Promhuad Khwanchat, Smitthipong Wirasak
Specialized center of Rubber and Polymer Materials in agriculture and industry (RPM), Department of Materials Science, Faculty of Science, Kasetsart University, Chatuchak, Bangkok 10900, Thailand.
Office of research integration on target-based natural rubber, National Research Council of Thailand (NRCT), Chatuchak, Bangkok 10900, Thailand.
Polymers (Basel). 2020 Mar 27;12(4):741. doi: 10.3390/polym12040741.
The main objective of this work is to study the effect of hydroxylamine sulfate or stabilizer states (solid vs liquid) on the storage hardening of natural rubber (NR). Several types of natural rubber samples were prepared: unstabilized NR samples and stabilized NR samples: (i) dry NR with 0.2 and 2.0 parts per hundred rubber (phr) of dry hydroxylamine sulfate, and (ii) natural latex with 0.2 and 2.0 phr of liquid hydroxylamine sulfate. The samples were characterized immediately (time 0) and after 12 weeks of storage at room temperature, respectively. We found that the Mooney viscosity, gel content, and Wallace plasticity of NR without a stabilizer increases with storage hardening for 12 weeks. However, two types of stabilized NR samples represent constant values of those three parameters, because hydroxylamine sulfate inhibits network and gel formation in NR. Interestingly, the mixing states (solid vs liquid) between natural rubber and the stabilizer affect the properties of stabilized NR. This could be explained by the better dispersion and homogeneous nature of liquid stabilizers in natural latex (liquid state), and thus the higher loading of the stabilizer in the liquid state. This is important, as the stabilization of NR properties as a function of time is required by rubber industry. This study is a utilization model from theory to application.
这项工作的主要目的是研究硫酸羟胺或稳定剂状态（固态与液态）对天然橡胶（NR）储存硬化的影响。制备了几种类型的天然橡胶样品：未稳定化的NR样品和稳定化的NR样品：（i）含有0.2和2.0份每百份橡胶（phr）干燥硫酸羟胺的干燥NR，以及（ii）含有0.2和2.0 phr液态硫酸羟胺的天然乳胶。分别在立即（时间0）和室温下储存12周后对样品进行表征。我们发现，没有稳定剂的NR的门尼粘度、凝胶含量和华莱士可塑性随储存硬化12周而增加。然而，两种类型的稳定化NR样品这三个参数呈现恒定值，因为硫酸羟胺抑制NR中的网络和凝胶形成。有趣的是，天然橡胶与稳定剂之间的混合状态（固态与液态）会影响稳定化NR的性能。这可以通过液态稳定剂在天然乳胶（液态）中更好的分散性和均匀性来解释，因此液态中稳定剂的负载量更高。这很重要，因为橡胶工业需要NR性能随时间的稳定化。本研究是一个从理论到应用的利用模型。
