@article {47099, title = {Mechanics of soft polymeric materials using a fractal viscoelastic model}, journal = {Mechanics of Time-Dependent Materials}, volume = {26}, year = {2022}, month = {JUN}, type = {Article}, abstract = {

Soft materials are known for their plethora of biomedical applications, intricate structure-property correlation and nonlinear mechanical response. Multiple length-time scale phenomena and hierarchical structure results in their nonlinearity. Phenomenological and continuum mechanical models have been developed to predict their mechanics, which have mostly been very material-specific with inability to predict the mechanics of different types of soft materials simultaneously. This shortcoming has been addressed in the present work, wherein a generic nonlinear viscoelastic model has been proposed to predict the mechanical response of hydrogels, sponges, and xerogels. A fractal derivative viscoelastic model is proposed considering a fractal Maxwell model in parallel with a nonlinear spring. In particular, this model is chosen to qualitatively mimic the material nonlinearity inherent in soft materials. The fractal dashpot in combination with the nonlinear spring accounts for the power law time-dependent rheology of generic soft materials. These two different aspects in the form of nonlinear stiffness and non-Newtonian rheology account for mechanics of most soft materials. The present model is shown to fit well the existing literature results for mechanical response of a multitude of soft material classes with different test conditions and loading rates, which is one of the salient features of the model, apart from its simplistic mathematical framework. Further, a parametric study is reported on the mechanics of nanocellulose loaded poly(vinyl alcohol) xerogel. The model predictions are observed to be in conjunction with the experimental observations.

}, keywords = {Mechanics, Nonlinear, Polymeric composites, Soft materials, viscoelastic}, issn = {1385-2000}, doi = {10.1007/s11043-021-09486-0}, author = {Pramanik, R. and Soni, F. and Shanmuganathan, K. and Arockiarajan, A.} } @article {49999, title = {Moisture- responsive controlled-release herbicide system using guar gum and nano cellulose for sustainable weed management in rainfed agriculture}, journal = {Results in Engineering}, volume = {27}, year = {2025}, month = {SEP}, pages = {106576}, type = {Article}, abstract = {

Weed management poses a significant challenge in rainfed agricultural system, with chemical control being the predominant strategy due to its expeditious nature. However, the efficacy of herbicides in these systems is heavily dependent on optimal soil moisture, making the application of pre-emergence herbicides difficult due to erratic rainfall patterns. Sudden rainfall events post-sowing can result in sticky or muddy fields, complicating the application process and leading to infrequent use of pre-emergence herbicides in rainfed agriculture. To address these challenges, an innovative approach was developed involving the herbicide molecules entrapment in hydrogel matrices synthesized from biopolymers. This study focuses on the design and preparation of atrazine-loaded hydrogel using guar gum and nanocellulose, aimed at managing weeds in maize crops, which are prevalent in rainfed regions. The paper details the protocol for synthesizing the hydrogels and entrapment of atrazine, characterizing the formulations, and conducting pot validation trials to assess phytotoxicity and weed control efficacy compared to commercial atrazine application. The results demonstrated high water retention capacities and entrapment efficiency of the hydrogel for preferable application. FTIR analysis confirmed the presence of atrazine at 802 cm-1\ and other excipients in the encapsulated formulations, while XRD analysis verified the presence of nanocellulose. The release pattern indicated a sustained and controlled release of atrazine from the hydrogels over 40 h in-vitro studies, compared to the complete dissolution of pure atrazine within three hours. Screening trial further validated the crop safety and improved weed control efficiency of the entrapped formulations relative to commercial atrazine. The encapsulated formulations using biopolymer-based hydrogels show promise as a viable alternative for weed management in rainfed agriculture, offering controlled herbicide release and improved application efficiency under variable moisture conditions.

}, doi = {https://doi.org/10.1016/j.rineng.2025.106576}, author = {Prasanna, Jakku and Marimuthu, S. and Gowtham, G. and Shanmuganathan, K. and Lakshmanan, A. and Chandana, Pebbeti and Karthikeyan, S. and Somasundaram, E.} }