Preparation Of Hyperbranched Flame Retardant Polymer And ITS Applicaion Into Rubber Composites

Montmorillonite (MMT) is a clay mineral with highly ordered lattice arrangement. Because of the unique structure, MMT has characteristics of cation exchange, absorption, and dispersivity, etc. By organic modification, MMT can be used in different polymer as reinforcing agents or flame-retardant additives Pentaerythritol (PER) is a polyatomic alcohol of highly symmetry, and it is widely used in rubbers, plastics, coatings and other fields. Its special structure is very suitable for the fabrication of dendrimers. With the characteristics of strong elasticity, good insulation, etc, natural rubber (NR) is largely used in automotive industry, construction, petrochemical, and other industries. The requirement of flame retardant NR is increasing nowadays. Halogenated flame retardants is commonly used in preparation of NR composites. Such kind of composites have good flame-retardant efficiency and reasonable costs, but they can produce pollution and are harful to environment. NR composites with common fillers such as magnesium hydroxide or aluminum hydroxide generally may have reduced physical and mechanical properties. Hyperbranched polymer has been concerned in the recent years for its plenty of end groups and highly branched structure. It also possesses good reaction activity and easy preparation characteristics.In this research, we attempted to make use of the good compatibility of hyperbranched polymer with common polymers and its charateristics of plentyful end groups. The phosphorus and nitrogen elements were thus introduced into the hyperbranched polymer, and its thermal stability was studied. The flame-retardant and tensile properties were researched after its application into NR composites. Detailly, our research focused on the four following aspects:(1) Preparation of hyperbranched flame-retardant organic montmorillonite (FR-HOMMT). FR-HOMMT was prepared by hyperbranched modification of OMMT. SEM, FTIR, XRD, TGA were used to characterize its structure and properties. Results showed that the lamellar structure of FR-HOMMT was successfully stripped, and FR-HOMMT had excellent thermal stability.(2) Application of FR-HOMMT in NR composites. Composites with different content of FR-HOMMT were prepared. Measurements such as the same burning duration, tensile strength, elongation at break, and abrasion loss, etc, were used in the the properties research of NR/FR-HOMMT composites. Results showed that flame-retardant, mechanical, and abrasion properties of the composite with10phr of FR-HOMMT were obviously improved.(3) Preparation of hyperbranched flame-retardant pentaerythritol (FR-HPER). Pentaerythritol (PER) was modified by hyperbranched technology, and FR-HPER was prepared by different molar ratio of monomer and PER. FTIR, TGA, MALDI-TOF, etc, were used to characterize its structure and properties. Results showed an excellent thermal stability was obtained of FR-HPER when the molar ratio of PER and monomer was1:4.(4) Application of FR-HPER into natural rubber. NR/FR-HPER composites were prepared by two methods. One serie of composites had same content but with different types of FR-HPER, and another series were prepared with the same FR-HPER but with different content. Measurements such as burning time at the same length, horizontal burning time, tensile strength, elongation at break, and abrasion loss, etc, were used to characterize the properties of NR/FR-HPER composites. Results showed the flame-retardance and mechanical properties of the composite with5phr of FR-HPER were improved in a certain extent, but its abrasion properties needed further improvement.