| Chitosan(CTS) is a kind of eco-friendly, renewable and natural riched polysaccharidemacromolecules. The complex is an ideal biological material in terms of food preservationand packaging due to its bactericidal function and film forming properties. But theapplication of CTS membrane was limited by the unsatisfactory physical mechanicalproperties and high cost. In order to broaden its application field, more and moreresearches were focused on improving the mechanical performance, water resistance andbarrier properties. Some inorganic materials such as, calcium phosphate, calcium carbonate,montmorillonite and carbon nanotube, can bring a good reinforcing effect on thoseproperties, but they can also bring significant undesirable differences on the interfaceproperties and the safety of these synthetic material was still unknown. Nowadays, somephysical modification indeed made an improvement of the mechanical properties on theCTS material. Meanwhile, these improvements sacrificed some inherent advantages ofCTS as biodegradation, and also bring some unknown negative impacts on the safety.Therefore, a new kind of enhanced material or component should be studied to improve theperformance of chitason material.As a kind of environmental-friendly bio-macromolecular material, nano-cellulosewhisker(NCC) has extensive sources, low cost, low density and can be easily prepared.Nano-crystalline cellulose which looks like rod has relatively high aspect ratio, perfectcrystal structure, good thermal stability and good mechanical properties which make it anew type of green reinforcing filler for chitosan.This article is focused on selecting nano whisker from pineapple leaf fiber(PALF) asreinforced material, blending modification was studied for the CTS, the influence of thepervious to light performance, mechanical properties, dynamic mechanical properties,swelling properties, thermal stability. Discuss this kind of composite material and value inthe field of the application of green packaging materials. Specific contents and results areas follows:(1) The nano-whiskers of PALF were characterized with a series of methods.Nano-particle size Analyzer, scanning electron microscopy (SEM) and transmission electron microscope analysis show that: rod-like nano-structure of the NCC has a typicallength of100~700nm and diameter of10~50nm, length/diameter is large. Fourier spectrum(FTIR) and x-ray diffraction (XRD) analysis show that the NCC has the basic chemicalcomposition in the structure of cellulose,and the crystallinity of nano-whiskers ofpineapple leaf fiber is from57.8%to82.7%.(2) The thermal stability of degumming of pineapple leaf fiber and pineapple leaffiber of nano-whiskers was studied by thermal analysis. The thermal stability ofnano-whiskers of pineapple leaf fiber was studied using thermogravimetric analysismethod. The results indicate that micro-whiskers after degumming of pineapple leaf fiberis a one-step reaction in nitrogen, while the thermal degradation of nano-whiskers ofpineapple leaf fiber in nitrogen is a two-step reaction. Degradation temperature of PALFand nano-whiskers rose with increasing of the heating rate; the degradation rate of CpandCfare not impacted by the heating rate of B; the thermal degradation activation energy (E)of PALF changes with α, first increase and then decrease.(3) The single facter experiment results of composite film show that ultrasonicpower and ultrasonic time was150w and24min respectively, the mechanical properties ofcomposite was biggest. Under this condition, when the glycerin content was0.25g,mechanical properties and of the composite membrane get the best combination(4) SEM images of cross sections exhibited a good dispersion at less percentage ofNCW of Pineapple leaf fiber. The electrostatic and hydrogen bonds can be found to form arigid reinforced cross-linking network through FT-IR. From the XRD patterns ofcomposite films, the addition of NCC of PALF influences the crystallinity of CTS whensolution casting.(5) Composite films under dry and wet conditon were tested for their mechanicalperformance. With increasing NCC content, the tensile strength significantly increasedfrom53.72Mpa to73.36MPa,12.88Mpa to26Mpa respectively. The breakingelongation of composite film decreased from31.12%to12.7%in the dry condition, whilethe breaking elongation of composite film increased from15.36%to35.2%in the wetcondition.(6) The dynamic mechanical properties test results showed that, with the enhancedchitosan composite membrane with pineapple leaf fiber nano-whiskers could increase thestorage modulus significantly, and the glass transition temperature was also improved.(7) The swelling property experimental results showed that, the swelling properties ofthe composite membrane with nano-whiskers of PALF were reduced clearly. The lighttransmission performance of the composite membrane showed a downward trend with increased the content of nano-whiskers from pineapple leaf fiber; however, it was still at ahigh level. Crystalline and the thermal stability of the composite membrane were bothincreased with increased the content of nano-whiskers from PALF. |
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