The kinetics of pyrolysis of predried coconut shell sample has been investigated in the temperature range of 523 K to I023 K in an inert atmosphere by captive sample technique. A kinetic scheme has been proposed where two parallel reactions are given for the production of volatiles and char. The reaction rate constants are found to decrease with high temperatures above 673 K due to chemical and physical changes of the reactant during devolatilisation reaction. Several deactivation models have been proposed to give good agreement with the experimental data.On a etudie la cinetique de la pyrolyse d'un echantillon de coquille de noix de COCO presechee a des temperatures comprises entre 523 K et 1023 K dans une atmosphere inerte par une technique basee sur des echantillons captifs. On propose un schema cinetique dans lequel deux reactions paralleles sont utilisees pour la production de volatils et de produits de la carbonisation. On a trouve que les constantes de vitesse de reaction diminuaient avec des temperatures au-dessus de 673 K en raison des changements chimiques et physiques subis par le reactif lors de la reaction de divolatilisation. Plusieurs modeles de desactivation sont proposes en vue de trouver un bon accord avec les donnees experimentales.

This study describes the lightfastness properties of printed foil samples due to long-time exposure. Lightfastness is an important property for any kind of print products to assess their print stability. The fastness properties of prints can be described in terms of print durability and image stability. It may also be used for verification of printed expiry date and authenticity or validity of the product. Moreover, any kind of deterioration in package print quality will affect the product's sale adversely. Little work has been conducted to study the fastness properties of printed films and foils. In this work, blister foils printed in the gravure printing process have been taken as the sample as they have extensive usage in food and medicine packaging. An artificial lightfastness tester BGD 865/A Bench Xenon Test Chamber (B-SUN) is used to study the light fastness of Cyan, Magenta, Yellow, and Black inks on the foil. The spectral curves and colorimetric values are measured using an Ocean Optics Spectroradiometer (DH2000BAL) before and after exposure. A kinetic model is proposed to predict the fading rate of the printed foil. The optimal model has given excellent prediction with a correlation coefficient of 0.90 to 0.93 for Cyan, Magenta, Yellow, and Black prints, respectively. The largest color difference ΔE 00 is achieved for Yellow print followed by Magenta. Cyan and Black prints have shown small changes with time when the gravure prints are exposed to the artificial aging chamber. K E Y W O R D S

The outcome of a print in production run plays a crucial role in commercial and packaging printing. In the growing packaging industry, colorfulness and saturated prints with high chroma attract the eye of the consumer. The design and layout of a packaging carton comprise of images that consist of halftones in the print process, which demand attractiveness and visibility using bright colors. In this research, an effort has been made to identify and analyze various parameters involved in offset lithography affecting color attributes of prints. This study also focused on the investigation of the best process conditions that would yield optimum color values through multiresponse factors such as chroma and lightness. A general full-factorial Design of Experiments (DOE) approach was used to evaluate the effect of prepress parameters such as screen ruling and dot shape and press parameters such ink viscosity and paper smoothness. These parameters were then optimized using a customized response surface design. From the experiment, it was observed that viscosity of the ink was a significant factor that majorly controls the color attributes. The surface smoothness of the paperboard was one of the factors influencing the improvement of color reproduction. A smoother surface makes even contact during ink transfer in the offset printing machine and hence reflects color with a higher chroma. The optimum parameters were as follows: 15 Pa s ink viscosity, 0.77 μm paper smoothness, and 200 lines per inch (lpi) screen ruling that resulted in increasing chroma (C*) in the middle and shadow tones in the halftones. K E Y W O R D Schroma, ink viscosity, lightness, response surface design

A mathematical model based on the mechanistic approach to the reaction kinetics of pyrolysis reactions and the realistic analysis of the interaction between simultaneous heat and mass transfer along with the chemical reaction has been developed for the design of smoothly running pyrolyzers. The model of a fixed-bed pyrolysis reactor has been proposed on the basis of the dimensionless parameters with respect to time and radial position. The variation of physical parameters like bed voidage, heat capacity, diffusivity, density, thermal conductivity, etc., on temperature and conversion has been taken into account. A deactivation model has also been incorporated to explain the behavior of pyrolysis reactions at temperaures above 673 K. The simulated results of the model have been explained by comparing them with the experimental results.

In the recent years, the demands for offset inks with better flow ability and viscosity have risen higher with the improvements of printing techniques. To ensure uniformity in printability sheet after sheet it is very important to maintain certain print conditions for that print job as approved by customers and use this data for future reference of printing. The quality of offset printing process depends on many chemical and physical specifications of the ma terials and components involved in the process. Most important being printing inks and its rheology. In this work, three process color cyan inks have been formulated with varying levels of viscosity with use of certain rheology modifiers. Trials on the printing machine were conducted using a systematic layout of test elements on a fully automatic offset lithography printing machine using a Solid Bleached Sulphite Board (SBS) and the print results were correlated to rheological parameters such as viscosity and thixotropy. The tone value increase (TVI) was measured and was correlated to viscosity and index of thixotropy. Higher viscosity yields lower dot gain and better color reproducibility. A mathematical relation has been established between ink viscosity, dot area and tone value increase. As the demands for packaging increases, the study about the ink rheology and its effect on print performance can help printers and ink manufacturers with better ink formulations to achieve precise print results.