Polyethylene LDPE resin properties

The MDPE and HDPE resins were developed to address formulator s needs when an LDPE resin was not adequate on the basis of parameters such as weight loss, adsorption, or additional package rigidity is required. The MDPE resins provide intermediate properties between low- and high-density polyethylene, where more rigidity than LDPE and less rigidity than HDPE are required. The HDPE resins are of a natural milky color with much better barrier properties than LDPE and MDPE. 

This chapter covers fundamental and applied research on polyester/clay nanocomposites (Section 31.2), which includes polyethylene terephthalate (PET), blends of PET and poly(ethylene 2,6-naphthalene dicarboxy-late) (PEN), and unsaturated polyester resins. Section 31.3 deals with polyethylene (PE) and polypropylene (PP)-montmorillonite (MMT) nanocomposites, including blends of low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE). Section 31.4 analyzes the fire-retardant properties of nanocomposites made of high impact polystyrene (HIPS), layered clays, and nonhalogenated additives. Section 31.5 discusses the conductive properties of blends of PET/PMMA (poly (methyl methacrylate)) and PET/HDPE combined with several types of carbon... 

Basell (USA) [6] have reported on the development of a family of high-density polyethylene (HOPE) resins which have a high resistance to bio-diesel fnels and it is currently being developed for use in automotive fuel tanks. Exposure of fuel tanks to biofuel for 11 years at 40 °C has, to date, produced no significant deterioration of the polymer properties and it is significantly better than the deterioration that occurs with current low-density polyethylene (LDPE) grades nsed in fuel tanks. 

Clearly, the combinations of resins and fillers and the resulting property variations are endless (see Fig. 6-2). The point is that each combination is in fact a new material with its own trade-offs. Some properties will be improved, others unchanged, and still others diminished from those of the basic unfilled plastic. In this chapter there is no relationship, direct or implied, between any plastic in terms of the space given it and its performance or the size of its market. The largest consumption of these plastics is low-density polyethylene (LDPE) formulations, at about 25 percent weightwise, followed by high-density polyethylene (HDPE), then polypropylene, polyvinyl chloride, and polystyrene. These together total about two-thirds of all plastic consumption. 

TPEs of SBS (and SEBS)-type are versatile. Compared to PVC compounds, ester plasticizers cannot be used in TPE compounds. Vulcanizing agents such as accelerators, sulfur, or peroxides are not required in SBS-type TPE block copolymers. EPDM is blended with SBS to increase ozone resistance. PS, polyethylene (LDPE, LLDPE, HDPE), and polypropylene (PP) are used as additive polymers with SBS and SEBS. Polystyrene (PS) is compatible with B-S block copolymers. Polystyrene is useful to adjust properties and cost of SBS compounds. The addition of polystyrene into SBS increases hardness, modulus, tensile strength, tear strength, and abrasion resistance. Styrenic resin (a-methyl styrene) can be used as a blend with PS or as an alternative for SBS compound. This resin can be used as a blend with polystyrene as an alternative. Styrenic resin enhances flow properties and physical properties. It is more compatible compared to polystyrene and assists in adhesion and coherent processing. 

A Killion 50 mm (2 in) single screw extruder was used. The two materials were an Equistar Petrothene low density polyethylene (LDPE) and a Chevron Phillips K-Resin styrene-butadiene copolymer (SBC). Figure 3 shows material properties as provided by the supplier. 

The effect of the components and conditions of preparation on the properties of a 70/30 LDPE/clay composite is shown in Table I. The 10/90 mixture of LDEE Bakelite Polyethylene Resin DYNH-1 (Union Carbide Corp.) and Hydrite 10 clay (Georgia Kaolin Co.) was compounded at 150 C in the Brabender Plasticorder in the presence of MAH and/or t-butyl perbenzoate (tBPB). The EE-coated clay was then mixed with additional DYNH-1 LDPE at 130°C to yield a 70/30 PE/clay composite. A 30 70 PE/clay concentrate was prepared in a similar manner at 150 C and converted to a 70/30 EE/ clay composite at 130 C. The 10/90 PE/clay concentrate is an easily handled, clay-like product while the 30/70 concentrate is... 

As a consequence, before 1953, the only possible blends were those of LDPE with other polymers than PO or with elastomers (e.g., chlorosulfonated polyethylene rubber, CSR chlorinated butyl mbber, CBR ethylene/propylene/diene copolymers, EPR, EPDM thermoplastic olefinic elastomer TPE, TPO). However, in addition to the original autoclave polymerization, already in 1938, a tubular reactor was introduced and its product had different properties than that from the autoclave. Also varying the reaction condition affected the degree of short- and long-chain branching in LDPE thus, blending different LDPEs offered a way for optimizing the resin to specific applications. 

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