Effect of chemical structure and shear force on the morphology and properties of jet printed black micropatterns using imide epoxy binders

Production of Starch Nanocrystals from Agricultural Materials Using Mild Acid Hydrolysis Method: Optimization and Characterization

Due to an insufficiency of fossil fuels and environmental pollution, sustainable and efficient material utilization has become the greatest importance. This work aimed to produce nanosized filler for biobased materials from renewable resource by an efficient production. Banana and tapioca starch nanocrystals (SNCs) were prepared from mild acid hydrolysis method. The effects of acid type, acid concentration, reaction time, and temperature on percent yield and degree of crystallinity were investigated in order to find the suitable condition for SNCs preparation. The chemical structure, degree of crystallinity, and morphology of the obtained SNCs were examined by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM), respectively. Thermal properties were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results revealed that the suitable conditions for preparing SNCs were by using 3.5 M H2SO4 at 40°C for 7 hrs or 10 hrs depending on starch type, which leading to high degree of crystallinity as 47.13% and 60.06% for banana and tapioca SNCs, respectively. The particle size of both SNCs was less than 200 nm, approximately 30–70 nm. The banana SNC displayed parallelepiped nanoplatelets with C-type crystallinity, while the tapioca SNC showed spherical nanoplatelets with A-type crystallinity. The degradation temperature of banana and tapioca SNCs occurred in ranging between 280 and 310°C, which was lower than their native starches due to the disintegration of the SNC molecular chain during acid hydrolysis reaction. Nevertheless, melting enthalpy (ΔH) of SNC fillers enhanced after hydrolysis indicating that there was an increment of degree of crystallinity owing to the chain rearrangement of starch molecules.

The principle and physical models of novel jetting dispenser with giant magnetostrictive and a magnifier

In order to develop jetting technologies of glue in LED and microelectronics packaging, giant-magnetostrictive-material (GMM) is firstly applied to increase jetting response, and a new magnifying device including a lever and a flexible hinge is designed to improve jetting characteristics. Physical models of the jetting system are derived from the magnifying structure and working principle, which involves circuit model, electro-magneto-displacement model, dynamic model and fluid-solid coupling model. The system model is established by combining mathematical models with Matlab-Simulink. The effectiveness of the GMM-based dispenser is confirmed by simulation and experiments. The jetting frequency significantly increases to 250 Hz, and dynamic behaviors jetting needle are evaluated that the velocity and displacement of the jetting needle reaches to 320 mm•s-1 and 0.11 mm respectively. With the increasing of the filling pressure or the amplitude of the current, the dot size will become larger. The dot size and working frequency can be easily adjusted.

The Influence of Processing and the Polymorphism of Lignocellulosic Fillers on the Structure and Properties of Composite Materials-A Review

Cellulose is the most important and the most abundant plant natural polymer. It shows a number of interesting properties including those making it attractive as a filler of composite materials with a thermoplastic polymer matrix. Production of such composite materials, meeting the standards of green technology, has increased from 0.36 million tons in 2007 to 2.33 million tons in 2012. It is predicted that by 2020 their production will reach 3.45 million tons. Production of biocomposites with lignocellulosic components poses many problems that should be addressed. This paper is a review of the lignocellulosic materials currently used as polymer fillers. First, the many factors determining the macroscopic properties of such composites are described, with particular attention paid to the poor interphase adhesion between the polymer matrix and a lignocellulosic filler and to the effects of cellulose occurrence in polymorphic varieties. The phenomenon of cellulose polymorphism is very important from the point of view of controlling the nucleation abilities of the lignocellulosic filler and hence the mechanical properties of composites. Macroscopic properties of green composites depend also on the parameters of processing which determine the magnitude and range of shearing forces. The influence of shearing forces appearing upon processing the supermolecular structure of the polymer matrix is also discussed. An important problem from the viewpoint of ecology is the possibility of composite recycling which should be taken into account at the design stage. The methods for recycling of the composites made of thermoplastic polymers filled with renewable lignocellulosic materials are presented and discussed. This paper is a review prepared on the basis of currently available literature which describes the many aspects of the problems related to the possibility of using lignocellulosic components for production of composites with polymers.

Preparation, properties and applications of polysaccharide nanocrystals in advanced functional nanomaterials: a review

Intensive exploration and research in the past few decades on polysaccharide nanocrystals, the highly crystalline nanoscale materials derived from natural resources, mainly focused originally on their use as a reinforcing nanophase in nanocomposites. However, these investigations have led to the emergence of more diverse potential applications exploiting the functionality of these nanomaterials. Based on the construction strategies of functional nanomaterials, this article critically and comprehensively reviews the emerging polysaccharide nanocrystal-based functional nanomaterials with special applications, such as biomedical materials, biomimetic optical nanomaterials, bio-inspired mechanically adaptive nanomaterials, permselective nanostructured membranes, template for synthesizing inorganic nanoparticles, polymer electrolytes, emulsion nano-stabilizer and decontamination of organic pollutants. We focus on the preparation, unique properties and performances of the different polysaccharide nanocrystal materials. At the same time, the advantages, physicochemical properties and chemical modifications of polysaccharide nanocrystals are also comparatively discussed in view of materials development. Finally, the perspective and current challenges of polysaccharide nanocrystals in future functional nanomaterials are outlined.