Implementation of Innovative Actions & Future Suggestion

I.    How a small thin O Ring stalls Motorcycle

One of the leading two wheeler manufacturer in India observed that the FKM component is changing in volume & other properties with each successive exposure to atmospheric Heat & Gasoline fumes. According to them with the first exposure certain volumetric expansion takes place ( X ) and then when  the part is kept out (dried in atmosphere) it does not return to it’s original state. In the second exposure it starts swelling again from an already swollen state. If in stage 2 the swelling is Y, the total swelling shall be X + Y”.

A swollen FKM ( or any Elastomer ) product will take very long period to dry but it can never come to its zero position , will be very close to zero. Question is after what period that stage will reach. These factors need to be kept in mind while designing the item.

This causes fuel vapour leakage stalling of Engine.

Swelling characteristic is linked to “Mass” (in turn thickness in this case)

This is explained below mathematical formulation.

                                                                                                1

SW  α  P *  PC *  SOL *  µ *  T * SH *  CD *   (DIM)            --------

                                                                                              TH

SW – Swelling  / P – Polymer type / PC – Polymer content  / SOL – Solvent / T – Temperature

SH – Hardness (SH-A) / CD – Crosslink Density  / DIM (Dimension) – Represented by Thickness ( TH )

µ - Interaction constant characteristic of the rubber and swelling liquid

In a particular case

P / PC / SOL /  T / SH / CD / µ  are constant

                    1

SW  α       --------

                  TH

                                                                          1

Using logarithm system Log SW  =  Log       --------

                                                                        TH

 Assuring Thickness changing form TH1 ……………… TH5, Plot of these

two dimension should indicate Swelling behavior with Thickness change. 

Fig. 2

II.   How much Tyres contribute to PM in the Environment

Study on the Impact of tyre usage on Environment – Indian perspective

It is the Tread of a Tyre wears , which is made of rubbers / reinforcing agents (fillers) Processing aids / Softeners (Process oils) / number of Chemicals , waxes. These (except Silica & Zinc oxide) are all Petroproducts. 

While running of a vehicle tyre has to provide friction (grip) to the road enabling the vehicle to roll and provide steering & braking effect and minimum Rolling resistance to reduce drag on engine & in-turn lower fuel consumption – the major polluting factor. During drive tyre abrades, NSD ( Non Skid Depth ) reduces to a point when the tyre is no more safe to drive due to different factors. This NSD varies strongly depending on tyre size & type & application.

Tyre abrades & NSD reduces – where do the worn tyre material goes ? Obviously to the atmosphere, rubbers & chemicals particles flow in the air (Particulate matter – size ?) which we inhale. Many of these Petroproducts are restricted under REACH and other laws and most of these are taken care of by the technologist. But not all.

Rubber Loss (debris / particle in environment) caused by wear of the tyre may be represented by the following relationship.

R L  α (TR₀ – TR₁) · (AI ·KM ·t · tan δ · RR ) X C  

Considering ( AI, KM, t, tan δ & RR) constant for a particular tyre run, R L is then related to wear .

i.e R L  α C  ·(TR₀ – TR₁).

R L         –           Robber Loss

TR₀          -           Tread Original NSD

TR_{1          -}             Tread NSD at remaining NSD (say 2 m for CV)

AI           –           Abrasion Index

KM        -            Kilometre run

t             -            time of run

tan δ     -             Heat development of the tyre

RR          -           Rolling Resistance

C            -           Constant (related to drive stretch / Vehicle & Load / Driving character /

atmosphere condition etc.)

Or                        R L α C  ·(x . TW) / TR₀                  

where x = (TR₀ – TR₁) in mm and TW is Tread wright of that particular tyre. 

Tyre Production for 2015-16 and other Data Information for Calculation of Rubber Loss

Table II

How may ingredients used in tyre compound attract REACH regulation? Extensive list of chemicals restricted under REACH is available in the literature. Next most important question is – can these be restricted / reduced and if so, how? 

1.    Developing highly wear resistant compound – internationally most of the tyre companies  are pursuing R&D in this direction. How much Indian tyre companies are active in this direction need to be made public.

2.    Thus, reduce quantum of material usage.

3.    Replace petro based ingredients – mainly CB & process oil – already in process of using Silica and PAH free process oil. Technical properties and cost factor to be watched. 

Chemical Loss from CV Tyre Tread, Cross Ply Lug type - Typical compound formulation, average tread weight 22 Kg 

Table III

Tyre Tread (Rubber) Loss

Table II gives the basic calculation of tyre loss and waste generation quantitative amount.

Total quantity of rubber loss adds up to 6756.83 MT. This is excluding Tractor Tyre and OTR. Hence the total quantity would be substantially higher than this. However, Tractor tyre & OTR are not for use on road, they remain in agricultural & mining / construction area and the particles generated from the usage of these tyres is small compared to other dust / particles generated in these activities.

Out of considered total output, T / B accounts for nearly 90% of the quantity, LCV nearly 4.4%, Passenger 3% and 2/3-Wheeler about 3%. Hence all concentration should be to T / B. 

III.     Vibration absorption of Washing Machine (Rubber Foot)

Basic Vibration Terminology - Below some basic vibration terminology discussed to aid better understanding in subsequent section. 

Natural Frequency - Natural frequency is the frequency at which a system tends to oscillate in the absence of any driving or damping force.  It is the system property, it can be altered by varying the mass, Stiffness and its damping.

Equation for natural frequency of simple single degree of freedom undamped system is given by,

Where k is stiffness and m is mass of system.

Forcing Frequency - is the force applied on the system. It can be running speed, or a frequency transmitted from nearby member. Here it is rotating speed of drum.

When forcing frequency (rotational speed of drum) matches with natural frequency of system resonance occurs.  Vibration of system increases significantly, and it can cause failure of system if vibration is not dampened out.

Transmissibility - It is a ratio of force transmitted to ground to exciting force to the system. Transmissibility should be should be as low as possible to reduce force transmitted to supporting structure.

Effect of rubber foot properties on machine vibration

Effect of Stiffness

•      Natural frequencies of system directly proportional to square root of stiffness. Similarly one of resonance frequency of washing machine associated with foot is also proportional stiffness of rubber foot.

•      If resonance frequency of washing machine falls near to operating region it will lead to severe vibration of machine and over period of time it may cause fatigue failure of components.

•       It is observed that natural frequency (around 1320 RPM) associated with foot comes in operating frequency of washing machine (up to 1400 RPM).

•   So when rotational frequency of drum matches with natural frequency, resonance occurs.

•     To avoid resonance during operation natural frequency should be kept outside operating region ( by increasing stiffness as shown in figure) 

Effect of damping

•    Damping has more effect on vibration amplitude rather than natural frequency of the system.

•    Moreover, effect of damping on vibration amplitude varies with operating frequencies. Damping affects vibration levels significantly near to resonance region while at higher frequency there is negligible influence on vibration level.

•    Here we are operating washing machine near to one of resonance region associated with foot so higher damping in rubber foot will help to reduce vibration level.

Effect of damping on transmissibility

•       To improve transmissibility, should operate the system at greater than at least √2 times N.F. (black curve) which needs to keep natural frequency as low as possible hence soft spring (K should low) and low damping (black curve) so that N.F. can be shifted to low frequency but this contradicts with earlier requirement ( to low vibration level, N.F. should be higher than maximum operational frequency).

•       Operating near resonance region (less than √2 times N.F.) to reduce transmitted force it need to increase damping property of foot material (green curve). 

Dynamic Mechanical Analysis of Rubber

In order to characterize material damping (tan δ) and stiffness (dynamic stiffness) properties in dynamic condition were carried out DMA (Dynamic mechanical analysis) of different rubber material which with presented below.

• By selecting material having higher dynamic stiffness in desired operating range (15 Hz - 25 Hz) modal frequency can be increased and postpone outside operating region.

• From above plots of dynamic stiffness of different rubber material at different frequencies, NBR SH 80 (Black & Grey) gave highest stiffness among all rubber composition in desired frequency range (15 Hz - 25 Hz). 

• Higher the tan δ of rubber, higher the damping and lower the vibration amplitude so it is recommended to select material having higher damping to reduce vibration level.

•  From above plots of tan δ of different rubber material at different frequencies, NBR SH 80 (Black) is giving highest tan δ among all rubber composition in desired frequency range (15 Hz - 25 Hz). 

Effect of thickness and diameter of the rubber was studied using different thickness level (3.0 & 3.5 mm) and diameter (30 & 34.5 mm) with radius of 215 & 160. Results are presented in following graphs. From these it is clear that sample based on NBR with 3.5 thickness, 34.5 mm dia and 215 radius provides the best damping characteristic. 

Conclusion

From all above analysis and results one can we concluded that NBR with shore hardness SH – 80 is most suitable for washing machine foot application to reduce vibrations and it will be 3.5 mm thickness 34.5 mm dia 215 roils use for further development.

Effect of Shore Hardness

From these tests comparison it can be concluded that by increasing shore harness of rubber foot material resonance frequency getting shifted toward higher frequency as it will increase storage modulus (stiffness) of material which suggest that it needs to choose material and shore hardness such that resonance frequency should be outside operating region.  

First & second modal frequencies with different foot material

• First and second modal frequencies of cabinet with different rubber material are plotted in above bar chart. Among all materials NBR - SH 80 and NR - SH 70 gives higher modal frequency due to higher stiffness of material. So from above results NR - SH 80 would give higher modal frequencies and better performance but NR can easily affects by chemical reaction which is not recommended.

• By comparing NBR-80- G (Grey) and NBR-80 (Black) it is observed that with black color modal frequencies are much higher than grey color due to higher content of carbon black. So it is recommended to select black rubber for washing machine foot application for vibration reduction.

• By comparing NBR-80-G and Butyl-80-G it is found that Butyl material will give higher modal frequencies hence lesser vibration than NBR. So if we developed Butyl SH 80 in black color it would give better performance but there are some practical limitation of Butyl over NBR i.e. higher cost, production difficulties, availability and productivity. So NBR is recommended over Butyl material.

IV.        Innovative Process for Measurement of Critical Rubber / Rubber Adhesion 

Studies on Adhesion – New Test Method for Measurement of Tack Modification of Peel Test for Testing Rubber to Rubber joint

A new test method has been developed to measure the autohesive tack between cap & base compounds at higher temperature of contact. This method is a modification of the 180° peel test by incorporating a separator or a perforated sheet at the interface. This gives reproducing a results & simulates the co-extrusion process at a relatively higher temperature of contact.

Use of perforated sheet has two functions:

(1) It prevents the tear from deviating from the interface or, in other words, it guides the tear propagation process in the plane of the interface. The sharp plastic sheet cuts the rubber when the tear deviates from the linear path.

(2) The number of contact points can be counted and visualized during the test. As a result, each peak force can be related to the number of contact points. 

V.    Ozonolysis & Amperometric Titration innovative method to establish 1, 2 & 3, 4 NR structure.

First Chemical (Method) Proof for 1, 2 & 3, 4 Structure of NR

Structure of Natural Rubber has been established as -1, 4 Cis Polyisoprene long back. Later, different instrumental studies, primarily IR Spectrophotometry, found that a certain portion of NR has -1,2- structure. I took up the work to identify the hydrolyzed ozonide NR products which resulted in Levulinic acid and Formic acid. The fractions were separated by Column Chromatography followed by estimation using Amperometry titration. This gave the evidence of – 1, 2- and – 3, 4 – structure presence in NR besides main – 1, 4 – structure of Polyisoprene.

Detection of Formic & Acetic acid in Ozonolysis product besides Levulinic acid using Paper & Column Chromatography with Silica gel column coupled with Amperometry titration method showed that NR has –1, 2- or -3, 4- structure besides predominant – 1, 4- structure. This was endorsed and the work was published in UK Journal in 1962. 

VI.        Effect of moisture on Sulphenamide accelerated CB compound

An incidence with Internal Mixer

New experience in the plant and development of technology enriched our knowledge. When the chamber of one of the internal mixers was changed to new one, we encountered unforeseen problem. Along with the master batch water droplets were also falling on the dump-mill during discharge of the batch. Obviously, doubts were that the water is coming from leakage somewhere in the machine. A thorough check was conducted but no clue found.

arrangement was made with BARC for short life radioactive Cobalt 60 which was mixed in the closed loop of cooling water system of the mixer and circulated to find leakage by testing radio activity of the water droplets. 

No radio activity was found on these water droplets. Finally, we could conclude that due to improved cooling effect of the new chamber, moisture evaporating from rubber and carbon black during mixing was condensing back causing water trace on the master batch.

This further led to the study – what will be the effect of moisture on sulphenamide accelerators used in the compound which are sensitive to moisture, on the cure characteristics of the compound. An elaborate study was carried out in collaboration with Bayer India which resulted in publications in Kautschuk U Gummi / Kunststoffe. 

VII. Bio-Polymer

Biodegradation is a process, not an end result

IS / ISO 17088 (2008) provides the specifications for compostable plastics.

Disintegration during composting

A plastic product is considered to have demonstrated satisfactory disintegration if, after 84 days in a controlled composting test, no more than 10 % of its original dry mass remains after sieving through a 2.0 mm sieve. The tests are carried out in accordance with ISO 16929, ISO 20200, ISO 14855-1 or ASTM D 5338 under thermophilic composting conditions without CO₂ trapping equipment.

Ultimate aerobic biodegradation

A plastic product is considered to have demonstrated a satisfactory rate and level of biodegradation if when tested in accordance with ISO 14855-1, ISO 14855-2 or ASTM D 5338, it achieves the ratio of conversion to carbon dioxide specified (90% of organic carbon in the polymer) within the time period specified (equal or less than 180 days).

Polyvinyl Alcohol

Polyvinyl alcohol (PVOH or PVA) is a water-soluble synthetic polymer.

PVA has excellent film forming, emulsifying and adhesive properties.

PVA is also resistant to oil, grease and solvents.

PVA has high tensile strength and flexibility, as well as high oxygen and aroma barrier properties.

However, these properties are dependent on humidity

PVA has a melting point of 230°C and 180 – 190°C for the fully hydrolyzed and partially hydrolyzed grades respectively and decomposes rapidly above 200°C.

CORN STARCH – PVA BLEND THERMOPLASTIC

Poly (butylene adipate co-terephthalate)

PBAT is a bio-degradable random co-polymer

Co-polyester of adipic acid, 1,4 butanediol and terephthalic acid from dimethyl terephthalate

Produced by random co-polymerization of 1,4-butanediol, adipic acid, and dimethyl terephthalate (DMT) monomers.

Main advantage of PBAT is that it is a biodegradable alternative to LDPE, having similar properties including high flexibility and toughness, allowing it to be used for various packaging applications. 

Polylactic Acid - PLA

Lactic acid (2-hydroxypropionic acid) is the most widely occurring hydroxycarboxylic optical active acid. Polylactide is based on lactic acid monomers obtained from the fermentation of sugars obtained from renewable sources such as sugar cane or corn starch. 

Direct polycondensation - leads to low molecular weight polymers which then can be converted to higher molecular weight polymers by addition of chain coupling agents.

Ring opening polymerization - PLA is produced by formation of lactide monomer first and formed lactide is then put through ROP using metal alkoxides as catalysts resulting in high molecular weight polyester.

Market Potential

• No reliable statistics for the production or consumption of plastic bags in India.
• Proxy to estimate total consumption of plastic bags in India
• Plastic bags are mainly based on LDPE or low density polyethylene.
• Domestic LDPE consumption in 2016 - 17 was around 700,000 metric tons.
• Assuming 60% of total LDPE consumption was for the manufacture of plastic bags, the LDPE polymer consumption was be around 420,000 metric tons.
• Based on this figure, the consumption of LDPE compound for plastic bags will be around 600,000 metric tons.
• Even a 5% market share for bio-degradable material plastic bags represents a consumption figure of 30,000 metric tons per year growing at 20 to 25% year on year.       

Global Scenario

VIII.    ISOSORBIDE BASED POLYMER 

Corn – Starch – Glucose – Sorbitol – Isosorbide

I

TPU – Excellent thermomechanical properties

Macromonomers for TPU / PU

Aromatic Polyester

Improved temperature resistance

Excellent clarity

Excellent chemical resistance

Polycarbonate

Excellent Optical properties

Chemical & V resistance

High temperature resistance

II      Isosorbide in Polyester

Isosorbide – 15 mol % - crystalline / Amorphus

                    5 & 10 mol %               15 mol & 20 mol %

Heat resistance improves with Isosorbide mol % increase. Isosorbide increase Tg of PET. 

Isosorbide in Polycarbonate

UV stability

Better compared to PC & PMMA

Suitable for outdoor application

Excellent dyeability, high gloss & scratch resistance 

IX.      ITACONIC ACID BASED POLYMER

Itaconic acid is an organic acid that is used as a platform chemical for the production of various value added chemicals such as poly-itaconic acid, resins biofuel components, ionomer cements etc. Itaconic acid and its derivatives have wide applications in the textile, chemical and pharmaceutical industries.

Dry distillation of citric acid affords itaconic anhydride, which undergoes hydrolysis to itaconic acid. Upon heating, itaconic anhydride isomerizes to citraconic acid anhydride, which can be hydrolyzed to citraconic acid (2-methylmaleic acid).

Steps in conversion of citric acid to citraconic acid via itaconic and aconitic acids

Application

Itaconic acid is primarily used as a co-monomer in the production of acrylonitrile butadiene styrene and acrylate latexes with applications in the paper and architectural coating industry.

X. New Concept of Waterless Washing Machine