Study On Structure And Properties Of Halogen-free Flame Retardant Silicone Rubber And Its Composites

It was well known that flame retardant without halogen element was applied inpolymer material became a hot topic in recent years. The addition of fire retardant canimprove the flame retardant. But this modification method had a bad influence onmechanical property of composite. The final objective of this work is to manufacture newflame retardant by microencapsulation technology. The physical properties of final SRand POM specimens were manufactured, in particularly the fire retardant property,mechanical property and thermal property.The microcapsule APP flame retardant was made by physical encapsulating method.The APP was coated by phenolic resin with microencapsulation method. Themicroencapsulation technique of chemical method was successfully applied on theMg(OH)2was coated by melamine resin. The phenolic resin and melamine resin weretested by Fourier Transform Infrared. The coating structure was observed clearly in thepictures of SEM test.The inflammable point of microcapsule APP flame retardant increased30.9℃compared to the pure APP material. The flame retardant of silicone rubber was improvedremarkably. The oxygen index of SR specimen was33%with40portion microcapsuleAPP flame retardant added. As compared to normal APP, the addition of microcapsuleAPP flame retardant not only could have an improvement of6%in oxygen index, butalso improve mechanical performance of final SR sample. The compatibility betweenmatrix and microcapsule APP flame retardant was better than sample with pure APP. Theinflammable point of microcapsule Mg(OH)2flame retardant was464.5℃. There had a123.1℃improvement compared to Mg(OH)2. The oxygen index of SR specimen withmicrocapsule Mg(OH)2flame was32.5%and this result shown that the specimen was afire resistance material. There was a16.3%increase in tensile strength compared to thesample with pure Mg(OH)2.In order to resolve the question of flame retardant without halogen element in SR,the Al(OH)3, APP and Fe2O3were added in SR specimen with different portion. Theeffect of synergy was shown in SR samples. The mechanical property was decrease tosome extent because of the addition of inorganic material.The POM/SR blends were preparation with different portion. The oxygen index of POM/SR (100/15) was25%. There was a38.9%improvement compared to the purePOM sample. The addition of SR had a good effect on the crystallization of POM as anucleating agent. The degree of crystallinity of POM/SR (100/10) blend was75.44%.The properties of POM/SR/Mg(OH)2composite was studied in this project. Themicrocapsule Mg(OH)2flame was applied in this composites. The flame retardantproperty of POM/SR/Mg(OH)2(100/15/10) composite was the best and the oxygenindex was27.5%. The impact property of POM/SR/Mg(OH)2(100/15/10) also had a43.28%improvement than POM/SR (100/15) blends. The addition of Mg(OH)2has aneffect of heterogeneous nucleation on POM crystal and increase the crystallization rate ofPOM sphaerocrystal. The storage modulus and loss modulus increased with the additionof Mg(OH)2. The POM sphaerocrystal structure was observed clearly in SEM graphics.