Preparation and characterization of micro and nano fiber reinforced natural rubber composites by latex stage processing

Use of short fibers as reinforcing fillers in rubber composites is on an increasing trend. They are popular due to the possibility of obtaining anisotropic properties, ease of processing and economy. In the preparation of these composites short fibers are incorporated on two roll mixing mills or in internal mixers. This is a high energy intensive time consuming process. This calls for developing less energy intensive and less time consuming processes for incorporation and distribution of short fibers in the rubber matrix. One method for this is to incorporate fibers in the latex stage. The present study is primarily to optimize the preparation of short fiber- natural rubber composite by latex stage compounding and to evaluate the resulting composites in terms of mechanical, dynamic mechanical and thermal properties. A synthetic fiber (Nylon) and a natural fiber (Coir) are used to evaluate the advantages of the processing through latex stage. To extract the full reinforcing potential of the coir fibers the macro fibers are converted to micro fibers through chemical and mechanical means. The thesis is presented in 7 chapters

The Economics of Rubber Based Industry in Kerala

The importance of industrialisation in achiering rapid economic growth has been recognised in India's development strategy ever since the inception of economic planning in the country. Being the secondary sector in the generation of national income. industry contributes significantly to the process of economic development. Extensive debates have taken place on the nature of the industrialisation strategy to be pursued in the economy since Independence. This is reflected in the industrial policy which evolved through the various five year plans and policy resolutions. Stupendous efforts have been made by the government since the commencement of planning and particularly since the 1960s to industrialise the Indian economy and develop the infrastructural base for sustained industrial development. It is difficult to assess the performance of the industrial sector over the past three decades with respect to the broad objectives of industrialisation. However. there are certain areas in which the achievements have been clearly significant.

”Investigations on The Finite Size Effects of Some Inverse Spinels and Studies on Their Composites Based on Nitrile Rubber”

In the present study, nano particles of NiFe3O4, I_.l()5Feg5O4 and CoFegO4 are prepared by sol gel method. By appropriate heat treatments, particles of different grain sizes are obtained. The structural, magnetic and electrical measurements are evaluated as a function of grain size and temperature. NiFe3O4 prepared in the ultrafine regime are then incorporated in nitrile rubber matrix. The incorporation was carried out according to a specific recipe and for various loadings of magnetic fillers. The cure characteristics, magnetic properties, electrical properties and mechanical properties of these elastomer blends are carried out. The electrical permittivity of all the rubber samples in the X — band are also conducted

“Studies on short polyester fiber - polyurethane elastomer composite with different interfacial bonding agents”

The work presented in this thesis is regarding the development and evaluation of new bonding agents for short polyester fiber - polyurethane elastomer composites. The conventional bonding system based on hexamethylenetetramine, resorcinol and hydrated silica was not effective as a bonding agent for the composite, as the water eliminated during the formation of the RF resin hydrolysed the urethane linkages. Four bonding agents based on MDI/'I‘DI and polypropyleneglycol, propyleneglycol and glycerol were prepared and the composite recipe was optimised with respect to the cure characteristics and mechanical properties. The flow properties, stress relaxation pattern and the thermal degradation characteristics of the composites containing different bonding agents were then studied in detail to evaluate the new bonding systems. The optimum loading of resin was 5 phr and the ratio of the -01 to isocyanate was 1:1. The cure characteristics showed that the optimum combination of cure rate and processability was given by the composite with the resin based on polypropyleneglycol/ glycerol/ 4,4’diphenylmethanediisocynate (PPG/GL/MDI). From the rheological studies of the composites with and without bonding agents it was observed that all the composites showed pseudoplastic nature and the activation energy of flow of the composite was not altered by the presence of bonding agents. Mechanical properties such as tensile strength, modulus, tear resistance and abrasion resistance were improved in the presence of bonding agents and the effect was more pronounced in the case of abrasion resistance. The composites based on MDI/GL showed better initial properties while composites with resins based on MDI/PPG showed better aging resistance. Stress relaxation showed a multistage relaxation behaviour for the composite. Within the-strain levels studied, the initial rate of relaxation was higher and the cross over time was lesser for the composite containing bonding agents. The bonding agent based on MDI/PPG/GL was found to be a better choice for improving stress relaxation characteristics with better interfacial bonding. Thennogravimetirc analysis showed that the presence of fiber and bonding agents improved the thennal stability of the polyurethane elastomer marginally and it was maximum in the case of MDI / GL based bonding agents. The kinetics of degradation was not altered by the presence of bonding agents

Effect of Feeding Rate in Polymer Extrusion ”

Starve feeding of single screw extruder was described as an important means of improving the performance characteristics of the extruder. In addition to such improvement with versatility, the starve feeding technique also may affect the mechanical properties of the extrudate since the heat transfer an(l mixing characteristics in the starve fed and Hood fed extruders are not the same. Since the material is more loosely packed in the channels of the starve fed extruder, there may be greater bed mobility and uniformity. Further, the. thermal an(l shear induced degradation are also less since possibilities of developing local high temperatures are less compared to a densely compacted extruder bed. This study has been undertaken mainly to explore the effect of feeding rate on the mechanical properties of rubber and plastic extrudates since the effect of feeding rate has not been analysed from this angle so far.

Diversity and effectiveness of tropical mangrove soil microflora on the degradation of polythene carry bags

The diversity and load of heterotrophic bacteria and fungi associated with the mangrove soil from Suva, Fiji Islands, was determined by using the plate count method. The ability of the bacterial isolates to produce various hydrolytic enzymes such as amylase, gelatinase and lipase were determined using the plate assay. The heterotrophic bacterial load was considerably higher than the fungal load. There was a predominance of the gram positive genus, Bacillus. Other genera encountered included Staphylococcus, Micrococcus, Listeria and Vibrio. Their effectiveness on the degradation of commercial polythene carry bags made of high density polyethylene (HDPE) and low density polyethylene (LDPE) was studied over a period of eight weeks in the laboratory. Biodegradation was measured in terms of mean weight loss, which was nearly 5 % after a period of eight weeks. There was a significant increase in the bacterial load of the soil attached to class 2 (HDPE) polythene. After eight weeks of submergence in mangrove soil, soil attached to class 1 and class 3 polythene mostly had Bacillus (Staphylococcus predominated in class 2 polythene). While most of the isolates were capable of producing hydrolytic enzymes such as amylase and gelatinase, lipolytic activity was low. Class 2 HDPE suffered the greatest biodegradation.

Microbial Treatment Of Rubber Latex Centrifugation Effluent

Many of the existing methods for the treatment of rubber latex centrifugation eflluent are not only unsatisfactory in their efliciency to effect near perfect treatment in bringing down the COD to optimum level, but also time consuming and need a large landspace. As the rate of effluent generation is extremely high (20 litres for kilogram of rubber) there is a need for development of efficient system,capable of rapid reduction of COD and BOD. Though the organic load of the rubber efiluent is very high, it does not contain much processed chemicals and therefore it can be considered as a ‘biological eflluent’. Further, the ratio of the Chemical Oxygen Demand to Biological Oxygen Demand (COD/BOD) of this effluent remain almost as a constant value. According to Montgomery (1967), estimation of BOD is not ideally suited for studies on process design, treatability, control of treatment plants, setting standards for treated effluents and assessing the effect of polluting discharges on the oxygen resources of receiving waters. Hence in the present study COD was measured to determine the impact of treatment system on the effluent. In the present study, attempts were made to evaluate the efficiencies of certain methods such as packed bed reactor using immobilized microbial cells, rotating biological contactor (RBC) and activated sludge process, for rapid and efficient treatment of natural rubber latex centrifugation effluent. In addition, studies were also carn'ed out to develop a suitable bioprocess for the coagulation of skim latex, as an alternative to the presently used acid coagulation process towards reducing the pollution load, besides recovering quality rubber

Formation of an unusual copper(II) complex from the degradation of a novel tricopper(II) carbohydrazone complex

An unusual copper(II) complex [Cu(L1a)2Cl2] CH3OH H2O H3O+Cl (1a) was isolated from a solution of a novel tricopper(II) complex [Cu3(HL1)Cl2]Cl3 2H2O (1) in methanol, where L1a is 3-(2-pyridyl)triazolo [1,5-a]-pyridine, and characterized with single crystal X-ray diffraction study. The tricopper(II) complex of potential ligand 1,5-bis(di-2-pyridyl ketone) carbohydrazone (H2L1) was synthesized and physicochemically characterized, while the formation of the complex 1a was followed by time-dependant monitoring of the UV–visible spectra, which reveals degradation of ligand backbone as intensity loss of bands corresponding to O?Cu(II) charge transfer

Biological coagulation of skim latex using Acinetobacter sp. isolated from natural rubber latex centrifugation effluent

An Acinetobacter sp, isolated from latex centrifugation effluent, effectively coagulated skim rubber from skim latex. After coagulation for 48 h without the addition of any nutrients, at an optimum dilution of 1:10(v/v) and with an inoculum concentration of 6.4 mg dry cell /ml, the yield of the skim rubber was 8 % (w/v) and the COD of the residual solution was only 0.4 g/l. chemical coagulation at the same dilution resulted in 7 % (w/v) yield of dry rubber content and 2.2 g COD /l.

A Novel Acinetobacter Sp. For 'Treating Highly Acidic Rubber Latex Cen'trifugation Effluent

A novel Acinetobacter sp. BTJR-IO isolated from highly acidic (pH 2.5-4.5) rubber latex centrifugation effluent with high COD (22000 rng/L) and BOD (5000 rng/L). This strain could effect 39.5% COD reduction on free cell inoculation of effluent without incorporation of additional nutrients after 8 days. CalciLnn alginate irrmobilized cells showed 16.4% and 25% COD reduction after 6 hra, without aeration and after 1 hr. with mild aeration under batch process respectively. Whereas 44.0% COD reduction could be achieved after 6 hrs. on continuous treatment in a packed bed reactor with mild aeration. Further, even after 3 cycles 37% COD reduction was recorded with continuous treatment

Marine bacterial prodigiosin as dye for rubber latex, polymethyl methacrylate sheets and paper

Prodigiosin is known for its immunomodulatory, antibacterial, antimycotic, antimalarial, algicidal and anticancer activities. Here, we reported the evaluation of prodigiosin pigment as a dyeing agent in rubber latex, paper and polymethyl methacrylate (PMMA) so that it can be considered as an alternative to synthetic pigments. Maximum color shade was obtained in rubber sheet prepared with 0.5 parts per hundred gram of rubber (phr) pigment and PMMA sheet incorporated with 0.08 μg pigment. Results indicate scope for utilization of prodigiosin as dye for PMMA and rubber and also prodigiosin dyed paper as a pH indicator. Further, being a natural and water insoluble pigment, it is ecofriendly

Evaluation of a.c. conductivity of rubber ferrite composites from dielectric measurements

The effect of frequency, composition and temperature on the a.c. electrical conductivity were studied for the ceramic, Ni1–xZnxFe2O4, as well as the filler (Ni1–xZnxFe2O4) incorporated rubber ferrite composites (RFCs). Ni1–xZnxFe2O4 (where x varies from 0 to 1 in steps of 0×2) were prepared by usual ceramic techniques. They were then incorporated into a butyl rubber matrix according to a specific recipe. The a.c. electrical conductivity (sa.c.) calculations were carried out by using the data available from dielectric measurements and by employing a simple relationship. The a.c. conductivity values were found to be of the order of 10–3 S/m. Analysis of the results shows that sa.c. increases with increase of frequency and the change is same for both ceramic Ni1–xZnxFe2O4 and RFCs. sa.c. increases initially with the increase of zinc content and then decreases with increase of zinc. Same behaviour is observed for RFCs too. The dependence of sa.c. on the volume fraction of the magnetic filler was also studied and it was found that the a.c. conductivity of RFCs increases with increase of volume fraction of the magnetic filler. Temperature dependence of conductivity was studied for both ceramic and rubber ferrite composites. Conductivity shows a linear dependence with temperature in the case of ceramic samples

Magnetic and processability studies on rubber ferrite composites based on natural rubber and mixed ferrite

Polycrystalline single phasic mixed ferrites belonging to the series Ni1−xZnxFe2O4 for various values of x have been prepared by conventional ceramic techniques. Pre-characterized nickel zinc ferrites were then incorporated into a natural rubber matrix according to a specific recipe for various loadings. The processability and cure parameters were then determined. The magnetic properties of the ceramic filler as well as the ferrite loaded rubber ferrite composites (RFC) were evaluated and compared. A general equation for predicting the magnetic properties was also formulated. The validity of these equations were then checked and correlated with the experimental data. The coercivity of the RFCs almost resemble that of the ceramic component in the RFC. Percolation threshold is not reached for a maximum loading of 120 phr (parts per hundred rubber by weight) of the filler. These studies indicate that flexible magnets can be made with appropriate magnetic properties namely saturation magnetisation (Ms) and magnetic field strength (Hc) by a judicious choice of x and a corresponding loading. These studies also suggest that there is no possible interaction between the filler and the matrix at least at the macroscopic level. The formulated equation will aid in synthesizing RFCs with predetermined magnetic

Tailoring magnetic and dielectric properties of rubber ferrite composites containing mixed ferrites

Rubber ferrite composites containing various mixed ferrites were prepared for different compositions and various loadings. The magnetic and dielectric properties of the fillers as well as the ferrite filled matrixes were evaluated separately. The results are correlated. Simple equations are proposed to predetermine the magnetic and dielectric properties. The validity of these equations is verified and they are found to be in good agreement. These equations are useful in tailoring the magnetic and dielectric properties of these composites with predetermined properties

Effect of Carbon Black on the Mechanical and Dielectric Properties of Rubber Ferrite Composites Containing Barium Ferrite

Fine particles of barium ferrite (BaFe12O19) were synthesized by the conventional ceramic technique. These materials were then characterized by the X-ray diffraction method and incorporated in the natural rubber matrix according to a specific receipe for various loadings of ferrite. The rubber ferrite composites (RFC) thus obtained have several applications, and have the advantage of molding into complex shapes. For applications such as microwave absorbers, these composites should have an appropriate dielectric strength with the required mechanical and magnetic properties. The N330 (HAF) carbon black has been added to these RFCs for various loadings to modify the dielectric and mechanical properties. In this article we report the effect of carbon black on the mechanical and dielectric properties of these RFCs. Both the mechanical and dielectric properties can be enhanced by the addition of an appropriate amount of carbon black