Study On Preparation And Properties Of Halogen-Free Flame Retardent Polypropylene Composites

Polypropylene(PP) was a kind of general-purpose plastics,which was used in many fields,such as chemicals, chemical fiber, construction, light industry, household appliances and packaging.But PP was a carbohydrate,so it was easy to fire.it’s oxygen index(OI) was 17%, therefore it was necessary that PP was modified by flame retardants.With the deepening of the concept of environmental protection,the halogen-free flame retardants were widely followed, and the intumescent flame retardants got very rapid development.In this thesis,PP was modified by halogen-free flame retardants,which regarded ammonium polyphosphate/pentaerythritol(APP/PER) as main flame retardant,and 4AZeolite/red phosphorus(MRP) as synergistic flame retardants.Halogen-free flame retardant polypropylene composites were produced by molten compound process of double screw.This thesis systematically studied the effects of the additives on flame retardant performances, and thermal stability performances.The burning charcoal layers were taken analysis by scanning electron microscope(SEM) and infrared spectroscopy.The content of main flame retardant was confirmed by studying the effects on the performances of polypropylene composites through the different ratios of APP/PER and contents.The results showed that with the increasing content of APP/PER, the flame retardant performance got better,and rheological properties were on the rise.But the mechanical properties decreased.Taking every properties into account,the optimal proportion of APP/PER was 2.5:1 and content was 25%.IO was 41%,and flame retardant performance was excellent, and mechanical properties and impact strength got little effect.4AZeolite and MRP were respectively added into flame retardant polypropylene composites,it turned out that with the increasing of the synergistic flame retardants content he flame retardant performances of polypropylene composites obviously improved,but the mechanical properties and rheological properties got slightly down.When the content of 4AZeolite reached 2%,the 10 attained 43%;When the content of MRP reached 5%,the 10 also attained 43%.From the SEM photographs of carbon layer surface it could be seen that the carbon layer was very dense.so it could protect the internal materials.and it was beneficial to flame retardant.To improve toughnesses of flame retardant polypropylene composites, ethylene propylene diene monomer (EPDM) was maxed.The experimental results showed that EPDM could vastly increase toughnesses,but meanwhile it reduced the tensile strength and bending strength,at the same time 10 decreased clearly.