Polyolefins with additives

T. McKee, Laser Marking of Polyethylene and Other Polyolefins with Additives, Plastics Formulating <6 Compounding. 

Cyclic Polyolefins (GPO) and Gycloolefin Copolymers (GOG). Japanese and European companies are developing amorphous cycHc polyolefins as substrate materials for optical data storage (213—217). The materials are based on dicyclopentadiene and/or tetracyclododecene (10), where R = H, alkyl, or COOCH. Products are formed by Ziegler-Natta polymerization with addition of ethylene or propylene (11) or so-called metathesis polymerization and hydrogenation (12), (101,216). These products may stiU contain about 10% of the dicycHc stmcture (216). 

There already exists a substantial literature devoted to the estimation of various material properties with the help of additive structual increments (Reid et. al, 1987, Van Krevelen, 1990). The regular solution theory in combination with additive structural increments has a wide application for estimating the relative solubilities of organic substances in polymers and the solubility of polymers in various solvents (Barton, 1983) and will be described later in this chapter. When estimating partition coefficient values, one is quickly confronted with this method s application limits, particularly with polar and non-polar structures, for example the partitioning of substances between polyolefins and alcohol (Baner and Piringer, 1991). 

In the following Dp-values calculated with the refined Eq. (15-3) and partition coefficients KpF assumed to equal 1 are used for estimating worst case migration rates for additives from polyolefins with Eq. (7-51). These estimated values are compared with experimentally obtained migration values carried out under well defined conditions for several additives from HDPE and different PP-types (Table 15-3a) into olive oil (O Brian et al., 1999 and 2000). The results are summarized in Table 15-3b. 

The cycloaddition to double bonds of the carbon cage is a major aspect in the organic chemistry of fuUerenes. As mentioned before, C o is an electron-deficient polyolefin with only moderate conjugation. These features clearly reflect in its behavior in cycloaddition reactions. In [4+2]-additions, for instance, it always acts as dienophile. A multifarious chemistry unfolded when exploring the whole range of possible cycloadditions. Today it allows for the attachment of virtually every functional group to the basic fullerene. 

Effect of talc on mechanical properties of polyolefins fypically depends on particle size of the filler. If is generally considered thaf fhe finer fhe falc particles, the better its effect on impact resistance, which generally suffers with addition of minerals. However, data in Table 4.7 show that it is not always so. Although introduction of talc indeed reduced impact resistance of the filled polypropylene regardless of particle... 

The investigation of the compatibilization and crystallization of blends of polyolefins with a semiflexible LCP leads to the following conclusions the compatibilization of polyolefin/LCP blends has been realized successfully by the addition of ad hoc synthesized polyolefin-g-LCP copolymers. The compatibilization results into materials, characterized by a stabilized morphology, improved crystallization kinetics under nonisothermal and isothermal conditions, and enhanced mechanical properties. Moreover, polyolefin processability has been enhanced by the addition of LCP, even in the presence of compatibilizers. New high quality materials with improved processability have been produced by technologies, which are economic, friendly to the environment, and socially acceptable. 

The present data show that TMPTA is a valuable additive for acceleratlnggrafting reactions involving monomers such as styrene to the polyolefins with both UV and ionising radiation. Inclusion of monomers like TMPTA in RRC formulations offers the potential of enhancing concurrent grafting with cure. This concept is... 

The reactive methods of compatibili2ation developed subsequently allowed the second generation Noryl (a blend of PPO with PA) to be developed. The compositions claimed usually cover 30-70% of each of the main ingredients, PPO and PA, with additionally up to four parts of such modifier as polycarboxylic acid, trimellitic anhydride acid chloride, quinine, oxidized polyolefin wax, and so on. In most cases, PA forms a matrix with spherical inclusions of PPO acting as compatibilized low-density filler. 

Molar mass distribution is a dominant microstracture parameter that, in copolymers, needs to be measured with additional information to account for long chain branching, comonomer incorporation, or ethylene propylene combinations (in the case of EP copolymers). The combination of GPC and IR spectroscopy has been shown to be of great value in the characterization of copolymers. The importance of automation and sample care, especially in the case of polypropylene, has been discussed as well as the significant improvement in sensitivity by the use of IR MCT detectors. There are big expectations for the analysis of ultrahigh molar mass polyolefins by the new AF4 technology. 

Polyolefin can be considered as an interdisciplinary material that needs the collaboration from different disciplines such as chemistry, physics, computer science, and engineering. The integration of different fields leads to new advanced technology and economic competitiveness to modify polyolefins for different applications. Polyolefins are replacing many other materials in diverse uses, and the scientists are trying to find new production, processing, and applications for the polyolefins with more friendly environment routs through new polymerization processes, modified catalysts and improved additives to have a wider application of these materials. 

Reduction in the properties can be seen when blending the polyolefin with a biodegradable component such as PLA, and this can be reduced by the addition of compatibilizers. 

Laminar composites are combinations of several layers of composite sheets that are bonded together. Polyolefin sandwich structures are a laminar composite. They are composed of two or more layers of polyolefin with a different material in between the layer (long fiber mat or short fiber). Sandwich panel and laminar composites are common methods for thermoset resins and thermoplastic composites. This simple method can be applied to natural fiber-reinforced thermoplastic composites using the hot press method. The addition of a reinforcement material between polyolefin layers does not require extrusion or injection molding and minimizes fiber degradation [35, 36]. 

However, the simple melt mixing of polyolefins with natural clays, does not guarantee a sufficient level of dispersion of the nanoparticles, which are often present in the form of micron-size agglomerates. In order to overcome this problem, two main strategies have been followed surface functionalization of needle-like clays (usually by alkyl-silanes) or addition of a third polymeric phase (usually maleic anhydrite modified PP PP-g-MA), which acts as a compatibilizer between the matrix and nanofiller. Both methods tend to modify the surface energies of the nanocomposite system, in order to reduce the interparticle interaction and improve the dispersion. In the case of a reactive surface treatment only, the polymer-day interaction is expected to be enhanced, along with better nanoclay dispersion, which is very important for the final mechanical properties. 

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