改性微胶囊化聚磷酸铵阻燃天然橡胶

Modified Microencapsulated Ammonium Polyphosphate Flame Retardant for Natural Rubber

通过原位聚合法制备了聚乙烯醇(PVA)改性的三聚氰胺(MEL)-甲醛树脂(VMF)微胶囊,并对聚磷酸铵(APP)/介孔分子筛MCM-41进行了包覆,得到了一种核壳结构的微胶囊阻燃剂[MVMF-(A/M)]。采用IR、SEM对包覆前后的阻燃剂结构及形貌进行了表征。并将其加入到天然橡胶(NR)中,通过LOI、UL 94、TG和拉伸测试考察了NR复合材料的阻燃和力学性能。实验结果表明:MVMF-(A/M)在20℃水中的溶解度为0.3474 g,相比APP溶解度降低了41.7%,且MVMF-(A/M)粒子表面更粗糙;与其他阻燃天然橡胶体系相比,添加了MVMF-(A/M)的NR复合材料(NR3)的极限氧指数最高,达到30.1%,UL-94达到了V-0级,拉伸强度为8.84 MPa,断裂伸长率为310.20%。

Polyvinyl alcohol（ PVA） modified melamine（ MEL）-formaldehyde resin（ VMF）microcapsules were prepared through in situ polymerization. Then,the obtained microcapsules was used to coat ammonium polyphosphate（ APP）/mesoporous molecular sieve MCM-41 to afford a kind of flame retardant（ MVMF-（ A/M）） with a novel core-shell structure. The structure and morphology of the flame retardant before and after coating was characterized by IR,solubility test and SEM. Subsequently,the flame retardant was added into natural rubber（ NR）,and the flame retardancy and mechanical properties of NR composites were tested by limited oxygen index（ LOI）,vertical burning test（ UL-94）,thermal gravimetric analysis（ TGA） and tensile test. The results showed that the solubility of prepared MVMF-（ A/M） was 3. 474 g/L in 20 ℃ water,which was a decrease of 41. 7% compared with APP. Meanwhile,MVMF-（ A/M） particle surface became rough. Compared with other flame retardants for NR systems,NRMVMF-（ A/M） composites achieved the highest limited oxygen index value due to the addition of MVMF-（ A/M）,the limited oxygen index of NR-MVMF-（ A/M） composites reached 30. 1%. Moreover,the samples could pass the V-0 rating in the UL-94 tests. Additionally,the tensile strength of the sample reached 8. 84 MPa and its elongation at break reached 310. 20%.