Design and synthesis of bio-based UV curable PU acrylate resin from itaconic acid for coating applications

UV curable PUA resin was successfully synthesized from polyol based on sustainable resource originated from itaconic acid (IA), isophorone diisocyanate (IPDI) and 2-hydroxyethyl methacrylate (HEMA). A polyol was synthesized by condensation reaction of IA with 16-hexanediol in the presence of p-Toluenesulfonic acid (pTSA). The synthesized PUA resin was characterized for its structural elucidation by using Fourier Transform Infrared Spectrophotometer (FTIR), ¹H and ¹³C NMR spectroscopy. The synthesized UV curable PUA resin was incorporated in varying concentrations in conventional PUA coating system. The effects of varying concentration of synthesized UV curable PUA resin on rheology, crystallinity, thermal and coating properties were evaluated. The rheological behavior of the resins were evaluated at variable stress and result showed decrease in viscosity of resin as concentration of synthesized UV curable PUA resin increases in conventional PUA resin. The cured coatings have been evaluated for glass transition temperature (T_g) and thermal behavior by differential scanning calorimeter and thermogravimetric analysis respectively. The degree of crystallinity of the coatings was determined from X-ray diffraction patterns using the PFM program. It was found that increase in the mass proportion of IA based PUA in coatings, the coating becomes more rigid and crystalline. The synthesized UV curable PUA coatings showed interesting mechanical, chemical, solvent and thermal properties as compared to the conventional PUA. Further, cured coatings were also evaluated for gel content and water absorption.     

Formation and Densification Behavior of MgAl2O4 Spinel: The Influence of Processing Parameters

Different types of dense stoichiometric and nonstoichiometric magnesium aluminate (MgAl₂O₄) spinel (MAS) ceramics were prepared following a conventional double-stage firing process using different commercially available alumina and magnesia raw materials. Stoichiometric, magnesia-rich, and alumina-rich spinels were sintered at 1500°–1800°C for 1–2.5 h. The influence of the different processing parameters (average particle size, degree of spinel phase, green density, mass of the powder compact, sintering temperature, holding time at the peak temperature, and starting composition) on the densification behavior of MAS was assessed by measuring the bulk density, apparent porosity, and water absorption capacity, and microstructural observations. Most of the MAS compositions tested exhibited excellent sintering properties.     

Formation and Densification Behavior of Mullite Aggregates from Beach Sand Sillimanite

Dense mullite aggregates with 60% and 70% Al₂O₃ have been prepared from precursor mixtures consisting of beach sand sillimanite and a high-purity aluminum hydroxide following conventional single- and double-stage firing processes. The bulk density (BD), apparent porosity (AP), and water absorption (WA) capacity of sintered mullite aggregates were found to be strongly influenced by the premullitization step of this precursor mixture. Mullite aggregates formed in a double-stage firing process exhibited higher BD and mullite content and lower AP and WA capacity in comparison with those obtained by the single-stage firing process. The values of coefficient of thermal expansion of sintered mullite aggregates are close to those found in the literature reports for high-purity stoichiometric mullite.     

Dual Electric Field Induced Alignment of Electrospun Nanofibers

A dual‐field method is described to produce aligned fibers by electrospinning. By applying a secondary electric field perpendicular to the primary field, control over the orientation of the fibers on the collector is obtained. The dual‐field approach is used in conjunction with dual electrodes and a rotating collector. Both approaches were used to electrospin poly(lactic acid) fibers under conditions intended to produce fibers with a diameter greater then 400 nm to aid observation by optical microscopy and digital photography. Digital photography was used to visualize a large area of aligned fiber and image analysis software was used to quantify the degree of alignment. Fibers aligned with the aid of a dual field showed better alignment than those from a single electric field under otherwise identical conditions.

     

A study on drying of textile substrates and a new concept for the enhancement of drying rate

Gravimetric absorption test system (GATS) is used to measure the absorption capacity, absorption rate and drying rate of knit hoses, prepared from different fibres. The fibres studied are cotton, polyester and variety of modified polyesters. The study has shown that desorption or drying rate is at least two orders of magnitude lower than absorption rate. This finding implies that drying is the limiting process in moisture management. Further experiments on knit fabrics made from polyester and cotton, show that the drying rates are independent of fibre type in the constant-rate period, while the drying rates in the falling-rate period are dependent on fibre type. Subsequently, it is shown on the polyester fabric that drying rate in the falling-rate period depends on water concentration. Based on this understanding, an approach for enhancing drying rate in the falling-rate period is defined. The approach is demonstrated on knit hoses prepared from cotton and polyester yarns in alternating stripe form. The drying rate in the falling-rate period is found to be higher in the polyester-cotton stripe knit hose. A hypothesis for the observed enhancement in drying rate by wicking is put forth in terms of the internal movement of water from polyester to cotton portion. Experimentally, it is shown that 16% improvement in drying time is achieved in the case of the polyester–cotton stripe samples. Further, indications of internal water movement from polyester to cotton portion have been obtained by tracking the surface temperatures of the knit hoses during drying by infrared (IR) thermography.     

Role of ceria in CO2 adsorption on NaZSM-5 synthesized using rice husk ash

Ceria (3, 5, 7, 11, 19 wt%) impregnated NaZSM-5 was synthesized and studied for adsorption of CO₂. They were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), CO₂-temperature programmed desorption (CO₂-TPD) and Brunauer–Emmett–Teller (BET) techniques. The heat of the reaction (ΔH_r) derived from differential scanning calorimetry (DSC) analysis was 490 Btu/lb. XRD analysis showed a decrease in the intensity of patterns with the increase in the ceria loading but crystallization of ceria to larger size was clearly evident for 11 and 19% loading. The surface area decreased for 3 and 5% loading, but increased for 7, 11 and 19% loading illustrating difference in dispersion. The maximum adsorption capacity of CeO₂(5%)/NaZSM-5 was 130 mg/g of sorbent. Extraction of silica from the agricultural waste, rice husk, and its use in the zeolite synthesis was an advantage in this study. Hence, from the study it was concluded that ceria impregnated NaZSM-5 could be treated as a novel material for CO₂ adsorption, as they were regenerable and recyclable. This study can also be applied to all other zeolites.     

Composition and functional properties of raw and electron beam-irradiated Mucuna pruriens seeds

The proximate, nutritional and functional properties of raw and electron beam-irradiated (0–30 kGy) Mucuna seeds were investigated. Irradiation increased crude protein and crude carbohydrates significantly than crude lipid, crude fibre and energy. Raw seeds were rich in minerals and were not affected by irradiation except for magnesium and phosphorus. Amino acids of raw seeds were comparable to soyabean and FAO/WHO reference pattern and except for 30 kGy, no significant changes were seen in amino acid profile. Raw seeds were rich in unsaturated fatty acids and some of them decreased on irradiation, while linoleic acid steadily elevated (0–14.35 mg g⁻¹ lipid). In vitro protein digestibility was dose dependent and significantly increased up to 15 kGy. Water and oil absorption capacities and foaming capacity significantly increased on irradiation, while protein solubility decreased (15 and 30 kGy) with an improvement of gelation property of seed flour. The cooking time of seeds significantly reduced on irradiation.