Due to general applicability of polymer products, their use is increasing, and so does plastic waste. In care of the environment, we want to recycle as much waste as possible, but this affects the material properties of polymers.
In research, we focused on high density polyethylene (HDPE) and studied the effect of recycling on mechanical, thermal and flow properties for blends of raw and recycled HDPE. Mixtures of raw and 10x, 30x, 50x and 100x recycled material were analysed. As part of this research, we measured flow properties for blends with added 10x and 30x recycled HDPE, other results were obtained from previous studies. We performed amplitude, frequency and flow tests on rotational rheometer.
Recycling has almost no effect on melting and crystallization temperature, but more on degree of crystallinity. Degree of crystallinity decreases with increasing percentage of recycled material and increasing recycling cycles, which also affects the values of hardness and elastic modulus. Flow properties deteriorate already at 10x recycled samples in mixtures where recycled material predominates and degradation is even higher after more recycling cycles. The reason for degradation of material properties after multiple recycling cycles are changes in material structure.
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