Deconvolution Protocols for Melt Crystallization Peaks in Recyclate Blends
Deconvolution of DSC melt crystallization peaks isolates PE and PP fractions in recyclates to verify composition before compounding.
Lamellar Morphology
Meaning
Structural arrangement in semi-crystalline polymers consists of thin plates that influence the optical clarity and mechanical strength of a part. Lamellar morphology dictates the performance of films and moulded components by organizing polymer chains into folded crystalline domains. These layers provide a rigid framework within the amorphous matrix.
The thickness of the lamellae and the distance between them are controlled by the temperature at which the resin crystallizes.
Mechanical Influence
Resistance to stress cracking and impact depends on the tie molecules that bridge the gaps between these plates. If the lamellar morphology is too coarse, the material may become brittle and prone to failure under load. In biaxially oriented films, stretching the material aligns these plates parallel to the surface, which notably improves the oxygen barrier properties.
Processing Impact
Melt temperature and mould cooling rates directly alter the size and orientation of these structures. A high melt temperature followed by rapid cooling tends to produce thinner lamellae and a more disordered arrangement. This results in a part with higher transparency but lower heat deflection temperature.
Microscopic Observation
Spherulites are larger-scale structures composed of these individual crystalline plates radiating from a central nucleus. These spherical aggregates grow until they impinge upon their neighbors during the solidification process.