Non‐isothermal crystallization kinetics of polypropylene/bamboo fiber/nano‐TiO₂composites

Abstract

Non-isothermal crystallization kinetics of polypropylene/bamboo fiber/nano-TiO 2 (PP/BF/nano-TiO 2 ) composites was investigated using differential scanning calorimetric technique with various cooling rates (2.5, 5, 10, 20, and 30 C min −1 ). The influence of different loading concentration (0, 0.1, 0.4, and 0.8 wt%) of TiO 2 nanoparticles on the nucleation ability of polypropylene was evaluated. The Avrami equation, Ozawa, and Mo model were applied to describe the non-isothermal crystallization behaviors and to analyze the experimental data of the PP/BF/nano-TiO 2 composites. The Friedman isoconversional model was employed to calculate the effective activation energy (Ea) of the samples. The experimental data were in perfect agreement with the Mo model during the investigated crystallization temperature and the loading concentration of TiO 2 nanoparticles. The TiO 2 nanoparticles concentration of 0.4 wt% was useful for improving crystallization process of the PP matrix in the composites by accelerating the crystallization rate along with the lower values of t 1/2 and Ea. However, we observed no significant changes in the onset crystallization temperature(T o ) and the crystallization peak temperature(T p ) with the incorporation of TiO 2 nanoparticles in the PP matrix, suggesting that the influence of TiO 2 nanoparticles was more remarkable at the crystal growth instead of nucleation stage for the PP/BF/nano-TiO 2 composites system.

Preparation of PP/PC light‐diffusing materials with UV‐shielding property

“…As small amount of nano‐TiO 2 was added, the crystallization temperature of the composites remained basically unchanged with a tiny increase in the degree of crystallinity (X c ). Here, nano‐TiO 2 played the role of heterogeneous nucleation, which increased the crystallization rate of PP phase and made it easier to form a regular crystalline structure 48,49 . The decline in the degree of crystallinity (X c ) was found when nano‐TiO 2 loading content was increased to 0.5 wt% owing to the possible agglomeration which would hinder the mobility of PP molecular chains 50 …”

“…Here, nano-TiO 2 played the role of heterogeneous nucleation, which increased the crystallization rate of PP phase and made it easier to form a regular crystalline structure. 48,49 The decline in the degree of crystallinity (X c ) was found when nano-TiO 2 loading content was increased to 0.5 wt% owing to the possible agglomeration which would hinder the mobility of PP molecular chains. 50 For composites with UV-P, the crystallization and melting temperature were in the absence of regular variation, but the crystallinity of PP phase continues to decrease.…”

Nonisothermal crystallization behavior and mechanical properties of poly(lactic acid)/ramie fiber biocomposites

“…[ 16–18 ] PLA is a semicrystalline polymer, and the crystallization behavior strongly influences mechanical and thermal properties. [ 19–21 ]…”

Effect of nano TiO2 on the cellular structure and mechanical properties of wood flour/polypropylene composite foams via mold‐opening foam injection molding

“…[25][26][27][28][29][30] The mainly is due to nanoparticles can significantly enhance the viscoelasticity and crystallization of the matrix, thereby improving the cell structure and mechanical properties of the foam. [31][32][33][34][35] Nano TiO 2 not only exhibits advantages of small particle size, large specific surface area and high surface activity, but also has strong stability, photocatalytic activity and UV shielding ability, [36][37][38] due to amphoteric oxide, a differentiated traditional nanoparticle filler generate a great expectation for foamed WPC. However, to the author's knowledge, there have been very few studies of the injection molding of WPC using nano TiO 2 particles to improve the foaming behavior and mechanical performances of PP-based WPC.…”

“…Previous studies have shown that the introduction of nanoparticles, such as talc, clay, fabric, and carbon and organic fibrils, can improve the melt strength, generate more foaming nucleation sites, and reduce cell collapse and coalescence by the wood flour (WF) to produce a microcellular‐foamed PP‐based WPC composed of uniform dense cells and enhanced mechanical and foaming performances 25–30 . The mainly is due to nanoparticles can significantly enhance the viscoelasticity and crystallization of the matrix, thereby improving the cell structure and mechanical properties of the foam 31–35 . Nano TiO 2 not only exhibits advantages of small particle size, large specific surface area and high surface activity, but also has strong stability, photocatalytic activity and UV shielding ability, 36–38 due to amphoteric oxide, a differentiated traditional nanoparticle filler generate a great expectation for foamed WPC.…”