Control of Material Properties by Coating of Fine Particles with High-Speed Rotational Impact Blending

首先，在砂浆中采用高速旋转冲击共混和手工搅拌的方法对白色聚乙烯粗粒进行包覆，考察了细粒配比、处理时间、转速和粗粒平均直径对混合度的影响。结果表明，在混合比小于100%时，混合度随处理时间的延长而增加，而在混合比大于100%时，旋转冲击会使混合比减小；混合度增加后，轻度降低至低于手工混合，但在冲击混合时，轻度基本保持不变。这意味着颗粒的轻度在很短的混合时间内达到稳定状态，导致使用旋转冲击式搅拌器时相同轻度效果的细颗粒量减少。然后，用二氧化钛粉作为细颗粒，通过旋转冲击共混的方法包裹粗的尼龙和聚乙烯颗粒。研究了涂膜比和粗颗粒大小对UV衰减效果的影响。研究发现，通过降低涂层比例可以提高紫外线防护的有效性，因为这导致形成较低水平的表面团块。用细二氧化钛涂覆大聚合物颗粒的另一个优点是改善了分散体，从而达到最佳的紫外线防护效果。

First, coarse white polyethylene particles were coated by fine pigment particles of red iron oxide by high-speed rotational impact blending and by hand mixing in a mortar, and the effects of the mixing ratio of fine particles, the treatment time, the rotational speed and the mean diameter of coarse particles were investigated with respect to the degree of mixing. It was found that the degree of mixing increased with the treatment time at a mixing ratio of less than 100%, but decreased the ratio of over 100% by rotational impact, and that the lightness decreased to lower than that by hand mixing due to the increased degree of mixing, but remained almost constant during the impact blending. This means that the lightness of particles reached a steady state in a very short mixing time, resulting in the reduction of the amount of fine particles for the same lightness effect when using the rotational impact blender. Then, titanium dioxide powder was used as the fine particles to coat coarse nylon and polyethylene particles by the rotational impact blending. The effects of coating ratio and size of the coarse particles were investigated on the effectiveness of UV attenuation. The effectiveness of UV protection was found to be increased by decreasing the coating ratio, as this led to a lower level of surface agglomerates being formed. A further advantage of coating large polymer particles with fine titanium dioxide was an improvement in the bulk dispersion, which resulted in optimum UV protection.