ﺑﺮرﺳﯽ ﺗﺨﺮﯾﺐ ﻧﻮري، ﺗﺠﺰﯾﻪ زﯾﺴﺘﯽ، ﺟﺬب آب و ﺧﺎﺻﯿﺖﻫﺎي ﻣﮑﺎﻧﯿﮑﯽ ﭘﻼﺳﺘﯿﮏﻫﺎي ﺗﺨﺮﯾﺐ ﭘﺬﯾﺮ ﺑﺮاي اﺳﺘﻔﺎده در ﺻﻨﻌﺖﻫﺎي ﺑﺴﺘﻪ ﺑﻨﺪي

Study of photodegradation, biodegradability, water absorption, and mechanical properties of biodegradable plastics for using in packaging industries

ﺳﺎﺑﻘﻪ و ﻫﺪف: ﭘﺴﻤﺎﻧﺪﻫﺎي ﺷﺎﻣﻞ ﻣﻮاد ﭘﻼﺳﺘﯿﮑﯽ، ﺗﺒﺪﯾﻞ ﺑﻪ ﻣﺸﮑﻞﻫﺎﯾﯽ در ﺳﺮاﺳﺮ ﺟﻬﺎن ﺷﺪه اﻧﺪ. زﯾﺮا ﻣﺪت زﻣﺎن ﺗﺠﺰﯾﻪ ﻣﻮاد ﭘﻠﯿﻤﺮي ﭘﺎﯾﻪ ﻧﻔﺘﯽ در ﻣﺤﯿﻂ زﯾﺴﺖ ﻃﻮﻻﻧﯽ ﻣﯽﺑﺎﺷﺪ. ﺑﺴﺘﻪ ﺑﻨﺪي ﭘﻼﺳﺘﯿﮑﯽ ﯾﮑﯽ از ﻣﻌﻤﻮلﺗﺮﯾﻦ ﻣﻨﺒﻊﻫﺎي ﺗﻮﻟﯿﺪ اﯾﻦ ﭘﺴﻤﺎﻧﺪﻫﺎ ﻣﯽﺑﺎﺷﺪ. ﯾﮑﯽ از راﻫﮑﺎرﻫﺎي ﻣﻘﺎﺑﻠﻪ ﺑﺎ اﯾﻦ ﻣﺸﮑﻞ، اﺳﺘﻔﺎده از ﭘﻼﺳﺘﯿﮏﻫﺎي ﺗﺨﺮﯾﺐ ﭘﺬﯾﺮ اﺳﺖ.ﯾﮑﯽ از روشﻫﺎي ﺗﻮﻟﯿﺪ ﭘﻼﺳﺘﯿﮏﻫﺎي زﯾﺴﺖ ﺗﺨﺮﯾﺐ ﭘﺬﯾﺮ، آﻣﯿﺰه ﺳﺎزي اﯾﻦ ﻣﻮاد ﺑﺎ ﭘﻠﯿﻤﺮﻫﺎي ﻃﺒﯿﻌﯽ اﺳﺖ. ﺗﺨﺮﯾﺐ ﻧﻮري ﻧﯿﺰ ﯾﮑﯽ از اﻧﻮاع روشﻫﺎي ﺗﺠﺰﯾﻪ اﯾﻦ ﻣﻮاد در ﻃﺒﯿﻌﯿﺖ ﻣﯽﺑﺎﺷﺪ ﮐﻪ ﺑﻪ ﻧﻈﺮ ﻣﯽرﺳﺪ ﺑﺮاي ﭘﻼﺳﺘﯿﮏﻫﺎي ﻗﺎﺑﻞ اﺳﺘﻔﺎده در ﺻﻨﻌﺖﻫﺎي ﺑﺴﺘﻪ ﺑﻨﺪي ﮐﻪ در ﺑﯿﺸﺘﺮ ﻣﻮارد داﻧﺴﺘﻪ ﯾﺎ ﻧﺪاﻧﺴﺘﻪ ﺗﻮﺳﻂ ﺷﻬﺮوﻧﺪان در ﻃﺒﯿﻌﺖ رﻫﺎ ﻣﯽﺷﻮد، راﻫﮑﺎر ﻣﻨﺎﺳﺒﯽ اﺳﺖ. ﻣﻮاد و روشﻫﺎ: در اﯾﻦ ﭘﮋوﻫﺶ آﻣﯿﺰه ﻗﺎﺑﻞ ﺗﺨﺮﯾﺐ ﻧﻮري و زﯾﺴﺖ ﺗﺨﺮﯾﺐ ﭘﺬﯾﺮي از ﻧﺸﺎﺳﺘﻪ و ﭘﻠﯽ اﺗﯿﻠﻦ ﺳﺒﮏ ﺧﻄﯽ، ﺑﺮاي اﺳﺘﻔﺎده در ﺻﻨﻌﺖﻫﺎي ﺑﺴﺘﻪ ﺑﻨﺪي ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮار ﮔﺮﻓﺘﻪ اﺳﺖ. ﻣﯿﺰانﻫﺎي ﻣﺨﺘﻠﻔﯽ از ﻧﺸﺎﺳﺘﻪ)%15% ،10% ،7,4%،3,7 و 20%( در آﻣﯿﺰه ﻫﺎ ﺗﻬﯿﻪ ﺷﺪه اﺳﺖ. از ﭘﻠﯽ اﺗﯿﻠﻦ ﻣﺎﻟﺌﯿﮏ اﻧﻬﯿﺪرﯾﺪ ﺑﻪﻋﻨﻮان ﮐﻮﭘﻠﯿﻨﮓ اﯾﺠﻨﺖ اﺳﺘﻔﺎده ﺷﺪه اﺳﺖ. ﺟﺬب آب و رﺷﺪ ﻗﺎرچ روي ﻧﻤﻮﻧﻪﻫﺎ اﻧﺠﺎم ﮔﺮﻓﺘﻪ و ﺧﺎﺻﯿﺖﻫﺎي ﻣﮑﺎﻧﯿﮑﯽ آنﻫﺎ ﺑﺮرﺳﯽ ﺷﺪه اﺳﺖ. ﻧﻤﻮﻧﻪﻫﺎ ﺑﻪ ﻣﺪت 3 ﻣﺎه در ﻧﻮر ﻣﺴﺘﻘﯿﻢ ﺧﻮرﺷﯿﺪ ﻗﺮار داده ﺷﺪهاﻧﺪ. آزﻣﻮن ﻣﻘﺎوﻣﺖ ﮐﺸﺸﯽ ﻗﺒﻞ و ﺑﻌﺪ از ﻗﺮارﮔﯿﺮي ﻧﻤﻮﻧﻪﻫﺎ در ﻣﻌﺮض ﻧﻮر ﺧﻮرﺷﯿﺪ اﻧﺠﺎم ﮔﺮﻓﺘﻪ اﺳﺖ و آنﻫﺎ ﺑﻪ ﻣﺪت 11 ﻣﺎه درون ﺧﺎك ﻗﺮار داده ﺷﺪﻧﺪ ﺗﺎ ﺗﺨﺮﯾﺐ زﯾﺴﺘﯽ ﺷﺎن ﺑﺮرﺳﯽ ﺷﻮد. ﻫﻤﭽﻨﯿﻦ آنﻫﺎ ﺑﻪ ﻣﺪت 84 روز در ﻣﻌﺮض آﺳﭙﺮژﯾﻠﻮس ﻧﯿﺠﺮ ﻗﺮار داده ﺷﺪﻧﺪ. ﻧﺘﺎﯾﺞ و ﺑﺤﺚ: ﺑﻨﺎﺑﺮ ﺑﺮرﺳﯽ ﻫﺎي اﻧﺠﺎم ﺷﺪه ﺑﺎ اﻓﺰاﯾﺶ ﻣﯿﺰان ﻧﺸﺎﺳﺘﻪ، ﻣﻘﺎوﻣﺖ ﮐﺸﺸﯽ آﻣﯿﺰه و ﻣﺪول ﯾﺎﻧﮓ ﮐﺎﻫﺶ ﻣﯽﯾﺎﺑﺪ، ﭘﺲ از 3 ﻣﺎه در ﻣﻌﺮض ﻧﻮر ﻗﺮار ﮔﺮﻓﺘﻦ، ﻣﻘﺎوﻣﺖ ﻣﮑﺎﻧﯿﮑﯽ و ﻣﺪول ﯾﺎﻧﮓ ﺑﻪ ﻣﺮاﺗﺐ ﮐﺎﻫﺶ ﯾﺎﻓﺖ. ﻧﺘﺎﯾﺞ آزﻣﻮن ﺟﺬب آب ﻧﺸﺎن داد ﮐﻪ ﺑﺎ اﻓﺰاﯾﺶ ﻣﯿﺰان ﻧﺸﺎﺳﺘﻪ ﺑﺮ ﺟﺬب آب ﻧﻤﻮﻧﻪﻫﺎ اﻓﺰوده ﺷﺪه اﺳﺖ. ﺟﺬب آب ﺑﻪ وزن ﻣﻠﮑﻮﻟﯽ و ﺗﻌﺪاد ﮔﺮوهﻫﺎي ﻫﯿﺪروﮐﺴﯿﻞ ﻣﻮﺟﻮد ﺑﺴﺘﮕﯽ دارد. ﻣﻘﺎﯾﺴﻪ وزن ﻧﻤﻮﻧﻪﻫﺎ ﻗﺒﻞ و ﺑﻌﺪ از دﻓﻦ در ﺧﺎك ﻧﺸﺎﻧﮕﺮ ﺗﺨﺮﯾﺐ زﯾﺴﺘﯽ آنﻫﺎﺳﺖ، ﻧﻤﻮﻧﻪﻫﺎي ﺷﺎﻣﻞ ﻧﺸﺎﺳﺘﻪ ﭘﺲ از 11 ﻣﺎه ﻗﺮار ﮔﯿﺮي در ﺧﺎك دﭼﺎر ﮐﺎﻫﺶ وزن ﺷﺪﻧﺪ و اﻓﺖ در ﺧﺎﺻﯿﺖﻫﺎي ﻣﮑﺎﻧﯿﮑﯽ ﺑﺮ اﺛﺮ آزاد ﺷﺪن و ﺧﺮوج ﻧﺸﺎﺳﺘﻪ رخ داده اﺳﺖ . ﻫﺮ ﭼﻪ ﻣﯿﺰان ﻧﺸﺎﺳﺘﻪ در آﻣﯿﺰهﻫﺎ ﮐﻤﺘﺮ ﺑﺎﺷﺪ، آﻣﯿﺰه ﺖ ﺗﺄﺛﯿﺮ ﻣﺎﺗﺮﯾﺲ ﭘﻠﯽاﺗﯿﻠﻦ ﺳﺒﮏ ﻗﺮار ﮔﺮﻓﺘﻪ و در دﺳﺘﺮس ﻣﯿﮑﺮوارﮔﺎﻧﯿﺴﻢﻫﺎ ﻗﺮار ﻧﻤﯽﮔﯿﺮد. ذرات ﻧﺸﺎﺳﺘﻪاي ﮐﻪ در ﺳﻄﺢ ﻧﻤﻮﻧﻪ ﻗﺮار دارﻧﺪ زودﺗﺮ در ﻣﻌﺮض ﺗﺨﺮﯾﺐ زﯾﺴﺘﯽ ﻗﺮار ﻣﯽﮔﯿﺮﻧﺪ. ﺑﺎ اﻓﺰاﯾﺶ زﻣﺎن ﻣﺎﻧﺪ، ﻧﻤﻮﻧﻪﻫﺎ در ﺧﺎك ﻣﯿﮑﺮوارﮔﺎﻧﯿﺴﻢﻫﺎ و آﻧﺰﯾﻢﻫﺎي آنﻫﺎ ﺑﻪ ﻗﺴﻤﺖﻫﺎي دروﻧﯽ ﻣﺎﺗﺮﯾﺲ ﭘﻠﯿﻤﺮي ﻧﻔﻮذ ﮐﺮده و ﺳﺒﺐ ﺗﺠﺰﯾﻪ ﮐﻞ ﭘﻠﯿﻤﺮ ﻣﯽﺷﻮﻧﺪ. رﺷﺪ ﻗﺎرچ روي ﻧﻤﻮﻧﻪﻫﺎ ﺷﺎﻣﻞ ﻣﯿﺰان ﻣﺨﺘﻠﻒ ﻧﺸﺎﺳﺘﻪ، ﻧﺸﺎﻧﮕﺮ ﻗﺎﺑﻠﯿﺖ ﺗﺠﺰﯾﻪ زﯾﺴﺘﯽ ﻧﻤﻮﻧﻪﻫﺎي ﭘﻠﯿﻤﺮي ﺗﻮﺳﻂ ﻣﯿﮑﺮوارﮔﺎﻧﯿﺴﻢﻫﺎ ﻣﯽﺑﺎﺷﺪ. زﯾﺴﺖ ﺗﺨﺮﯾﺐﭘﺬﯾﺮي ﻣﯿﮑﺮوﺑﯽ ﺑﻪ ﻇﺮﻓﯿﺖ ﻣﯿﮑﺮوارﮔﺎﻧﯿﺴﻢ و ﻣﺘﺎﺑﻮﻟﯿﺴﻢ ﻣﯿﮑﺮوﺑﯽ واﺑﺴﺘﻪ اﺳﺖ. ﻧﺘﯿﺠﻪﮔﯿﺮي: ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻧﺘﺎﯾﺞ ﺑﻪدﺳﺖ آﻣﺪه ﭘﻠﯿﻤﺮ ﺗﻮﻟﯿﺪي زﯾﺴﺖ ﺗﺨﺮﯾﺐ ﭘﺬﯾﺮ و ﻗﺎﺑﻞ ﺗﺨﺮﯾﺐ ﻧﻮري ﻣﯽﺑﺎﺷﺪ. و ﻗﺎﺑﻠﯿﺖ اﺳﺘﻔﺎده در ﺻﻨﻌﺖﻫﺎي ﺑﺴﺘﻪ ﺑﻨﺪي را دارد. دﻓﻦ در ﺧﺎك ﺷﺒﯿﻪ ﺳﺎزي ﻣﺤﻞ دﻓﻦ زﺑﺎﻟﻪ ﻣﯽﺑﺎﺷﺪ. در ﺻﻮرﺗﯽﮐﻪ اﮔﺮ اﯾﻦ ﻧﻤﻮﻧﻪﻫﺎ در ﻣﺤﯿﻂ ﺗﺠﺰﯾﻪ ﻣﻨﺎﺳﺐ ﻗﺮار ﮔﯿﺮﻧﺪ ﮐﻤﺘﺮ دﭼﺎر اﻓﺖ ﺧﺎﺻﯿﺖﻫﺎ ﻣﯽﺷﻮﻧﺪ و ﺷﺮوع ﺑﻪ ﺗﺨﺮﯾﺐ ﻣﯽﻧﻤﺎﯾﻨﺪ. ﺷﺎﯾﺎن ﺗﻮﺟﻪ اﺳﺖ ﮐﻪ ﻧﻤﻮﻧﻪﻫﺎي ﺗﻮﻟﯿﺪ ﺷﺪه ﺑﺮاي ﺑﺴﺘﻪ ﺑﻨﺪي ﻣﻮاد ﻏﯿﺮ ﺧﻮراﮐﯽ ﻣﻨﺎﺳﺐ ﻣﯽﺑﺎﺷﻨﺪ.

Introduction: Plastic wastes are becoming a major problem all around the world. Degradation of synthetic polymers takes a long time, and so they remain in the environment for many years. Plastic packagings are one of the main sources of solid wastes. Using biodegradable plastic may be a solution to this problem. Mixing synthetic polymers with biopolymers is one way to produce biodegradable plastics. Another way to degraded plastic materials is photodegradation. Photodegradable plastics could be used in packaging industries because a huge amount of packaging plastics are being thrown away in nature. Materials and methods: In this research, photodegradable and biodegradable compounds of starch and linear low-density polyethylene were prepared. Samples with different levels of starch (i.e., 3.7, 7.4, 10, 15, and 20 %wt) with a constant amount of 5% PE-g-MA were prepared. PE-g-MA used as coupling agent. The mechanical properties of polymer sample were done by santam instrument. Water absorpton of starch base polymer were evaluated. Soil burial tests shown the biodegradability of samples in the nature. starch-based polymer was exposed to mold growth to simulate biotic degradation. Photodegradability of samples were measured by exposure them to sunlight for 3 months. In order to determine bacterial degradability, samples were exposed to aspergilus niger for 84 days. Results and discussion: The tensile strength and Young’s modulus were decreased by the increase in starch content of the samples. The results of water absorption of the samples showed that when the starch percentage was higher, the water absorption was significantly increased. After being buried in soil for 11 months, the weight of the blends was decreased by increasing the starch level, which is an indication of biodegradation. The weight loss after removal of starch was probably caused by soil microorganisms. If the amount of starch is low, the compound would be affected by the low-density polymer matrix and unavailable to soil microorganisms. The more the samples remained in the soil, the more consumption of polymer chain by microorganism happened. Mold growth on polymeric samples confirmed the biodegradability of LLDPE/starch sheets. Mould biodegradation depends on microorganisms and their metabolism. Conclusion: According to the results, the blends are biodegradable and photodegradable and so are applicable in packaging industries. Soil burial is a simple simulation of the landfill. These blends are suitable for packaging goods