Self-assembled propylene-based compositions and methods of production thereof

A propylene-based bi-layer composition comprising:

• a skin layer comprising 90 wt % or more of a propylene-based elastomer-toughened composition based on the weight of the skin layer, wherein the skin layer is from about 200 to about 300 microns thick;
• and
• a core layer comprising 90 wt % or more of a propylene-based fiber-reinforced composition based on the weight of the core layer,
• wherein the elastomer-toughened composition is formed from (i) a functionalized low molecular weight (LMW) propylene polymer having a number average molecular weight (Mn) within the range from 5,000 g/mol to 40,000 g/mol, wherein the LMW propylene polymer comprises a functional group selected from the group consisting of vinyl, vinylidene and combinations thereof, and (ii) at least one functionalized elastomer, wherein a functional chain of the low molecular weight propylene polymer is coupled to a functional chain of the at least one functionalized elastomer;
• wherein the fiber-reinforced composition is formed from (i) a high molecular weight (HMW) propylene polymer having an Mn greater than 40,000 g/mol and (ii) reinforcing fibers,
• wherein the weight concentration of the elastomer-toughened composition gradually decreases from a maximum concentration at the surface of the skin layer to a minimum concentration within the core layer,
• wherein the elastomer-toughened composition and the fiber-reinforced composition self-assemble upon mixing into the skin layer and the core layer, and
• wherein the thickness of the skin layer is from about 5% to about 25% of the total thickness of the propylene-based bi-layer composition.