High impact strength polypropylene composites

Abstract

A method of making a HIPP composite comprising blending polypropylene-coated functionalized multiwall carbon nanotubes (PP/f-MWNT) with a first PP to produce a PP and PP/f-MWNT mixture, wherein PP/f-MWNT comprise f-MWNT coated with a second PP via non-covalent interactions, wherein PP and PP/f-MWNT mixture comprises 0.0005 to 5 wt. % f-MWNT, based on the weight of PP and PP/f-MWNT mixture, wherein the first PP and the second PP are the same or different; melt blending the PP and PP/f-MWNT mixture to form a molten PP and PP/f-MWNT mixture; and shaping the molten PP and PP/f-MWNT mixture to form the HIPP composite. A HIPP composite comprising a continuous polymeric phase having dispersed therein a plurality of PP/f-MWNT, wherein the continuous polymeric phase comprises a first PP, wherein PP/f-MWNT comprise f-MWNT coated with a second PP via non-covalent interactions, wherein HIPP composite comprises 0.0005 to 5 wt. % f-MWNT, based on the weight of HIPP.

1 . A method of making a high impact strength polypropylene (HIPP) composite, the method comprising:
 (a) blending polypropylene-coated functionalized multiwall carbon nanotubes (PP/f-MWNT) with a first polypropylene (PP) to produce a PP and PP/f-MWNT mixture, wherein the PP/f-MWNT comprise functionalized multiwall carbon nanotubes (f-MWNT) coated with a second PP via non-covalent interactions, wherein the PP and PP/f-MWNT mixture comprises PP/f-MWNT in an amount of from about 0.0005 wt. % to about 5 wt. % f-MWNT, based on the total weight of the PP and PP/f-MWNT mixture, and wherein the first PP and the second PP are the same or different;   (b) melt blending at least a portion of the PP and PP/f-MWNT mixture to form a molten PP and PP/f-MWNT mixture; and   (c) shaping at least a portion of the molten PP and PP/f-MWNT mixture to form the HIPP composite.   
     
     
         2 . The method of  claim 1 , further comprising drying the first PP and/or the PP/f-MWNT at a temperature of from about 50 C to about 100 C, a pressure of from about 50 millibar (mbar) to about 1,013 mbar, for a time period of from about 30 minutes to about 24 hours prior to step (a), wherein the first PP is a powder characterized by an average powder particle size of from about 10 μm to about 1 mm, and wherein the PP/f-MWNT are a powder characterized by an average powder particle size of from about 10 μm to about 1 mm. 
     
     
         3 . The method of  claim 1 , wherein step (a) further comprises subjecting the PP and PP/f-MWNT mixture to grinding, crushing, milling, chopping, or combinations thereof to form a PP and PP/f-MWNT mixture powder, wherein the PP and PP/f-MWNT mixture powder is characterized by an average powder particle size of from about 10 μm to about 1 mm. 
     
     
         4 . The method of  claim 1 , wherein melt blending comprises one or more selected from the group consisting of compounding, melt mixing, and extruding. 
     
     
         5 . The method of  claim 1 , wherein the step (b) blending comprises heating the PP and PP/f-MWNT mixture to a temperature of from about 150 C to about 240 C to form the molten PP and PP/f-MWNT mixture. 
     
     
         6 . The method of  claim 1 , wherein shaping comprises one or more selected from the group consisting of molding, die casting, and extrusion. 
     
     
         7 . The method of  claim 1 , wherein the step (c) shaping comprises:
 (i) introducing at least a portion of the molten PP and PP/f-MWNT mixture to a mold, wherein the mold is characterized by a temperature of from about 50 C to about 120° C.; and   (ii) cooling the molten PP and PP/f-MWNT mixture in the mold to ambient temperature to form the HIPP composite.   
     
     
         8 . A method of making a high impact strength polypropylene (HIPP) composite, the method comprising:
 (a) blending polypropylene-coated functionalized multiwall carbon nanotubes (PP/f-MWNT) with a first polypropylene (PP) to produce a PP and PP/f-MWNT mixture, wherein the PP/f-MWNT comprise functionalized multiwall carbon nanotubes (f-MWNT) coated with a second PP via non-covalent interactions, wherein the PP and PP/f-MWNT mixture comprises PP/f-MWNT in an amount of from about 0.0005 wt. % to about 5 wt. % f-MWNT, based on the total weight of the PP and PP/f-MWNT mixture, and wherein the first PP and the second PP are the same or different;   (b) melt blending at least a portion of the PP and PP/f-MWNT mixture to form a molten PP and PP/f-MWNT mixture; and   (c) shaping at least a portion of the molten PP and PP/f-MWNT mixture to form the HIPP composite; wherein the HIPP composite has:
 an impact strength of from about 4.0 kJ/m 2  to about 6.5 kJ/m 2 , as determined in accordance with ASTM D256; 
 a strain to failure of from about 100% to about 400%, as determined in accordance with ASTM D638; 
 a heat deflection temperature that is increased by equal to or greater than about 5 C when compared to a heat deflection temperature of the first PP without the PP/f-MWNT, as determined in accordance with ASTM D648; and 
 a crystallization half time at 135 C of from about 1 minute to about 25 minutes, as determined by differential scanning calorimetry (DSC) thermal analysis in accordance with ASTM E2070-13. 
   
     
     
         9 . A high impact strength polypropylene (HIPP) composite comprising a continuous polymeric phase having dispersed therein a plurality of polypropylene-coated functionalized multiwall carbon nanotubes (PP/f-MWNT), wherein the continuous polymeric phase comprises a first polypropylene (PP), wherein the PP/f-MWNT comprise functionalized multiwall carbon nanotubes (f-MWNT) coated with a second PP via non-covalent interactions, wherein the HIPP composite comprises PP/f-MWNT in an amount of from about 0.0005 wt. % to about 5 wt. % f-MWNT, based on the total weight of the HIPP, and wherein the first PP and the second PP are the same or different. 
     
     
         10 . The HIPP composite of  claim 9 , having an impact strength of from about 4.0 kJ/m 2  to about 6.5 kJ/m 2 , as determined in accordance with ASTM D256. 
     
     
         11 . The HIPP composite of  claim 9 , having an impact strength that is increased by equal to or greater than about 150% when compared to an impact strength of the first PP without the PP/f-MWNT, wherein the impact strength is determined in accordance with ASTM D256. 
     
     
         12 . The HIPP composite of  claim 9 , having an impact strength that is increased by equal to or greater than about 200% when compared to an impact strength of the first PP without the PP/f-MWNT, wherein the impact strength is determined in accordance with ASTM D256. 
     
     
         13 . The HIPP composite of  claim 9 , having a tensile modulus that is equal to or greater than a tensile modulus of the first PP without the PP/f-MWNT, wherein the tensile modulus is determined in accordance with ASTM D638. 
     
     
         14 . The HIPP composite of  claim 9 , having a yield stress that is equal to or greater than a yield stress of the first PP without the PP/f-MWNT, wherein the yield stress is determined in accordance with ASTM D638. 
     
     
         15 . The HIPP composite of  claim 9 , having a strain to failure of from about 100% to about 400%, as determined in accordance with ASTM D638. 
     
     
         16 . The HIPP composite of  claim 9 , having a heat deflection temperature that is increased by equal to or greater than about 5 C when compared to a heat deflection temperature of the first PP without the PP/f-MWNT, as determined in accordance with ASTM D648. 
     
     
         17 . The HIPP composite of  claim 9 , having a crystallization temperature that is increased by equal to or greater than about 1 C when compared to a crystallization temperature of the first PP without the PP/f-MWNT, as determined by differential scanning calorimetry (DSC) thermal analysis in accordance with ASTM E794-06. 
     
     
         18 . The HIPP composite of  claim 9 , having a crystallization half time at 135 C of from about 1 minute to about 25 minutes, as determined by differential scanning calorimetry (DSC) thermal analysis in accordance with ASTM E2070-13. 
     
     
         19 . The HIPP composite of  claim 9 , wherein a volumetric concentration of the PP/f-MWNT in any 1 mm 3  of HIPP composite differs by less than about 10% from an average volumetric concentration of the PP/f-MWNT in the HIPP composite as a whole. 
     
     
         20 . An article comprising the HIPP composite of  claim 9 , wherein the article is formed by injection molding of the HIPP composite.