| Abstract: | The main objective of the present study was to explore ways of making latex products more cost effective and versatile. Polyethylene glycol was identified as a surface active agent in latex compounds which improves the filler-polymer interaction and also distributes the filler more uniformly. The use of such surface active agents can develop filled latex products with improved mechanical properties at a lower cost. In this study dispersions of carbon black and silica were successfully added to NR latex under high speed stirring without destabilizing latex. |
| Description: | Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3483 |
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| Dyuthi-T1447.pdf | (6.177Mb) |
| Abstract: | The primary aim of this work has been to develop a cost effective process that can be operated at room temperature for developing latex reclaim with superior mechanical properties. With this objective in mind the researcher proposes to study the reclaiming action of four different chemicals on latex products waste. Waste latex products are chosen because it has a higher potential to generate good quality rubber hydrocarbon since all latex products are based on either high quality concentrated latex or creamed latex. Moreover, all latex products are only lightly crosslinked and not masticated and hence not mechanically degraded. The author also proposes to fully explore the possible application of latex reclaim in various fields.. |
| Description: | Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3392 |
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| Dyuthi-T1369.pdf | (9.181Mb) |
| Description: | Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2695 |
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| Dyuthi-T0747.pdf | (4.052Mb) |
| Abstract: | The thesis comprises a set of experiments mainly focused on the improvement of L-glutamic acid fennentation. Much attention has been given to use of locally available raw materials, culturing the organism on inert solid substrates and also immobilization of the bacterial cells from the view point of long term utilization of biocatalyst and continuous operation of the stabilized system. Studies were also carried out for the down stream processing for the extraction and purification of L-glutamic acid. An attempt was made to study the morphological features of the microorganism including the cell premeability. In relation with the accumulation of glutamic acid within the cells an approach was made to study the behaviour of the Brevibacterium cells when they are exposed to hyper osmotic environment. Attempts were also made to study the requirement of iron and production of siderophores by this microbial strain. The search for a suitable nitrogen source for glutamate fermentation ended with a promising result that they got a potent urease activity and it can be utilized for many biotransfonnation studies. The entire thesis is presented in three sections, viz. introductory section, experimental section and the concluding section |
| Description: | Department Of Biotechnology,Cochin University Of Science And Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3517 |
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| Dyuthi-T1490.pdf | (7.191Mb) |
| Abstract: | Plasticized poly(vinyl chloride) (pPVC), although a major player in the medical field, is at present facing lot of criticism due to some of its limitations like the leaching out of the toxic plasticizer, di ethylhexyl phthalate (DEHP) to the medium and the emission of an environmental pollutant,dioxin gas,at the time of the post use disposal of PVC Products by incineration. Due to these reasons, efforts are on to reduce the use of pPVC considerably in the medical field and to find viable alternative materials. The present study has been undertaken in this context to find a suitable material for the manufacture of medical aids in place of pPVC. The main focus of this study has been to find out a non-DEHP material as plasticizer for pPVC and another suitable material for the complete repalcement of pPVC for blood/ blood component storage applications.Two approaches have been undertaken for this purpose-(1)the controversial plasticizer, DEHP has been partially replaced by polymeric plasticizers(2) an alternative material, namely, metallocene polyolefin (mPO) has been used and suitably modified to match the properties of flexible PVC used for blood and blood component storage applications. |
| Description: | Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2194 |
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| Dyuthi-T0544.pdf | (8.355Mb) |
| Description: | Dept.of Polymer Science and Rubber Technology,Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2957 |
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| Dyuthi-T0948.pdf | (2.247Mb) |
| Description: | Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2684 |
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| Dyuthi-T0736.pdf | (2.605Mb) |
| Abstract: | The most important part of any footwear is the sole (or sole and heel) which withstands all the hannful external factors such as rouglmess of the ground or road, sharp objects, thorns and stones, heat, dampness and cold during walking. The properties desirable in soling material, therefore, would be 1. lightness 2. resistance to wear and tear for long service life 3. flexibility/softness for wearing comfort 4. thennal insulation Rubber soling surpasses all other soling materials in better performance and lower cost. Because MC sole is soft and very light, and has good abrasion resistance, flex properties and set behaviour it has become very popular all over the world and demand for better quality product is ever increasing. Due to the traditional approach adopted by the footwear industry in foot wear design, the rubber based footwear export surprisingly contributes only a small percentage. The essence of success for any industry lies in the expansion of the export market. Microcellular soles are manufactured for the last three decades without much change in the traditional design and colour pattern. In recent years domestic customers have also started demanding better quality products. In view of the changing taste of the customer and growing competition from other countries, substantial improvement in the export potential will require new base materials for regular or fashion rubber based footwears. The main objective of the present study is to develop new base materials for making MC soles with good quality, viz., light weight, durability and bright colours |
| Description: | Department of Polymer Science and Rubber Technology Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3898 |
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| Dyuthi-T1788.pdf | (13.44Mb) |
| Description: | Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2200 |
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| Dyuthi-T0556.pdf | (6.323Mb) |
| Abstract: | In the first part of the study we probed the effectiveness of rice bran oil as a multipurpose compounding ingredient for nitrile (NBR) and chloroprene (CR) rubbers. This oil has already been successfully employed in the compounding of NR and SBR in this laboratory.In this context we thought it worthwhile to try this oil in the polar rubbers viz, NBR and CR also. The principle of like dissolves like as applicable to solvents is equally applicable while selecting a plasticiser, elastomer combination. Because of the compatibility considerations polar plasticisers are preferred for polar rubbers like NBR and CR. Although plasticisation is a physical phenomenon and no chemical reaction is involved, the chemical structure of plasticisers determines how much physical attraction there is between the rubber and the plasticiser. In this context it is interesting to note that the various fatty acids present in rice bran oil have a long paraffinic chain, characteristic of waxes, with an acid group at the end of the molecule. The paraffinic end of the molecule contributes lubricating effects and limits compatibility whereas the acid end group contributes some polarity and is also chemically reactive. Because of absorption of acid group on the surface of pigments, these acids will have active pigment wetting characteristics also. These factors justifies the role of rice bran oil as a co-activator and lubricating agent for NBR and CR. In fact in our study we successfully replaced stearic acid as co-activator and aromatic oillDOP as processing aid for CR and NBR with rice bran oil.This part of the study has got special significance in the fact that rubber industry now heavily depends on petroleum industry for process oils. The conventional process oils like aromatic, naphthenic and paraffinic oils are increasingly becoming costlier, as its resources in nature are fast depleting. Moreover aromatic process oils are reported to be carcinogenic because of the presence of higher levels of polycyclic aromatic compounds in these oils.As a result of these factors, a great amount research is going on world over for newer processing aids which are cost effective, nontoxic and performanance wise at par with the conventional ones used in the rubber industry. Trials with vegetable oils in this direction is worth trying.Antioxidants are usually added to the rubber compound to minimise ageing effects from heat, light, oxygen etc. As rice bran oil contains significant amount of tocopherols and oryzanol which are natural antioxidants, we replaced a phenolic antioxidant like styrenated phenol (SP) from the compound recipe of both the rubbers with RBO and ascertained whether this oil could function in the role of antioxidant as well.Preparation and use of epoxidised rice bran oil as plasticiser has already been reported.The crude rice bran oil having an iodine value of 92 was epoxidised in this laboratory using peracetic acid in presence of sulphuric acid as catalyst. The epoxy content of the epoxidised oil was determined volumetrically by treating a known weight of the oil with excess HCI and back titrating the residual HCI with standard alkali solution. The epoxidised oil having an epoxy content of 3.4% was tried in the compounding of NBR and CR as processing aids. And results of these investigations are also included in this chapter. In the second part of the study we tried how RBO/ERBO could perform when used as a processing aid in place of aromatic oil in the compounding of black filled NRCR blends. Elastomers cannot have all the properties required for a particular applications, so it is common practice in rubber industry to blend two elastomers to have desired property for the resulting blend.In this RBO/ERBO was tried as a processing aid for plasticisation, dispersion of fillers, and vulcanisation of black filled NR-CR blends.Aromatic oil was used as a control. The results of our study indicate that these oils could function as a processing aid and when added together with carbon black function as a cure accelerator also.PVC is compatible with nitrile rubber in all proportions, provided NBR has an acrylonitrile content of 25 to 40%. Lower or higher ACN content in NBR makes it incompatible with PVC.PVC is usually blended with NBR at high temperatures. In order to reduce torque during mixing, additional amounts of plasticisers like DOP are added. The plasticiser should be compatible both with PVC and NBR so as to get a homogeneous blend. Epoxidised soyaben oil is reported to have been used in the compounding of PVC as it can perfonn both as an efficient plasticiser and heat stabilizer.At present DOP constitute the largest consumed plasticiser in the PVC compounding. The migration of this plasticiser from food packaging materials made of PVC poses great health hazards as this is harmful to human body. In such a scenario we also thought it worthwhile to see whether DOP could be replaced by rice bran oil in the compounding of NBR-PVC blends Different blends of NBR-PVC were prepared with RBO and were vulcanized using sulphur and conventional accelerators. The various physical and mechanical properties of the vulcanisates were evaluated and compared with those prepared with DOP as the control plasticiser. Epoxidised rice bran oil was also tried as plasticiser for the preparation of NBR-PVC blends. A comparison of the processability and cure characteristics of the different blends prepared with DOP and ERBO showed that ERBO based blends have better processability and lower cure time values. However the elastographic maximum torque values are higher for the DOP based blends. Almost all of the physical properties evaluated are found to be slightly better for the DOP based blends over the ERBO based ones. However a notable feature of the ERBO based blends is the better percentage retention of elongation at break values after ageing over the DOP based blends. The results of these studies using rice bran oil and its epoxidised variety indicated that they could be used as efficient plasticisers in place of DOP and justifies their role as novel, nontoxic, and cheap plasticisers for NBR-PVC blends. |
| Description: | Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2648 |
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| Dyuthi-T0708.pdf | (9.727Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5233 |
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| Dyuthi T-2268.pdf | (4.339Mb) |
| Description: | Department of Polymer Science and Rubber Technology,Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2193 |
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| Dyuthi-T0545.pdf | (7.852Mb) |
| Abstract: | The study is undertaken on PVC blends because of their all-round importance-One of the most prominent needs of PVC in application end-use is permanent plasticizationlo. Butadiene-acrylonitrile rubber (NBR) has been utilized as permanent plasticizer for PVC since the 1940s for wire and cable insulation, food contact, and pondliners used for oil containment23'24. Also plasticized PVC has been added to vulcanizable nitrile rubber, to yield improved ozone, thermal ageing, and chemical resistance resulting in applications including fuel hose covers, gaskets, conveyor belt covers, and printing roll covers. This blend is miscible in the range of 23 to 45 per cent acrylonitrile content in the butadiene-acrylqnitrile copolymerzs. The first phase of the study was directed towards modification blends. These blends, in addition to the polymers, require a host of additives like curatives for the NBR phase and stabilizers for the PVC phase26of the existing PVC blends, especially NBR/PVC. The second phase of the study was directed towards the development of novel PVC based blends. Chloroprene rubber (polychloroprene) (CR) is structurally similar to PVC and hence is likely to form successful blends with PVC32. |
| Description: | Department of polymer science & rubber technology, Cochin University of Science And Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3325 |
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| Dyuthi-T1294.pdf | (5.727Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1339 |
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| George K E 1987.PDF | (189.8Kb) |
| Abstract: | The primary aim of this work has been to prepare efficient and cost effective polymer bound antioxidants by direct’ attachment of conventional antioxidants to a modified polymer. Due to the importance and easy availability of natural rubber in Kerala, it is proposed to make use of low molecular weight natural rubber as the polymer substrate for binding the antioxidant in most cases. The molecular weight of such low molecular weight natural rubber can be easily manipulated by varying the time of mastication, UV—irradiation etc. Further, the bound antioxidant may also get vulcanized during the vulcanization of the elastomer to which it is added, making the antioxidant non—volatile and non extractable. Several methods are proposed to be investigated for attaching the antioxidant to the low molecular weight natural rubber such as modified Friedel-Craft's alkylation reaction, binding during UV—irradiation, binding during aggressive mastication etc. The efficiency of such rubber bound antioxidants is proposed to be compared with that of conventional antioxidants in terms of volatility, extractability in solvents, ageing resistance etc. Naturally occuring antioxidants such as cardanol, are also proposed to be modified by binding them to low molecular weight natural rubber. The study is undertaken with the intention of generating a class of bound antioxidants which can be used in elastomers for aggressive and long term application. |
| Description: | Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3229 |
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| Dyuthi-T1203.pdf | (3.081Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1309 |
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| Ravindran T 1989.PDF | (814.3Kb) |
| Abstract: | In the present study, the photochemical depolymerisation of NR in toluene, in presence of H202 and a homogenizing solvent (Methanol/Tetrahydro— furan) so as to get hydroxyl terminated liquid natural rubber (HTNR) has been carried out. The copolymeri— sation of this product with butane 1,4 diol and toluene 2,4 diisocyanate in presence of a catalyst, dibutyl tin dilaurate, to produce polyurethanes with HTNR soft segments is also reported. The preparation of block copolymers based on poly(ethylene oxide) with varying molecular weights and HTNR are also discussed along with a detailed study on their thermal and mechanical properties |
| Description: | Department of Polymer science and Rubber technology, Cochin University of Science And Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3589 |
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| Dyuthi-T1593.pdf | (8.524Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5242 |
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| Dyuthi T-2278.pdf | (8.581Mb) |
| Abstract: | Systematic investigations on prevulcanization of NR latex with special reference to the influence of storage of latex and after-treatments of films, have been carried out. The other aspects studied include the effect of temperature on sulphur prevulcanization, the extent of crosslinking, tensile properties, stress relaxation characteristics, water absorption and leaching characteristics of prevulcanizcd latex films |
| Description: | Rubber Research Institute of India Rubber Board, Kottayam |
| URI: | http://dyuthi.cusat.ac.in/purl/3456 |
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| Dyuthi-T1437.pdf | (3.239Mb) |
| Description: | Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2674 |
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| Dyuthi-T0726.pdf | (3.709Mb) |
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