Search

Thermoplastic cassava starch (TPS)/sisal fiber (SF) composites were prepared by the melting method. The effect of SF on the retrogradation kinetics, morphology and size of spherulites, molecular interactions, short-range molecular structure, and crystal type of TPS was investigated. The results indicate that the retrogradation degree and rate of TPS increase with the addition of SF, and the spherulites become clearer and denser. The neat TPS sample forms an A-type crystal through double helix structure and a V-type crystal through single helix structure. After the addition of SF, the A-type crystal of the TPS/SF composite decreases and the V-type crystal increases. With the further increase of SF content, the TPS/SF composite mainly presents the V-type crystal. The TPS/SF composite has higher crystallinity, but smaller crystal size and interplanar spacing. The storage modulus, loss modulus, and glass transition temperature (Tg) of TPS get enhanced with the addition of SF. [ABSTRACT FROM AUTHOR]

Thermoplastic cassava starch (TPS)/silica (SiO2) composites were prepared through melt-mixing, and the effect of different SiO2 particle size (20 nm, 200 nm, and 23 µm) on the structure, morphology, and properties of TPS/SiO2 composites was investigated. TPS/SiO2 composite containing 200 nm SiO2 has the lowest plasticizing time and torque, and the highest tensile and impact strength. The 23 µm SiO2 particle has the strongest effect on promoting retrogradation of starch, while the 200 nm SiO2 particle could inhibit the retrogradation of starch. TPS/SiO2 composite containing 200 nm SiO2 has the highest thermal stability, resistant water absorption, and light transmittance. The 200 nm SiO2 particle could be uniformly and finely dispersed in the starch matrix, however 20 nm SiO2 particle easily aggregated in TPS. The spherulites size was uniform in TPS/SiO2 composite containing 200 nm SiO2. TPS/SiO2 composite indicates the mixture of A + V types of crystalline structure, and TPS/SiO2 composite containing 23 µm SiO2 had the largest crystal size. [ABSTRACT FROM AUTHOR]