Polyolefins polyethylene growth

Harden s (27) market survey of the growth of polyolefin foams production and sales shows that 114 x 10 kg of PE was used to make PE foam in 2001. The growth rate for the next 6 years was predicted as 5-6% per year, due to recovery in the US economy and to penetration of the automotive sector. In North America, 50% of the demand was for uncrosslinked foam, 24% for crosslinked PE foams, 15% for EPP, 6% for PP foams, 3% for EVA foams and 2% for polyethylene bead (EPE) foam. As protective packaging is the largest PE foam use sector, PE foam competes with a number of other packaging materials. Substitution of bead foam products (EPP, EPE, ARCEL copolymer) by extruded non-crosslinked PE foams, produced by the metallocene process was expected on the grounds of reduced costs. Compared with EPS foams the polyolefin foams have a lower yield stress for a given density. Compared with PU foams, the upper use temperature of polyolefin foams tends to be lower. Eor both these reasons, these foams are likely to coexist. 

Abstract The fracture properties and microdeformation behaviour and their correlation with structure in commercial bulk polyolefins are reviewed. Emphasis is on crack-tip deformation mechanisms and on regimes of direct practical interest, namely slow crack growth in polyethylene and high-speed ductile-brittle transitions in isotactic polypropylene. Recent fracture studies of reaction-bonded interfaces are also briefly considered, these representing promising model systems for the investigation of the relationship between the fundamental mechanisms of crack-tip deformation and fracture and molecular structure. 

The family of polymers, and in particular polyolefins, is important in the modern world because of the very high number of applications in all fields. Among plastic materials, polypropylene is one of the most important, having undergone rapid growth since its discovery in 1954 by the Nobel Prize winner G. Natta of Politecnico di Milano. Today, polypropylene demand is about 40 million ton per year with a market share, among all thermoplastic materials, of about 26%, which is second only to polyethylene (39%). 

Much of the growth in LLDPE demand will be at the expense of other polyolefins, especially conventional high-pressure, LDPE. Its proponents claim that LLDPE can replace LDPE in 70 to 80% of its markets and that "the last conventional polyethylene plant has been built." Another sign of the times is the fact that ICI, originator of the high-pressure process, has now ceased production. 

The production of polyolefins such as polyethylene (PE) or polypropylene (PP) and their copolymers increases continuously due to their outstanding product properties and their environmental compatibility. They are commonly applied as packing material. foils, fibers, as well as components for the automotive and electrical industry. In 1996 the worldwide production of PE and PP counted 40 million and 20 million tons, respectively. On the basis of the global demand. the growth rate of PP production is predicted to rise up to 7% per year until 2002/ 2003. 

We briefly review these discoveries, chronologically, and see how they led to several industrial processes that were the foundation of the significant growth of the polyethylene industry since the 1950s. We then see how this technology was rapidly extended to create the polypropylene industry. The growth of the polyolefin industry in these last 60 years is the story primarily—in terms of volume and impact —of the growth of polyethylene and polypropylene. 

As indicated in the introduction there is a distinct correlation between the commercial growth of linear low density polyethylene and the resurgence of interest in the temperature rising elution fractionation technique. It is clear, however, from the wide variety of examples noted in this review that the scope of TREF extends well beyond the LLDPE area. Since the TREF technique is becoming available to many more research workers it is anticipated that there will be continued growth and development which will lead to greater sophistication in the way the technique is utilized, particularly in the polyolefin area. The power of TREF for blend analysis and cross-fractionation is certain to be exploited in the coming years. 

Wood fiour is often added to thermoplastics as a low cost filler to alter mechanical performance, especially the stiffness of low melt temperature, commodity thermoplastics such as polypropylene and polyethylene without increasing density excessively. Wood is much stiffer than the commodity thermoplastics usually used as matrices. Additionally, vood and pulp fibers can nucleate crystal growth in polyolefins resulting in a transcrystalline layer that can infiuence mechanical behavior [33, 34[. 

The popular belief that hydrocarbon polymers do not biodegrade at molar mass above 500 is shown to be based on a misinterpretation of earlier work. Bioerosion of carboxylic acids, the oxidation products of polyolefins, occurs at the surface of polyethylene and these act as nutrients for the growth of non-pathogenic bacteria and fungi in the absence of any other source of carbon. 

An instractive example of polyolefin epitaxy concerns the growth of polyethylene (PE) lamellae on aromatic crystals of p-terphenyl and anthracene. On these two... 

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