Study Of The Surface Modification Of Pyrophyllite And Its Application In Rubber

Pyrophyllite is a kind of new industrial mineral of layered silicate which is consisted of Al-O octahedron and Si-O tetrahedron. Compared with other mineral, pyrophyllite showed a lot of advantages such as resistance to chemical attack, excellent insulating characteristic, lubrication performance and low price, and drawing more and more attention by polymer industry. When pyrophyllite was filled in rubber matrix directly or with high quantity, it was difficult to disperse uniformly which resulted in descent of the properties of composites because of their poor interfacial interaction. So we need to modify the surface of pyrophyllite power to increase the consistency and the dispersion of pyrophyllite power in rubber material.In the second chapter, pyrophyllite slurry and powder were modified by titanate coupling agents (NDZ-101, NDZ-201), silane coupling agents (KH-550, KH-560). The influences of modified pyrophyllite contents, modification methods, coupling agent type and dosage on the pyrophyllite/SBR composite properties were studied, when the modified pyrophyllite were used as the filler of SBR. The main results were as followed.The modified pyrophyllite had a reinforcing effect on SBR, and the mechanical properties of compound increased distinctly, when pyrophyllite slurry was modified by NDZ-101 which dosage was 2.0% of pyrophyllite dosage. The quantity of modified pyrophyllite had more effect on the properties of rubber, when filled with 120 phr modified pyrophyllite, the tensile strength and the tear strength of vulcanizates increased 253%, 133%. As for this, pyrophyllite could be modified, activated and filled with large amount of modified pyrophyllite in SBR was completely feasible.In the third chapter, pyrophyllite was wet-modified by KH-550, KH-560, NDZ-101, NDZ-201. Effect of coupling agent type, dosage and the ratios of modified pyrophyllite/CB on processability, mechanical properties and curing characteristics of covers rubber were studied, when the modified pyrophyllite were filled in conveyor belt with NR cover. The result showed that reinforcement of modified pyrophyllite to covers rubber was good, when the dosage of KH-550 was about 2.0% of pyrophyllite contents. Compared with N330, the reinforcing property and wear resistance of modified pyrophyllite were low, but the processability and aging resistance were high. So filled with a certain amount of pyrophyllite modified in covers rubber could improve the performance of conveyor belt.In the forth chapter, pyrophyllite slurry and powder were modified by KH-550, KH-560, NDZ-101, NDZ-201. By evaluating the dispersibility, activation index, pervasion time, oil absorption value, the chapter determined the efficient coupling agent type, dosage and the corresponding modification methods. The results showed that for the modified pyrophyllite, pervasion time to distilled water was increased markedly, absorption of DOP was decreased, activation index and sedimentation volume were increased. Those results indicated that the surface of pyrophyllite was covered with a layer organic molecular, the modification changed the polarity of the surface of pyrophyllite, the surface changed from hydrophilic to hydrophobic.The optimal technology factors were determined. For dry modification, the optimal condition was as follows: time was about 60-65min, and the dosage of coupling agent was about 1.5%-2.0% of pyrophyllite contents. For wet modification, time was about 45 min and coupling agent dosage was also about 1.5%-2.0%. And titanate coupling agent NDZ-101 exhibited higher modification effect than other coupling agents.This research work has important significance in expanding the application of pyrophyllite in SBR and NR.