flow SANS data for two ethylene-hexene copolymers and a linear polyethylene.