Tuesday, September 22, 2009
Sunday, September 20, 2009
Reinforcement of Rubber Compounds with Nano- Filler
Reinforcement of Rubber Compounds with Nano- Filler
S.N. Chakravarty & A. Chakravarty
KPS Consultants & Impex Pvt.Ltd., 812, 6 Nehru Place, New Delhi 110019 (India)
E.mail : kpsimpex@airtelmail.in
Abstract
Nano CaCO3 is one of the many emerging applications of nanotechnology that is already finding successful commercial application. Reinforcing effect of Nano CaCO3 in different compounds – NR and NR / NBR blend used in Sports Goods (laminated sheet for inflated balls), NR based cycle tube, bromobutyl based pharmaceutical closures and CPE / CSM blend used for coated fabric was studied with one characteristics in mind that is to improve barrier properties as all these products have requirement of one common property – air retention. Rheometric study and physical properties of the vulcanized compounds have been reported.
Introduction
In 1974 Norio Taniguchi defined nanotechnology as manufacturing of materials at the nanometer level. A more contemporary definition of nano technology is the science and technology of devices fabricated from single atoms and molecules. One might add nanotechnology is a hybrid science, combining science as well as engineering to control single atoms and molecules by various means in order to build desired materials / devices from the “ bottom up”.
Nano CaCO3 is one of the many emerging applications of nanotechnology that is already finding successful commercial application . The inorganic nano particles such as CaCO3 have unique functions in the reinforcement of polymers & control of reheological properties
Filler like calcium carbonate, clay etc. with average particle size in the range 01 to 100 nanometer may be defined as a nanofiller. Unlike traditional fillers, mainly used for cost reduction, nanofillers are performance-enhancing fillers used in
relatively small amounts (5 - 10%) in order to provide substantial improvements in physical and other properties.
Nano sized particles (average diameter around 40 nano meter) form a very fine and homogenous distributed system in polymer matrix. As compared to micron size filler particles the nano size filler particles are able to occupy substantially greater number of sites in the polymer matrix. The significant increase in specific surface area of filler particles contributes to the enhanced physical property of the polymer matrix.
Nano sized fillers increase barrier properties by creating a maze or “ tortuous path” that slows the progress of gas molecules through the polymer matrix thereby substantially improving the gas / air permeability of the polymer. Nano sized fillers in polymer matrix substantially improve surface properties like gloss, surface finish, grip (friction) etc.
Knowledge of rheological properties of elastomers is of considerable importance in predicting and comprehending their processing characteristics. Both the viscous and elastic behavior of an elastomer can be analyzed and correlated with its flow behavior. The viscous flow is related to the output rate , whereas the elastic behavior corresponds to the dimensional.
Background of the Study
Studies with specific compounds reinforced with Nano CaCO3 were carried out with one characteristic in mind i.e. to improve barrier properties. NR and NR / NBR blend compounds are used in sports goods (e.g. laminated sheet for inflated balls), cycle tube compound, bromobutyl compounds used in pharmaceutical closures and CPE / CSM blend compound used for coated fabric which in turn is used in the manufacture of inflated boat & container. All these have requirement of one common property – air retention which is expected to improve by the usage of Nano CaCO3 in the compound.
Present study reports about the reinforcing effect of Nano CaCO3 in different compounds as mentioned above.
Experimental
Typical properties of Nano CaCO3 used for the studies are given in Table I
Mixing of compounds was carried out with open laboratory mixing mill (200 mm X 400 mm, friction ratio 1:1.1, approx.70°C) following standard procedure of mixing. Compound formulations are given in Table II, III ,IV & V.
Rheometery of the compound was carried out with Oscillating Disc Rheometer (Monsanto R-100, 3ยบ arc, upgraded with computer interface & software) at 150°C from which optimum cure time (t90) was taken for slab cure. Physical testing was carried out as per ASTM D different specification using Instron 430.
For cycle tube compounds Rheometery was carried out at 150° & 160°C using MDR Type of Rheometer ( Flexys make ) with 1° ARC and 12 mints chart.
Compound slab of 150 X 150 mm was cured at 150°C in an electrically heated laboratory hydraulic press (platen size 300 X 300 mm, operating pressure 1.5 tons) for specific time & temperature as mentioned in the Tables. Slabs were cooled at lab temperature (27+-2°C, 65+-5% RH) for 16 hrs after which dumbbells (Type 1 ) were punched. Physical properties of cured slabs were determined with the help of Tensile Tester (Instron 4301) – both before & after ageing in circulating hot air oven at 100 ± 2 °C for 48 hrs.
Results & Discussion
Evaluation in NR and NR & NBR blend based compounds
The use of particulate fillers in polymer / elastomer is known since very long time and their usage continue to play very important role, especially with respect to reinforcement of properties and product cost. Selection and use of such particulate fillers are guided by different factors like cost, particle size and shape, filler surface structure etc. 1,2
The inorganic nanoparticle such as Calcium Carbonate (CaCO3) has unique functions in the reinforcement of polymers and control of rehological properties. The effect of Nano CaCO3, having mean size of 40-nano meter (nm), on properties of PVC has been investigated and reported in the literature. There is hardly any work reported on the effect of Nano CaCO3 on natural rubber compound in the literature, through some work has been reported about its effect on EPDM, SBS etc. 3
Studies with Natural Rubber (RMA 5 & Pale Crepe) compounds containing non black filler – both reinforcing (precipitated silica) & non reinforcing (china clay) and with lower dosage of Nano CaCO3 compared to silica were carried out to understand the reinforcement contribution of such Nano CaCO3 by determining classical physico-mechanical properties, before and after ageing at an elevated temperature.
From the Rheometry (Table VI A ) it is observed that replacement of 15 phr precipitated Silica by 5 phr Nano CaCO3 has minor effect on different characteristics like Max. Torque, TS 5 (Scorch time),& TC 90 (Optimum cure time) of different compounds in two types of Natural rubber ( RMA & Pale Crepe) and blend of NR with Nitrile rubber (33% ACN content). These characteristics are closely comparable in most of the cases; there is a minor effect on scorch time (minor lower tendency) and cure rate (minor slowing down) with compound containing Nano CaCO3, which might be due to pH factor.
Physical properties, before and after ageing, of compounds are given in Table – VI B. All tests were carried out as per ASTM D (Vol.9.01) different specification.
It can be seen from the values of different physical properties presented in Table– VI B, that these are quite close for both, silica and Nano CaCO3 containing compounds though in later case only one third quantity of filler was used replacing Silica. These values clearly indicate the superior reinforcing effect of Nano CaCO3 compared to precipitated Silica. Nano CaCO3 containing compounds give little lower hardness compared to Silica compound. This could be modified by adjusting the proportion of other filler, as the case may be, in the compound.
Drop in values of different properties after ageing clearly indicate superior trend with Nano CaCO3 compounds indicating better performance of the product based on Nano CaCO3. Percentage drop in properties on ageing at 100°C for 48 hrs (values in bracket), clearly indicate that compounds with Nano CaCO3 retains the properties at a higher level compared to compounds with precipitated silica filler only.
Further work was carried out with NR + NBR blend (30:70 ) compound (III B ) as reported in Table – III wherein part of the precipitated Silica filler was replaced by Nano CaCO3 (10 phr pptd. Silica + 5 phr Nano CaCO3). Results, given in Table – III, clearly indicate that part replacement of precipitated Silica by Nano CaCO3 gives rise to improved physical properties in all respect compared to alone precipitated Silica reinforced compound.
Evaluation in NR Bicycle Tube Compound
Different Physical property values are given in Table – VII A & B.
It is noticed that improved Tensile Strength and Modulus (at 300%) values are obtained with compound containing Nano CaCO3 compared to that with precipitated Silica, even at one third proportion of Nano CaCO3 to Silica indicating higher reinforcing character of Nano CaCO3. This was expected because of finer particle size of Nano CaCO3 resulting in thorough and uniform dispersion of filler in the compound resulting in higher reinforcement. Elongation at break reduces which corresponds to higher modulus.
Elastomer nanocomposites are characterized by better filler dispersion within matrix compared to the conventional filler system. This is noticed from the effect of small dosage of Nano CaCO3 on the physical properties of compounds.
Tensile Strength of compounds containing Nano CaCO3 increases substantially in case of non-black compound and marginally in case of black compounds containing reinforcing carbon black which itself provides high Tensile & Tear properties due to carbon black reinforcing characteristics.
Similarly, Compression Set values of compounds containing Nano CaCO3 improves substantially with non-black compound and marginally with black compounds containing reinforcing carbon black which also contributes towards this property masking the effect of Nano CaCO3.
In case of Abrasion Resistance a clear improvement with non-black compound containing nano CaCO3 is observed which is marginally better in case of black compound containing reinforcing carbon black.
Evaluation in Bromobutyl Compound
Nano CaCO3 was evaluated in a typical Bromobutyl rubber based pharmaceutical compound (Table –V) as full and part replacement of precipitated Silica. Results are presented in Table VIII.
Nano CaCO3 imparts better Scorch Safety but slows down the cure a little.
Tensile strength values increase substantially with nano CaCO3 containing compound, even as part replacement of precipitated Silica. Same trend is observed with Modulus at 300% elongation. Hardness of all compounds are closely comparable. Compression Set values are better with nano CaCO3 containing compounds – as full or part replacement of precipitated Silica.
Tear strength values of different compounds are more or less at same level. Improvement in Modulus, Tensile strength & Compression set at same Hardness level of compounds with nano CaCO3 as part or full replacement of precipitated Silica, which are the performance criteria properties, indicate towards an improved product performance.
Studies on Nano CaCO3 usage in CSM – CPE blend
Reinforcement with Carbon Black & Nano CaCO3 of CPE (Chlorinated polyethylene rubber) and CSM (Chlorosulphonated Polyethylene) blends (Table V) were studied as a part of the evaluation of polymer blends of CPE and CSM. 4
With increase in Nano CaCO3 in the compound, ML4 (Mooney Viscosity) values and Max. torque (Rheometry) goes up. Scorch time and cure time decreases with increase in the filler content. With high filler level, polymer – filler interaction increases causing drop in scorch safety & cure time and increase in max. torque (Table IX)
Compound containing Nano CaCO3 only shows drop in tensile strength after 30 phr level but the modulus remains constant. Compound containing 40 phr CB with varying nano CaCO3 phr in the compound, the properties levels off after 10 phr nano CaCO3 content in the compound. (Table X)
Increase in storage & loss modulus as well as tan d value indicating higher heat development on dynamic application with Nano CaCO3 containing compound is much lower compared to CB containing compound. Thus usage of Nano CaCO3 as part replacement of CB can reduce heat development of compound.
For detail results you may refer to Kautschuk Gummi Kunststofee, Nov. 2007, p 619-622
or Contact us : kpsimpex@airtelmail.in
Acknowledgement:
Authors wish to acknowledge help in some of the experimental work done by Ralson India Ltd. and CPSE, IIT Delhi reported in this article.
References
1. Rapra Handbook, Particulate filled polymer composites, 2nd Ed.
2. Inorganic nanoparticle filled nano composites – Prof. Jain Feng Chen, Research Centre of the Ministry of Education for High Gravity Engineering & Technology, Dec. 2002.
3. Ultrafine Precipitated Calcium Carbonate & its Function as Rubber Additive. – S. Tsutsui, Shirashi Central Laboratories Co. Ltd., Nippon Gomu Kyokaishi (2005), 78 (6), 218-233
4. Studies on Reinforcement of Carbon Black and Nano Filler in Chlorinated Polyethylene and Chlorosulphonated Polyethylene Blend – S. Mondal
M.Tech Thesis, IIT, Delhi, May 2006.
Studies with Shungit
Studies with Shungit – a non-Petro versatile economic filler for tire & non – tire application
A.Chakravarty & S.N.Chakravarty
KPS Consultants & Impex Pvt. Ltd., New Delhi (India)
E-mail: kpsimpex@airtelmail.in
Shungit are natural composite materials having unusual structure, consist of uniformly distributed highly dispersed crystalline silicate particles in amorphous carbon matrix (Ref.1). It’s main component is fullerene like Shungit carbon (upto 80%). There is strong bond between carbon and silicate components. Shungit are characterized by high density, chemical stability and electrical conductivity. Shungit in finely ground state can partly replace carbon black and Silica in rubber compound (Ref. 2, 3 & 4 ).
Work on usage of Shungit as filler in rubber and polymers (Ref.5), polymer Composite (Ref.6), different rubber products (Ref. 7 & 8) have been reported in the literature.
Studies with Shungit, a non petro based performance carbon filler, in additional quantity to Carbon black in typical automotive tire carcass, bead & apex and tread compounds as well as against pptd. Silica, as part replacement in typical tire tread compounds have been carried out and reported here.
Basic properties of Shungit
Shungit consists of ~ 30% globular, X-ray amorphous and metastable carbon and of ~70% highly dispersive silicate particles. According to X-ray characteristics Shungit carbon is a non-crystalline form of carbon with a graphitic structure. Fine Shungit powder is characterized by heat conductivity, heat capacity, electric conductivity & diamagnetic properties, microwave absorption effect. On the surface of Shungit particles there is a certain quantity of solvent-extractable organic substances that may perform the role of “internal” plasticisers or processing aids (Ref.2, 3 & 4). These have been identified as aliphatic compounds by NMR analysis.
Basic properties and composition of Shungit is given in Table 1 (Ref.2 &3)
Rubber industry uses three categories of fillers to reach the balance between the processing properties of rubber compounds, technical properties of vulcanizates and cost.: (i) reinforcing, (ii) semi-reinforcing and (iii) cost-reducing. In terms of the overall physico-chemical properties and structure-dispersion parameters Shungit can be classified as filler belonging to category ii and iii, but their function in rubber compounds extends further.
For detail results you may refer to Rubber World, Aug. 2008, Vol. 238, No. 5, p 27-32
or Contact us : kpsimpex@airtelmail.in
Friday, September 18, 2009
Rubbery Life
Rubbery Life
A journey through rubber science & technology and industry
Dr.S.N. Chakravarty
Polym Consultants, New Delhi
A journey through rubber science & technology and industry
Dr.S.N. Chakravarty
Polym Consultants, New Delhi
PART- 1
Entering Research Life
“ What do you know about Rubber ? “ was the question asked at the interview for CSIR Fellowship at Indian Association for the Cultivation of Science, Jadavpur, Calcutta by my would be research guide. After my Master’s in Chemistry from Banaras Hindu University in 1960 and a short stint of lecturer-ship at Kharagpur, I applied for this research scholarship and was called for the interview.
I replied “nothing“ and thought that the case is closed. Surprisingly my would be research guide Dr. Anil K. Sircar told “don’t worry, I also had no knowledge of rubber when I started to work with it. If you are serious and laborious then you should be able to also do it”. At that time a research scholarship was not easy to get, that even CSIR fellowship. Obviously I was delighted when I was selected for this fellowship.
The fellowship was for Rs 250 per month, which today looks to be ridiculous but was substantial and sufficient about 50 years back. We could live comfortably ( no luxury ) and carry out research activity with out tension with this amount though I lost Rs 20 per month from my earlier stint of lectureship at a Degree college for a short period of few months where my salary was Rs 270 per month.
Attraction of scientific research and a Ph.D. degree was far more than the small loss. Only factor was that the research and industrial activity at that time in India was insignificant and properly paid employment opportunities in the country was remote. Ultimately, on completion of degree I had to look for interesting opening abroad and left for West Germany.
I have spent over 40 years in rubber industry, both in India and abroad, and thought to chronicle this journey which might interest younger generation. Rubber industry in India was never an enlightened one and in the initial stage it was mistry driven industry. In the initial stage there were very few qualified persons in the industry. Perhaps, Dr. D. Banerjee was the first person who started organized and systematic R & D activity and established well equipped laboratory in rubber industry in India. 1970’s saw the entry of a bunch of qualified persons in rubber industry scenario pursuing development work actively and presenting these in different workshop / seminar / conferences. The situation improved over the years but remained confined to bigger organized units. Medium and small scale industries remained mistry driven till today.
At that time India was emerging in the field of rubber / elastomer science & technology and certain laboratories like Indian Association for the Cultivation of Science in Calcutta, (Anil K Sircar, P.K.Chatterjee ), National Chemical Laboratory in Poona ( Sivaramakrishnan ), Indian Institute of Technology , Kharagpur ( S.K.Banerjee ) had nucleus team conducting research in this field with limited facilities at their disposal. Of course, there was Rubber Research Institute, Kottayam under Rubber Board which was fully devoted to work on rubber development and its application. However, RRI activity was primarily focused to the plantation & botanical research. US, UK, France, Germany, Russia & Japan were very active in rubber / elastomer research field those years. In fact largest number of research publication in this field is credited to one Russian scientist named Dogadkin.
Major rubber industry in the country during that period were multinational , like Dunlop , Firestone , Bata , little later Good Year , whose technology & every detail was guided from their Principal and R & D was neither persuaded locally nor encouraged. Situation started changing over the years with the introduction of Indian companies, many of them with foreign technical collaboration but financially independent.
Association with Dr. D. Banerjee
This CSIR Fellowship was under Dr. D.Banerjee through his scheme on “Mechanism on Vulcanization of Rubber “. Dr. D. Banerjee was the father of Indian Rubber Industry and at that time was the Managing Director of National Rubber Manufacturers Ltd. & Inchek Tyre Ltd. During 1960’s Calcutta was the centre of rubber technology & rubber industry, having two tyre companies namely Dunlop and Inchek , Bata, NRM ,Exide and many medium and big size rubber units manufacturing wide range of products. It was centre of cycle tyre, railway products, automotive components, hose, conveyor & Vee belt, hawai chappal etc.
I started the work with Dr. D. Banerjee and Dr. Anil K. Sircar , who was the R & D Chief of NRM which had a well equipped laboratory and processing equipments / pilot plants for rubber products. Often, I had to use these facilities during my research work. This personal association with Dr. Banerjee continued for more than four decades till his death in 2007.
Besides Calcutta , Bombay had also well organized rubber industry including a tyre company i.e Firestone. Bombay ( Cosmos / Lalitmohan Jamnadas, Oriental Rubber / Vijay Makar , Modak Rubber / V.N.Modak , Basant Rubber / Sangtani ) – Thane ( Rubber Reclaim / W.G.Deasi ), Pune ( Swastik Rubber / B.G.Vaidya / Pendse ) and Gujarat areas close to Maharastra border like Dhanu , Vapi etc and upto Surat had a number of small / medium size units. At that time ICI was active in rubber technology & development field and had a well equipped laboratory headed by Dr Roy Chowdhury at Tiljala in Calcutta . ICI rendered technical service to the industry very effectively ( to mention some names who were known to the industry – Mr. Dilip Chatterjee , Dr.Sanjoy Roy , Mr. Samajpati , specially for latex technology ) for quite long which was rivaled by Bayer India in 1970s. Even in rivalry, unlike today, there was a congenial atmosphere and friendly relationship among technologists from different companies. ICI conducted regularly technical training course for the benefit of the industry and was quite popular. This declined in subsequent years and the technical training course initiated by Bayer India in 1970s became very popular in rubber industry.
Synthetics & Chemicals, only synthetic rubber producer in the country manufacturing Styrene Butadiene Rubber in 1960s , had it’s factory in Bareily , UP. Head office and Technical Service Laboratory were in Bombay ( at Worli ) . S & C was also active in rubber industry rendering technical guidance to the industry and also conducted training courses. Mr. M.M.Patel , Mr.R.R.Pandit ( later joined Bayer India and was my colleague for about a decade ) , Mr. N.M.Rege etc. made notable contribution to the rubber field in early years. This laboratory was the centre for training course, especially for IRI / PRI. Later years I have been closely associated to many courses and delivered lectures over the years for IRI / PRI students.
Research Institute
Thus, my research life in the field of rubber started at Department of Macromolecules, Indian Association for the Cultivation of Science, Calcutta in mid 1961. This was the most prestigious research Institute of the country at that time which had people like Dr. C.V. Raman, Dr. Meghnad Saha , Prof. Satyen Bose, Prof. Shanti Ranjan Palit etc. The Institute was established in 19th Century by the then well known medical practitioner & philanthropist, Dr. Mahendralal Sarkar.
The institute had five departments, Physics & Theoretical Physics , Physical Chemistry & Organic Chemistry and Macromolecules covering rubber & polysaccharides. It had a very good library, open till late in the evening.
Early 1960’s infrastructural facilities for Research in the country were lacking. There were no Calculator, Computer , Photocopier, Fax etc. Graphs were prepared manually and multiplied by Ammonia print. Research papers and Thesis were typed with manual typewriter. Those days there were few automatic testing equipments and no software ( all statistical analysis were done manually ) and hence many things had to be done manually which was laborious and time consuming. For example, Column for Liquid Elution Chromatography had to be prepared patiently over hours with Silica gel and solvent which had to be carefully stored all the period so that it does not dry. Similarly, the plate for Thin Layer Chromatography had to be prepared manually by coating the glass plate with silica gel. Due to absence of fraction collector, the fractions of liquid elution chromatography had to be collected manually after every five milliliter followed by manual titration of each fraction so that ultimately at day’s end one graph was produced.
Due to lack of fund, we could not buy all the major equipment and often improvised the same as well as the method. We developed simpler equipments with the help of our workshop technicians who were willing partner to such development. The most important example was the Amperometric Titration apparatus. There was a strong camaraderie among the staff and assistant in the Institute with the research personnel which was a very healthy atmosphere towards the research work. All were actively participating in different games played after the office hours regularly which was participated by even senior professors.
We had one Ozonizer in Organic Chemistry department of the Institute which I had to use extensively at the initial stage of my research work to establish the structure of natural rubber and this resulted in the first experimental ( chemical ) proof of 1 , 2 addition in natural rubber. Earlier this was established by IR Spectrophotometry. In other departments like Physical Chemistry , there were IR & UV Spectrophotometer which were in much use.
Indian Association for the Cultivation of Science had a very good Library and a Librarian who was very cooperative. He had very good knowledge of the subject, especially the availability of cross reference in other libraries in the city or in the country. He was very helpful in our research work.
Initially there was no hostel of the institute which was a problem for the students from outside Calcutta or West Bengal. It was difficult to get a rented place for young bachelor and arrange for food etc. with the scholarship amount. Inspite of repeated appeal to the management of the institute about our problem no action was taken. Hence. ten of us , who were from outside Calcutta / outside West Bengal , one Sunday simply moved into five empty laboratory rooms with our bag & bedding and lived there for four years. We started a kitchen in a room on the terrace hiring a cook which solved our food problem. Subsequently, management relented and provided basic amenities like cot, table & chair etc. Ultimately, after about five years a proper hostel was constructed. Shortly after this I left the institute for Germany.
Calcutta at that time
Calcutta was different at that time and cannot be compared with today’s Calcutta. It was friendly and vibrant and active, specially left ideology. It was a routine that all highly educated youth were inclined towards socialism or radical left ideology. Cultural scenario – avante guard literature, drama, cinema all were very well spread over and actively persuaded during those days. Calcutta was always a financially affordable city.
Once we moved in the institute, we saved lot of time and energy and cost for traveling. This allowed much more time for research work and other pastime activity. We used to initiate our work with our morning tea and close the work just before dinner. Evening we used to spend lot time in the library. High level of scientific research work was carried out by a team of young researcher & post doctoral fellows under the guidance of well known Professors who have left mark in scientific field. Many of my co-researcher made high impact in science & technology & academic field all over the country and in highly developed countries including USA & Europe. From Department of Macromolecules many researcher went to USA and settled there – like Dr. P.K.Chatterjee , Dr. Anil K Sircar etc, whereas many preferred to return back - Dr N.V.C.Rao , Dr. Kunal Roy etc. I was the only person from the institute who went to West Germany at that time.
My first Paper in a conference was presented in CSIR Conference held at Aligarh Muslim University in 1962 or 1963. The Paper was on Ozonization of Natural Rubber & it’s structure which was subsequently published in the Journal of Institution of Rubber Industry, UK. I was absolutely alone at the conference, neither my guide nor anybody else from the Institute were present. Even in winter month it was a sweaty experience. Subsequently, presentation in conferences was a regular affair and made series of research publications in international journals.
“ What do you know about Rubber ? “ was the question asked at the interview for CSIR Fellowship at Indian Association for the Cultivation of Science, Jadavpur, Calcutta by my would be research guide. After my Master’s in Chemistry from Banaras Hindu University in 1960 and a short stint of lecturer-ship at Kharagpur, I applied for this research scholarship and was called for the interview.
I replied “nothing“ and thought that the case is closed. Surprisingly my would be research guide Dr. Anil K. Sircar told “don’t worry, I also had no knowledge of rubber when I started to work with it. If you are serious and laborious then you should be able to also do it”. At that time a research scholarship was not easy to get, that even CSIR fellowship. Obviously I was delighted when I was selected for this fellowship.
The fellowship was for Rs 250 per month, which today looks to be ridiculous but was substantial and sufficient about 50 years back. We could live comfortably ( no luxury ) and carry out research activity with out tension with this amount though I lost Rs 20 per month from my earlier stint of lectureship at a Degree college for a short period of few months where my salary was Rs 270 per month.
Attraction of scientific research and a Ph.D. degree was far more than the small loss. Only factor was that the research and industrial activity at that time in India was insignificant and properly paid employment opportunities in the country was remote. Ultimately, on completion of degree I had to look for interesting opening abroad and left for West Germany.
I have spent over 40 years in rubber industry, both in India and abroad, and thought to chronicle this journey which might interest younger generation. Rubber industry in India was never an enlightened one and in the initial stage it was mistry driven industry. In the initial stage there were very few qualified persons in the industry. Perhaps, Dr. D. Banerjee was the first person who started organized and systematic R & D activity and established well equipped laboratory in rubber industry in India. 1970’s saw the entry of a bunch of qualified persons in rubber industry scenario pursuing development work actively and presenting these in different workshop / seminar / conferences. The situation improved over the years but remained confined to bigger organized units. Medium and small scale industries remained mistry driven till today.
At that time India was emerging in the field of rubber / elastomer science & technology and certain laboratories like Indian Association for the Cultivation of Science in Calcutta, (Anil K Sircar, P.K.Chatterjee ), National Chemical Laboratory in Poona ( Sivaramakrishnan ), Indian Institute of Technology , Kharagpur ( S.K.Banerjee ) had nucleus team conducting research in this field with limited facilities at their disposal. Of course, there was Rubber Research Institute, Kottayam under Rubber Board which was fully devoted to work on rubber development and its application. However, RRI activity was primarily focused to the plantation & botanical research. US, UK, France, Germany, Russia & Japan were very active in rubber / elastomer research field those years. In fact largest number of research publication in this field is credited to one Russian scientist named Dogadkin.
Major rubber industry in the country during that period were multinational , like Dunlop , Firestone , Bata , little later Good Year , whose technology & every detail was guided from their Principal and R & D was neither persuaded locally nor encouraged. Situation started changing over the years with the introduction of Indian companies, many of them with foreign technical collaboration but financially independent.
Association with Dr. D. Banerjee
This CSIR Fellowship was under Dr. D.Banerjee through his scheme on “Mechanism on Vulcanization of Rubber “. Dr. D. Banerjee was the father of Indian Rubber Industry and at that time was the Managing Director of National Rubber Manufacturers Ltd. & Inchek Tyre Ltd. During 1960’s Calcutta was the centre of rubber technology & rubber industry, having two tyre companies namely Dunlop and Inchek , Bata, NRM ,Exide and many medium and big size rubber units manufacturing wide range of products. It was centre of cycle tyre, railway products, automotive components, hose, conveyor & Vee belt, hawai chappal etc.
I started the work with Dr. D. Banerjee and Dr. Anil K. Sircar , who was the R & D Chief of NRM which had a well equipped laboratory and processing equipments / pilot plants for rubber products. Often, I had to use these facilities during my research work. This personal association with Dr. Banerjee continued for more than four decades till his death in 2007.
Besides Calcutta , Bombay had also well organized rubber industry including a tyre company i.e Firestone. Bombay ( Cosmos / Lalitmohan Jamnadas, Oriental Rubber / Vijay Makar , Modak Rubber / V.N.Modak , Basant Rubber / Sangtani ) – Thane ( Rubber Reclaim / W.G.Deasi ), Pune ( Swastik Rubber / B.G.Vaidya / Pendse ) and Gujarat areas close to Maharastra border like Dhanu , Vapi etc and upto Surat had a number of small / medium size units. At that time ICI was active in rubber technology & development field and had a well equipped laboratory headed by Dr Roy Chowdhury at Tiljala in Calcutta . ICI rendered technical service to the industry very effectively ( to mention some names who were known to the industry – Mr. Dilip Chatterjee , Dr.Sanjoy Roy , Mr. Samajpati , specially for latex technology ) for quite long which was rivaled by Bayer India in 1970s. Even in rivalry, unlike today, there was a congenial atmosphere and friendly relationship among technologists from different companies. ICI conducted regularly technical training course for the benefit of the industry and was quite popular. This declined in subsequent years and the technical training course initiated by Bayer India in 1970s became very popular in rubber industry.
Synthetics & Chemicals, only synthetic rubber producer in the country manufacturing Styrene Butadiene Rubber in 1960s , had it’s factory in Bareily , UP. Head office and Technical Service Laboratory were in Bombay ( at Worli ) . S & C was also active in rubber industry rendering technical guidance to the industry and also conducted training courses. Mr. M.M.Patel , Mr.R.R.Pandit ( later joined Bayer India and was my colleague for about a decade ) , Mr. N.M.Rege etc. made notable contribution to the rubber field in early years. This laboratory was the centre for training course, especially for IRI / PRI. Later years I have been closely associated to many courses and delivered lectures over the years for IRI / PRI students.
Research Institute
Thus, my research life in the field of rubber started at Department of Macromolecules, Indian Association for the Cultivation of Science, Calcutta in mid 1961. This was the most prestigious research Institute of the country at that time which had people like Dr. C.V. Raman, Dr. Meghnad Saha , Prof. Satyen Bose, Prof. Shanti Ranjan Palit etc. The Institute was established in 19th Century by the then well known medical practitioner & philanthropist, Dr. Mahendralal Sarkar.
The institute had five departments, Physics & Theoretical Physics , Physical Chemistry & Organic Chemistry and Macromolecules covering rubber & polysaccharides. It had a very good library, open till late in the evening.
Early 1960’s infrastructural facilities for Research in the country were lacking. There were no Calculator, Computer , Photocopier, Fax etc. Graphs were prepared manually and multiplied by Ammonia print. Research papers and Thesis were typed with manual typewriter. Those days there were few automatic testing equipments and no software ( all statistical analysis were done manually ) and hence many things had to be done manually which was laborious and time consuming. For example, Column for Liquid Elution Chromatography had to be prepared patiently over hours with Silica gel and solvent which had to be carefully stored all the period so that it does not dry. Similarly, the plate for Thin Layer Chromatography had to be prepared manually by coating the glass plate with silica gel. Due to absence of fraction collector, the fractions of liquid elution chromatography had to be collected manually after every five milliliter followed by manual titration of each fraction so that ultimately at day’s end one graph was produced.
Due to lack of fund, we could not buy all the major equipment and often improvised the same as well as the method. We developed simpler equipments with the help of our workshop technicians who were willing partner to such development. The most important example was the Amperometric Titration apparatus. There was a strong camaraderie among the staff and assistant in the Institute with the research personnel which was a very healthy atmosphere towards the research work. All were actively participating in different games played after the office hours regularly which was participated by even senior professors.
We had one Ozonizer in Organic Chemistry department of the Institute which I had to use extensively at the initial stage of my research work to establish the structure of natural rubber and this resulted in the first experimental ( chemical ) proof of 1 , 2 addition in natural rubber. Earlier this was established by IR Spectrophotometry. In other departments like Physical Chemistry , there were IR & UV Spectrophotometer which were in much use.
Indian Association for the Cultivation of Science had a very good Library and a Librarian who was very cooperative. He had very good knowledge of the subject, especially the availability of cross reference in other libraries in the city or in the country. He was very helpful in our research work.
Initially there was no hostel of the institute which was a problem for the students from outside Calcutta or West Bengal. It was difficult to get a rented place for young bachelor and arrange for food etc. with the scholarship amount. Inspite of repeated appeal to the management of the institute about our problem no action was taken. Hence. ten of us , who were from outside Calcutta / outside West Bengal , one Sunday simply moved into five empty laboratory rooms with our bag & bedding and lived there for four years. We started a kitchen in a room on the terrace hiring a cook which solved our food problem. Subsequently, management relented and provided basic amenities like cot, table & chair etc. Ultimately, after about five years a proper hostel was constructed. Shortly after this I left the institute for Germany.
Calcutta at that time
Calcutta was different at that time and cannot be compared with today’s Calcutta. It was friendly and vibrant and active, specially left ideology. It was a routine that all highly educated youth were inclined towards socialism or radical left ideology. Cultural scenario – avante guard literature, drama, cinema all were very well spread over and actively persuaded during those days. Calcutta was always a financially affordable city.
Once we moved in the institute, we saved lot of time and energy and cost for traveling. This allowed much more time for research work and other pastime activity. We used to initiate our work with our morning tea and close the work just before dinner. Evening we used to spend lot time in the library. High level of scientific research work was carried out by a team of young researcher & post doctoral fellows under the guidance of well known Professors who have left mark in scientific field. Many of my co-researcher made high impact in science & technology & academic field all over the country and in highly developed countries including USA & Europe. From Department of Macromolecules many researcher went to USA and settled there – like Dr. P.K.Chatterjee , Dr. Anil K Sircar etc, whereas many preferred to return back - Dr N.V.C.Rao , Dr. Kunal Roy etc. I was the only person from the institute who went to West Germany at that time.
My first Paper in a conference was presented in CSIR Conference held at Aligarh Muslim University in 1962 or 1963. The Paper was on Ozonization of Natural Rubber & it’s structure which was subsequently published in the Journal of Institution of Rubber Industry, UK. I was absolutely alone at the conference, neither my guide nor anybody else from the Institute were present. Even in winter month it was a sweaty experience. Subsequently, presentation in conferences was a regular affair and made series of research publications in international journals.
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