Mohini Sain - Academia.edu (original) (raw)

Papers by Mohini Sain

Applied Spectroscopy Reviews, 1995

Infrared (IR) drying of paper in a pilot scale has been investigated by several researchers in th... more Infrared (IR) drying of paper in a pilot scale has been investigated by several researchers in the past [1–3]. Both high-intensity electric heating and medium-intensity gas heating are now being used industrially either to preheat wet paper before conventional steam drying [1] or as a moisture-profile corrector just before paper sizing press [2]. Our own investigation [3] on the use

Carbohydrate Polymers, 2014

Cellulose nanofibers (diameter=10-70 nm) were produced using chemical treatments (alkali treatmen... more Cellulose nanofibers (diameter=10-70 nm) were produced using chemical treatments (alkali treatment and bleaching) and high pressure homogenization from de-pectinated sugar beet pulp (DSBP). Chemical analysis and Fourier transform infrared spectroscopy (FTIR) indicated that the chemical treatments greatly removed the hemicellulose and lignin from the DSBP and significantly increased the cellulose content. The crystallinity of the cellulose nanofibers increased from 35.67% to 69.62% after alkali treatment and bleaching. The thermal degradation temperature of DSBP cellulose nanofibers was 271.7 °C which was found to be 47.3 °C higher than that of the untreated DSBP. The DSBP cellulose nanofibers can be preferably used as reinforcement in the biocomposite material at high temperature.

Comptes Rendus Chimie, 2012

Carbohydrate Polymers, 2012

Nanocomposite films of bacterial cellulose (10-50 wt%) and polyurethane-based resin were prepared... more Nanocomposite films of bacterial cellulose (10-50 wt%) and polyurethane-based resin were prepared and characterized for physical, mechanical and dielectric properties. It was observed that the bacterial cellulose swelled in ethanol, and that bacterial cellulose sheets prepared from fibre suspension in ethanol exhibited a relatively less dense structure in comparison to those processed from aqueous fibre suspension. Nanocomposites fabricated from ethanol suspension also showed inferior mechanical properties but superior dielectric properties. Higher amounts of free proton generated from ethanol can induce more dipole mechanism; therefore, there is higher mobility of proton localized along cellulose chain, indicating that higher dielectric constants can be obtained.

Advances in Polymer Technology, 1993

The influence of solid-state modified polypropylene on the physical performance of uncoated or th... more The influence of solid-state modified polypropylene on the physical performance of uncoated or thermoset-resin coated sawdust-filled polypropylene composites was studied. The effect of composition of the composites on tensile strength, Young's modulus, tensile toughness, elongation, and impact strength was determined through two 23 factorial rotatable designs. The results of this investigation show that both the rn-phenylene dismaleimide-modified polypropylene precompounded sawdust as well as solid-state modified maleated polypropylene can be successfully used to prepare sawdust-filled polypropylene composites with good tensile strength. On the whole, this property improved compared to that of unfilled polypropylene. According to the analysis of factorial design, the optimum composition to prepare a composite with highest tensile strength within the experimental range was 30-40 wt% phenolic resin coated sawdust together with 4-6 wt% solid-state modified maleated polypropylene; while the product composition for the worst design was a combination of high amount of phenolic resin modified polypropylene with phenolic resin coated sawdust. The experimental design also concluded that effect of compositions on impact strength of composites was not significant in most of the cases. Overall, the empirical models constructed in this study provided a good approximation to actual experimental measurements; we are encouraged to extend this approach to processing conditions for manufacturing these composites.

Developments in Fiber-Reinforced Polymer (FRP) Composites for Civil Engineering

BioResources

Microbial modification of starch with Ophiostoma spp . was investigated, with the purpose of deve... more Microbial modification of starch with Ophiostoma spp . was investigated, with the purpose of developing a novel packaging material for the food or pharmaceutical industries. Various starch sources, such as tapioca, potato, corn, rice and amylopectin were tested as raw materials. The initial screening demonstrated that tapioca and potato starch had better performance for biopolymer production. The yield was about 85%. Preliminary characterization of the modified biopolymer was also conducted. Following microbial conversion, the percentage of molecules with at least a Mw of 10M Daltons increased from 25% to 89% after 3 days, confirming that the modification increased the weight of the starch polymer. Fourier Transform Infrared (FT-IR) revealed changes in the chemical structure of the starch after the modification. Both pure starches and the modified biopolymers were cast into films and tested for mechanical properties. The tensile tests showed that after treatment with the fungus, the...

BioResources

Because of their wide abundance, their renewable and environmentally benign nature, and their out... more Because of their wide abundance, their renewable and environmentally benign nature, and their outstanding mechanical properties, a great deal of attention has been paid recently to cellulosic nanofibrillar structures as components in nanocomposites. A first major challenge has been to find efficient ways to liberate cellulosic fibrils from different source materials, including wood, agricultural residues, or bacterial cellulose. A second major challenge has involved the lack of compatibility of cellulosic surfaces with a variety of plastic materials. The water-swellable nature of cellulose, especially in its non-crystalline regions, also can be a concern in various composite materials. This review of recent work shows that considerable progress has been achieved in addressing these issues and that there is potential to use cellulosic nano-components in a wide range of high-tech applications.

Current pharmaceutical design, Jan 10, 2018

Tea polyphenols have received much attention from the pharmaceutical and food industries owing to... more Tea polyphenols have received much attention from the pharmaceutical and food industries owing to their extraordinary antioxidant and antibacterial characteristics. However, tea polyphenols are very unstable to processing and storage, since they are sensitive to the environmental factors like temperature, light and pH. Therefore, the effective application of tea polyphenols requires a protective mechanism to maintain its activity. The utilization of compounded tea polyphenols, instead of raw materials, can potentially help to improve their stability. This review focuses on the summarization of the compounding technologies for tea polyphenols, including physical technologies, chemical-interfacial technologies and nano-scale compounding technologies. Of which, the emerging nanocellulose bio-carrier, as a promising technology, is particularly proposed.

Carbohydrate Polymers

Although there is a growing interest in utilizing nanocellulose fibres (NCFs) based composites fo... more Although there is a growing interest in utilizing nanocellulose fibres (NCFs) based composites for achieving a higher sustainability, mechanical performance of these composites is limited due to the poor compatibility between fibre reinforcement and polymer matrices. Here we developed a bio-nanocomposite with an enhanced fibre/resin interface using a hybrid-toughened epoxy. A strong reinforcing effect of NCFs was achieved, demonstrating an increase up to 88% in tensile strength and 298% in tensile modulus as compared to neat petro-based P-epoxy. The toughness of neat P-epoxy was improved by 84% with the addition of 10wt% bio-based E-epoxy monomers, which also mitigated the amount of usage of bisphenol A (BPA). The morphological analyses showed that the hybrid epoxy improved the resin penetration and fibre distribution significantly in the resulting composites. Thus, our findings demonstrated the promise of developing sustainable and high performance epoxy composites combing NCFs with a hybrid petro-based and bio-based epoxy resin system.

Journal of Analytical and Applied Pyrolysis, 2016

In order to broaden the applications of bio-epoxy resins in high performance sector, an understan... more In order to broaden the applications of bio-epoxy resins in high performance sector, an understanding of thermal behavior of these environmentally-friendly biopolymers is essential. This study investigates the thermal degradation mechanism of a bio-epoxy resin (E-epoxy) derived from bark extractives in comparison with a petroleum-based epoxy resin. The thermogravimetric analysis (TGA) results show that the activation energy of E-epoxy varied significantly with the extent of degradation indicating a multistage degradation mechanism involving a variety of compounds. According to Fourier transform infrared spectroscopy (FTIR) analysis, the dehydration and crosslinking reactions occurred at low temperatures, while the Claisen chain rearrangement and chain–scission reactions dominated at high temperatures. The pyrolysis-gas chromatography–mass spectrometry (Py-GC/MS) results show that a significant amount of methyl abieta-8,11,13-trien-18-oate, diethyl phthalate, 2,2-isopropylidenebis(3,5-dimethylbenzofuran), and epimanool were detected in the bio-epoxy resins. The newly proposed degradation mechanism of bio-epoxy resins based on structural illustration through FTIR and Py-GC/MS can provide guidance for design of high performance bio-based epoxies.

Http Dx Doi Org 10 1081 Ppt 100100019, Feb 14, 2007

Journal of Polymer Materials

Polymers and Polymer Composites

ABSTRACT

Applied Spectroscopy Reviews, 1995

Infrared (IR) drying of paper in a pilot scale has been investigated by several researchers in th... more Infrared (IR) drying of paper in a pilot scale has been investigated by several researchers in the past [1–3]. Both high-intensity electric heating and medium-intensity gas heating are now being used industrially either to preheat wet paper before conventional steam drying [1] or as a moisture-profile corrector just before paper sizing press [2]. Our own investigation [3] on the use

Carbohydrate Polymers, 2014

Cellulose nanofibers (diameter=10-70 nm) were produced using chemical treatments (alkali treatmen... more Cellulose nanofibers (diameter=10-70 nm) were produced using chemical treatments (alkali treatment and bleaching) and high pressure homogenization from de-pectinated sugar beet pulp (DSBP). Chemical analysis and Fourier transform infrared spectroscopy (FTIR) indicated that the chemical treatments greatly removed the hemicellulose and lignin from the DSBP and significantly increased the cellulose content. The crystallinity of the cellulose nanofibers increased from 35.67% to 69.62% after alkali treatment and bleaching. The thermal degradation temperature of DSBP cellulose nanofibers was 271.7 °C which was found to be 47.3 °C higher than that of the untreated DSBP. The DSBP cellulose nanofibers can be preferably used as reinforcement in the biocomposite material at high temperature.

Comptes Rendus Chimie, 2012

Carbohydrate Polymers, 2012

Nanocomposite films of bacterial cellulose (10-50 wt%) and polyurethane-based resin were prepared... more Nanocomposite films of bacterial cellulose (10-50 wt%) and polyurethane-based resin were prepared and characterized for physical, mechanical and dielectric properties. It was observed that the bacterial cellulose swelled in ethanol, and that bacterial cellulose sheets prepared from fibre suspension in ethanol exhibited a relatively less dense structure in comparison to those processed from aqueous fibre suspension. Nanocomposites fabricated from ethanol suspension also showed inferior mechanical properties but superior dielectric properties. Higher amounts of free proton generated from ethanol can induce more dipole mechanism; therefore, there is higher mobility of proton localized along cellulose chain, indicating that higher dielectric constants can be obtained.

Advances in Polymer Technology, 1993

The influence of solid-state modified polypropylene on the physical performance of uncoated or th... more The influence of solid-state modified polypropylene on the physical performance of uncoated or thermoset-resin coated sawdust-filled polypropylene composites was studied. The effect of composition of the composites on tensile strength, Young's modulus, tensile toughness, elongation, and impact strength was determined through two 23 factorial rotatable designs. The results of this investigation show that both the rn-phenylene dismaleimide-modified polypropylene precompounded sawdust as well as solid-state modified maleated polypropylene can be successfully used to prepare sawdust-filled polypropylene composites with good tensile strength. On the whole, this property improved compared to that of unfilled polypropylene. According to the analysis of factorial design, the optimum composition to prepare a composite with highest tensile strength within the experimental range was 30-40 wt% phenolic resin coated sawdust together with 4-6 wt% solid-state modified maleated polypropylene; while the product composition for the worst design was a combination of high amount of phenolic resin modified polypropylene with phenolic resin coated sawdust. The experimental design also concluded that effect of compositions on impact strength of composites was not significant in most of the cases. Overall, the empirical models constructed in this study provided a good approximation to actual experimental measurements; we are encouraged to extend this approach to processing conditions for manufacturing these composites.

Developments in Fiber-Reinforced Polymer (FRP) Composites for Civil Engineering

BioResources

Microbial modification of starch with Ophiostoma spp . was investigated, with the purpose of deve... more Microbial modification of starch with Ophiostoma spp . was investigated, with the purpose of developing a novel packaging material for the food or pharmaceutical industries. Various starch sources, such as tapioca, potato, corn, rice and amylopectin were tested as raw materials. The initial screening demonstrated that tapioca and potato starch had better performance for biopolymer production. The yield was about 85%. Preliminary characterization of the modified biopolymer was also conducted. Following microbial conversion, the percentage of molecules with at least a Mw of 10M Daltons increased from 25% to 89% after 3 days, confirming that the modification increased the weight of the starch polymer. Fourier Transform Infrared (FT-IR) revealed changes in the chemical structure of the starch after the modification. Both pure starches and the modified biopolymers were cast into films and tested for mechanical properties. The tensile tests showed that after treatment with the fungus, the...

BioResources

Because of their wide abundance, their renewable and environmentally benign nature, and their out... more Because of their wide abundance, their renewable and environmentally benign nature, and their outstanding mechanical properties, a great deal of attention has been paid recently to cellulosic nanofibrillar structures as components in nanocomposites. A first major challenge has been to find efficient ways to liberate cellulosic fibrils from different source materials, including wood, agricultural residues, or bacterial cellulose. A second major challenge has involved the lack of compatibility of cellulosic surfaces with a variety of plastic materials. The water-swellable nature of cellulose, especially in its non-crystalline regions, also can be a concern in various composite materials. This review of recent work shows that considerable progress has been achieved in addressing these issues and that there is potential to use cellulosic nano-components in a wide range of high-tech applications.

Current pharmaceutical design, Jan 10, 2018

Tea polyphenols have received much attention from the pharmaceutical and food industries owing to... more Tea polyphenols have received much attention from the pharmaceutical and food industries owing to their extraordinary antioxidant and antibacterial characteristics. However, tea polyphenols are very unstable to processing and storage, since they are sensitive to the environmental factors like temperature, light and pH. Therefore, the effective application of tea polyphenols requires a protective mechanism to maintain its activity. The utilization of compounded tea polyphenols, instead of raw materials, can potentially help to improve their stability. This review focuses on the summarization of the compounding technologies for tea polyphenols, including physical technologies, chemical-interfacial technologies and nano-scale compounding technologies. Of which, the emerging nanocellulose bio-carrier, as a promising technology, is particularly proposed.

Carbohydrate Polymers

Although there is a growing interest in utilizing nanocellulose fibres (NCFs) based composites fo... more Although there is a growing interest in utilizing nanocellulose fibres (NCFs) based composites for achieving a higher sustainability, mechanical performance of these composites is limited due to the poor compatibility between fibre reinforcement and polymer matrices. Here we developed a bio-nanocomposite with an enhanced fibre/resin interface using a hybrid-toughened epoxy. A strong reinforcing effect of NCFs was achieved, demonstrating an increase up to 88% in tensile strength and 298% in tensile modulus as compared to neat petro-based P-epoxy. The toughness of neat P-epoxy was improved by 84% with the addition of 10wt% bio-based E-epoxy monomers, which also mitigated the amount of usage of bisphenol A (BPA). The morphological analyses showed that the hybrid epoxy improved the resin penetration and fibre distribution significantly in the resulting composites. Thus, our findings demonstrated the promise of developing sustainable and high performance epoxy composites combing NCFs with a hybrid petro-based and bio-based epoxy resin system.

Journal of Analytical and Applied Pyrolysis, 2016

In order to broaden the applications of bio-epoxy resins in high performance sector, an understan... more In order to broaden the applications of bio-epoxy resins in high performance sector, an understanding of thermal behavior of these environmentally-friendly biopolymers is essential. This study investigates the thermal degradation mechanism of a bio-epoxy resin (E-epoxy) derived from bark extractives in comparison with a petroleum-based epoxy resin. The thermogravimetric analysis (TGA) results show that the activation energy of E-epoxy varied significantly with the extent of degradation indicating a multistage degradation mechanism involving a variety of compounds. According to Fourier transform infrared spectroscopy (FTIR) analysis, the dehydration and crosslinking reactions occurred at low temperatures, while the Claisen chain rearrangement and chain–scission reactions dominated at high temperatures. The pyrolysis-gas chromatography–mass spectrometry (Py-GC/MS) results show that a significant amount of methyl abieta-8,11,13-trien-18-oate, diethyl phthalate, 2,2-isopropylidenebis(3,5-dimethylbenzofuran), and epimanool were detected in the bio-epoxy resins. The newly proposed degradation mechanism of bio-epoxy resins based on structural illustration through FTIR and Py-GC/MS can provide guidance for design of high performance bio-based epoxies.

Http Dx Doi Org 10 1081 Ppt 100100019, Feb 14, 2007

Journal of Polymer Materials

Polymers and Polymer Composites

ABSTRACT