Constructing many different types of shish-kebab structure is an effective way to understand its influence on mechanical properties and expand its functional applications. In this work, a new shish-kebab structure was obtained employing high molecular weight PE (HMW-PE) and low molecular weight PE (HMW-PE). As shown in Fig.1a, a layer-multiplying system was firstly used to prepare the alternating layered HMW-PE/LMW-PE composites with 32 layers. Subsequently, the hot stretching was conducted with a stretching ratio of about 850% to achieve the high orientation. The PLM figures (Fig.1b) revealed a well defined multilayer structure of 32-layer sample, where the HMW-PE layers and the LMW-PE layers exhibited different colors, i.e. blue and red respectively. The discrepancy of color might be related to the different oriented and closely packed crystalline structure. Meanwhile the melt-recrystallization results showed that the LMW-PE layers melted firstly at 137°C but the HMW-PE layers re-crystallized firstly. It indicated that the crystalline structure of the HMW-PE layer had the enhanced thermal stability than that of LMW-PE layer. The SEM figures show that the HMW-PE layer (Fig.2a) consisted of a large number of shish connected with short kebabs, but the LMWPE layer (Fig.2b) consisted of a large number of kebabs. Thus, a multilayered structure with the shish and kebab layers alternatingly dispersing was obtained. The HMW-PE layer formed the shish layer because the long chains of HMW-PE layer have longer relaxation time While the short chains of LMW-PE layers were easily relaxed and crystallized as the kebab nucleating on the shish located on the layer interfaces. Because of the highly oriented shish structure, the yield strength gained a remarkable enhancement from 19.7 MPa for PE containing spherulites to 54.0 MPa for PE containing multilayer shish/kebab structure.

Structure and formation mechanism of flow-induced alternating multilayer shish/kebab of polyethylene

256th National Meeting (2018)

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