Research Of Laminaria Japonica Foamed Cushioning Materials

During the transport and distribution process, using of reasonable cushioning package canreduce the impact of external mechanical vibrations such as various factors on the productproduced. Currently, the most popular cushioning material is the foamed polymer. However,petroleum resources are limited and the foamed polymer isn’t degradable, which have theseriously negative effects to the environment. Development of a biodegradable, renewablebiomass cushioning material with excellent performance is an effective way to overcome theproblem of foamed polymer and attracted much attention. Biomass cushioning material is a mostalternative due to its wide distribution, renewable, biodegradation. Laminaria japonica isinexpensive and rich in the sea, which is the most important and highest yield of algaecultivation class, and is considered as a typical third-generation biomass material. Alginate isrich in laminaria japonica, which form sodium alginate with sodium ions. Sodium alginate notonly has good plastic viscosity, emulsification, shape retention and stability, but also has theability to form fibers and films, being co-solvent with easy protein and starch.In this paper, foam cushioning material laminaria japonica (LFCM) was prepared byfreeze-drying method without the addition of any aid conditions material, from laminariajaponica alginate and sodium ions solution. The sodium ions solution of NaOH and Na2CO3were used.It was found that the foaming cushioning material from laminaria japonica with thetreatment of NaOH solution (LFCMh) showed a dense branch structure, and was made of somethin-walled openings. With the concentration of NaOH solution increasing, the complexviscosity of LFCMhreduced, became more brittle and collapsed easily. The range of pore sizedistribution narrowed down and the average pore size gradually decreased with increase of theconcentration of NaOH solution. The density of cushioning material (ρ*) increased while theporosity (θ) decrease. The energy absorption of compression decreased. The initial elasticmodulus decreased, reached a minimum value and then increased. The maximum value of theenergy absorption and the initial elastic modulus were42.38kJ/m3and0.15MPa, respectively.Laminaria japonica became viscous gel after treatment of NaOH solution due to the formation of sodium alginate. However, sodium alginate easily depolymerized with a strongalkaline NaOH solution. Hence, the complex viscosity of LFCMhdecreased, LFCMhbecomeseasy to collapse and fragile, and its porous structure is difficult to maintain. Sodium alginate alsocan be obtained using Na2CO3solution to treat the laminaria japonica, and the depolymerizationof sodium alginate can be reduced due to its less weak alkaline. Laminaria japonica foamcushioning material from Na2CO3solution (LFCMc) was stable without collapse. As theconcentration of Na2CO3solution increase, the porous structure is more obvious and dense. Thedistribution of pore size became narrowed coupling with the decreasing average pore diameter.Like the LFCMh, the density of LFCMc(ρ*) increased while the porosity (θ) decrease.Nevertheless, the porosities of all the LFCMcsamples are over90%. The initial elastic modulusand the energy absorption increased with their maximum value of0.627MPa, and329.81kJ/m3,respectively. In comparison with the LFCMh, the distributions of pore sizes located at a largerrange, and the average pore diameters were slightly larger, the change in ρ*with theconcentration of Na ions was less, and energy absorption of compression is much larger. Hence,LFCMcwas more stable the porous structure and larger θ, and larger energy absorption ofcompression.Based on the analysis of the mechanical properties of LFCMcand according to thestaggered cube model, we constructed a mechanical constitutive relation model of LFCM.Finally, the experimental data were fitted according to the model. In this model, the twodirections (x1and x2) of force interaction of the cushioning material were also considered,reflecting the linear elastic material and yield the platform, and densification stage of thematerials prepared by vacuum freeze-drying method. The model can be easily predicted therelation of the mechanics of materials under different orientations and pore cell size.