Diffusion and polymerization behaviour of styrene (St) in commercially-available high density polyethylene (HDPE) pellets were studied and HDPE/PS nanoblend pellets were synthesized.Both the diffusion and polymerization steps were carried out in water medium.At 70-90℃

diffusion behaviour of St towards HDPE pellets showed features of Fickian Diffusion.The saturation values of diffused St were different at different diffusion temperatures

and higher diffusion temperature meant higher saturation value

higher diffusion rate and shorter time to reach the saturation value.The amount of the initiator BPO was important in view of PS content in the pellets.With 0.5 wt%-1 wt% BPO

PS content was 11 wt% when diffusion and polymerization were carried out at 90℃

while the PS content increased to about 16 wt% when excess amount of BPO (5 wt%) was used.The diametrical distribution of PS was investigated by Micro Fourier Transform Infrared Spectroscopy

showing that PS appeared throughout the HDPE pellets.PS distributions along the diameters of the pellets showed similar "M" shape curves for HDPE/PS pellets synthesized with different amounts of BPO.The peaks of the curves appeared at 200 μm area to the surface and were related to crystalline structure of HDPE pellets.The phase morphology of PS in the blend pellets were characterized by field emission scanning electron microscopy.Typical sea-island morphology was revealed with an average particle size of less than 100 nm.The HDPE/PS blend pellets were melt-processed into cylindrical bars.PS phases in the extrusion bars of the blend pellets synthesized with 0.5 wt% BPO showed Ci Rice morphology

reflecting that PS particles were aggregating instead of coalescing during processing

and particle sizes were from tens of nm to 200 nm.The disperse PS phase and HDPE matrix had good interaction and the HDPE/PS bars did not break with elongation of 600% and showed higher tensile stress than pure HDPE bars

which meant that 0.5 wt% BPO was fairly good condition for preparing HDPE/PS nanoblends or other modified HDPE materials.