Study On Controlling Pore Structure Of Foam Materials Based On Plant Fibers

Foam plastic is an indispensable cushion packaging material in the fields of construction,industry,and agriculture.Traditional foam plastics are prepared by petroleum derivatives.They are non-biodegradable and difficult to recycle.The discarded products cause damage to the environment.Plant fiber-based foam materials have a broad prospect in replacing traditional foams because of their completely biodegradation.However,there are a few hydrogen bonds formed due to large size of fibers.Many issues are coming along with it,such as oversize pores,non-uniform stucture and poor performance.In this work,pore structure was controlled by designing the foam structure,optimizing the preparation process and improving the bubbles stability.Those preparation technologies above are discussed to prepare plant fiber-based foam materials.Structure of fibers was redesigned by fibrillating.The generated microfibrils helped to form more hydrogen bonds and pore structure.And then,the influence of the degree of fibrillation on the pore structure was investigated.Research had shown the pores of treated foams with smaller apertures became more uniform compared with untreated foams,the quantities of pores also increased.The shape and density of pores closed to round and maximum,respectively,so the foam had the best compressive mechanical properties when the fibers were fibrillated to 60°SR.Further studies were carried out,the technologies such as fiber solid content,surfactant dosage,and drying temperature could control the size and shape of pores.The results showed the density and uniformity of pores increased gradually with increasing solid content.The mechanical properties of the materials also become excellent.The number and uniformity of pores is reduced when the solid content exceeded 3 wt%.When the temperature raised up to 60?,the structure of pores distributed evenly and the density of them improved progressively,along with mechanical properties index of materials.Improper amount of sodium lauryl sulfate lead to the shape and distribution of pores are irregular.When the content of SDS is 0.2%~0.3%,the more pores distributed uniformly,for the reason that the foams had a better compressive mechanical property.Amylopectin as a reinforcing phase was added to further increase the number of hydrogen bonds and optimize the pore structure.The impact of the dosage of amylopectin on the pore structure was studied.A lamellar starch wall structure appeared in the SEM image after adding amylopectin.The average areas of pores decreased with increasing amylopectin content,and the distribution of pores became uniform gradually.All the indexes of the compressive properties of the foam were improved,for instance,yield strength and energy absorption value increased about 50%.The dodecanol as foam stabilizer was used to make bubbles more stable and optimize the pore structure.The study found that the incorporation of dodecanol can increase the strength of the liquid film and the drainage time,the stability of the foam is as well improved.According to study,the proper content of dodecanol could put the number and size of the pores up,thus the foams' energy absorption value increased nearly 248.39%.According to the above results,the pore structure of plant fiber-based foam materials was controlled by ways of fibrillating,optimizing process and adding amylopectin and dodecanol.This study provides theoretical basis and application reference for the preparation of full-degradable plant fiber-based foams.