不同稳定剂对天然胶乳稳定性的影响

Effects of Different Stabilizers on the Stability of Natural Rubber Latex

低氨、无氨浓缩胶乳在乳胶制品加工应用过程中存在性能不足的问题,包括稳定性较差、硫化速度慢、湿凝胶强度低等,主要与稳定剂的使用有关。稳定剂对天然胶乳的性能影响很大,本研究选用氢氧化钾(KOH)、氨、十二烷基硫酸钠(SDS)和月桂酸钾4种稳定剂添加到天然胶乳中,研究不同稳定剂对鲜胶乳和超低氨浓缩胶乳稳定性的影响。结果表明:KOH能快速提升天然胶乳pH;维持鲜胶乳黏度稳定;提升鲜胶乳的机械稳定性(MST),尤其是当用量超过0.3%时作用更明显;但KOH会使浓缩胶乳黏度上升,导致浓缩胶乳增稠,对提升浓缩胶乳MST和氧化锌机械稳定性(ZST)作用不明显;KOH能显著提升浓缩胶乳的热稳定性以及橡胶粒子的粒径。氨用量较低时能快速提升天然胶乳的pH,但用量较高时提升作用下降;氨能稳定鲜胶乳的黏度,提升鲜胶乳MST,但当用量超过0.2%时提升作用不明显;同时,氨能维持浓缩胶乳的流动性,稳定黏度值;氨对提升浓缩胶乳的MST、ZST和热稳定性作用不明显;对胶乳橡胶粒子的粒径影响较小。SDS单独添加时会导致鲜胶乳增稠;但能维持浓缩胶乳流动性,抑制黏度升高;能缓慢提升浓缩胶乳的MST和ZST,提高橡胶粒子粒径,但对热稳定性提升作用不明显。月桂酸钾单独使用时同样会导致鲜胶乳增稠,同时也会导致浓缩胶乳缓慢增稠;但月桂酸钾能快速提升浓缩胶乳MST和ZST,同时月桂酸钾会导致浓缩胶乳热稳定性快速下降,对提高橡胶粒子粒径也有一定效果,但当用量超过0.3%时粒径降低。因此,在浓缩胶乳生产过程中需要控制稳定剂的种类和用量。

In this study,potassium hydroxide(KOH),ammonia,sodium dodecyl sulfate(SDS)and potassium laurate were added to NRL to study the effects of different stabilizers on the stability of NRL.The results showed that KOH could quickly increase pH value of NRL,maintain the viscosity of fresh latex,improve the mechanical stability(MST)of fresh latex,especially when the dosage exceeds 0.3%.But KOH would increase the viscosity of concentrated natural rubber latex(CNRL),lead to the thickening of the CNRL.It had no obvious effect on improving MST and the me-chanical stability(ZST)of the concentrated latex.KOH could significantly improve the thermal stability of the CNRL,significantly improve the particle size of the rubber particles.When the dosage of ammonia was low,pH value of NRL could quickly increased,but when the dosage was high,the effect of improvement was not obvious.Aammonia could stabilize the viscosity of fresh latex,increase MST of fresh latex,but when the dosage exceeded 0.2%,the increase was no longer obvious.At the same time,ammonia could maintain the fluidity of CNRL and stabilize the viscosity value.Ammonia had no obvious effect on improving MST,ZST and thermal stability of CNRL,it had no obvious effect on the particle size of latex rubber particles.SDS would increase the viscosity of the fresh latex,resulting in the thickening of the fresh latex,but it could maintain the fluidity of the CNRL and inhibit the viscosity increase.It could slowly increase MST and ZST of CNRL.Increasing the average particle size of rubber particles also had a certain effect.Potassium laurate would increase the viscosity of fresh latex,resulting in thickening of fresh latex,at the same time,it would also cause CNRL to thicken slowly.Potassium laurate could also rapidly increase MST and ZST of concentrated latex,and cause CNRL to heat up the stability decreases rapidly.It also had a certain effect on increasing the average particle size of rubber particles,but when the dosage exceeded 0.3%,the particle size would also decrease.Therefore,the type and dosage of stabilizers need to be controlled during the production of CNRL.