| Recently, with the irritation of ethrel in tapping rubber tree and the adjustment of distribution and processing of natural rubber, the traditional preservative ammonia, ammonia and Tetramethyl Thiuradsulfide (TMTD)/ZnO have been difficult to meet the actual need of production. As the awareness of environmental protection increased, research on the new efficient, economical, environmental friendly no ammonia or low ammonia natural rubber latex(NRL) preservative has become a hot topic in the rubber latex industry.Our team has successfully chosen a nonammonia preservative HY (a triazine derivative) which has a good performance in saving fresh NRL and concentrated NRL. However, the high price limited its widely use. This subject is to solve this problem, combining HY with cheap ammonia to study the effects of composite preservative HY/NH3on the preservation for fresh NRL and concentrated NRL, performances of raw rubber, vulcanized rubber, vulcanized rubber films. Compare the properties with high ammonia(HA) and ammonia and TMTD/ZnO samples. The results are shown as below:When ammonia is0.10%and HY is0.05%or ammonia is0.05%and HY is0.10%(by weight), the fresh NRL can be steadily saved for at least48h and72h, respectively. And the volatile acid number(VFA NO.) is both below1.0. The physical and chemical properties of raw rubber are according to the standard of SCR5in GB/T8081-2008. The mixed rubber show a good processing ability and the vulcanized rubber show good physical and mechanical properties. The tensile strength of composite preservative samples are1.94MPa and5.81MPa higher than ammonia samples, respectively; and the tear strength are3.94kN/m and7.34kN/m higher than ammonia samples, respectively. The aging factor of composite preservative samples are about1, and ammonia sample is0.52, which is smaller than that of composite samples.When ammonia is0.4%and HY is0.1%, concentrated NRL can be steadily preserved for at least6months. The VFA NO. is below0.06and the mechanical stability test(MST) can arrive at650s according to the national standard GB/T8289-2008. Besides, lowest cost will spend in this composite formula. The cost of this composite formula is just14.41yuan and22yuan higher than that of HA and ammonia and TMTD/ZnO, respectively.The processing performance show that the concentrated natural rubber latex with composite formulas has good film-forming property and drying property. It has a high drying speed and it is4and3.5times than that of HA sample and ammonia and TMTD/ZnO, respectively. The vulcanized films show good comprehensive physical and chemical properties. Its tensile strength and tear strength are at least2.11MPa and1.77kN/m higher than HA samples, respectively. They share a close thermal degradation performance.HY/NH3dipped product has a good film forming property with even surface and homogeneous thickness. And there are no pinholes and cracks. The color of HY/NH3dipped product is lighter than that of HA products. |
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