Polypropylene characterization

Billiani, J. and Lederer, K., Polypropylene characterization by high temperature SEC coupled with LALLS, /. Liq. Chromatogr., 13, 3013, 1990. 

Polyester / Polyolefin / Polypropylene Characterization and Comments References... 

Me2C(cyclopentadienyl)(9-fluorenyl)ZrCl2 (3) and MAO result in a predominantly syndiotactic polypropylene, characterized by the chain-migratory statistics that show both single and double m as defects (c). 

Polyester/polyolefin/polypropylene Characterization and comments References... 

Miyoshi T, Mamun A, Hu W. Molecular Ordering and Molecular Dynamics in Isotactic-Polypropylene Characterized by Solid State NMR. J Phys Chem B 2010 114 92. 

Table 4. Molecular Weight Characterization Data for Polypropylene Samples ...

Polypropylene fibers are used in every aspect of carpet constmetion from face fiber to primary and secondary backings. Polypropylene s advantages over jute as carpet backing are dimensional stabiUty and minimal moisture absorption. Drawbacks include difficulty in dyeing and higher cost. Bulked-continuous-filament (BCF) carpet yams provide face fiber with improved crimp and elasticity. BCF carpet yams are especially important in contract carpets, characterized by low dense loops, where easy cleaning is an advantage. 

Some of the most difficult heterophase systems to characterize are those based on hydrocarbon polymers such as mbber-toughened polypropylene or other blends of mbbers and polyolefins. Eecause of its selectivity, RuO staining has been found to be usehil in these cases (221,222,230). Also, OsO staining of the amorphous blend components has been reported after sorption of double-bond-containing molecules such as 1,7-octadiene (231) or styrene (232). In these cases, the solvent is preferentially sorbed into the amorphous phase, and the reaction with OsO renders contrast between the phases. 

Artificial surfaces must be resistant to cigarette bums, vandaUsm, and other harm. Fire resistance is most critically evaluated by the NBS flooring radiant panel test (10). In this test, a gas-fired panel maintains a heat flux, impinging on the sample to be tested, between 1.1 W/cm at one end and 0.1 W/cm at the other. The result of the bum is reported as the flux needed to sustain flame propagation in the sample. Higher values denote greater resistance to burning results depend on material and surface constmction. Polypropylene turf materials are characterized by critical radiant flux indexes which are considerably lower than those for nylon and acryflc polymers (qv) (11). 

Polyethylene and polypropylene are semitransparent plastics made by polymerization. They are produced from ethylene and propylene in a variety of grades. Their mechanical properties are determined mainly by density (degree of crystallinity) and molecular weight, characterized by the Melt Index (MI). 

The effect of thermal aging on polyethylene and isotactic polypropylene have been studied by Konar et al. [49]. They used contact angle, contact angle hysteresis, and XPS to characterize the modified surfaces of the polymers. Hysteresis increased with aging temperature. In the case of polyethylene, thermal aging led to a significant increase in adhesion strength of polyethylene with aluminium, but the increase in the case of polypropylene was much less marked. 

The most important olefins used for the production of petrochemicals are ethylene, propylene, the butylenes, and isoprene. These olefins are usually coproduced with ethylene by steam cracking ethane, LPG, liquid petroleum fractions, and residues. Olefins are characterized by their higher reactivities compared to paraffinic hydrocarbons. They can easily react with inexpensive reagents such as water, oxygen, hydrochloric acid, and chlorine to form valuable chemicals. Olefins can even add to themselves to produce important polymers such as polyethylene and polypropylene. Ethylene is the most important olefin for producing petrochemicals, and therefore, many sources have been sought for its production. The following discusses briefly, the properties of these olefmic intermediates. 

Chattopadhyay S., Chaki T.K., and Bhowmick A.K., New thermoplastic elastomers from poly(ethyle-neoctene) (engage), poly(ethylene-vinyl acetate) and low-density polyethylene by electron beam technology structural characterization and mechanical properties. Rubber Chem. TechnoL, 74, 815, 2001. Roy Choudhury N. and Dutta N.K., Thermoplastic elastomeric natural rubber-polypropylene blends with reference to interaction between the components. Advances in Polymer Blends and Alloys Technology, Vol. 5 (K. Finlayson, ed.), Technomic Publishers, Pensylvania, 1994, 161. 

Blend with Isotactic Polypropylene and Thermoplastic Olefin—Theory AND Characterization... 

Shanmugharaj, A.M., Kim, J.K., and Ryu, S.H., UV surface modification of waste tire powder Characterization and its influence on the properties of polypropylene/waste powder composites. Polymer Test., 24, 739, 2005. 

In some cases it is possible to differentiate between the various alkyl substituents. Primary, secondary and tertiary nitrates and nitrites all show clearly different infrared absorptions. The spectra of acid fluorides can be used to differentiate chain-end groups from pendant acid groups. Furthermore, the loss of all -OH species upon sulfur tetrafluoride exposure allows the reliable estimation of ketones, esters and lactones without the complication of hydrogen-bonding induced shifts in the spectra. Preliminary results from the use of these reactions to characterize y-ray oxidized polyethylene and polypropylene are used to illustrate the scope of the methods. 

The history of dendrimer chemistry can be traced to the foundations laid down by Flory [34] over fifty years ago, particularly his studies concerning macro-molecular networks and branched polymers. More than two decades after Flory s initial groundwork (1978) Vogtle et al. [28] reported the synthesis and characterization of the first example of a cascade molecule. Michael-type addition of a primary amine to acrylonitrile (the linear monomer) afforded a tertiary amine with two arms. Subsequent reduction of the nitriles afforded a new diamine, which, upon repetition of this simple synthetic sequence, provided the desired tetraamine (1, Fig. 2) thus the advent of the iterative synthetic process and the construction of branched macromolecular architectures was at hand. Further growth of Vogtle s original dendrimer was impeded due to difficulties associated with nitrile reduction, which was later circumvented [35, 36]. This procedure eventually led to DSM s commercially available polypropylene imine) dendrimers. 

With the exception of LDPE, polyolefins like other polyethylenes and polypropylene, which represent the largest amount of vinyl-type polymers produced in the world, are neither synthesized by radical nor by classical ionic polymerisation processes. Different types of polymerisation catalysts are in use for these purposes. The Cr-based Phillips catalyst, Ziegler-Natta type catalysts, metallocene or other more recently discovered catalysts, including late transition metal catalysts, are all characterized by their propagation step where the olefin monomer inserts into a carbon-transition metal link. ... 

The case of isotactic polypropylene (iPP) presents some differences with respect to those just discussed. While both sPP and PET adopt in their mesophases disordered, extended, essentially non-helical conformations, iPP is characterized by a unique, relatively well ordered, stable chain structure with three-fold helical symmetry [18,19,36]. More accurately we can state that an iPP chain segment can exist in the mesophase either as a left handed or as the enantiomeric right-handed three-fold helix. The two are isoener-getic and will be able to interconvert only through a rather complex, cooperative process. From a morphological point of view Geil has reported that thin films of mesomorphic iPP quenched from the melt to 0 °C consist of... 

In a crystalline polymer the chains can be nonparallel for instance, the structure of the y-form of isotactic polypropylene is characterized by the packing of nearly perpendicular chains.141142... 

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