مقايسه الياف طبيعي سلولزي و الياف سنتزي آراميد بر ويژگي هاي مكانيكي كامپوزيت بستر اپوكسي

Comparative study on natural cellulosic and synthesized aramid fibers on mechanical properties of epoxy composite

در ﺑﺴﯿﺎري از ﮐﺎرﺑﺮدﻫﺎي ﻣﻬﻨﺪﺳﯽ، ﺑﻪ ﺗﻠﻔﯿﻘﯽ از وﯾﮋﮔﯽﻫﺎ ﻧﯿﺎزﺳﺖ و ﯾﮏ ﻣﺎده ﻧﻤﯽ-ﺗﻮاﻧﺪ ﺗﻤﺎﻣﯽ اﻟﺰاﻣﺎت را ﺑﺮآوردهﺳﺎزد. ﺑﻨﺎﺑﺮاﯾﻦ ﺗﻮﻟﯿﺪ و ﮐﺎرﺑﺮد ﮐﺎﻣﭙﻮزﯾﺖﻫﺎ در ﺻﻨﺎﯾﻊ ﻣﺨﺘﻠﻒ از ﻃﺮﯾﻖ ﺗﺮﮐﯿﺐ ﻣﻮاد، ﮐﺎرﺑﺮد وﺳﯿﻌﯽ ﯾﺎﻓﺘﻪاﺳﺖ. ﺑﺎاﯾﻨﺤﺎل، ﻣﺴﺎﺋﻞ زﯾﺴﺖ-ﻣﺤﯿﻄﯽ ﮐﺎرﺑﺮد اﺟﺰاي دوﺳﺘﺪار ﻣﺤﯿﻂزﯾﺴﺖ را در ﺗﺮﮐﯿﺐ ﮐﺎﻣﭙﻮزﯾﺖﻫﺎ اﻟﺰام ﻣﯽﻧﻤﺎﯾﺪ. از اﯾﻦرو در اﯾﻦ ﭘﮋوﻫﺶ، اﻣﮑﺎن ﺟﺎﯾﮕﺰﯾﻨﯽ اﻟﯿﺎف ﻃﺒﯿﻌﯽ ﺳﻠﻮﻟﺰي ﺑﺎ اﻟﯿﺎف ﺳﻨﺘﺰي وارداﺗﯽ آراﻣﯿﺪ در ﺗﺮﮐﯿﺐ ﮐﺎﻣﭙﻮزﯾﺖ ﭘﺎﯾﻪ اﭘﻮﮐﺴﯽ در ﺣﻀﻮر و ﻋﺪم ﺣﻀﻮر ﻧﺎﻧﻮﺑﻨﺘﻮﻧﯿﺖ ﺑﺮرﺳﯽﺷﺪ. اﻟﯿﺎف ﻣﺰﺑﻮر در ﺳﻄﻮح 0/5 و 0/25 درﺻﺪ و ﻧﺎﻧﻮﺑﻨﺘﻮﻧﯿﺖ در ﺳﻄﻮح 0/1 و 0/2 درﺻﺪ در رزﯾﻦ اﭘﻮﮐﺴﯽ ﻣﺨﻠﻮط و ﭘﺲ از ﺣﺒﺎبزداﺋﯽ و ﺗﮑﻤﯿﻞ ﮔﯿﺮاﯾﯽ ﮐﺎﻣﭙﻮزﯾﺖ، ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮارﮔﺮﻓﺖ. ﻧﺘﺎﯾﺞ ﻧﺸﺎنداد ﮐﻪ ﮐﺎﻫﺶ ﻣﯿﺰان ﺣﺒﺎب و ﻧﯿﺰ ﺑﻬﺒﻮد ﯾﮑﻨﻮاﺧﺘﯽ ﺷﮑﻞﮔﯿﺮي ﻇﺎﻫﺮي از ﻃﺮﯾﻖ ﮐﺎﻫﺶ ﮐﺎرﺑﺮد اﻟﯿﺎف، ﺑﯿﺸﺘﺮﯾﻦ ﺗﺎﺛﯿﺮ را ﺑﺮ وﯾﮋﮔﯽﻫﺎ دارد. ﺑﻨﺤﻮﯾﮑﻪ ﻣﻘﺎوﻣﺖ ﮐﺸﺸﯽ ﮐﺎﻣﭙﻮزﯾﺖ ﺣﺎوي %0/5 اﻟﯿﺎف ﮐﻮﻻر ﮐﻤﺘﺮ از 0/%25 ﺑﻮد. ﺑﺮﺧﻼف اﻟﯿﺎف آراﻣﯿﺪ، اﻓﺰاﯾﺶ ﮐﺎرﺑﺮد ﻣﻨﻔﺮد اﻟﯿﺎف ﺳﻠﻮﻟﺰي از 0/25 درﺻﺪ ﺑﻪ 0/5 درﺻﺪ ﻣﻨﺠﺮ ﺑﻪ ﺑﻬﺒﻮد ﭼﺸﻤﮕﯿﺮ ﻣﻘﺎوﻣﺖ ﮐﺸﺸﯽ و ﻣﺪولﻫﺎي اﻻﺳﺘﯿﺴﯿﺘﻪ ﮐﺸﺸﯽ و ﮔﺴﯿﺨﺘﮕﯽ ﮔﺮدﯾﺪ. ﺑﻨﺤﻮﯾﮑﻪ در ﺳﻄﺢ ﮐﺎرﺑﺮد % 0/5، وﯾﮋﮔﯽﻫﺎي ﻣﺬﮐﻮر و ﻧﯿﺰ ﺳﻄﺢ ﺗﺨﺮﯾﺐﺷﺪه ﮐﺎﻣﭙﻮزﯾﺖ ﺳﻠﻮﻟﺰي ﺑﺮ اﺛﺮ ﺿﺮﺑﻪ ﺑﺎﻟﺴﺘﯿﮏ، ﺣﺎﺋﺰ ﺑﺮﺗﺮي ﺑﻮده ﮐﻪ ﻣﯽﺗﻮان ﻋﻠﺖ را ﺑﻪ ﻃﻮل ﮐﻮﺗﺎهﺗﺮ اﻟﯿﺎف ﺳﻠﻮﻟﺰي )1/8mm( در ﻣﻘﺎﯾﺴﻪ ﺑﺎ اﻟﯿﺎف ﮐﻮﻻر )4/8mm( و ﺗﻮزﯾﻊ ﯾﮑﻨﻮاﺧﺖﺗﺮ اﻟﯿﺎف در ﻣﺎده زﻣﯿﻨﻪ ﻧﺴﺒﺖ داد. ﻟﯿﮑﻦ ﺟﺬب اﻧﺮژي در اﻟﯿﺎف ﮐﻮﻻر )54 ژول( ﺑﯿﺸﺘﺮ از اﻟﯿﺎف ﺳﻠﻮﻟﺰي )50 ژول( ﺑﻮد. ﮐﺎرﺑﺮد ﻣﻨﻔﺮد اﻟﯿﺎف ﺳﻠﻮﻟﺰي و ﮐﻮﻻر و ﺗﻠﻔﯿﻖ آﻧﻬﺎ ﺑﺎ ﻧﺎﻧﻮﺑﻨﺘﻮﻧﯿﺖ ﻣﻨﺠﺮ ﺑﻪ ﺗﻘﺎرن ﺷﮑﺴﺖ و ﮐﺎﻫﺶ ﭼﺸﻤﮕﯿﺮ ﺳﻄﺢ ﺗﺨﺮﯾﺐ )ﺗﺎ 40 درﺻﺪ( و ﺗﺮكﻫﺎي ﺑﺴﺘﺮ ﮐﺎﻣﭙﻮزﯾﺖ در ﻣﻘﺎﯾﺴﻪ ﺑﺎ ﻧﻤﻮﻧﻪ ﺷﺎﻫﺪ )cm2 17( رزﯾﻦ اﭘﻮﮐﺴﯽ ﮔﺮدﯾﺪ.

Most of engineering applications require a series of properties which is not provided by a certain material. Therefore, composites production and utilization have extensively developed in various industries by materials combining. On the other hand, environmentally concerns compel environmentally friendly components in the composites manipulation. Then in this study, substitutability of imported synthesized Kevlar fiber by natural cellulosic fiber in epoxy resin matrix were investigated at presence and absence of nano bentonite. Dosages of 0.25 and 0.5 of fibers and 0.1 and 0.2 of nano bentonite were mixed into the epoxy resin and after bubble removal and complete curing, the composite panels were tested. The results showed that bubble removal and formation evenness mostly influenced the mechanical properties. So, tensile strength of 0.5% Kevlar composites was lower than its 0.25%. But opposite to the Kevlar, cellulose fiber increasing addition improved tensile strength and elasticity and rupture moduli properties, significantly. Consequently, 0.5% cellulosic fiber composite revealed higher the properties with lesser surface area demolished by the ballistic impact, which all attributed to shorter length of cellulosic fiber (1.8mm) compared to Kevlar (4.8mm), resulted in better composite formation. But Kevlar composite energy absorption (54 J) was higher than cellulosic composite (50 J). Individual incorporation of Kevlar and cellulose fiber into epoxy resin and their combinations with nano bentonite drastically reduced the demolished surface area (up to 10 cm2) and matrix cracks propagation with symmetrically pinned hole compared to the solely epoxy panels (10 cm2).