Give the expression for alkalinity of latex

'Grams of ammonia per 100gm of water in the latex' OR 'milliequivalent of alkali per 100gm of water in the latex'

What is the drying time for TSC in ASTM procedure?

16 hour

What is the drying temperature for TSC in ASTM procedure?

70 degree celsius

What is the dimension of the dish used for TSC in ASTM procedure?

32 square centimeter

Name the monomer of Natural rubber

Isoprene.

What are elastomers?

Elastomers are high polymers having elastic properties in excess of 300%.
eg: Rubber.

How is TSC expressed?

TSC is expressed in unit of % TSC or % of TSC.

What are the principal sources of error in determinig TSC of latex?

Weighing error, Incomplete drying & oxidation.

How is DRC expressed?

It is expressed in unit of DRC.

What is the principal source of error in determining DRC of latex?

Incomplete drying.

Define Total Solid Content (TSC) of Latex

TSC is defined as the % by weight of the whole which is non volatile at a definite temperature in an open atmosphere.

Determination of Dry Rubber content(DRC) of field latex

ABOUT DRC :
DRC is the quantity in gm of rubber present in 100gm latex.

AIM OF THIS EXPERIMENT :
To determine the DRC of field latex.

APPARATUS :

• Cotton waste
• 50ml erlenmeyer flask
• Rubber stopper
• Electronic balance
• 250ml beaker
• Air oven
• Glass rod
• Wash bottle
  

REQUIREMENTS:

• Field latex
• Distilled water
• 2% Acetic acid

PROCEDURE:

• Shake well the given sample of latex bottle.
• Transfer 20-25ml of latex into a 50ml erlenmeyer flask provided with a stopper.
  

• Weigh about 10-20gm latex using an electronic balance into a 250ml beaker.
• Note the weight.
• Add equal amount of distilled water using a wash bottle & measuring cylinder.
  

  

• Keep the above contents undisturbed for a while.
• Add about 2-3ml of 2% acetic acid per gm of latex with gentle stirring.
  

• Keep the solution undisturbed for 15minutes in a water bath.
• When the serum is clear, filter the serum through whatman No:1 filter paper.
• Thickness of the coagulum is reduced to about 2mm by handroller.
• Collect any small particles of coagulum in the beaker by rubbing with main bulk.
• Wash the coagulum with running water for atleast 6 changes of water.
• Dry the coagulum at a temperature of 70 degree celsius for 1 day or for 50 degree celsius for 2 days.
• Cool & take the weight of the coagulum.
• Determination must be duplicated

Preparation of 5% Ammonium Molybdate solution

• Weigh 5gm Ammonium molybdate.
• Dissolve it in 100ml hot distilled water.
• This is how 5% Ammonium molybdate solution is prepared.

DRC of Cenex

AIM:
To determine the DRC of Cenex(Concentrated latex.

REAGENTS:

• 2% acetic acid solution
• distilled water.

APPARATUS:

• Cotton waste
• Rubber stopper
• Wash bottle
• 50ml Erlenmeyer flask
• Electronic balance
• 250ml beaker
• Oven
• Glass rod
• Measuring jar

PROCEDURE:

• Shake the sample bottle of latex.
• Transfer 20-25ml of above latex into 50ml Erlenmeyer flask provided with a stopper.

• Weigh about 7-10gm latex in a 250ml beaker.

• Note the weight. A duplicate is also done.
• Add twice the amount of distilled water per gm of latex.

• Add double the amount of 2% acetic acid per gm of latex with constant stirring using a glass rod till the serum gets clear.

• When the serum gets clear, filter through whatman No:1 filter paper
• Thickness of the coagulum is reduced to about 2mm by hand roller.
• Collect any small particles of coagulum from the beaker & filter paper by rubbing with the main bulk.
• Wash the coagulum with running water for atleast 6 changes of water.
• Dry the coagulum at a temperature of 50 degree celsius in an oven for 12 hours.

• If it is not dried uniformly, then pass the coagulum through a mixing mill. Again dry in an oven at 60 degree for1 hour.
• Cool for a while & take the final weight.

• From the weight of the dried film & the initial weight of latex taken, the DRC of Cenex can be calculated.

Preparation of 2% Acetic acid solution in 1 litre water

Method is very simple.
Take 20ml acetic acid  solution & dilute to 1 litre in a large vessel.This is how 2% acetic acid solution is prepared.

Define Dry Rubber Content (DRC) of latex

DRC of latex is defined as the quantity in gm of rubber present in 100gm of latex
         
        DRC =  (weight of dried film/ initial weight of latex)* 100

Conversion of phenol to p-nitrosophenol

CARE SHOULD BE TAKEN WHILE DOING THIS EXPERIMENT
 In my M.Sc project I got the opportunity to do the synthesis of paracetamol from phenol  at Kerala State Drugs & pharmaceuticals Ltd in Kerala State.This experiment is the first stage in the conversion of phenol  to paracetamol.

AIM:

To convert phenol to p-nitrosophenol.

RAW  MATERIALS:

• Phenol 9.41gm
• distilled water  10ml
• 20ml 50 % con sulphuric acid
• Ice
• Sodium nitrite solution( 6.9gm  dissolved in 10ml distilled water)
• Chilled water

APPARATUS:

• 250ml beaker
• Vessel filled with water( for cooling purpose)
• Thermometer
• Centrifuge
• glass rod

PROCEDURE:

• In a beaker approximately 9.41g phenol & 10ml water  is taken.
• The contents in the beaker are cooled to +9 degree celsius by placing it in a vessel filled with water.
• The temperature is noted with the help of a thermometer.
• When the temperature is +9 degree celsius add 20ml 50% con sulphuric acid slowly with the help of a glass rod & ice is charged to it to bring down the temperature to +2 degree celsius.
• When the temperature is +2 degree celsius, sodium nitrite solution is slowly added to the beaker.
• On complete addition, the beaker is taken out from the vessel & the contents are kept stirred for 1 hour to complete the formation of nitroso product.
• This is then centrifuged  & washed with chilled water to remove sulphates.
• The p-nitrosophenol obtained is kept ready for the next reaction.

I took 2 hours  for completing the reaction.

STUDENTS SHOULD PERFORM THIS EXPERIMENT ONLY WITH THE HELP OF A TEACHER.

Total Solid Of Latex

AIM:
To determine the total solid of given latex.

 

APPARATUS:
50ml Erlenmeyer flask,Rubber stopper,2 petridish, Electronic balance, dessicator, oven

 

REQUIREMENTS:
Latex

 

PROCEDURE:

• Take about 20ml of well mixed latex sample in a stoppered erlenmeyer flask.

 

• .Before adding latex, the erlenmeyer flask should be cleaned & dried.
• Wash & dry a petridish of 60mm diameter in an air oven.

• Cool the petridish for a while & take the weight. Note the weight.
• Weigh about 2gm latex from the erlenmeyer flask & pour it into the previously weighed petridish.
  

• Note the weight of latex taken.
• Swirl the petridish gently to ensure that latex cover the bottom of the dish.
• Dry the test portion in an air oven at a temperature of 70 degree celsius for 16 hour.

• Cool in a dessicator & weigh as quickly as possible .

• Repeat the drying operation until the loss in weight is less than 1mg during a period of 30 minutes for temperature between 70-75 degree celsius.
• From the weight of latex taken,weight of petridish alone & the weight of the dried film, the Total Solid Content of latex can be calculated.

Preparation Of 0.1N HCl in 100ml standard flask

PROCEDURE:

• 1ml con HCl  is diluted to 100ml
• This is how 0.1N HCl is prepared in 100ml standard flask.

Total Alkalinity OR Ammonia Content Of Latex

AIM:

To determine the Total alkalinity or Ammonia content of  latex .

DEFINITION  OF TOTAL ALKALINITY OR AMMONIA CONTENT :

The term denotes the free alkali content of latex.

APPARATUS:

50ml Erlenmeyer flask,Stopper,500ml beaker, glass rod, Electronic balance,burette.

REQUIREMENTS:

Latex, distilled water, Methyl Red indicator, 0.1N HCl

PROCEDURE:

• Take about 20-25ml of well mixed sample of latex in a stoppered erlenmeyer flask.
• Take 200ml distilled water in a 500ml beaker.Add 5-6 drops of methyl red indicator. A yellow color is obtained.
• Weigh 2gm latex from the erlenmeyer flask & note the weight.
• Pour this latex into the beaker containing methyl red indicator.( step 2 mentioned above).
• The contents are titrated with 0.1N HCl from the burette till the yellow color changes to pink.Note down the volume of the acid.

CALCULATION:

From the weight of latex taken, volume of HCl & the normality of HCl, the Ammonia content of latex can be calculated

What is an indicator?

Indicator is the substance which denotes the completion of a reaction in a titration by colour change. Examples of indicators are Methyl Red, Methyl Orange,Phenolphthalein

Liquid Ammonia Purity

Care should be taken while handling liquid Ammonia.This is a simple experiment.In the lab students should open the bottle of Ammonia  under the guidance of a teacher.
When I was at Rubber Research Institute Of India, I got the opportunity to test the purity of liquid Ammonia.

Lets go to the experiment.

 APPARATUS:

Electronic balance,50ml Erlenmeyer flask, 500ml beaker, burette, glass rod.

REAGENTS:

Distilled water,methyl red indicator,1N HCl

PROCEDURE:

• Transfer 20- 25ml liquid ammonia to a 50ml erlenmeyer flask provided with a stopper.

• Take 300ml distilled water in a 500ml beaker.

• Weigh 1-2 gm of liquid Ammonia from erlenmeyer flask using the electronic balance.

• Note the weight.
• The above weight of liquid Ammonia is added to 300ml distilled water taken in 500ml beaker.(already mentioned)
• This step should be immediately done.
• Add 1 drop of methyl red indicator to the beaker.
• Titrate against 1N HCl taken in the burette.

• Stirr the contents in the beaker using a glass rod  while the titration is done.

• At the endpoint a pink color is obtained.

CALCULATION:

  From the normality of HCl, volume of HCl & the weight of the sample taken , the purity of liquid Ammonia can be calculated