Elastic blends comprising crystalline polymer and crystallizable polymers of propylene

Abstract

Improved thermoplastic polymer blend compositions comprising an isotactic polypropylene component and an alpha-olefin and propylene copolymer component, said copolymer comprising crystallizable alpha-olefin sequences. In a preferred embodiment, improved thermoplastic polymer blends are provided comprising from about 35% to about 85% isotactic polypropylene and from about 30% to about 70% of an ethylene and propylene copolymer, wherein said copolymer comprises isotactically crystallizable propylene sequences and is predominately propylene. The resultant blends manifest unexpected compatibility characteristics, increased tensile strength, and improved process characteristics, e.g., a single melting point.

1 - 31 . (canceled)  
     
     
         32 : A propylene/ethylene copolymer comprising at least about 88.4 weight percent of units derived from propylene and about 5.8 to about 11.6 weight percent of units derived from ethylene, the copolymer characterized as having a DSC curve with a T me  that remains essentially the same and a T max  that decreases as the amount of ethylene in the copolymer is increased.  
     
     
         33 : The copolymer of  claim 32  further characterized as having an X-ray diffraction pattern exhibiting more gamma-form crystals than a comparable propylene/ethylene copolymer prepared with a Ziegler-Natta catalyst.  
     
     
         34 : The copolymer of  claim 32  further characterized as having a B-value of about 1.4 when the ethylene content of the copolymer is about 5.8 weight percent.  
     
     
         35 : The copolymer of  claim 33  further characterized as having a B-value of about 1.4 when the ethylene content of the copolymer is about 5.8 weight percent.  
     
     
         36 : A propylene/ethylene copolymer comprising at least about 88.4 weight percent of units derived from propylene and about 5.8 to about 11.6 weight percent of units derived from ethylene, the copolymer characterized as having an X-ray diffraction pattern exhibiting more gamma-form crystals than a comparable copolymer prepared with a Ziegler-Natta catalyst.  
     
     
         37 : The copolymer of  claim 36  further characterized as having a B-value of about 1.4 when the ethylene content of the copolymer is about 5.8 weight percent.  
     
     
         38 : The copolymer of  claim 36  further characterized as having a skewness index, S ix , of about −0.32.  
     
     
         39 : The copolymer of  claim 37  further characterized as having a skewness index, S ix , of about −0.32.  
     
     
         40 : A propylene/ethylene copolymer comprising about 94.2 weight percent of units derived from propylene and about 5.8 weight percent of units derived from ethylene, the copolymer characterized as having (i) a skewness index, S ix , of about −0.32, and (ii) a DSC curve with a T me  that remains essentially the same and a T max  that decreases as the amount of ethylene in the copolymer is increased.  
     
     
         41 : The copolymer of  claim 40  further characterized as having an X-ray diffraction pattern exhibiting more gamma-form crystals than a comparable propylene/ethylene copolymer prepared with a Ziegler-Natta catalyst.  
     
     
         42 : The copolymer of  claim 40  further characterized as having a B-value of about 1.4 when the ethylene content of the copolymer is about 5.8 weight percent.  
     
     
         43 : The copolymer of  claim 41  further characterized as having a B-value of about 1.4 when the ethylene content of the copolymer is about 5.8 weight percent.