Pötschke Petra, Villmow Tobias, Krause Beate, Kretzschmar Bernd
Leibniz-Institut für Polymerforschung Dresden e.V. (IPF), Hohe Straße 6, 01069 Dresden, Germany.
Polymers (Basel). 2024 Sep 24;16(19):2694. doi: 10.3390/polym16192694.
The processing conditions were varied during the production of polycarbonate-based composites with the multiwalled carbon nanotubes (MWCNTs) Baytubes C150 P (Bayer MaterialScience AG, Leverkusen, Germany), by melt mixing with an extruder on a laboratory scale. These included the screw design, rotation speed, throughput, feeding position and MWCNT content. Particular attention was paid to the shortening of the MWCNT length as a function of the conditions mentioned. It was found that there is a correlation between the applied specific mechanical energy (SME) during the melt mixing process and MWCNT dispersion, which was quantified by the agglomerate area ratio of the non-dispersed nanotubes based on optical microscopic analysis. The higher the SME value, the lower this ratio, which indicates better dispersion. Above an SME value of about 0.4 kWh/kg, no further improvement in dispersion was achieved. The MWCNT length, as measured by the quantitative analysis of TEM images of the MWCNTs dissolved from the composites, decreased with the SME value down to values of 44% of the original MWCNT length. At a constant loading of 3 wt.%, the tensile strength and tensile modulus were almost independent of the SME, while the elongation at break and notched impact strength showed an increasing trend. The variation in the feeding position showed that feeding the MWCNTs into a side feeder led to slightly better electrical and mechanical properties for both types of MWCNTs studied (Baytubes C150 P and Nanocyl™ NC7000 (Nanocyl S.A., Sambreville, Belgium)). However, feeding into the hopper led to better CNT dispersion with Baytubes C150 P, while this was the case with Nanocyl™ NC7000 when feeding into the side feeder. The screw profile had an influence on the dispersion, the MWCNT length and the electrical resistance, but only to a small extent. Distributive screws led to a greater shortening of the MWCNT length than dispersive screws. By varying the MWCNT content, it was shown that a greater MWCNT shortening occurred at higher loadings. Two-stage masterbatch dilution leads to stronger shortening than composite production with direct MWCNT incorporation.
在实验室规模下，通过使用挤出机进行熔融混合，制备基于聚碳酸酯的多壁碳纳米管（MWCNTs）复合材料（Baytubes C150 P，德国拜耳材料科技公司，勒沃库森）时，对加工条件进行了改变。这些条件包括螺杆设计、转速、产量、进料位置和MWCNT含量。特别关注了MWCNT长度随上述条件的变化情况。研究发现，熔融混合过程中施加的比机械能（SME）与MWCNT分散之间存在相关性，基于光学显微镜分析，通过未分散纳米管的团聚面积比来量化这种相关性。SME值越高，该比例越低，这表明分散效果越好。当SME值高于约0.4 kWh/kg时，分散效果没有进一步改善。通过对从复合材料中溶解的MWCNT的TEM图像进行定量分析测量，MWCNT长度随着SME值降低至原始MWCNT长度的44%。在3 wt.%的恒定负载下，拉伸强度和拉伸模量几乎与SME无关，而断裂伸长率和缺口冲击强度呈上升趋势。进料位置的变化表明，将MWCNT进料到侧进料器中，对于所研究的两种类型的MWCNT（Baytubes C150 P和Nanocyl™ NC7000，比利时Nanocyl S.A.公司），都能带来略好的电学和力学性能。然而，将其进料到料斗中，对于Baytubes C150 P能带来更好的CNT分散，而对于Nanocyl™ NC7000而言，进料到侧进料器中时情况则相反。螺杆外形对分散、MWCNT长度和电阻有影响，但程度较小。分布型螺杆导致MWCNT长度的缩短程度比分散型螺杆更大。通过改变MWCNT含量表明，在较高负载下MWCNT的缩短程度更大。两步母粒稀释导致的缩短程度比直接加入MWCNT制备复合材料时更大。
