Ultra low density polyethylene ULDPE

Fig. 20 Analytical TREF profiles of a random copolymer, an OBC, and a blend of HDPE with ultra-low density polyethylene (ULDPE) of similar overall densities [46]...

Products Product density is controlled from ultra low density polyethylene (ULDPE) (<900 g/ml) to HDPE (>960 g/ml). Melt index (MI) E capability ranges from 0.01 to 100 gr/10. ... 

The presence of a comonomer in the polymerization process, when a stereo-specific catalyst is used, results in the production of a rather linear polymer with very short branch-like pendant groups. This polymer is called linear low density polyethylene (LLDPE) or ultra low density polyethylene (ULDPE), depending on the density achieved by the addition of the comonomer. The larger the amount of comonomer added, the lower is the density of the copolymer. For example, if hexene is used, the pendant groups are as follows ... 

Polyethylenes with larger amounts of comonomer and consequently density below the normal LLDPE range are called very low density polyethylene, VLDPE, or ultra low density polyethylene, ULDPE. While these can be produced using Ziegler-Natta catalysts, often they are made using metallocene catalysts, as described next. 

Material Family ULTRA LOW DENSITY POLYETHYLENE (ULDPE) ... 

Ultra-low-density polyethylene (ULDPE) polymers with densities ranging fiom 0.890 to 0.905 g/cm, that contains a comonomer ... 

Linear low-density polyethylene (LLDPE) is a variation of HDPE. It is synthesized similarly, but LLDPE has a much higher content of comonomer, such as hexene or octene. Incorporation of comonomer in the chain yields short chain branches of a specified length (Fig. 1.5). By controlling the amount of branch points through comonomer content, degree of crystallinity - hence density - can be controlled. Variants of LLDPE are known as very low-density polyethylene (VLDPE) and ultra low-density polyethylene (ULDPE). LLDPE density is generally in the range of 0.88 to 0.93 g/cm. ... 

Ahane Ultra low-density polyethylene, ULDPE Dow Chem. Co. 

Metallocene plastomers are plastomers made using metallocene single-site catalysts. Other polyolefins exist in this composition range made with conventional catalysts Dow ATTANE (10), Union Carbide FLEXOMER (11), and Mitsui TAFMER products (12). These are generally called very-low-density poly-ethylenes (VLDPEs) and ultra-low-density polyethylenes (ULDPEs), and are not discussed in this chapter. 

To this category belong PP blends with 4-6wt.% of either chloro-sulfonated polyethylene (CSR), or chlorinated polyethylene (CPE). These blends show good processability and mechanical properties. In 1990, PP blends with CSR and ultra-low density polyethylene (ULDPE) were first partially vulcanized then dispersed within a thermoplastic CSR. The alloys showed good processability, hot-weld strength, interplay adhesion and crack resistance. 

SEM photomicrograph of the smoothed and toluene-etched surfece of a PET ultra-low-density polyethylene (ULDPE)-g-DEM blend obtained in a discontinuous mixer by adding Ti(OBu)4 as a transesterification catalyst. (From M. B. ColtelH, Catalysed Reactive Compatibilization of Polyolefin and Poly(ethylene terephthalate) Blends Reactions Mechanisms and Phase Morphology Development, Ph.D. thesis. University of Pisa, Italy, 2005.)... 

Ultra-Low-Density-Polyethylene (ULDPE) Any linear polyethylene with density less than 0.90 g/cm, and possibly as low as 0.86 g/cm. ULDPE films have better optical properties and better resistance to puncture, impact, and tearing than conventional linear low-density PEs. 

Metallocene polyethylene (mPE) plastomers 0.900-0.915 Coextrusion, heat seal layers Ethylene-vinyl acetate (EVA) resins with 9% vinyl acetate, ultra low density polyethylene (ULDPE), very low density polyethylene (VLDPE)... 

Fluid contact layer Ultra low density polyethylene (ULDPE), preferably with no additives, used for maximum biocompatibility and chemical resistance with minimum extractables some manufacturers use EVA copolymers. 

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