Study On Thermoplastic Starch Reinforced With Oxidized Lignocellulose

Cellulose has advantages of low cost, low density, renewable and biodegradable; it can beused as a reinforcement to prepare composites. Thermoplastic starch (TPS) is considered as themost promising biodegradable plastic, because it can be processed as a thermoplastic materialand completely degraded at low cost. Although several studies have been carried out onplasticized starch materials, the wide application of starch plastic products is still limited due totheir poor mechanical properties and pronounced sensitivity to moisture. When cellulose wasused as a reinforcement，the properties of cellulose/TPS composite can be improved. However，using cellulose without modification as a reinforcement hinders properties of thermoplasticstarch, and far from practical production.In this study，dialdehyde cellulose (DAC) was oxidized from microcrystalline cellulose(MCC) sold, and used as a reinforcement to prepare DAC/TPS composites. The objective is toform strong interactions between aldehyde and hydroxyl of TPS. Consider to the high price andsize of MCC, another kind of cellulose was used. Dialdehyde lignocellulose (DLC) also wasoxidized from lignocellulose (LC) which was homemade by hydrolysis of wood pulp cellulosecardboard. However, TPS reinforced with DAC or DLC still cannot be used in daily life for itspoor properties. And then, in order to obtain the high performance starch plastics, low-densitypolyethylene (LDPE) was melt-blended with DAC and DLC reinforced TPS. The specific workcarried out in this paper is follows:(1) Study on TPS reinforced with MCC or DAC: DAC was prepared by the oxidation ofMCC. MCC and DAC reinforced thermoplastic starch (TPS) were prepared. MCC (DAC)/TPScomposites were investigated by the FTIR, SEM, thermal stability, mechanical properties, andcontact angle testing and so on. The results showed that: Thermal stability and water resistancewere improved by adding MCC and DAC. When the concentration of sodium periodate was0.03mol/L, DAC content was12wt%, the tensile strength of DAC/TPS was the best of4.05MPa,and has a breaking elongation of139.46%, accompanying with the maximum surface contactfor78.4°. The fluidity of TPS would be decreased with increasing content or oxidation degreeof DAC.(2) Study on TPS reinforced with DLC: DLC was prepared by the oxidation oflignocellulose which homemade by hydrolysis of wood pulp cellulose cardboard with differentratio of m(NaIO4)/m(LC), and DLC/TPS composites were prepared using OWPC as areinforcement. DLC/TPS composites were investigated by the FTIR, SEM, thermal stability,mechanical properties, and contact angle testing and so on. The results showed that: whenm(NaIO4)/m(LC) was0.25, and DLC content was9wt%, the tensile strength of DLC/TPS wasthe best of6.48MPa.(3) Study on MCC&DAC/TPS/LDPE starch-based plastics: Low-density polyethylene (LDPE) was melt-blended with MCC and DAC reinforced TPS by secondary extrusion withMA-g-PE as a compatibilizer. MCC&DAC/TPS/LDPE starch-based plastics were investigatedby the FTIR, SEM, thermal stability, mechanical properties, and contact angle testing and so on.The results showed that with the increase of starch-based content, the tensile strength,elongation at break, water resistance and processing flow properties all decreased. Addingcompatibilizer MA-g-PE could improve the mechanical properties and water resistance of thematerial, while would reduce its flow properties. When LDPE and DAC/TPS mass ratio was2:1, MA-g-PE content was2.5wt%, the tensile strength of DAC/TPS/LDPE starch-basedplastics was up to14.20MPa.(4) Study on DLC/TPS/LDPE starch-based plastics: LDPE was melt-blended with DLCreinforced TPS by secondary extrusion with MA-g-PE as a compatibilizer. DLC/TPS/LDPEstarch-based plastics were investigated by the FTIR, SEM, thermal stability, mechanicalproperties, and contact angle testing and so on. The results was same asMCC&DAC/TPS/LDPE starch-based plastics. When LDPE and DAC/TPS mass ratio was2:1,MA-g-PE content was2.5wt%, the tensile strength of DLC/TPS/LDPE starch-based plasticswas up to13.22MPa.