Vijay Kumar Sinha

Polyurethane adhesive system from biomaterial-based polyol for bonding wood

Polyester polyols for use in the preparation of polyurethane (PU) adhesives were synthesized from potato starch and natural oils by a transesterification reaction. These polyester polyols were combined with an aromatic adduct based on toluene 2,4-diisocyanate to form a PU adhesive. Both the polyols and the PU adhesives were characterized by means of FTIR spectroscopy. The adhesive performance of the PU adhesives in bonding wood was evaluated by lap shear tests. The effect on adhesion of variation of NCO/OH ratio and hydroxyl value were studied. The change in lap shear strength before and after exposure to cold water, hot water, acid, and alkali were evaluated. Development of bond strength to wood was determined by means of tests at regular intervals, and also curing time required for different adhesive formulations were determined. The PU adhesive derived from natural products was found superior to the commercially available adhesive.

Polyester Polyol-Based Polyurethane Adhesive; Effect of Treatment on Rubber Surface

Polyester polyols were synthesized using vegetable oil fatty acids having different characteristics (mainly in terms of hydroxyl functionality) and epoxy resin, using triethylamine as a catalyst. Polyols were characterized by the FTIR spectroscopy. Polyurethane adhesives were synthesized from it and used in bonding rubber. Treatment of sulphuric acid on the non-polar styrene butadiene rubber (SBR) surface was studied for the bond strength improvement via an increase in wettability of the rubber surface. Wettability was found by measuring the contact angle using Goniometer. Bond strength was evaluated by a 180° T-peel test. The surface modification and mode of bond failure were studied by Scanning Electron Microscopy (SEM). The synthesized polyurethane adhesives were compared with the commercial adhesive.

Synthesis, Characterization and Optimization of Water-Soluble Chitosan Derivatives

Chitosan was chemically modified using monochloroacetic acid at various reaction conditions. Chemical structure was confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and x-ray diffraction (XRD). The carboxymethyl chitosan (CM-chitosan) was prepared at different temperatures, water/isopropanol (IPA) ratios and alkali concentrations. Reaction conditions have great influence on the degree of substitution (DS) and, in turn, the solubility. The water solubility of chitosan derivatives depended upon modification conditions and degree of substitution.

Value-based Polymer Precursors from Paper Waste and its Application in Polyurethane Foams

Increase in generation of the paper waste around the world, especially in developing countries, has created a need to develop new ways to use this waste to obtain value-oriented products. Due to limited availability of petroleum resources and related environmental concerns, petroleum-based precursors for polymeric materials are being replaced by renewable resources, which are abundant in nature and economic. Paper waste is a rich source of cellulose, which can be chemically modified to produce valuable products. Polymeric precursors (polyols) were synthesized by glycosylation of cellulose of paper waste, obtained from magazines and transesterifying the obtained product using castor oil. The synthesized products were characterized by Fourier transform infrared spectroscopy, high performance liquid chromatography, and physicochemical analysis. The resultant polyols were of dark color, low viscosity, % nonvolatile mater <1, hydroxyl value ranging 200—400, moisture content <1%, and acid value <2.5. These synthesized precursors with good characteristics to use it for the synthesis of polymeric materials were used for the synthesis polyurethane foams, which were tested for their physical, mechanical, thermal (thermogravimetric analysis), and morphological (scanning electron micrograph) characteristics.

Study of the effect of reaction variables on grafting of acrylic acid onto carboxymethyl chitosan

Carboxymethyl chitosan (CMCH) was prepared and characterized by FT-IR spectroscopy. Grafting of acrylic acid (AA) onto CMCH using ceric ammonium nitrate (CAN) as an initiator was carried under nitrogen atmosphere in aqueous solution. Evidence of grafting was confirmed by comparing the FT-IR spectra of CMCH and the grafted co-polymer, as well as scanning electron microscopy (SEM) and X-ray diffraction of the products. The effects of concentration of CAN, concentration of acrylic acid, reaction time and temperature on graft co-polymerization were studied by determining the grafting percentage, grafting efficiency, percentage add-on and percentage total conversion. Keeping the other conditions constant, the optimum grafting conditions were obtained as follows: CMCH = 2 g, CAN = 0.2 M and AA = 0.729 M, reaction temperature = 35°C and reaction time = 4 h.

Chemical scavenging of post-consumed clothes.

Aiming toward the rectification of fiber grade PET waste accumulation as well as recycling and providing a technically viable route leading to preservation of the natural resources and environment, the post consumed polyester clothes were chemically recycled. Post consumed polyester clothes were recycled into bis(2-hydroxyethyl) terephthalate (BHET) monomer in the presence of ethylene glycol as depolymerising agent and zinc acetate as catalyst. Depolymerized product was characterized by chemical as well as analytical techniques. The fiber grade PET was eventually converted into BHET monomer with nearly 90% yield by employing 1% catalyst concentration and at optimum temperature of 180°C without mechanical input of stirring condition.

TWO PACK POLYURETHANE COATINGS FROM ISOPHTHALIC ACID AND BIOMATERIAL BASED POLYESTER POLYOL

A Polyester polyol was developed from isophthalic acid and starch derived glycol glycosides. Two pack polyurethane system based on this polyester polyol and isocynate adduct was formulated. The performance property reveals that the coatings formed can be successfully used for heavy duty maintenance coating (H.D.M.C) and are considerably influenced by amount of isophthalic acid (IPA) and glycol glycosides.

Two Pack Polyurethane coating system based on styrenated polyols from renewable resource

Abstract A series of styreneated polyols have been prepared from unsaturated glycol glycoside and argemone oil. Upto 50% by weight. styrene was loaded by generating free radical onto hydroxyl functionalised polyester, using. AIBN as initiator. The extent of unsaturation in styrenated polyols was determined by its Iodine Value. its molecular weight was determined by Gel Permeation Chromatogram (GPC) and functional group by Infrared Spectroscopy. A series of such prepared styrenated polyols was mixed with an aromatic adduct based on toluene di isocyanates (TDI) in different ratios of their equivalents (OH: NCO) to form Two Pack Polyurethane. Polyurethane resin thus prepared was coated on test panel and were compared with a set of unstyreneated polyols and isocyanate adduct admixtures for Flexibility. Scratch hardness. Impact resistance, % Adhesion and Chemical resistance. Structure of the polyurethane was confirmed by FTIR. Thermal stability of styreneated polyurethane was determined and compared with unstyreneated polyurethane by TGA.

2-HEMA-g-Na-PCMS: A Novel Polymeric Matrix for the Controlled Release of Paracetamol

2-hydoxyethyl methacrylate (2-HEMA) was graft copolymerized with sodium salt of partially carboxymethylated starch (Na-PCMS). Thus prepared, graft copolymer (2-HEMA-g-Na-PCMS) was used as a polymeric matrix for preparing controlled-release tablets of paracetamol. Tablets of standard specification were prepared using the wet granulation method. Ingredients utilized for tablet preparation were 2-HEMA-g-Na-PCMS graft copolymer, paracetamol and excipients. Tablets were characterized for disintegration time (min), hardness, angle of repose and percent friability. It was found that tablets prepared by the compression of graft copolymer, excipients and drug in specified ratios resulted in an excellent controlled-release tendency of paracetamol.

Environmentally degradable blends of low density polyethylene (LDPE) and partially carboxymethylated starch (PCMS)

Abstract Sodium - salt of partially carboxymethylated starch (Na-PCMS) with degree of substitution (DS) 0.21 and 0.58 was synthesized by etherification of starch. These starch ethers and low density polyethylene (LDPE) were mixed with and without poly(vinylacetate) (PVAc) in various proportions using Brabender mixer. FTIR confirmed the etherification reaction of starch and blending. Positive changes in the mechanical properties as a function of blending, and environmental degradation have been observed. Addition of 5 wt% PVAc improves the blend quality. Samples were exposed to direct sunlight for one month and environmental degradation was measured in terms of change in tensile strength and per cent elongation.