Preparation And Properties Of PBAT/Modified Cellulose Composites

Biodegradable plastics are widely developed in order to solve environmental pollution problem caused by traditional plastics. As a biodegradable polyester, poly(butylene adipate-co-terephthalate)(PBAT) is one of the aliphatic-aromatic polyesters and has both flexibility of aliphatic chains and rigidity of aromatic chains. However, expensive price and weak strength of PBAT limit its widespread application. Therefore, the research focus in this area is to increase the strength and reduce cost of PBAT.Cellulose was chosen to blend with PBAT due to lower prices and higher strength. In order to increase the compatibility, cellulose were modified by silanization or esterification and then blended with PBAT to obtain PBAT/silanized cellulose(SG) or PBAT/cellulose laurate(LACE) composite. Mechanism of compatibility and mechanical properties were revealed. The effect of SG and LACE on mechanical properties and degradation of composites were studied. Details were as follows:(1) Three kinds of silaned cellulose SG1, SG2 and SG3 were prepared by varying ratio of MCC to HTDMS from 1:10, 3:10 to 5:10. Water absorption test found that SG became more hydrophobic with the increasing of the ratio. PBAT/SG was prepared by mixing SG with PBAT via solution blending method. IR, TEM, TGA and SEM confirmed that the composites had a good thermal stability and compatibility. PBAT/SG2 showed best mechanical properties, when the blend ratio was 85/15. The tensile strength reached 22.0 MPa while elongation at break was 577.6%.(2) LACE with substitution degree of 2.3 was synthesized by homogeneous method. PBAT/LACE composites were prepared by solution blending method. Static mechanical properties found tensile strength increased with the increase of the blend ratio. when the blend ratio was 85/15, the tensile strength was up to 21.5 MPa and elongation at break was 560.2%. IR, TEM, TGA and SEM revealed that composites had good thermal stability and compatibility when LACE content was less than 20%.(3) Degradation experiment of PBAT/SG and PBAT/LACE were investigated in phosphate buffer solution. IR and mass loss results showed that alkaline solution was more conducive to material degradation than the acidic solution in the two series of materials. The degradation order in PBAT/SG system was PBAT/SG2(85/15)>PBAT/SG3(90/10)>PBAT/SG1(90/10)>PBAT under the same pH. A faster degradation rate was observed at a larger blending ratio of LACE to PBAT in PBAT/LACE system.