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首页> 外文学位 >Alkyl ketene dimer and precipitated calcium carbonate interactions in wet-end papermaking.
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Alkyl ketene dimer and precipitated calcium carbonate interactions in wet-end papermaking.

机译：湿端造纸中的烷基烯酮二聚体和沉淀的碳酸钙相互作用。

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This thesis investigates the interactions between alkyl ketene dimer (AKD) and precipitated calcium carbonate (PCC). Although the mechanisms behind AKD sizing and reactions with cellulose have been studied in-depth, methods describing AKD retention are poorly understood. The aim of this research was to determine the conditions and time-scale under which AKD and PCC heteroflocculate, and to determine the influence of PCC on non-retained AKD. We also wanted to understand the mechanisms behind AKD interactions with cPAM, and perform experiments on the twin-wire sheet former. We outline a procedure for creating an AKD emulsion coated by cationic starch and free of extraneous substances. We find that AKD and PCC each homoflocculate, but no heteroflocculation occurs between the two chemicals. This suggests that PCC and AKD do not directly interact. Instead, starch removal from the AKD particle surface aids the homoflocculation of PCC (via polymer bridging). This indicates that the alkaline environment is the most significant factor contributing to AKD hydrolysis. More importantly, we find that AKD and PCC are not likely to interact in the whitewater cycle. This refutes the general idea that PCC lowers AKD retention. Adsorption kinetic experiments revealed that although cationic AKD and cPAM do not flocculate, cPAM does increase the retention of AKD by assisting its deposition onto fibers. Asymmetrical polymer bridging explains both the increase in AKD retention and the behavior of AKD flocculation kinetics with cPAM. Although the initial kinetics are nearly independent of cPAM dosage, excess cPAM delays the achievement of maximum possible AKD retention due to starch and cPAM re-conformation. Lastly, it was found that the addition of cPAM results in an increase in the bond strength between AKD and fibers, thereby eliminating AKD detachment. Studies on the twin-wire sheet former found that cPAM increases the first-pass retention of AKD three-fold. The twin-wire former was proven to be a useful tool for studying AKD retention.
机译：本文研究了烷基烯酮二聚体（AKD）与沉淀碳酸钙（PCC）之间的相互作用。尽管已深入研究了AKD上浆和与纤维素反应的机理，但对AKD保留的方法了解甚少。这项研究的目的是确定AKD和PCC异絮凝的条件和时间尺度，并确定PCC对非保留AKD的影响。我们还想了解AKD与cPAM交互作用的机制，并在双金属丝成型机上进行实验。我们概述了创建由阳离子淀粉包覆且不含外来物质的AKD乳液的程序。我们发现AKD和PCC均均絮凝，但两种化学物质之间未发生异絮凝。这表明PCC和AKD不直接交互。相反，从AKD颗粒表面去除淀粉有助于PCC的均相絮凝（通过聚合物桥联）。这表明碱性环境是导致AKD水解的最重要因素。更重要的是，我们发现AKD和PCC在白水循环中不太可能相互作用。这驳斥了PCC降低AKD保留的一般想法。吸附动力学实验表明，尽管阳离子AKD和cPAM不会絮凝，但cPAM确实会通过帮助其沉积到纤维上来增加AKD的保留率。不对称聚合物桥联解释了AKD保留量的增加和cPAM的AKD絮凝动力学行为。尽管初始动力学几乎与cPAM剂量无关，但是由于淀粉和cPAM的重新构象，过量的cPAM会延迟最大可能的AKD保留时间。最后，发现添加cPAM导致AKD和纤维之间的粘合强度增加，从而消除了AKD的分离。对双金属丝成型机的研究发现，cPAM将AKD的首过保留率提高了三倍。事实证明，双线成型机是研究AKD保持力的有用工具。

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