| Wood-Plastic Composites (WPCs) is a kind of green and environment-friendlymaterial developed in the last few years, they are made from all kinds of thermo-plasticsand wooden fibers (or rice husks, wheat straw, corn stalks, peanut shells and other plantfibers) with a certain amount of additives and fillers through different composite approachesand they are of high performance and high added value. WPCs combine the maincharacteristics of wood and plastics and they are widely used to replace plastics and woodinnumerous occasions.They can help to alleviate the shortage of wood resources and therecycling difficulties of plant fiber and plastic waste, therefore, they have great developmentvalue and social benefits.Since WPCs are flammable materials and they are required to be flame retardant inmany application fields, it is necessary to research their fire-retardant property; on the otherhand, WPCs contain plant fibers and they may be infected by fungi, as a result, their servicelife will be affected, so mould-proof treatment of WPCs is very significant. This paperfocused mainly on the above two aspects, treated and studied WPCs based on polyethylenefunctionally.Firstly, this paper discussed the effect of the kind and content of plant fiber on theperformance of WPCs. The study found that: with the increase of the content of plant fiber,the tensile strength, flexural strength, flexural modulus and VST got significantimprovement, while the impact strength and MFR of WPCs decreased. At the same time,through the research of water absorption and combustion performance of WPCs, we foundthe water absorption of WPCs increased with increasing content of wood fiber. In the caseof the same dosage, the water absorption of HDPE/PF composites is higher than that ofHDPE/BF composites. The water absorption of composites is lower when the plant fibercontent is less, however, when the plant fiber content is more than40phr, the waterabsorption of composites improved significantly.Plant fiber could reduce the horizontal flame spread rate to some extent, improve themelt dripping of composites during burning effectively and increase the char yield. The LOI of composites increased gradually with the increase in the content of plant fiber, the LOI ofpure HDPE was18.7, when wood fiber content was60%, the LOI of HDPE/PF, HDPE/BFcomposites were25.3,25.0respectively, which were35.3%,33.7%higher than that of pureHDPE.Intumescent flame retardant APP and APP/PER complex were adopted to modifyWPCs, the results showed that APP could dramatically improve the flame-retardantproperty of WPCs. With the increase of the content of APP, the LOI of the material increasegradually, when the dosage of APP was20phr, UL-94test achieved V-0grade and the LOIof flame retardant composites was29.4. Besides, APP could improve the thermal stabilityof composites. There were some holes on the surface of char residue of flame retardantmaterial system containing APP and the surface was loose. The flame-retardant effect ofAPP was better than APP/PER complex, that is, the synergistic effect of PER was limited inWPCs. The wood flour could be used as a charring agent instead of PER. Kie and La2O3were conducive to form more compact and dense char layer, which may effectively stop thetransfer of heat and oxygen.Different types of mould-proof reagent were employed to treat WPCs. It was foundthat: A moderate amount of mould-proof reagent could effectively improve the resistance tomould of WPCs, the mould-proof capabilities of HDPE/PF composites were better than thatof HDPE/BF composites: only a small amount of mould-proof reagent could makeHDPE/PF composites against fungal infection. For HDPE/BF composites, the effect ofmould-proof treatment with1#mould-proof reagent was the best. A small number ofmould-proof reagent might enhance the mechanical properties of HDPE/BF composites to acertain extent, while it had little effect on HDPE/BF composites. Besides, there was littleimpact on the thermal stability of composites. |
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