The Study Of Packaging Film And Hollow Capsule Material Based On Nanocrystalline Cellulose

In the past 10 years,the average demand for plastic film is growing at a rate of 10.0%per years in the mainland of China.The plastic film and packaging industry is in the stage of rapid development which will last for a very long time.Polyethylene,polyvinyl chloride,etc.,are the main packaging film materials.However,these materials can not be degraded,so it has brought serious white pollution.In the situation of environment pollution and energy shortage,people began to develop biodegradable food packaging film.Biodegradable materials which can be used in large-scale industrial processing are gelatin,chitosan and starch.But the source of gelatin in not clear,the metal ions in chitosan exceed the standard,the starch based films are mechanically not strong enough and optically not sufficiently transparently.So,finding and developing new natural polymer materials has became a very important research topic.Nanocrystalline cellulose(NCC)is the material which can be obtained from plant fiber by hydrolysis or mechanical method.The degree of NCC is close to the limit of polymerization degree,and it's size is in the nanometer level.In this paper,We prepared NCC from bleached hardwood pulp by acid hydrolysis.Then we prepared NCC/GG and NCC/GL film,which has better mechanical properties and oxygen barrier properties.At the same time,NCC hollow capsule was prepared with the addition of polyethylene glycol(PEG)and glycerol.The results show that the hardness of GG film increased by 96.2%and the elastic modulus of film increased by 50.6%with the addition of NCC.At the same time,the optical properties of the films improved by 50%,and the oxygen barrier properties improved by 65.3%.NCC/GG film could be completely dissolved in water after 5 hours.The packaging properties of NCC/GG film were also evaluated,and the difference between the preservative film and NCC/GG film was not significant.NCC/GG film meets the standards of food packaging film,and it will have a good application prospectNCC/gelatin films prepared by blast drying method have many advantages compared with the films prepared by freeze drying method.The addition of NCC can improve the mechanical properties of the composite films,and decrease the oxygen transmission rate of the films.But when the content of NCC reached 40.0%,the mechanical properties of the composite films were becoming worse.The reason of this phenomenon may be that,NCC content has exceeded a critical value,so NCC particles began to accumulate.It is found that the shear stress decreased with the additon of PEG and glycerol in the system.The mechanical properties study of the capsule showed that the elastic modulus of the capsule continued to decrease with the additon of PEG.But with the increase of the glycerol content,the elastic modulus of the capsule increased at first and then decreased.The elongation at break of the capsule increased with the addition of glycerol and PEG.By studying the swelling property of the capsule,we found that the swelling ratio tends to be a stable value after forty minutes.