Studies On The Structure And Properties Of HDPE Wood Composites Modified With Artificial Marble Powder

In recent years,wood plastic composites(WPC),as a new type of composite material,develops rapidly around the world.Because it looks like wood and does not contain formaldehyde,it can replace some wood products,which will protect the forest resources.Inorganic filler is a commonly used additives in WPC,which can improve the mechanical properties and heat resistance of WPC and reduce the cost.This subject chose artificial marble powder(AMP),which was large number of abandoned and hard to recycle,to modify the HDPE-wood composites.The influence on mechanical properties,thermal stability,processing properties,aging properties and flammbilies of composites were studied systematically.Physical and chemical properties of AMP were investigated.It turned out that AMP,an industrial waste generated from artificial marble processing,was mainly made of aluminum hydroxide(Al(OH)3)and unsaturated polyester,which occupied 59.8% and 39.3% respectively.The median diameter of AMP was 65.5 μm and it had a wide particle distribution.The particle size of AMP was in a range from several to hundreds of micrometers.And the shapes of AMP varied with different particle sizes.The effects on the properties of HDPE-wood composites filled with AMP were investigated.Incorporating AMP into HDPE-wood composites could increase the flexural strength and flexural modulus of composites but obviously decrease the notched impact strength.The interface modifiers could improve the mechanical properties of composites and compatibilizers performed better than coupling agents on the comprehensive performance of composites.When the content of maleic anhydride grafted polyethylene(MAPE)was 20% of the content of fillers,the notched impact strength and tensile strength increased by 108% and 55.6% respectively compared to the composites without MAPE.Scanning electron microscopy(SEM)photographs revealed that MAPE improved the interfacial adhesion between fillers and HDPE matrix.In addition,the incorporation of AMP increased the vicat softening temperature(VST),the char residue,the degree of crystallinity and decreased the water absorption.However,the addition of AMP had adverse effect on processing property.The incorporation of AMP improved the oxidation induction time(OIT)and thermal aging property of the HDPE-wood composites.With 60 phr(parts per hundreds of resin)AMP,the OIT reached to 78.0 min,increased by 71.4% compared to pure HDPE-wood composite.When the aging time was 14 days,the retention of notched impact strength,tensile strength and flexural strength reached to 102.6%,101.7% and 100.8%,respectively.There were no obvious bubbles,cracks and other defects on the surface of the composites after aging.The apparent activation energy of the composites decreased with the increase of AMP content by Flynn-WallOzawa method.Based on Toop equation to predict the service life,when the composites was exposed to 60℃,it took a few hundred years to reach the 5% weight loss,which indicated that the degradation rate of composites under natural conditions was extremely slow.The incorporation of AMP could improve the flame retardant property of HDPE-wood composites.The increase of AMP content could decrease horizontal burning rate,heat release rate and total heat release quantity.Ammonium polyphosphate(APP)had better flame retardant property compared to AMP modified by DOPO-KH560.With the addition of APP,the heat release rate peak,average heat release rate and total heat release decreased significantly.APP could obviously promote the char yield of the composites.When the APP content was 30 phr,AMP content was 30 phr,the vertical burning test reached V-0 rating and limit oxygen index(LOI)reached to 30.4.