Preparation And Study On The Water Resistant Properties Of Plant Oil Based Polymer/Nanocellulose Composites

Recently,due to the over-exploitation of fossil fuels and the increasing environmental pollution problems,the development of environmentally friendly,renewable,and degradable bio-based materials from agricultural waste has received extensive attention in order to actively respond to the global call for green environmental protection.Cellulose,which comes from plants and is inexhaustible,is the most abundant biopolymer on earth.Due to its internal natural hydrogen-bonded crystalline structure,membrane materials based on cellulose exhibited high mechanical properties,excellent thermal properties,low oxygen permeability,favorable optical properties and biocompatibility.At present,cellulose film materials have great potential application value in emerging functional materials such as optoelectronics,smart textiles,and high-performance packaging.The field has not been further promoted widely.Based on the above research background,in this work,lignocellulose was used as raw material,and vegetable oil-based polymer was used as wet performance modifier of cellulose composites,and prepares cellulose-based composite films by two techniques:Pickering emulsion compounding and Pickering emulsion polymerisation,respectively.The main research work and conclusions of this paper are as follows:(1)Cellulose nanofilaments(CNFs)were prepared from home-made wood pulp type I cellulose in the laboratory by mechanical defibrillation such as grinding and high-pressure homogenisation.Sunflower oil-based epoxy polymers(EPSFMA)were prepared by esterification,amidation,polymerization and epoxidation of sunflower oil.The EPSFMA/CNFs composite microspheres were prepared by Pickering emulsion compounding,then blended,filtered and cured by drying to produce high moisture strength composite membranes.SEM photographs showed that the EPSFMA/CNFs composite membranes had a similar three-dimensional network structure compared to the pure cellulose membrane material,but with a slightly looser structure and increased porosity between the fibrils.The moisture resistance of the composite membrane gradually increases with increasing EPSFMA content,and when the oil content reaches 30%,the surface water contact angle of the composite membrane can reach 114.2°,with typical hydrophobic material properties.Compared with the pure CNFs film,the equilibrium water absorption of the material is reduced from 140 wt%to 43 wt%,the wet tensile strength after water absorption is increased from 14.7 MPa to 73.1 MPa,while the strength reduction of the wet film is reduced from 91.5%to 42%.(2)Rubber seed oil polymer(EPRSMA)Pickering emulsions(O/W type)were prepared using CNFs as stabilizers to investigate the adsorption and assembly of CNFs at the rubber seed oil epoxy monomer(ERSMA)/water interface.The EPRSMA composite microspheres were synthesized by a one-step process,followed by blending,extraction and drying and curing to prepare high wet strength composite films.Nuclear magnetic mapping(~1H NMR)showed that the synthetic conversion of EPRSMA was up to 95%.According to TEM photographs and DLS tests,the synthesized EPRSMA composite microspheres have a particle size of about 350 nm and a narrow distribution,and this O/W type microsphere can be rapidly and uniformly dispersed in water.After compounding the EPRSMA composite microspheres with the micro-nanocellulose suspension,the surface water contact angle of the composite membrane can reach more than 90°.Compared to the pure cellulose membrane,the tensile strength value after water absorption increases from 12.6MPa to 50.2 MPa,while the strength reduction rate of the wet membrane decreases from91.8%to 45%.