Madhavan Nanpoothiri, K; Dr.Ashok, Pandey(Cochin University Of Science And Technology, July 8, 1997)
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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
Sunny, M C; Dr.George, K E(Cochin University of Science & Technology, July , 2006)
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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
Srilathakutty, R; Dr.George, K E(Cochin University of Science And Technology, August 19, 1998)
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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
Mohan, Varghese; Dr.Kuriakose, A P(Cochin University of Science & Technology, August , 2001)
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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
George,K E; Dr.Joseph,Francis D(Cochin University of Science And Technology, March , 1987)
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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
Shanti,Avirah A; Dr.Rani,Joseph(Cochin University of Science and Technology, March 20, 1995)
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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
Ravindran, T; Dr.Joseph,Francis D(Cochin University of Science And Technology, March , 1989)
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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
Claramma, N M; Dr.Mathew, N M(Cochin University of Science and Technology, April 22, 1997)
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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
The research work has been in the area of compounding and characterization of rubbers for use in under water electro acoustic transducers. The study also covers specific material system such as encapsulation materials, baffle material, seal material, etc. Life prediction techniques of under water rubbers in general have been established with reference to more than one functional property. Ranges of passive materials, besides the active sensing material go into the construction of underwater electro acoustic transducers. Reliability of the transducer is critically dependent on these passive materials. Rubbers are a major class of passive materials. The present work concentrates on these materials. Conventional rubbers are inadequate to meet many of the stringent function specific requirements. There exists a large gap of information in the rubber technology of underwater rubbers, particularly relating to underwater electro acoustic transducers. This study is towards filling up the gaps of information in this crucial area. Water intake into rubber is considered as the single most important issue for the long-term performance of rubbers, especially Neoprene. In this study, the cause and effects of a range of parameters affecting the water absorption by diffusion and permeation have been investigated.