VLDPE density polyethylene

At the end of the 1970s considerable interest developed in what became known as linear low density polyethylenes (LLDPE) which are intermediate in properties and structure to the high pressure and low pressure materials. While strictly speaking these are copolymers it is most convenient to consider them alongside the homopolymers. The LLDPE materials were rapidly accepted by industry particularly in the manufacture of film. The very low density polyethylenes (VLDPE) introduced by Union Carbide in 1985 were closely related. 

Metallocene-catalysed very low density polyethylene (m-VLDPE) has become available with densities of as low as 0.903. This is of use for sealing layers of multi-layer films since sealing can commence at lower temperatures than with conventional materials such as LLDPE and EVA (see Section 11.6) with the polymer seal exhibiting both cold strength and hot tack strength. 

Figure 18,2 d) illustrates the general structure of very low density polyethylene, which we also call ultra low density polyethylene. In common with linear low density polyethylene, these resins are copolymers of ethylene and 1-alkenes. The comonomer level ranges from approximately 8 to 14 mole %. We normally refer to these polymers as VLDPE or ULDPE. The molecules of very low density polyethylene contain a distribution of lengths and branch placements. 

To demonstrate this technology, we targeted a copolymer with blocks of both high density polyethylene (HDPE, density 0.94 g cm 3) and very low density polyethylene (VLDPE, density -0.88 g cm 3). Process and product characterization details are given in Table 6. We chose the pyridylamide precatalyst 18 [41] for this study due to its high comonomer reactivity, high M°, and demonstrated CCTP ability. 

Plastomers is the name given to copolymers of ethylene that have a little crystallinity, but are largely amorphous. They are also called very low-density polyethylene (VLDPE). They are more elastic than LLDPE but less stiff. They are used as a sealing layer in film applications and controlled permeation packaging for vegetables and fruits. 

PS PSF PSU PTFE PU PUR PVA PVAL PVB PVC PVCA PVDA PVDC PVDF PVF PVOH SAN SB SBC SBR SMA SMC TA TDI TEFE TPA UF ULDPE UP UR VLDPE ZNC Polystyrene Polysulfone (also PSU) Polysulfone (also PSF) Polytetrafluoroethylene Polyurethane Polyurethane Poly(vinyl acetate) Poly(vinyl alcohol) poly(vinyl butyrate) Poly(vinyl chloride) Poly(vinyl chloride-acetate) Poly(vinylidene acetate) Poly(vinylidene chloride) Poly(vinylidene fluoride) Poly(vinyl fluoride) Poly(vinyl alcohol) Styrene-acrylonitrile copolymer Styrene-butadiene copolymer Styrene block copolymer Styrene butadiene rubber Styrene-maleic anhydride (also SMC) Styrene-maleic anhydride (also SMA) Terephthalic acid (also TPA) Toluene diisocyanate Ethylene-tetrafluoroethylene copolymer Terephthalic acid (also TA) Urea formaldehyde Ultralow-density polyethylene Unsaturated polyester resin Urethane Very low-density polyethylene Ziegler-Natta catalyst... 

Application To produce linear polyethylene from very low density polyethylene (VLDPE) to linear low density polyethylene (LLDPE) to high density polyethylene (HDPE) and other specialty types using the Spherilene gas-phase technology and a single Ziegler-Natta titanium-based catalysts family. 

Also worthy of mention are the new very-low-density polyethylenes (VLDPEs), which are produced using metallocene-based catalysts [9]. These materials, which remain largely experimental at the moment, have a density of less than 0.9g/cm. ... 

PEMA Polyethylmethacrylate VLDPE Very low density polyethylene... 

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. 

A new class of linear polyethylene copolymers with densities ranging between 0.890 and 0.915 g/cm, known as very low-density polyethylene (VLDPE), was introduced commercially in late 1984 by Union Carbide. These resins are produced by copolymerization of ethylene and alpha-olefins in the presence of a catalyst. 

Chemical properties Low density (LDPE) and very low density polyethylenes (VLDPE) have branched chains which do not pack together well, imparting low density. High density polyethylene (HOPE) has longer, less branched chains, imparting stiffness and strength. No solvents at ambient temperature due to PE s high crystallinity, but chlorinated liquids can swell the plastic. 

VAM vacuum-assist molding VLDPE very-low-density polyethylene (or... 

General Description Ultra low density polyethyl-enes (ULDPEs) and very low density polyethylenes (VLDPEs) are essentially synonymous designations for linear polyethylenes with densities down to 0.880 g/cu in. ULDPEs are finding applications as impact modifiers for other polyolefins. Dow Chemicals Attane ULDPE is an Ethylene/Octene copoly-... 

Very low-density polyethylene (VLDPE) polymers with densities ranging fiom 0.905 to 0.915 g/cm that contains a comonomer ... 

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