Polyethylene silane-crosslinkable

M. Bengtsson and K. Oksman. One-step process of silane crosslinked polyethylene/wood flour composites. In Eighth International Conference on Woodfiber-Plastic Composites, Madison, WI, May 23-25, 2005. 

Fig. 3. Plot of idative dongation of samples loaded with 0.2 MPa at 200 °C on the content of a gd in low density polyethylene. Polyethylene was crosslinked by dicumyl peroxide (/) and vinyltri-methoxy silane (2)...

WuT-S. Silane crosslinkable polyethylene compounds applications and manufacturing methods. Plastics Addit Compound [trade journal—Elsevier Ltd ] Novemher/Decemher 2007. 

R. Nordin, H. Ismail, Z. Ahmad, A. Rashid, Performance improvement of (linear low-density polyethylene)/poly(vinyl alcohol) blends by in situ silane crosslinking. J. Vinyl Add. Tech. 18, 120-128 (2012)... 

In the early 1960s, UHMWPE was classified as a form of HDPE among members of the polymer industry (Chubberley 1965). Thus, Chamley s earlier references fo UHMWPE as HDPE are fechnically accurafe for his time (Chamley 1963), but they have contributed to some confusion over the years as to exactly what kinds of polyethylenes have been used clinically. From a close reading of Chamley s works, it is clear that HDPE is used synonymously with RCH-1000, the trade name for UHMWPE produced by Hoechst in Germany (Chamley 1979). With the exception of a small series of 22 patients who were implanted with silane-crosslinked HDPE at Wrighington (Wroblewski et al. 1996), there is no evidence in the literature that lower molecular weight polyethylenes have been used clinically. 

Atkinson JR, Cicek RZ. Silane crosslinked polyethylene for prosthetic applications. Part II. Creep and wear behavior and a preliminary moulding test. Biomaterials 1984 5 326-35. 

Goran Grubbstrom, Allan Holmgren, Kristiina Oksman. Silane-crosslinking of recycled low-density polyethylene/wood composites. Composites Part A. 41 (5), 678-683 (2010). 

FT-IR spectroscopy has been used in the investigation of welding crosslinked polyethylene pipes [23]. Three types of crosslinking systems were used namely, peroxide (PEXa), silane (PEXb) and electron beam (PEXc). Scholten and co-workers [23] observed that only PEXa pipes have a satisfactory electrofusion quality. The strength of electrofusion welds of PEXb and PEXc pipes is not acceptable. The most likely explanation for the differences in weld quality is related to the adhesion theory and more specifically to differences in composition. Figure 5.6 shows the infrared spectra of medium density polyethylene (MDPE), PEXa, PEXb and PEXc. 

Vinyl functional silanes have been used for over 35 years to crosslink polyethylene. The most common commercial products using this crosslinking technology are crosslinked PE insulations for the global wire and cable market [11] and crosslinked HDPE pipes for potable water and natural gas. Some work recently has been done to combine this crosslinking technology with wood-filled polyethylene. 

As far as the thermoelasticity performance of a polymer network k concerned, it is generally true that the hi er the concentration of crosslinks or the lower the dimensions of loopholes in the network, the more significant are the changes in the polymer I operties. The elasticity of a polymer is also enhanced by i iyskally entangled chains, whose number increases with the number of crosslinks, the character of the crosslinks being interrdated with the character of the physical aitan ements [27]. This may be illustrated by experiments with two crosslinked samples prepared from low density polyethylene. The first sample was crosslinked via the silane pathway, the second by... 

The choice of peroxide used is determined by the temperature of its decomposition. Peroxide should be effectively dispersed in the polymer melt brfore a substantial homolysis of 0—0 bonds can occur. For such a purpose, dicumyl peroxide which may be dissolved in vinyl trimethoxy silane (b.p. 120 °C) is suitable. The required degree of crosslinking was attained if 2 % w. of silane with 5-10% w. of peroxide were added to polyethylene. At the silylation, grafting should not commence before both compounds (peroxide, ane) are well dispersed in the polymer melt [141]. NonhcMno-geneous dispersion of additives reduces efficiency of grafting and of subsequent crosslinking. 

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