Research on rice starch gel preparation and crosslink network structure-rheological property based on direct-writing 3D printing.

Amylopectin and amylose components are natural polymers within rice starch granules, intertwined in specific conditions to form gel polymerized with pore crosslink network, has potential printing properties. In this study, a rice starch gel preparation scheme is proposed for stable properties, and starch granule phase transition mechanism is analyzed based on RVA test during preparation, it can be divided into four-stage, swelling, reacting, homogenizing and self-assembling stages. Gel surface tension and contact angle tested with starch concentration effect, a correlation is developed, reflecting a competition result to gel droplet macro-morphology between the intermolecular cohesion and crosslink network. SEM is used to reveal typical crosslink structures of different starch molecular component proportions, providing objective support for starch gel rheologic property change. Results indicate gel interior crosslink network formed under concentration 12 %, the gel with amylose 4.475 % presents better printing accuracy. Gel shear modulus positively correlated with amylose proportion. Japonica gel under 20 % is of higher viscosity and rapid reassembly ability after interior crosslink network is broken. Max dynamic viscosity is positively correlated with starch concentration. The study aims to provide theoretical and practical support for in-depth analysis of rice starch material application in direct-write 3D printing.

The effect of the secondary reactions on volatile composition during the pyrolysis treatment of scrap tires.

The phenomenon of the secondary reactions of volatiles prevails during the pyrolysis process of scrap tires, but less is known about the influence of volatiles' residence time and temperature on the pyrolytic oil compositions. Experiments on the secondary reactions caused by residence time and temperature of volatiles were carried out on a lab-scale fixed bed reactor. The regularity of the secondary reactions was presented in detail according to the distribution of liquid and gaseous pyrolytic products. Considering the inadequacy of lab-to-industry research, experiments were further carried out on a pilot-scale auger reactor. The results of the pilot-scale system were corresponding well to the regularity obtained in lab-scale experiment, demonstrating the universality of the regularity in this work. At in situ pyrolysis condition without any secondary reactions, limonene content reached up to 46.24% while a high yield of BTEX (50.55%) was obtained at 700℃/60 s. A remarkable increase of methane and ethane was observed at 700℃/60 s, reaching 0.058 and 0.040 g·(g scrap tire)-1, respectively. This paper provided a novel strategy to selectively produce target products in a simple and economical method. The results were of great significance for guiding the optimisation of pyrolysis parameters in industrial equipment to obtain desired valuable products.