Polymer blends thesis

Abstract: Temperature dependence on the phase structure was investigated for drawn and undrawn ultrahigh molecular weight polyethylene (UHMWPE) by solid-state high resolution 13C NMR. The fully relaxed DD/MAS 13C NMR spectra provided the fractions of crystalline, interphase, and amorphous, and the analysis on molecular mobility by spin-lattice relaxation time provided three components in the orthorhombic phase, two components in the monoclinic phase and a single component in the interphase and amorphous phase, respectively. The molecular mobility of orthorhombic phase for drawn UHMWPE was the lowest of three samples, corresponding to the most rigid. This closely relates with good mechanical properties for drawn UHMWPE. The T1C was as high as 2040 s even at 100 °C for drawn UHMWPE. With increasing temperature, a part of the most mobile chain in the orthorhombic phase which locates at the lamellar surface transforms to that in the interphase, and then the interphase also transforms to the amorphous. The drawn UHMWPE had high fraction of the monoclinic phase and lattice defect which are induced by highly drawing. These fractions decreased with increasing temperature. So the monoclinic phase exists as a defect in the orthorhombic phase, and the molecular chain corresponding to the lattice defect would connect the monoclinic and orthorhombic phases. The monoclinic phase transforms to the orthorhombic phase with increasing temperature. This resulted in the small fractional decrement of orthorhombic phase.

Most polystyrene products are currently not recycled due to the lack of incentive to invest in the compactors and logistical systems required. Due to the low density of polystyrene foam, it is not economical to collect. However, if the waste material goes through an initial compaction process, the material changes density from typically 30 kg/m 3 to 330 kg/m 3 and becomes a recyclable commodity of high value for producers of recycled plastic pellets. Expanded polystyrene scrap can be easily added to products such as EPS insulation sheets and other EPS materials for construction applications; many manufacturers cannot obtain sufficient scrap because of collection issues. When it is not used to make more EPS, foam scrap can be turned into products such as clothes hangers, park benches, flower pots, toys, rulers, stapler bodies, seedling containers, picture frames, and architectural molding from recycled PS. [54] Currently, around 100 tonnes of EPS are recycled every month in the UK. [55]

Polymer blends thesis

polymer blends thesis


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