The Preparation And Characterization Of Nanocellulose Crystal/polyving Akohol Composite Material From Bamboo

The objective of this paper is to study the preparation of the NCC which was used as reinforcement to add to the NCC/PVA composites.The physical,mechanical and chemical properties of the composites with different NCC contents were investigated to support to explain the effects of NCC contents on the mechanical and thermal properties of the resulted composites.Transmission electron microscopy(TEM),Fourier infrared analyzer(FTIR)and X-ray diffraction analyzer(XRD)were used to used to acquire the microscopic feature and crystallization properties of the composites.Thermogravimetric analyzer(TG)Dynamic thermomechanical analyzer(DMA)and ultraviolet-visible spectrophotometer were used to acquier the themal decomposition properties,the viscoelasticity properties and the transparency properties of the composites.The main research conclusions showed as follows:Firstly,with the increase of the bamboo ages,the content of Klasson lignin content had no significant changes from 23.22% to 23.40%(bamboo shell except).Simultaneously,The alpha cellulose content of different age bamboos increased from 51.80% to 53.12%,but increased from tip parts to base patrs.The extractive content was increase before the decrease,but has a maximum for the three years bamboo.However,the extractive content had a gradually decrease from tip part to base part.So,the six month bamboo was the best raw materials for preparing of the purified cellulose.Secondly,the TEM testing results showed that the length and diameter of the NCC were 150-250 nm and 8-10 nm respectively which showed as rod-like structure and had a large length to diameter ratio.Thirdly,the FTIR results showed that the remaining ingredient was cellulose after the chemical treatment and the XRD testing results show that the crystal structure of NCC had no change after the chemical treatment,but the crystallinity of the cellulose from raw material to NCC was increase from 59.87% to 71.91%.The TG results showed that the thermal stability of the NCC was lower than alpha cellulose,but higher than the raw bamboo fiber.Fourthly,the characterization of the composite film materials tested by SEM showed that NCC had a good uniform distribution and compatibility in PVA hybrid system when the lower amounts of NCC to be added.However,NCC occured together and had poor compatibility in the mixed system when the amounts of NCC to be added by 5%-7%.The light transmittance tests showed that the light transmittance of the composite films reduced gradually with the increase of NCC content.XRD testing showed that the pure PVA has a certain degree of crystallinity which has no influence with that of NCC.Fifth,mechanics performance testing showed that the addition of NCC can improve the mechanical properties of the composite materials obviously.The higher tensile strength,which increased by 55.8%,of the composites occured when the addion of NCC was 3%.With the increment of NCC,the tensile modulus increased gradually while the elongation at break decreased gradually.TG testing showed that the additon of NCC could improve the thermal stability of the composite films effectively,which will also fell,due to the reunion phenomenon,when the addition of NCC was more than 7%.DMA testing showed that the additon of NCC could raise the glass transition temperature of the PVA composite film and the degradation of the composite material films increased with the increase of the NCC content.The swelling degree of the composite films decreased with the increase of the NCC content.