UHMWPE/HDPE composites

Xue et al. (16) observed that the wear rate of the UHMWPE/HDPE blend can be significantly reduced by adding CNTs, which can be correlated with an increase of the Young s modulus. The addition of 0.5 wt% CNTs to the UHMWPE/HDPE blend caused about 50% reduction of the wear rate, which is shown in Table 5.7. Besides, the composites reinforced with untreated CNTs had a better wear performance than the composites with pre-treated CNTs and the graphical... 

PE, being a commodity polymer, is used in its different physical forms viz. fibres, sheets, membranes, moulds with different backbone chemical configurations (LPE, LLDPE, LDPE, HDPE, UHMWPE, UHSPE etc). Each of these forms of PE requires surface modification at some stage of application. The surfaces of PE fibres are often modified to make them compatible in the composites, whereas PE sheets/tapes are modified to achieve adhesion. Moulds are frequently surface-modified for probability and membranes for selective permeation. In the same way, different chemical configurations of PE, by the virtue of their properties, are used for different applications after surface modification. 

Table 5.7. Properties of UHMWPE+20%HDPE+MWCNT composites, Xue et al. (16)...

J. Suwanprateeb, Binary and ternary particulated composites UHMWPE/CaCOa/HDPE. 

The presence of small additions of UHMWPE resrrlts in an increased initial crystalh-zation temperature of HDPE and an acceleration of the isothermal crystallization rate." The fold surface free energy of polymer chairts in HDPE/UHMWPE composites was lower than that in neat HDPE." UHMWPE promotes the nucleation rate of HDPE and it is an effective nucleating agent in HDPE matrix." ... 

Devaux and Caze reported the characterisation of model composites comprising single UHMWPE fibres embedded in LDPE [47,48], It was shown that an oxidising chemical treatment of the UHMWPE fibre prior to embedding in the LDPE matrix improved the interface between the UHMWPE fibre and the LDPE matrix [48]. Ogawa et al. also reported the creation of unidirectimial UHMWPE fibre-reinforced PE composites [49], The authors report the use of commercial UHMWPE fibre to produce composites by the combination of these fibres with films of HDPE or LDPE to yield composites with >70% fibre weight fraction. 

V aisman et al. [52] reported the effect of bromination of the surface of commercial UHMWPE fibres in order to polarise the surface of the fibres. This bromination process was shown to result in an increase in the degree of order of the transcrystalline zone when these fibres were combined with HDPE to produce a self-reinforced polymer model composite. While these pubUcations report the use of different types of PE to create self-reinforced polymer composites, UHMWPE fibres have also been combined with ethylene-based copolymers. Kazanci et al. [53, 54] reported the creation of commercial UHMWPE fibre-reinforced ethylene-butene copolymers. Filament wormd structiues were produced, with fibre volume fractions of 65%, with the suggestirm of a potential application for these materials in unspecified medical devices. 

Examples of PE-containing composites are hydroxyapatite-filled PE composites, HDPE/wood flonr or ElDPE/wood flake, UHMWPE/gold, HDPE/layered silicate nanocomposites, and nanocomposites comprising HDPE, organically modified clay, and maleated PE. 

This introductory chapter starts with the basics, assuming the reader is not famihar with polymers, let alone polyethylene. The chapter provides basic information about polymers in general, describes the structure and composition of polyethylene, and explains how UHMWPE differs from other polymers (including high density polyethylene [HDPE]) and from other materials (e.g., metals and ceramics). The concepts of crystallinity and thermal transitions are introduced at a basic level. Readers familiar with these basic pwlymer concepts may want to consider skipping ahead to the next chapter. 

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