Bhabendra Nath Das

Recycling of finished leather wastes: a novel approach

Preparation of leather like material, i.e., regenerated leather (RGL) from finished leather wastes is economical and helps in reducing environmental pollution. Incorporating plant fibers (PFs) into RGL enhances its mechanical properties. Plant fibers are exploited as reinforcement materials owing to their low cost, fairly good mechanical properties, high specific strength, non-abrasive, eco-friendly and bio-degradability characteristics. Fiberized leather wastes and PFs were mixed in various proportions to prepare regenerated leather composites (RLCs). Plant fibers viz., coconut, sugarcane, banana and corn silk were used for the study. RGL and RLCs were characterized physicochemically using Fourier transform infrared spectroscopy, thermo gravimetric analysis and scanning electron microscopy. Results clearly portrayed that PFs significantly improved the mechanical and thermal properties of RLCs. Among the composites, RLC prepared using leather waste and coconut fiber (50:40 ratio) proved to be a better composite with potent properties. RLCs are promising for the preparation of leather goods and footwear materials in addition to its cost-effectiveness and environmental pollution abatement.Graphical Abstract

Preparation of feather keratin hydrolyzate-gelatin composites and their graft copolymers

With the aim of utilizing the Keratinous waste material, poultry feather, which is up till now discarded as a waste, was hydrolyzed to form keratin hydrolyzate (FH). As FH does not form a film, it was mixed with gelatin (G) and FH‐G composite was prepared in film form. FH‐G was further graft co‐polymerized with 2‐hydroxyethyl methacrylate (HEMA) to achieve better physico‐chemical properties for the resultant hydrogels. Percentage grafting studies and IR studies confirmed the grafting of PHEMA onto FH‐G. FH‐G‐PHEMA exhibited better mechanical properties compared to FH‐G and FH‐PHEMA. TG studies clearly indicated the grafting of HEMA onto FH and FH‐G. SEM (Scanning Electron Microscopy) pictures of FH‐G and FH‐PHEMA films exhibited brittle nature on their surface, whereas continuity and A smooth surface was observed on for the FH‐G‐PHEMA films.

Surface modified and medicated polyurethane materials capable of controlling microorganisms causing foot skin infection in athletes

Foot odor and foot infection are major problems of athletes and persons with hyperhidrosis. Many shoes especially sports shoes have removable cushion insoles/foot beds for foot comfort. Polyurethane (PU) foam and elastomer have been used as cushion insole in shoes. In the present work, new insole materials based on porous viscoelastic PU sheets having hydrophilic property and antimicrobial drug coating to control foot infection and odor were developed. Bacteria and fungus that are causing infection and bad odor of the foot of athletes were isolated by microbial cell culturing of foot sweat. The surface of porous viscoelastic PU sheets was modified using hydrophilic polymers and coated with antimicrobial agent, silver sulfadiazine (SS). The surface modified PU sheets were characterized using ATR-FTIR, TGA, DSC, SEM, contact angle measurement and water absorption study. Results had shown that modified PU sheets have hydrophilicity greater than that of original PU sheet. FTIR spectra and SEM pictures confirmed modification of PU surface with hydrophilic polymers and coating with SS. Minimum inhibitory concentration studies indicated that SS has activity on all isolated bacteria of athletic foot sweat. The maximum inhibition was found for Pseudomonas (20mm) followed by Micrococci (17 mm), Diphtheroids (16 mm) and Staphylococci (12 mm). During perspiration of foot the hydrophilic polymers on PU surface will swell and release SS. Future work will confirm the application of these materials as inserts in athletic shoes.

Utilisation of finished leather wastes for the production of blended fabrics

Ignorance regarding finished and used leather wastes leads to environmental pollution. Conversion of these solid wastes into energy and resource efficient products proves to be challenging. Nevertheless, leather fibres (LFs) were extracted from these solid wastes and they are mixed with various proportions of natural (cotton, CF) and synthetic (polyester, PF) fibres to prepare LF:CF and LF:PF composites. These composites were further processed into leather blended yarns (LBYs) and leather blended fabrics (LBFs). The fibres, LBYs, LBFs were characterized for their physicochemical and mechanical properties. Scanning electron microscopic images revealed the structure and compactness of the yarn. Mechanical properties of LBYs and LBFs were promising, which enables their use in leather and textiles industry applications. Blended fabrics made from LF:CF and LF:PF were of good quality with smooth finish. Hence, the study has unravelled a novel concept of fabric manufacture which is energy efficient, eco-friendly and cost effective.Graphical Abstract

Leather fibres as reinforcement for epoxy composites: A novel perspective

Developing composite materials with better mechanical and electrical properties is the need of hour, particularly in developing and third world countries. Keeping this objective in view, composite material was prepared, in sheet form, containing leather fibres (LF), isolated from used leather products. Reinforced composite material was produced using LF as reinforcing material for epoxy resin (ER) laminates. To impart additional strength, charcoal carbon nano particles (CCNP) were incorporated (LF:ER:CCNP) in the composite. Fourier transform infrared spectroscopy (FTIR) and thermo gravimetric analysis (TGA) of the samples have revealed the chemical nature and thermal stability of the composites, respectively, while SEM pictures revealed the fiber-matrix interface. LF:ER:CCNP possessed good mechanical properties viz., tensile strength, elongation at break (%), flexural strength, hardness etc, in addition to its electrical property. Hence, the composite possess multifunctional applications, it addition to its cost effectiveness and environmental pollution abatement.

Leather Insole with Acupressure Effect: New Perspectives

Some wastes contain many reusable substances of high value. Solid leather waste is one such potential waste which can be converted into value added products. This study attempts to prepare leather insoles with acupressure effect from finished leather wastes and used leather wastes. Leather with acupressure effect (LAE) was fabricated using regenerated leather. LAE was characterized physico-chemically using Fourier transform infrared spectroscopy, thermo gravimetric analysis and scanning electron microscopy. Foot pressure measurements were done using LAE insoles on healthy individuals. Results proved that LAE insoles were able to increase the foot pressure of the wearer and thereby created an acupressure effect in them. Wearing of footwear with LAE insoles were beneficial compared to regular insoles. LAE possessed the required mechanical properties for insole production and it was also biodegradable in nature. The study proves that these composites could be successfully used for the production of cost-effective leather goods and therapeutic footwear. Production of useful byproducts from wastes is income generating and at the same time reduces environmental pollution and a feasible technology for waste recycling has been proved in this study.

Efficacy of PU foam materials for scientific investigation in footwear research

Abstract People across the world are primarily concerned with the importance of inserts in footwear in terms of their effectiveness to accomplish therapeutic benefits. Body weight has been implicated as a factor in plantar heel pain, and foot orthoses are commonly used in its conservative treatment and are helpful in reducing symptoms of strain in the fascia during standing and ambulation. It is necessary to investigate the effectiveness of footwear inserts and their impact especially for people with high body mass index (BMI). Hence, research on polyurethane (PU) foams is warranted to identify an ideal material that provides comfort for high-BMI individuals. This article presents details on the physical characteristics of PU foam and its efficacy on functional performances as footwear inserts. PU foam materials have been assessed on various physical characteristics such as density, hardness, compression set followed by resilience, and cushioning behaviors. Of the four densities evaluated, D120 has the highest resilience on static and dynamic conditions. The cushion energy behaviors with respect to walking/running on static and dynamic condition were superior, as they possess better cushioning performance on footwear applications. Hence, the D120 PU foam material is concluded to be the best material for footwear insert for alleviating foot and ankle pain-related problems and for providing therapeutic benefits to high-BMI individuals.

Plantar Pressure Analysis on Polyurethane Foam Materials in Footwear Exclusive for Overweight/Obese

The overweight/obese individuals, in general, develop varied foot consequences during walk of life. The body weight and the prevalence of flat foot on the plantar surface are the primary indicators for the discomfort in respect of high BMI individuals. The body weight has been implicated as a factor in plantar heel [4, 11, 12]. The role of PU foam materials is of greater importance to render therapeutic advantages in footwear. The PU foam materials are widely used as varied elements in footwear and the consumers’ gain benefits and sense of satisfaction on comfort parameters. The main objective of research is to scientifically investigate the characteristics PU foam materials and explore these materials for plantar pressure analysis using In-shoe pressure measurement device on footwear designed and developed exclusively for overweight/obese individuals. The foot or thoses are commonly used in the conservative treatment of plantar fasciitis and are helpful to reduce the symptoms of strain during standing and ambulation [1,5,6,7].The investigation on PU foam materials and their efficacy as footwear inserts to provide therapeutic solutions especially for high BMI individuals has been not scientifically attempted in the domain of footwear research. Hence, the investigation on choosing ideal material thereby minimising the foot related problems being experienced by high BMI individuals is aimed at using plantar pressure analysis in this paper. The polyurethane foam materials possessing uniform substance of 4mm with varied densities such as D55, D75, D95 and D120 have been assessed on a range of physical characteristics such as Density, Hardness, Compression set followed Resiliency and cushioning behaviours. These materials are employed as foot inserts in footwear specifically designed and developed for overweight/obese individuals and the pressure analysis has been carried out using In-shoe pressure measurement method in the phase of human locomotion. Based on the results obtained on pressure analysis experiments, the ideal material aid in alleviating foot problems of high BMI individuals has been scientifically revealed and recommended to the beneficiaries.

Improved design and development of a functional moulded prosthetic foot.

Abstract Purpose: In the Indian scenario, the Jaipur foot is a low-cost breakthrough that enabled the disabled person to adapt to the Indian environment. The aim of this study is to modify the present foot in terms of ankle support design and method of fabrication, foot moulds profile and the inner core material in order to improve the performance and durability. Method: The optimized design of ankle support and flat foot profile moulds suitable for both left and right foot were developed through CAD/CAM and prosthetic feet were fabricated using ethylene vinyl acetate (EVA) foam as an appropriate alternative core material for microcellular rubber (MCR). The developed prosthetic feet were tested for rigidity by load-deflection analysis in universal testing machine. Result: EVA foot had shown better rigidity than conventional MCR foot, which will help in weight transfer during walking and increase the durability. The CAD modeled ankle support and single block EVA had made the manufacturing process easy and reduced the weight of foot and improved Gait to the person fitted with it due to improved flat foot profile. Conclusion: The new artificial foot had proven to be efficacious technically as well as functionally, which is clearly borne out from the extremely positive feedback given by the amputees. Implications of Rehabilitation Persons with below knee amputation are usually provided with transtibial prosthesis, which allows for easier ambulation and helps them to get back to their normal life. Transtibial prosthesis is an artificial limb that replaces a lower limb that is amputated below the knee. In our study, a new prosthetic foot with a modified ankle support and flat foot profile using better inner-core material than the conventional Jaipur foot was developed and the process was also optimized for mass production. The developed prosthetic foot can be fitted with both above and below knee exoskeleton type of prosthesis.

MANUFACTURING ALGORITHMS FOR APPROPRIATE DIABETIC FOOTWEAR FOR VARIOUS RISK CATEGORIES

INTRODUCTION This paper aims at characterizing the diabetic foot complications into various risk categories. The parameters of the diabetic foot with respect to each risk category are identified. Algorithms facilitating the manufacture of specific diabetic footwear unique to each risk category with respect to Materials, Fit and Design unique to each Risk Category are suggested. Footwear best suited to tackle the problems associated with each risk category are manufactured and their efficacy in minimizing complications studied.