تهيه و مشخصه يابي فيلم كامپوزيت هاي زيست تخريب پذير بر پايه پلي وينيل الكل/ نشاسته تقويت شده با نانو الياف سلولزي خاك اره

چكيده انگليسي :

Preparation and Characterization of PVA Starch Nanocomposites Reinforced by Cellulose Nanofibers from Aspen Wood Sawdust Mohsen Sadeghi Shapourabadi mohsen sadeghi@ce iut ac ir 22 January 2014 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor TayebeBehzad tbehzad@cc iut ac irAbstract Recently usage of biodegradable polymers instead of common petroleum polymers has been grown Starchis considered as the most capable biopolymer for the production of biodegradable plastics because of itsimmense potential and low price to use in nonfood industries However starch has issues like weakmechanical properties and low moisture resistance To improve these problems starch can be blended withsuperior polymers or reinforced materials Poly vinyl alcohol PVA is a polymer with appropriatemechanical and optical properties which can be a good candidate for blending with starch The main purposeof this research is to produce and characterize PVA starch nano biocomposite reinforced with cellulosenanofibers CNF extracted from aspen wood sawdust as an inexpensive and unusable waste source Toextract cellulose nanofibers from sawdust a chemo mechanical method was used Chemical treatment causesto remove lignin hemicelluloses and pectin from cellulose structure and then mechanical treatmentdisintegrates cellulose micro fibers to nanofibers In chemical stage first sawdust extraction was exhaustedwith ethanol for 6 hours in a soxhlet extractor and then bleached with 3 hydrogen peroxide solution toremove some of insoluble lignin Afterward acidic hydrolyze with hydrochloric acid alkali treatment withdilute sodium hydroxide and bleaching with sodium chlorite were carried out to eliminate hemicellulose pectin soluble lignin and insoluble lignin After the chemical stages the final isolation of cellulosenanofibers was executed with a super grinder Chemical characterization of fiber was performed with amodified TAPPI standard test on raw material and chemically treated fibers and concluded that cellulosecontent was increased from 49 9 to 79 1 that indicate appropriate elimination of non cellulosicsubstances In addition FTIR characterization on untreated and chemically treated fibers showed thathemicellulose and lignin were removed and lateral Order Index which is an indication of crystallinity of fiberwas increased from 0 893 to 1 201 SEM images also showed that the average diameter of isolated nanofibersis 74 nanometers The next stage of this research is preparation of PVA starch composites with extractedcellulose nanofiber as the reinforcement phase 3 5 7 10 wt glycerol as the plasticizer and borax as thecrosslinking agent applying solution casting method Mechanical properties of composites were investigatedand showed 24 increase in tensile strength 5 cellulose nanofibers In addition Young s modulus wasincreased from 12 to 27 MPa SEM images of fracture surface of composites demonstrated suitabledispersion of nanofibers in matrix Also moisture absorption of composite reinforced by 5 CNF wasreduced from 54 3 to 41 Dissolution of nanocomposite include 5 CNF in water was also decreased by62 compare to pure PVA Starch sample Finally transparency test of samples with spectrophotometerindicated that increasing cellulose nanofiber content of composites causes to reduce transparency of films Key words Cellulose Nanofiber Sawdust Aspen Wood Nanocomposite PVA Starch

صادقي شاپورآبادي، محسن

تهيه و مشخصه يابي فيلم كامپوزيت هاي زيست تخريب پذير بر پايه پلي وينيل الكل/ نشاسته تقويت شده با نانو الياف سلولزي خاك اره

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