Polymeric sandwich structure having enhanced thermal conductivity and method of manufacturing the same

A polymeric sandwich structure having enhanced thermal conductivity, comprising:

• a first layer formed from a first polymer matrix and including a first fiber reinforcing sheet embedded within the first polymer matrix;
• a second layer formed from a second polymer matrix and including a second fiber reinforcing sheet embedded within the second polymer matrix;
• and
• a third layer disposed between the first and second layers, the third layer formed from a third polymer matrix having graphene nanoplatelets interspersed therein and including at least 50% by volume of hollow microspheres having an average diameter of about 10 to 100 microns;
• wherein each of the first and second fiber reinforcing sheets is made of reinforcing fibers and includes a respective set of staggered discontinuous perforations formed therein having an average width or diameter of about 10 to 300 microns and an average density of about 100 to 60,000 perforations per square meter, wherein each respective set of staggered discontinuous perforations defines a respective first plurality of reinforcing fibers having a respective first length and a respective second plurality of reinforcing fibers having a respective second length longer than the respective first length;
• and
• wherein the polymeric sandwich structure is effective to enable each of the first, second and third polymer matrices to be heated from (i) a first temperature upon placement of the polymeric sandwich structure in a heated mold with the first layer in contact with the heated mold, to (ii) at least a predetermined second temperature by continuous application of heat from the heated mold to the first layer, in 20% to 50% less time than if the third polymer matrix did not contain the graphene nanoplatelets.

A method of manufacturing a flowable polymeric sandwich structure having enhanced thermal conductivity, comprising:

• dispersing graphene nanoplatelets in a solvent to produce a graphene nanoplatelet/solvent mixture;
• ultrasonically mixing the graphene nanoplatelet/solvent mixture to achieve a predetermined level of homogeneity;
• combining the graphene nanoplatelet/solvent mixture with a polymer matrix to produce a graphene nanoplatelet/solvent/polymer matrix mixture;
• evaporating at least a majority of the solvent from the graphene nanoplatelet/solvent/polymer matrix mixture to produce a graphene nanoplatelet/polymer matrix mixture;
• pressurizing the graphene nanoplatelet/polymer matrix mixture according to a pressure profile;
• dispersing the graphene nanoplatelet/polymer matrix mixture onto a first carrier film;
• sending the graphene nanoplatelet/polymer matrix mixture and first carrier film through a doctor blade arrangement to achieve a predetermined thickness of graphene nanoplatelet/polymer matrix mixture on the first carrier film;
• heating the graphene nanoplatelet/polymer matrix mixture to achieve a predetermined degree of cure and/or a predetermined viscosity of the graphene nanoplatelet/polymer matrix mixture, thereby producing a core layer;
• providing a first layer formed from a first polymer matrix with a first fiber reinforcing sheet embedded within the first polymer matrix, and a second layer formed from a second polymer matrix with a second fiber reinforcing sheet embedded within the second polymer matrix, wherein each of the first and second fiber reinforcing sheets is made of reinforcing fibers;
• producing a respective set of staggered discontinuous perforations in each of the first and second fiber reinforcing sheets using a perforation cutting head or a laser, thereby producing respective first and second perforated layers, wherein each respective set of staggered discontinuous perforations defines a respective first plurality of reinforcing fibers having a respective first length and a respective second plurality of reinforcing fibers having a respective second length longer than the respective first length;
• and
• stacking the core layer between the first and second perforated layers.