SUN, Likuo (14306 Providence Pine, Houston, TX, 77062, US)
MUSGRAVE, Mike (14226 Lofty Mountain Trail, Houston, TX, 77062, US)
COFFY, Tim (4226 Noble Oak Trail, Houston, TX, 77059, US)
SUN, Luyi (2213 Cambridge Shores Lane, Pearland, TX, 77584, US)
SUN, Likuo (14306 Providence Pine, Houston, TX, 77062, US)
MUSGRAVE, Mike (14226 Lofty Mountain Trail, Houston, TX, 77062, US)
COFFY, Tim (4226 Noble Oak Trail, Houston, TX, 77059, US)
What is claimed is:
1. An injection stretch blow molded (ISBM) article comprising: a propylene based polymer comprising a melt flow rate of less than 10 g/10 min.
2. The article of claim 1, wherein the propylene based polymer comprises a homopolymer.
3. The article of claim 1, wherein the propylene based polymer comprises a random copolymer.
4. The article of claim 3, wherein the random copolymer comprises less than about 10.0 wt.% ethylene.
5. The article of claim 1, wherein the propylene based polymer comprises a heterophasic copolymer.
6. The article of claim 1, wherein the propylene based polymer is formed from a metallocene catalyst.
7. The article of claim 6 further exhibiting improved optical properties and stiffness over propylene based polymers formed from Ziegler-Natta catalysts.
8. The article of claim 1, wherein the propylene based polymer is formed from a catalyst selected from Ziegler-Natta, metallocene and combinations thereof.
9. The article of claim 1, wherein the article comprises a bottle.
10. A method of forming an injection stretch blow molded (ISBM) article comprising: providing a propylene based polymer comprising a melt flow rate of less than 10 g/10 min.; injection molding the propylene based polymer into a preform; and
stretch-blowing the preform into an article.
11. The process of claim 10, wherein the process comprises an efficiency at a rate of 1000 articles/(hourcavity) of at least about 90%.
12. The process of claim 10, wherein the propylene based polymer is formed from a metallocene catalyst.
13. The process of claim 10, wherein the propylene based polymer further comprises ethylene.
14. An injection stretch blow molded (ISBM) article comprising: a propylene based polymer comprising a melt flow rate of less than 10 g/10 min., wherein the propylene based polymer is formed from a metallocene catalyst and the article is formed in a process experiencing an efficiency of at least about 90%.
15. The article of claim 14, wherein the propylene based polymer further comprises ethylene.
LOW MFR PROPYLENE BASED POLYMERS FOR INJECTION STRETCH BLOW MOLDING
 Embodiments of the present invention generally relate to injection stretch blow molding, including articles made therefrom, hi particular, embodiments of the invention relate to injection stretch blow molding propylene based polymers.
 Historically, polyester terephthalate (PET) has been utilized for the formation of injection stretch blow molding preforms, which are used to form injection stretch blow molded (ISBM) articles, such as liquid containers including bottles and wide mouth jars, for example. Attempts have been made to utilize lower cost materials, such as polypropylene, for the preforms. However, properties of propylene based polymers have generally resulted in preforms exhibiting lower processability than preforms formed by PET, primarily during the reheat, stretch and blowing steps.
 Therefore, a need exists to produce propylene based polymers capable of use in injection stretch blow molding.
 Embodiments of the present invention include injection stretch blow molded
(ISBM) articles, hi one or more embodiments, the articles include a propylene based polymer having a melt flow rate of less than 10 g/10 min.
 hi one or more embodiments, the propylene based polymer is formed from a metallocene catalyst and the article is formed in a process experiencing an efficiency of at least about 90%.
 Embodiments further include methods of forming the injection stretch blow molded (ISBM) articles. The methods generally include providing a propylene based polymer having a melt flow rate of less than 10 g/10 min., injection molding the propylene based polymer into a preform and stretch-blowing the preform into an article.
BRIEF DESCRIPTION OF DRAWINGS
 Figure 1 illustrates the top load properties of bottles formed from various polymer samples.
 Figure 2 illustrates the bumper compression properties of bottles formed from various polymer samples.
 Figure 3 illustrates the haze of bottles formed from various polymer samples.  Figure 4 illustrates the gloss of bottles formed from various polymer samples.
Introduction and Definitions
 A detailed description will now be provided. Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only, hi other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims. Each of the inventions will now be described in greater detail below, including specific embodiments, versions and examples, but the inventions are not limited to these embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the inventions when the information in this patent is combined with available information and technology.
 Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing. Further, unless otherwise specified, all compounds described herein may be substituted or unsubstituted and the listing of compounds includes derivatives thereof.  Various ranges are further recited below. It should be recognized that unless stated otherwise, it is intended that the endpoints are to be interchangeable. Further, any point within that range is contemplated as being disclosed herein.
 As used herein, the term "room temperature" means that a temperature difference of a few degrees does not matter to the phenomenon under investigation, hi some environments, room temperature may include a temperature of from about 2O 0 C to about 28 0 C (68 0 F to 82 0 F), while in other environments, room temperature may include a temperature of from about 50 0 F to about 9O 0 F, for example. However, room temperature measurements generally do not include close monitoring of the temperature of the process and therefore such a recitation does not intend to bind the embodiments described herein to any predetermined temperature range.
 Catalyst systems useful for polymerizing olefin monomers include any catalyst system known to one skilled in the art. For example, the catalyst system may include metallocene catalyst systems, single site catalyst systems, Ziegler-Natta catalyst systems or combinations thereof, for example. As is known in the art, the catalysts may be activated for subsequent polymerization and may or may not be associated with a support material. A brief discussion of such catalyst systems is included below, but is in no way intended to limit the scope of the invention to such catalysts.
 For example, Ziegler-Natta catalyst systems are generally formed from the combination of a metal component (e.g., a catalyst) with one or more additional components, such as a catalyst support, a cocatalyst and/or one or more electron donors, for example.  Metallocene catalysts may be characterized generally as coordination compounds incorporating one or more cyclopentadienyl (Cp) groups (which may be substituted or unsubstituted, each substitution being the same or different) coordinated with a transition metal through π bonding. The substituent groups on Cp may be linear, branched or cyclic hydrocarbyl radicals, for example. The cyclic hydrocarbyl radicals may further form other contiguous ring structures, including indenyl, azulenyl and fluorenyl groups, for example. These contiguous ring structures may also be substituted or unsubstituted by hydrocarbyl radicals, such as C 1 to C 20 hydrocarbyl radicals, for example.
 A specific, non-limiting, example of a metallocene catalyst is a bulky ligand metallocene compound generally represented by the formula:
[L] 1n M[A] n ; wherein L is a bulky ligand, A is a leaving group, M is a transition metal and m and n are such that the total ligand valency corresponds to the transition metal valency. For example m may be from 1 to 4 and n may be from 0 to 3.
 The metal atom "M" of the metallocene catalyst compound, as described throughout the specification and claims, may be selected from Groups 3 through 12 atoms and lanthanide Group atoms, or from Groups 3 through 10 atoms or from Sc, Ti, Zr, Hf, V, Nb, Ta, Mn, Re, Fe, Ru, Os, Co, Rh, Ir and Ni. The oxidation state of the metal atom "M" may range from 0 to +7 or is +1, +2, +3, +4 or +5, for example.
 The bulky ligand generally includes a cyclopentadienyl group (Cp) or a derivative thereof. The Cp ligand(s) form at least one chemical bond with the metal atom M to form the "metallocene catalyst." The Cp ligands are distinct from the leaving groups bound to the
catalyst compound in that they are not as highly susceptible to substitution/abstraction reactions as the leaving groups.
 Cp ligands may include ring(s) or ring system(s) including atoms selected from group 13 to 16 atoms, such as carbon, nitrogen, oxygen, silicon, sulfur, phosphorous, germanium, boron, aluminum and combinations thereof, wherein carbon makes up at least 50% of the ring members. Non-limiting examples of the ring or ring systems include cyclopentadienyl, cyclopentaphenanthreneyl, indenyl, benzindenyl, fluorenyl, tetrahydroindenyl, octahydrofluorenyl, cyclooctatetraenyl, cyclopentacyclododecene, 3,4- benzofluorenyl, 9-phenylfluorenyl, 8-H-cyclopent[a]acenaphthylenyl, 7-H-dibenzofluorenyl, indeno[l,2-9]anthrene, thiophenoindenyl, thiophenofluorenyl, hydrogenated versions thereof (e.g., 4,5,6,7-tetrahydroindenyl or "H 4 Ind"), substituted versions thereof and heterocyclic versions thereof, for example.
 Cp substituent groups may include hydrogen radicals, alkyls (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, fluoromethyl, fiuoroethyl, difluoroethyl, iodopropyl, bromohexyl, benzyl, phenyl, methylphenyl, tert-butylphenyl, chlorobenzyl, dimethylphosphine and methylphenylphosphine), alkenyls (e.g., 3-butenyl, 2-propenyl and 5- hexenyl), alkynyls, cycloalkyls (e.g., cyclopentyl and cyclohexyl), aryls, alkoxys (e.g., methoxy, ethoxy, propoxy and phenoxy), aryloxys, alkylthiols, dialkylamines (e.g., dimethylamine and diphenylamine), alkylamidos, alkoxycarbonyls, aryloxycarbonyls, carbamoyls, alkyl- and dialkyl-carbamoyls, acyloxys, acylaminos, aroylaminos, organometalloid radicals (e.g., dimethylboron), Group 15 and Group 16 radicals (e.g., methylsulfide and ethylsulfide) and combinations thereof, for example. In one embodiment, at least two substituent groups, two adjacent substituent groups in one embodiment, are joined to form a ring structure.
 Each leaving group "A" is independently selected and may include any ionic leaving group, such as halogens (e.g., chloride and fluoride), hydrides, C 1 to C 12 alkyls (e.g., methyl, ethyl, propyl, phenyl, cyclobutyl, cyclohexyl, heptyl, tolyl, trifiuoromethyl, methylphenyl, dimethylphenyl and trimethylphenyl), C 2 to C 12 alkenyls (e.g., C 2 to C 6 fluoroalkenyls), C 6 to C 12 aryls (e.g., C 7 to C 20 alkylaryls), C 1 to C 12 alkoxys (e.g., phenoxy, methyoxy, ethyoxy, propoxy and benzoxy), C 6 to C 16 aryloxys, C 7 to C 18 alkylaryloxys and C 1 to C 12 heteroatom-containing hydrocarbons and substituted derivatives thereof, for example.
 Other non-limiting examples of leaving groups include amines, phosphines, ethers, carboxylates (e.g., C 1 to C 6 alkylcarboxylates, C 6 to C 12 arylcarboxylates and C 7 to C 18
alkylarylcarboxylates), dienes, alkenes, hydrocarbon radicals having from 1 to 20 carbon atoms (e.g., pentafluorophenyl) and combinations thereof, for example. In one embodiment, two or more leaving groups form a part of a fused ring or ring system.  hi a specific embodiment, L and A may be bridged to one another to form a bridged metallocene catalyst. A bridged metallocene catalyst, for example, may be described by the general formula:
XCp A Cp B MA n ; wherein X is a structural bridge, Cp A and Cp B each denote a cyclopentadienyl group or derivatives thereof, each being the same or different and which may be either substituted or unsubstituted, M is a transition metal and A is an alkyl, hydrocarbyl or halogen group and n is an integer between 0 and 4, and either 1 or 2 in a particular embodiment.
 Non-limiting examples of bridging groups "X" include divalent hydrocarbon groups containing at least one Group 13 to 16 atom, such as, but not limited to, at least one of a carbon, oxygen, nitrogen, silicon, aluminum, boron, germanium, tin and combinations thereof; wherein the heteroatom may also be a C 1 to C 12 alkyl or aryl group substituted to satisfy a neutral valency. The bridging group may also contain substituent groups as defined above including halogen radicals and iron. More particular non-limiting examples of bridging group are represented by C 1 to C 6 alkylenes, substituted C 1 to C 6 alkylenes, oxygen, sulfur, R 2 C=, R 2 Si=, -Si(R) 2 Si(R 2 )--, R 2 Ge= or RP= (wherein "=" represents two chemical bonds), where R is independently selected from hydrides, hydrocarbyls, halocarbyls, hydrocarbyl-substituted organometalloids, halocarbyl-substituted organometalloids, disubstituted boron atoms, disubstituted Group 15 atoms, substituted Group 16 atoms and halogen radicals, for example, hi one embodiment, the bridged metallocene catalyst component has two or more bridging groups.
 Other non-limiting examples of bridging groups include methylene, ethylene, ethylidene, propylidene, isopropylidene, diphenylmethylene, 1,2-dimethylethylene, 1,2- diphenylethylene, 1,1,2,2-tetramethylethylene, dimethylsilyl, diethylsilyl, methyl-ethylsilyl, trifluoromethylbutylsilyl, bis(trifluoromethyl)silyl, di(n-butyl)silyl, di(n-propyl)silyl, di(i- propyl)silyl, di(n-hexyl)silyl, dicyclohexylsilyl, diphenylsilyl, cyclohexylphenylsilyl, t- butylcyclohexylsilyl, di(t-butylphenyl)silyl, di(p-tolyl)silyl and the corresponding moieties, wherein the Si atom is replaced by a Ge or a C atom; dimethylsilyl, diethylsilyl, dimethylgermyl and/or diethylgermyl.
 In another embodiment, the bridging group may also be cyclic and include 4 to 10 ring members or 5 to 7 ring members, for example. The ring members may be selected from the elements mentioned above and/or from one or more of boron, carbon, silicon, germanium, nitrogen and oxygen, for example. Non-limiting examples of ring structures which may be present as or part of the bridging moiety are cyclobutylidene, cyclop entylidene, cyclohexylidene, cycloheptylidene, cyclooctylidene, for example. The cyclic bridging groups may be saturated or unsaturated and/or carry one or more substituents and/or be fused to one or more other ring structures. The one or more Cp groups which the above cyclic bridging moieties may optionally be fused to may be saturated or unsaturated. Moreover, these ring structures may themselves be fused, such as, for example, in the case of a naphthyl group.  In one embodiment, the metallocene catalyst includes CpFIu Type catalysts (e.g., a metallocene catalyst wherein the ligand includes a Cp fluorenyl ligand structure) represented by the following formula:
X(CpR 1 X1 R 2 ^(FlR 3 P ); wherein Cp is a cyclopentadienyl group or derivatives thereof, Fl is a fluorenyl group, X is a
1 • 9 structural bridge between Cp and Fl, R is an optional substituent on the Cp, n is 1 or 2, R is an optional substituent on the Cp bound to a carbon immediately adjacent to the ipso carbon, m is 1 or 2 and each R 3 is optional, may be the same or different and may be selected from C 1 to C 20 hydrocarbyls. In one embodiment, p is selected from 2 or 4. In one embodiment, at least one R 3 is substituted in either the 2 or 7 position on the fluorenyl group and at least one other R 3 being substituted at an opposed 2 or 7 position on the fluorenyl group.  In yet another aspect, the metallocene catalyst includes bridged mono-ligand metallocene compounds (e.g., mono cyclopentadienyl catalyst components). In this embodiment, the metallocene catalyst is a bridged "half-sandwich" metallocene catalyst, m yet another aspect of the invention, the at least one metallocene catalyst component is an unbridged "half sandwich" metallocene. (See, U.S. Pat. No. 6,069,213, U.S. Pat. No. 5,026,798, U.S. Pat. No. 5,703,187, U.S. Pat. No. 5,747,406, U.S. Pat. No. 5,026,798 and U.S. Pat. No. 6,069,213, which are incorporated by reference herein.)
 Non-limiting examples of metallocene catalyst components consistent with the description herein include, for example cyclopentadienylzirconiumA n ; indenylzirconiumA n ; (l-methylindenyl)zirconiumA n ; (2-methylindenyl)zirconiumA n , (1- propylindenyl)zirconiumA n ; (2-propylindenyl)zirconiumA n ; (1 -butylindenyl)zirconiumA n ; (2-butylindenyl)zirconiumA n ; methylcyclopentadienylzirconiumA,,; tetrahydroindenylzirconiumA n ; pentamethylcyclopentadienylzirconiuniA n ;
cyclopentadienylzirconiumA n ; pentamethylcyclopentadienyltitaniumA n ; tetramethylcyclopentyltitaniumA n ; (l,2,4-trimethylcyclopentadienyl)zirconiumAn; dimethylsilyl(l,2,3,4-tetramethylcyclopentadienyl)(cyclopent adienyl)zirconmmA n ; dimethylsilyl(l ,2,3,4-tetramethylcyclopentadienyl)(l ,2,3- trimethylcyclopentadienyl)zirconiumA n ; dimethylsilyl(l ,2,3,4- tetramethylcyclopentadienyl)(l,2-dimethylcyclopentadienyl)zi rconiumA n ; dimethylsilyl(l,2,3,4-tetramethylcyclopentadienyl)(2-methylc yclopentadienyl)zirconiumA n ; dimethylsilylcyclopentadienylindenylzirconiumA n ; dimethylsilyl(2- methylindenyl)(fluorenyl)zirconiumA n ; diphenylsilyl(l,2,3,4-tetramethylcyclopentadienyl)(3- propylcyclopentadienyl)zirconiumA n ; dimethylsilyl (1,2,3,4-tetramethylcyclopentadienyl) (3- t-butylcyclopentadienyl)zirconmmA n ; dimethylgermyl(l,2-dimetliylcyclopentadienyl)(3- isopropylcyclopentadienyl)zirconiumA n ; dimethylsilyl(l,2,3,4- tetramethylcyclopentadienyl)(3-methylcyclopentadienyl)zircon iumA n ; diphenylmethylidene(cyclopentadienyl)(9-fluorenyl)zirconiumA n ; diphenylmethylidenecyclopentadienylindenylzirconmniA n ; isopropylidenebiscyclopentadienylzirconiuniA n ; isopropylidene(cyclopentadienyl)(9- fluorenyl)zirconiumA n ; isopropylidene(3-methylcyclopentadienyl)(9-fluorenyl)zirconi uniA n ; ethylenebis(9-fluorenyl)zirconiumA n ; ethylenebis(l -indenyl)zirconiumA n ; ethylenebis( 1 - indenyl)zirconiumA n ; ethylenebis(2 -methyl- 1 -indenyl)zirconiumA n ; ethylenebis(2-methyl- 4,5,6,7-tetrahydro-l-indenyl)zirconiumA n ; ethylenebis(2-propyl-4,5,6,7-tetrahydro-l- indenyl)zirconiumA n ; ethylenebis(2-isopropyl-4,5,6,7-tetrahydro-l-indenyl)zirconi umA n ; ethylenebis(2-butyl-4,5,6,7-tetrahydro- 1 -indenyl)zirconiumA n ; ethylenebis(2-isobutyl-
4,5,6,7-tetrahydro-l-indenyl)zirconiumA n ; dimethylsilyl(4,5,6,7-tetrahydro-l- indenyl)zirconiumA n ; diphenyl(4,5,6,7-tetrahydro-l-indenyl)zirconiumA n ; ethylenebis(4,5,6,7-tetrahydro- 1 -indenyl)zirconiumA n ; dimethylsilylbis(cyclopentadienyl)zirconiumA n ; dimethylsilylbis(9-fluorenyl)zirconiuniA n ; dimethylsilylbis(l-indenyl)zirconmmA n ; dimethylsilylbis(2-methylindenyl)zirconiumA n ; dimethylsilylbis(2-propylindenyl)zirconiumA n ; dimethylsilylbis(2-butylindenyl)zirconiumA n ; diphenylsilylbis(2-methylindenyl)zirconiumA n ; diphenylsilylbis(2- propylindenyl)zirconiumA n ; diphenylsilylbis(2-butylindenyl)zirconiumA n ; dimethylgeπnylbis(2-methylindenyl)zirconiuniA n ; dimethylsilylbistetrahydroindenylzirconiumA n ; dimethylsilylbistetramethylcyclopentadienylzirconmmA n ; dimethylsilyl(cyclopentadienyl)(9- fluorenyl)zirconiuniA n ; diphenylsilyl(cyclopentadienyl)(9-fluorenyl)zirconiumA n ;
diphenylsilylbismdenylzirconmmA n ; cyclotrimethylenesilyltetramethylcyclopentadienylcyclopentad ienylzirconiumA n ; cyclotetramethylenesilyltetramethylcyclopentadienylcyclopent adienylzirconiumA n ; cyclotrimethylenesilyl(tetramethylcyclopentadienyl)(2-nietli ylmdenyl)zirconmmA n ; cyclotrimethylenesilyl(tetramethylcyclopentadienyl)(3-methyl cyclopentadienyl)zirconiuniA n ; cyclotrimethylenesilylbis(2-niethylindenyl)zirconiumA n ; cyclotrimethylenesilyl(tetramethylcyclopentadienyl)(2,3,5- trimethylclopentadienyl)zirconiumA n ; cyclotrimethylenesilylbis(tetrametliylcyclopentadienyl)zirco niumA n ; dimethylsilyl(tetrametliylcyclopentadieneyl)(N-tertbutylamid o)titaniumA n ; biscyclopentadienylchromiumA n ; biscyclopentadienylzirconiumA n ; bis(n- butylcyclopentadienyl)zirconiumA n ; bis(n-dodecyclcyclopentadienyl)zirconiumA n ; bisethylcyclopentadienylzirconiumAn; bisisobutylcyclopentadienylzirconmmA n ; bisisopropylcyclopentadienylzirconiumA n ; bismethylcyclopentadienylzirconiumA n ; bisoctylcyclopentadienylzirconiumA n ; bis(n-pentylcyclopentadienyl)zirconiumA n ; bis(n- propylcyclopentadieny^zirconiumA n ; bistriniethylsilylcyclopentadienylzirconiuniA n ; bis(l,3- bis(trimethylsilyl)cyclopentadienyl)zirconiumA n ; bis(l-ethyl-2- methylcyclopentadienyl)zirconiumA n ; bis(l-ethyl-3-methylcyclopentadienyl)zirconiumA n ; bispentaniethylcyclopentadienylzirconiumA n ; bispentamethylcyclopentadienylzirconmmA n ; bis(l-propyl-3-methylcyclopentadienyl)zirconiumA n ; bis(l-n-butyl-3- methylcyclopentadienyl)zirconiumA n ; bis(l -isobutyl-3 - methylcyclopentadienytyzirconiumA n ; bis(l-propyl-3-butylcyclopentadienyl)zirconmmA n ; bis(l,3-n-butylcyclopentadienyl)zirconiumA n ; bis(4,7-dimethylindenyl)zirconiumA n ; bisindenylzirconiumA n ; bis(2-methylindenyl)zirconiumA n ; cyclopentadienylindenylzirconiumA n ; bis(n-propylcyclopentadienyl)hafhiumA n ; bis(n- butylcyclopentadienyl)hafniumA n ; bis(n-pentylcyclopentadienyl)hafhiumA n ; (n- propylcyclopentadienyl)(n-butylcyclopentadienyl)hafhiumA n ; bis[(2- trimethylsilylethyl)cyclopentadienyl]hafiiiumA n ; bis(trimethylsilylcyclopentadienyl)hafhmmA n ; bis(2-n-propylindenyl)hafniumA n ; bis(2-n- butylindenyl)hafhiumA n ; dimethylsilylbis(n-propylcyclopentadienyl)hafhiumA n ; dimethylsilylbis(n-butylcyclopentadienyl)hafiiiumA n ; bis(9-n-propylfluorenyl)hafhiumA n ; bis(9-n-butylfluorenyl)hafiiiumA n ; (9-n-propylfluorenyl)(2-n-propylindenyl)haMumA n ; bis(l-n-propyl-2-methylcyclopentadienyl)hafhiumA n ; (n-propylcyclopentadienyl)(l-n- propyl-3-n-butylcyclopentadienyl)hafhiumA n ;
dimethylsilyltetramethylcyclopentadienylcyclopropylamidotita niumA n ; dimethylsilyltetramethyleyclopentadienylcyclobutylamidotitan iuniA n ; dimethylsilyltetramethyleyclopentadienylcyclopentylamidotita niuniA n ; dimethylsilyltetramethylcyclopentadienylcyclohexylamidotitan iumA n ; dimethylsilyltetramethylcyclopentadienylcycloheptylamidotita niumA n ; dimethylsilyltetramethylcyclopentadienylcyclooctylamidotitan iumA n ; dimethylsilyltetrametliylcyclopentadienylcyclononylamidotita niuniA n ; dimethylsilyltetramethylcyclopentadienylcyclodecylamidotitan iumA n ; dimethylsilyltetramethylcyclopentadienylcycloundecylamidotit aniumA n ; dimethylsilyltetraniethylcyclopentadienylcyclododecylamidoti taniumA n ; dimethylsilyltetramethylcyclopentadienyl(sec-butylamido)tita niumA n ; dimethylsilyl(tetramethylcyclopentadienyl)(n-octylamido)tita niumA n ; dimethylsilyl(tetramethylcyclopentadienyl)(n-decylamido)tita niumA n ; dimethylsilyl(tetramethylcyclopentadienyl)(n-octadecylamido) titaniumA n ; dimethylsilylbis(cyclopentadienyl)zirconiumA n ; dimetliylsilylbis^etramethylcyclopentadieny^zirconiumA n ; dimethylsilylbis^ethylcyclopentadieny^zirconiumA n ; dimethylsilylbis(dimethylcyclopentadienyl)zirconiumA n ; dimethylsilyl(2,4- dimethylcyclopentadienyl) (S'^'-diniethylcyclopentadieny^zirconiumA n ; dimethylsilyl(2,3,5- trimethylcyclopentadienyl)(2',4',5'-dimethylcyclopentadienyl )zirconiumA n ; dimetliylsilylbis^-butylcyclopentadieny^zirconiumA n ; dimethylsilylbis^rimethylsilylcyclopentadieny^zirconiumA n ; dimethylsilylbis(2- trimethylsilyl-4-t-butylcyclopentadienyl)zirconiumA n ; dimethylsilylbis(4,5,6,7-tetrahydro- indenyl)zirconiuniA n ; dimethylsilylbis(indenyl)zirconiumA n ; dimethylsilylbis(2- methylindenyl)zirconiumA n ; dimethylsilylbis(2,4-dimetliylindenyl)zirconmmA n ; dimethylsilylbis(2,4,7-trimethylindenyl)zirconiumA n ; dimethylsilylbis(2-methyl-4- phenylindenyl)zirconiumA n ; dimethylsilylbis(2-ethyl-4-phenylindenyl)zirconiumA n ; dimethylsilylbis(benz[e]indenyl)zirconiumA n ; dimethylsilylbis(2- methylbenz[e]indenyl)zirconiumA n ; dimethylsilylbis(benz[f]indenyl)zirconiumA n ; dimethylsilylbis(2-metliylbenz[flindenyl)zirconiumA n ; dimethylsilylbis(3- methylbenz[f]indenyl)zirconiumA n ; dimethylsilylbis(cyclopenta[cd]indenyl)zirconiumA n ; dimethylsilylbis(cyclopentadienyl)zirconiuniA n ; diniethylsilylbis^etrametliylcyclopentadieny^zirconiumA n ; dimethylsilylbis^ethylcyclopentadieny^zirconiumA n ;
dimethylsilylbis(dimethylcyclopentadienyl)zirconiumA n ; isopropylidene(cyclopentadienyl- fluorenyl)zirconiumA n ; isopropylidene(cyclopentadienyl-indenyl)zirconiumA n ; isopropylidene^yclopentadienyl-ljT-di-t-butylfluoreny^zircon iumA n ; isopropylidene(cyclopentadienyl-3-methylfluorenyl)zirconiumA n ; isoropylidene(cyclopentadienyl-4-methylfluorenyl)zirconiumA n ; isopropylidene(cyclopentadienyl-octahydrofluorenyl)zirconium A n ; isopropylidenefmethylcyclopentadienyl- fluorenyl)zirconiuniA n ; isopropylidene(dimethylcyclopentadienylfluorenyl)zirconiumA n ; isopropylidene^etramethylcyclopentadienyl-fluoreny^zirconium A n ; diphenylmethylene(cyclopentadienyl-fluorenyl)zirconiumA n ; diphenylmethylene(cyclopentadienyl-indenyl)zirconiumA n ; diphenylmethylene(cyclopentadienyl-2,7-di-t-butylfluorenyl)z irconiumA n ; diphenylmetb.ylene(cyclopentadienyl-3-methylfluorenyl)zircon iumA n ; diphenylmethylene(cyclopentadienyl-4-methylfluorenyl)zirconi umA n ; diphenylmethylene^yclopentadienyloctahydrofluoreny^zirconium A n ; diphenylmethylene^ethylcyclopentadienyl-fluoreny^zirconiuniA n ; diphenylmethylene(dimetliylcyclopentadienyl-fluorenyl)zircon iumA n ; diphenylmethylene^etramethylcyclopentadienyl-fluoreny^zircon iuniA n ; cyclohexylidene(cyclopentadienyl-fluorenyl)zirconiumA n ; cyclohexylidene(cyclopentadienylindenyl)zirconiumA n ; cyclohexylidene(cyclopentadienyl-
2,7-di-t-butylfluorenyl)zirconiumA n ; cyclohexylidene(cyclopentadienyl-3- methylfluorenyl)zirconiumA n ; cyclohexylidene(cyclopentadienyl-4- methylfluorenyl)zirconiumA n ; cyclohexylidene(cyclopentadienyloctahydrofluorenyl)zirconium A n ; cyclohexylidene(methylcyclopentadienylfluorenyl)zirconmmA n ; cyclohexylidene(diniethylcyclopentadienyl-fluorenyl)zirconiu mA n ; cyclohexylidene(tetramethylcyclopentadienylfluorenyl)zirconi umA n ; dimethylsily^cyclopentadienyl-fluoreny^zirconiumA n ; dimethylsilyl(cyclopentadienyl- indenyl)zirconiumA n ; dimethylsilyl(cyclopentdienyl-2,7-di-t-butylfluorenyl)zircon iumA n ; dimethylsily^cyclopentadienyl-S-methylfluoreny^zirconiumA n ; dimethylsilyl(cyclopentadienyl-4-methylfluorenyl)zirconiumA n ; dimethylsilyl(cyclopentadienyl-octahydrofluorenyl)zirconiumA n ; dimethylsily^niethylcyclopentanedienyl-fluoreny^zirconiumA n ; diniethylsily^dimethylcyclopentadienylfluoreny^zirconiumA n ;
dimethylsilyl^etramethylcyclopentadienylfluoreny^zirconiuniA n ; isopropylidene(cyclopentadienyl-fluorenyl)zirconiumA n ; isopropylidene(cyclopentadienyl- indenyl)zirconiumA n ; isopropylidene(cyclopentadienyl-2,7-di-t-butylfluorenyl)zirc oniumA n ; cyclohexylidene(cyclopentadienylfluorenyl)zirconiumA n ; cyclohexylidene(cyclopentadienyl-
2,7-di-t-butylfluorenyl)zirconiumA n ; dimethylsily^cyclopentadienylfluoreny^zirconiumA n ; methylphenylsilyltetramethylcyclopentadienylcyclopropylamido titaniumA n ; methylphenylsilyltetramethylcyclopentadienylcyclobutylamidot itaniumA n ; methylphenylsilyltetramethylcyclopentadienylcyclopentylamido titaniumA n ; methylphenylsilyltetrametb.ylcyclopentadienylcyclohexylamido titaniumA n ; methylplienylsilyltetramethylcyclopentadienylcycloheptylanii dotitanmmA n ; methylplienylsilyltetrametliylcyclopentadienylcyclooctylamid otitaniumA n ; methylphenylsilyltetramethylcyclopentadienylcyclononylamidot itaniuniA n ; methylphenylsilyltetrametliylcyclopentadienylcyclodecylamido titaniumA n ; methylphenylsilyltetramethylcyclopentadienylcycloundecylamid otitaniumA n ; methylphenylsilyltetramethylcyclopentadienylcyclododecylamid otitaniumA n ; methylphenylsilyl(tetramethylcyclopentadienyl)(sec-butylamid o)titaniumA n ; methylphenylsilyl(tetraniethylcyclopentadienyl)(n-octylamido )titaniumA n ; niethylphenylsilyl(tetramethylcyclopentadienyl)(n-decylamido )titaniumA n ; methylphenylsilyl(tetramethylcyclopentadienyl)(n-octadecylam ido)titaniumA n ; diphenylsilyltetramethylcyclopentadienylcyclopropylamidotita niumA n ; diphenylsilyltetramethylcyclopentadienylcyclobutylamidotitan iumA n ; diphenylsilyltetramethylcyclopentadienylcyclopentylamidotita niuniA n ; diphenylsilyltetramethylcyclopentadienylcyclohexylamidotitan iumA n ; diphenylsilyltetramethylcyclopentadienylcycloheptylamidotita niuniA n ; diphenylsilyltetramethylcyclopentadienylcyclooctylamidotitan iumA n ; diphenylsilyltetramethylcyclopentadienylcyclononylamidotitan iumA n ; diphenylsilyltetramethylcyclopentadienylcyclodecylamidotitan iumA n ; diphenylsilyltetramethylcyclopentadienylcycloundecylamidotit aniumA n ; diphenylsilyltetramethylcyclopentadienylcyclododecylamidotit aniumA n ; diphenylsilyl(tetramethylcyclopentadienyl)(sec-butylamido)ti taniumA n ; diphenylsilyl(tetramethylcyclopentadienyl)(n-octylamido)tita nmmA n ; diphenylsilyl^etramethylcyclopentadieny^^-decylamido^itaniun iA n ; and diphenylsilyl(tetramethylcyclopentadienyl)(n-octadecylamido) titaniumA n .
 The metallocene catalysts may be activated with a metallocene activator for subsequent polymerization. As used herein, the term "metallocene activator" is defined to be any compound or combination of compounds, supported or unsupported, which may activate a single-site catalyst compound (e.g., metallocenes, Group 15 containing catalysts, etc.) This may involve the abstraction of at least one leaving group (A group in the formulas/structures above, for example) from the metal center of the catalyst component. The metallocene catalysts are thus activated towards olefin polymerization using such activators.  Embodiments of such activators include Lewis acids, such as cyclic or oligomeric polyhydrocarbylaluminum oxides, non-coordinating ionic activators (NCA), ionizing activators, stoichiometric activators, combinations thereof or any other compound that may convert a neutral metallocene catalyst component to a metallocene cation that is active with respect to olefin polymerization.
 The Lewis acids may include alumoxane (e.g., "MAO"), modified alumoxane (e.g., "TIBAO") and alkylaluminum compounds, for example. Non-limiting examples of aluminum alkyl compounds may include trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum and tri-n-octylaluminum, for example.  Ionizing activators are well known in the art and are described by, for example, Eugene You-Xian Chen & Tobin J. Marks, Cocatalysts for Metal-Catalyzed Olefin Polymerization: Activators, Activation Processes, and Structure-Activity Relationships 100(4) CHEMICAL REVIEWS 1391-1434 (2000). Examples of neutral ionizing activators include Group 13 tri-substituted compounds, in particular, tri-substituted boron, tellurium, aluminum, gallium and indium compounds and mixtures thereof (e.g., trisperfluorophenyl boron metalloid precursors), for example. The substituent groups may be independently selected from alkyls, alkenyls, halogen, substituted alkyls, aryls, arylhalides, alkoxy and halides, for example. In one embodiment, the three groups are independently selected from halogens, mono or multicyclic (including halosubstituted) aryls, alkyls, alkenyl compounds and mixtures thereof, for example, hi another embodiment, the three groups are selected from C 1 to C 20 alkenyls, C 1 to C 20 alkyls, C 1 to C 20 alkoxys, C 3 to C 2 o aryls and combinations thereof, for example. In yet another embodiment, the three groups are selected from the group highly halogenated C 1 to C 4 alkyls, highly halogenated phenyls, and highly halogenated naphthyls and mixtures thereof, for example. By "highly halogenated", it is meant that at least 50% of the hydrogens are replaced by a halogen group selected from fluorine, chlorine and bromine.
 Illustrative, not limiting examples of ionic ionizing activators include trialkyl- substituted ammonium salts (e.g., triethylarnmoniumtetraphenylborate, tripropylammoniumtetraphenylborate, tri(n-butyl)ammoniumtetraphenylborate, trimethylammoniumtetra(p-tolyl)borate, trimethylammoniumtetra(o-tolyl)borate, tributylammoniumtetra(pentafluorophenyl)borate, tripropylammoniumtetra(o,p- dimethylphenyl)borate, tributylammoniumtetra(m,m-dimethylplienyl)borate, tributylammoniumtetra(p-tri-fluorometb.ylphenyl)borate, tributylammoniumtetra(pentafluorophenyl)borate and tri(n-butyl)ammoniumtetra(o- tolyl)borate), N,N-dialkylanilinium salts (e.g., N,N-dimethylaniliniumtetraphenylborate, N,N-diethylaniliniumtetraphenylborate and N,N-2,4,6- pentamethylaniliniumtetraphenylborate), dialkyl ammonium salts (e.g., diisopropylammoniumtetrapentafluorophenylborate and dicyclohexylammoniumtetraphenylborate), triaryl phosphonium salts (e.g., triphenylphosphomumtetraphenylborate, trimethylphenylphosphoniumtetraphenylborate and tridimethylphenylphosphoniumtetraphenylborate) and their aluminum equivalents, for example.
 In yet another embodiment, an alkylaluminum compound may be used in conjunction with a heterocyclic compound. The ring of the heterocyclic compound may include at least one nitrogen, oxygen, and/or sulfur atom, and includes at least one nitrogen atom in one embodiment. The heterocyclic compound includes 4 or more ring members in one embodiment, and 5 or more ring members in another embodiment, for example.  The heterocyclic compound for use as an activator with an alkylaluminum compound may be unsubstituted or substituted with one or a combination of substituent groups. Examples of suitable substituents include halogens, alkyls, alkenyls or alkynyl radicals, cycloalkyl radicals, aryl radicals, aryl substituted alkyl radicals, acyl radicals, aroyl radicals, alkoxy radicals, aryloxy radicals, alkylthio radicals, dialkylamino radicals, alkoxycarbonyl radicals, aryloxycarbonyl radicals, carbomoyl radicals, alkyl- or dialkyl- carbamoyl radicals, acyloxy radicals, acylamino radicals, aroylamino radicals, straight, branched or cyclic, alkylene radicals or any combination thereof, for example.  Non-limiting examples of hydrocarbon substituents include methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopentyl, cyclohexyl, benzyl, phenyl, fluoromethyl, fluoroethyl, difluoroethyl, iodopropyl, bromohexyl or chlorobenzyl, for example.
 Non-limiting examples of heterocyclic compounds utilized include substituted and unsubstituted pyrroles, imidazoles, pyrazoles, pyrrolines, pyrrolidines, purines, carbazoles,
indoles, phenyl indoles, 2,5-dimethylpyrroles, 3-pentafluorophenylpyrrole, 4,5,6,7- tetrafluoroindole or 3,4-difluoropyrroles, for example.
 Combinations of activators are also contemplated by the invention, for example, alumoxanes and ionizing activators in combinations. Other activators include aluminum/boron complexes, perchlorates, periodates and iodates including their hydrates, lithium (2,2'-bisphenyl-ditrimethylsilicate)-4T- HF and silylium salts in combination with a non-coordinating compatible anion, for example, hi addition to the compounds listed above, methods of activation, such as using radiation and electro-chemical oxidation are also contemplated as activating methods for the purposes of enhancing the activity and/or productivity of a single-site catalyst compound, for example. (See, U.S. Pat. No. 5,849,852,
U.S. Pat. No. 5,859,653, U.S. Pat. No. 5,869,723 and WO 98/32775.)
 The catalyst may be activated in any manner known to one skilled in the art. For example, the catalyst and activator may be combined in molar ratios of activator to catalyst of from 1000:1 to 0.1:1, or from 500:1 to 1:1, or from about 100:1 to about 250:1, or from 150:1 to 1:1, or from 50:1 to 1:1, or from 10:1 to 0.5:1 or from 3:1 to 0.3:1, for example.
 The activators may or may not be associated with or bound to a support, either in association with the catalyst (e.g., metallocene) or separate from the catalyst component, such as described by Gregory G. Hlatky, Heterogeneous Single-Site Catalysts for Olefin
Polymerization 100(4) CHEMICAL REVIEWS 1347-1374 (2000).
 Metallocene Catalysts may be supported or unsupported. Typical support materials may include talc, inorganic oxides, clays and clay minerals, ion-exchanged layered compounds, diatomaceous earth compounds, zeolites or a resinous support material, such as a polyolefm, for example.
 Specific inorganic oxides include silica, alumina, magnesia, titania and zirconia, for example. The inorganic oxides used as support materials may have an average particle size of from 5 microns to 600 microns or from 10 microns to 100 microns, a surface area of from 50 ni 2 /g to 1,000 m 2 /g or from 100 m 2 /g to 400 m 2 /g and a pore volume of from 0.5cc/g to 3.5 cc/g or from 0.5 cc/g to 2.5 cc/g, for example.
 Methods for supporting metallocene catalysts are generally known in the art.
(See, U.S. Patent No. 5,643,847, which is incorporated by reference herein.)
 Optionally, the support material, the catalyst component, the catalyst system or combinations thereof, may be contacted with one or more scavenging compounds prior to or during polymerization. The term "scavenging compounds" is meant to include those compounds effective for removing impurities (e.g., polar impurities) from the subsequent
polymerization reaction environment. Impurities may be inadvertently introduced with any of the polymerization reaction components, particularly with solvent, monomer and catalyst feed, and adversely affect catalyst activity and stability. Such impurities may result in decreasing, or even elimination, of catalytic activity, for example. The polar impurities or catalyst poisons may include water, oxygen and metal impurities, for example.  The scavenging compound may include an excess of the aluminum containing compounds described above, or may be additional known organometallic compounds, such as Group 13 organometallic compounds. For example, the scavenging compounds may include triethyl aluminum (TMA), triisobutyl aluminum (TIBAl), methylalumoxane (MAO), isobutyl aluminoxane and tri-n-octyl aluminum. In one specific embodiment, the scavenging compound is TIBAl.
 In one embodiment, the amount of scavenging compound is minimized during polymerization to that amount effective to enhance activity and avoided altogether if the feeds and polymerization medium may be sufficiently free of impurities.  While use of any catalyst known to one skilled in the art is contemplated for use in this invention, including Ziegler-Natta and metallocene catalysts, it has been observed that articles (discussed in further detail below) formed with metallocene catalysts via the embodiments of the invention exhibit greater clarity, haze (e.g., optical properties) and stiffness as compared to articles formed with Ziegler-Natta catalysts.
 As indicated elsewhere herein, catalyst systems are used to form polyolefin compositions. Once the catalyst system is prepared, as described above and/or as known to one skilled in the art, a variety of processes may be carried out using that composition. The equipment, process conditions, reactants, additives and other materials used in polymerization processes will vary in a given process, depending on the desired composition and properties of the polymer being formed. Such processes may include solution phase, gas phase, slurry phase, bulk phase, high pressure processes or combinations thereof, for example. (See, U.S. Patent No. 5,525,678; U.S. Patent No. 6,420,580; U.S. Patent No. 6,380,328; U.S. Patent No. 6,359,072; U.S. Patent No. 6,346,586; U.S. Patent No. 6,340,730; U.S. Patent No. 6,339,134; U.S. Patent No. 6,300,436; U.S. Patent No. 6,274,684; U.S. Patent No. 6,271,323; U.S. Patent No. 6,248,845; U.S. Patent No. 6,245,868; U.S. Patent No. 6,245,705; U.S. Patent No. 6,242,545; U.S. Patent No. 6,211,105; U.S. Patent No. 6,207,606;
U.S. Patent No. 6,180,735 and U.S. Patent No. 6,147,173, which are incorporated by reference herein.)
 In certain embodiments, the processes described above generally include polymerizing one or more olefin monomers to form polymers. The olefin monomers may include C 2 to C 30 olefin monomers, or C 2 to C 12 olefin monomers (e.g., ethylene, propylene, butene, pentene, methylpentene, hexene, octene and decene), for example. The monomers may include olefmic unsaturated monomers, C 4 to C 18 diolefϊns, conjugated or nonconjugated dienes, polyenes, vinyl monomers and cyclic olefins, for example. Non-limiting examples of other monomers may include norbornene, nobornadiene, isobutylene, isoprene, vinylbenzocyclobutane, sytrene, alkyl substituted styrene, ethylidene norbornene, dicyclopentadiene and cyclopentene, for example. The formed polymer may include homopolymers, copolymers or terpolymers, for example.
 Examples of solution processes are described in U.S. Patent No. 4,271,060, U.S. Patent No. 5,001,205, U.S. Patent No. 5,236,998 and U.S. Patent No. 5,589,555, which are incorporated by reference herein.
 One example of a gas phase polymerization process includes a continuous cycle system, wherein a cycling gas stream (otherwise known as a recycle stream or fluidizing medium) is heated in a reactor by heat of polymerization. The heat is removed from the cycling gas stream in another part of the cycle by a cooling system external to the reactor. The cycling gas stream containing one or more monomers may be continuously cycled through a fluidized bed in the presence of a catalyst under reactive conditions. The cycling gas stream is generally withdrawn from the fluidized bed and recycled back into the reactor. Simultaneously, polymer product may be withdrawn from the reactor and fresh monomer may be added to replace the polymerized monomer. The reactor pressure in a gas phase process may vary from about 100 psig to about 500 psig, or from about 200 psig to about 400 psig or from about 250 psig to about 350 psig, for example. The reactor temperature in a gas phase process may vary from about 30°C to about 12O 0 C, or from about 60 0 C to about 115 0 C, or from about 7O 0 C to about HO 0 C or from about 70 0 C to about 95 0 C, for example. (See, for example, U.S. Patent No. 4,543,399; U.S. Patent No. 4,588,790; U.S. Patent No. 5,028,670; U.S. Patent No. 5,317,036; U.S. Patent No. 5,352,749; U.S. Patent No. 5,405,922; U.S. Patent No. 5,436,304; U.S. Patent No. 5,456,471; U.S. Patent No. 5,462,999; U.S. Patent No. 5,616,661; U.S. Patent No. 5,627,242; U.S. Patent No. 5,665,818; U.S. Patent No. 5,677,375 and U.S. Patent No. 5,668,228, which are incorporated by reference herein.)
 Slurry phase processes generally include forming a suspension of solid, particulate polymer in a liquid polymerization medium, to which monomers and optionally hydrogen, along with catalyst, are added. The suspension (which may include diluents) may be intermittently or continuously removed from the reactor where the volatile components can be separated from the polymer and recycled, optionally after a distillation, to the reactor. The liquefied diluent employed in the polymerization medium may include a C 3 to C 7 alkane (e.g., hexane or isobutane), for example. The medium employed is generally liquid under the conditions of polymerization and relatively inert. A bulk phase process is similar to that of a slurry process with the exception that the liquid medium is also the reactant (e.g., monomer) in a bulk phase process. However, a process may be a bulk process, a slurry process or a bulk slurry process, for example.
 In a specific embodiment, a slurry process or a bulk process may be carried out continuously in one or more loop reactors. The catalyst, as slurry or as a dry free flowing powder, may be injected regularly to the reactor loop, which can itself be filled with circulating slurry of growing polymer particles in a diluent, for example. Optionally, hydrogen may be added to the process, such as for molecular weight control of the resultant polymer. The loop reactor may be maintained at a pressure of from about 27 bar to about 50 bar or from about 35 bar to about 45 bar and a temperature of from about 38°C to about 121 0 C, for example. Reaction heat may be removed through the loop wall via any method known to one skilled in the art, such as via a double-jacketed pipe or heat exchanger, for example.
 Alternatively, other types of polymerization processes may be used, such as stirred reactors in series, parallel or combinations thereof, for example. Upon removal from the reactor, the polymer may be passed to a polymer recovery system for further processing, such as addition of additives and/or extrusion, for example.
 The polymers (and blends thereof) formed via the processes described herein may include, but are not limited to, polypropylene and polypropylene copolymers, for example.  In one or more embodiments, the polypropylene and polypropylene copolymers include propylene based polymers. Unless otherwise specified, the term "propylene based" refers to polymers whose primary component is propylene (e.g., at least about 50 wt.%, or at least about 75 wt.%, or at about least 80 wt.% or at least about 89 wt.%).
 In one or more embodiments, the polypropylene and polypropylene copolymers include propylene based random copolymers (used interchangeably herein with the term "random copolymer"). Unless otherwise specified, the term "propylene based random copolymer" refers to those copolymers composed primarily of propylene and an amount of other comonomers, wherein the comonomers make up at least about 0.5 wt.%, or at least about 0.8 wt.% or at least about 2 wt.% by weight of polymer, for example. The comonomers may be selected from C 2 to C 10 alkenes. For example, the comonomers may be selected from ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1- nonene, 1-decene, 4-methyl- 1-pentene and combinations thereof. In one specific embodiment, the comonomer includes ethylene.
 In one or more embodiments, the polypropylene includes propylene homopolymers. Unless otherwise specified, the term "propylene homopolymers" refers to those polymers composed primarily of propylene and limited amounts of other comonomers, such as ethylene, wherein the comonomer make up less than about 2 wt.% (e.g., mini random copolymers), or less than about 0.5 wt.% or less than about 0.1 wt.% by weight of polymer.  It is to be noted that although the ranges of random copolymers and homopolymers may overlap, whether the compound is a random copolymer or a homopolymer will be clear from the context of its use.
 Unless otherwise designated herein, all testing methods are the current methods at the time of filing.
 Prior attempts to form injection stretch blow molding (ISBM) articles from polypropylene have generally included forming ISBM preforms from polypropylene exhibiting a melt flow rate of greater than 10 g/10 min. (e.g., high melt flow (MFR) polypropylene), for example (as measured by ASTM D1238). Unfortunately, high MFR polypropylenes generally exhibit low melt strength and thus low processability, thereby reducing the efficiency of the ISBM process. However, the propylene based polymers utilized herein generally exhibit higher melt strength than the polypropylene having the "high melt flow rate".
 hi one or more embodiments, the propylene based polymers have a low melt flow rate (MFR). As used herein, the term low melt flow rate refers to a polymer having an MFR of less than 10 g/min., of less than about 6 g/10 min., or less than about 2.6 g/10 min., or from about 0.5 g/ 10 min. to less than 10 g/10 min., or from about 0.5 g/10 min. to about 6 dg./10 min., for example.
 The polymers and blends thereof are useful in applications known to one skilled in the art, such as forming operations (e.g., film, sheet, pipe and fiber extrusion and co-extrusion as well as blow molding, injection molding and rotary molding). Films include blown, oriented or cast films formed by extrusion or co-extrusion or by lamination useful as shrink film, cling film, stretch film, sealing films, oriented films, snack packaging, heavy duty bags, grocery sacks, baked and frozen food packaging, medical packaging, industrial liners, and membranes, for example, in food-contact and non-food contact application. Fibers include slit-films, monofilaments, melt spinning, solution spinning and melt blown fiber operations for use in woven or non-woven form to make sacks, bags, rope, twine, carpet backing, carpet yarns, filters, diaper fabrics, medical garments and geotextiles, for example. Extruded articles include medical tubing, wire and cable coatings, sheet, thermoformed sheet, geomembranes and pond liners, for example. Molded articles include single and multi- layered constructions in the form of bottles, tanks, large hollow articles, rigid food containers and toys, for example.
 In one embodiment, the polymers are used in injection stretch blow molding (ISBM). ISBM may be used to produce thin-walled, high-clarity bottles. Such processes are generally known to one skilled in the art. For example, ISBM processes may include injecting molding the polymer into a preform, reheating the preform and subsequently stretching and blowing the preform into an article.
 It has been discovered that the low melt flow rate polymers described herein generally result in higher process efficiency (e.g., at least about 80%, or at least about 85%, or at least about 90%, or at least about 95% or at least about 98%) than the higher melt flow rate polymers used previously. As used herein, the term "process efficiency" refers to the percentage of acceptable articles produced per run. The term "acceptable articles" refers to articles that are not susceptible to failure, as defined further below.
 It has further been observed that the low melt flow rate polymers result in a broader processing window than the high melt flow rate polymers. As used herein, the term "processability", which is used interchangeable with the term "processing window", refers to the sensitivity of a polymer to changes in the heating temperature from a predetermined set point. For example, a narrower processing window generally results in more sensitivity to temperature change and vice versa. When a polymer is "sensitive" to the temperature change, a slight non-uniform heating will have a significant effect on the resin distribution. This can lead to polymer unevenly distributing in the mold, resulting in an article weakness
that may lead to failure. As used herein, "failure" is measured by visual inspection and usually results from concentrating (either stretching too much or too little) in a region of an article or blow-out of the article. The article defects may further be measured via mechanical testing for mechanical failure.
 It has further been observed that articles formed by embodiments of the invention utilizing metallocene catalysts generally result in articles having improved clarity and mechanical properties over articles formed with Ziegler-Natta catalysts. The metallocene polypropylene resins often also have a short circle time during the preform injection molding compared to their Ziegler-Natta counterparts. Both of the above properties are useful for commercial applications.
 Several bottles were formed via injection stretch blow molding from various polypropylene samples. Polymer "A" included a propylene homopolymer formed from a metallocene catalyst having a melt flow rate (MFR) of 3.5 g/10 min and a xylene solubles content of 1.0 wt.%. Polymer "B" included TOTAL Petrochemicals 3270, a propylene homopolymer formed from a Ziegler-Natta catalyst having a MFR of 2.0 g/10 min., a xylene solubles content of 0.8 wt.% and commercially available from TOTAL Petrochemicals, USA, Inc. Polymer "C" included TOTAL Petrochemicals 3287WZ, a propylene polymer including 0.6 wt.% ethylene, formed from a Ziegler-Natta catalyst having a MFR of 1.8 g/10 min., a xylene solubles content of 4.0 wt.% and commercially available from TOTAL Petrochemicals, USA, Inc. Polymer "D" included TOTAL Petrochemicals 7231, a propylene polymer including 2.9 wt.% ethylene, formed from a metallocene catalyst having a MFR of 1.5 g/10 min., a xylene solubles content of 5.5 wt.% and commercially available from TOTAL Petrochemicals, USA, Inc. Polymer "E" included TOTAL Petrochemicals 7525MZ, a propylene polymer including 2.2 wt.% ethylene, formed from a metallocene catalyst having a MFR of 10 g/10 min., a xylene solubles content of 4.5 wt.% and commercially available from TOTAL Petrochemicals, USA, Inc. Polymer "F" included TOTAL Petrochemicals M3282MZ, a propylene polymer formed from a metallocene catalyst having a MFR of 2.3 g/10 min., a xylene solubles content of 1.0 wt.% and commercially available from TOTAL Petrochemicals, USA, Inc. Polymer "G" included TOTAL Petrochemicals M6823MZ, a propylene polymer formed from a metallocene catalyst having a MFR of 30 g/10 min., a xylene solubles content of 1.0 wt.% and commercially available from TOTAL Petrochemicals, USA, Inc.
 Each polymer was injection molded to form a 21 g. preform, which was then stretch blow molded to form bottles.
 It was observed that Polymers A, B, C and F formed bottles experiencing superior top load (see, Figure 1) and bumper compression (see, Figure 2) performance.
 It was further observed that Polymers B, C and D experienced an efficiency of at least 98%, while Polymer E (comparison) experienced an efficiency of about 60% at 1000 bottles/(hourcavity). Polymers B, C, and D further experienced an efficiency of at least
95%, while Polymer E experienced an efficiency of about 40% at 1500 bottles/hour-cavity.
See, Table 1.
 In addition, it was observed that overall Polymers A, F and G (formed from metallocene catalyst) exhibited improved clarity (as measured by sidewall haze and shown in
Figure 3 and gloss as shown in Figure 4) and higher stiffness over the Ziegler-Natta formed polymers.
 While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof and the scope thereof is determined by the claims that follow.
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