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A Study of Casein Plastic and Starch Thermoplastic

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Brian Niebuhr

on 19 April 2015

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Transcript of A Study of Casein Plastic and Starch Thermoplastic

What is Plastic?
Any synthetic
semi-synthetic organic polymer

Popular for their wide range of properties allowing for many applications
A Study of Casein Plastic and Starch Thermoplastic

Brian Niebuhr
Intermolecular Forces
This is the main factor of which gives plastics the variety of properties seen and used today
Added to change the properties by altering the IMFs
The differences in structure on the molecular level translate to the variety of macroscopic properties
Polymers and Monomers
Polymers are long chains made up of smaller molecules called monomers
Polymers are often long chains of these monomers
Plastic is only a type of polymer
Plastic Polymers
Most made up of Organic Polymers
Consisting of C-atoms or mixture of C-atoms, S-atoms, or N-atoms
Concepts Covered:
Monomers / Polymers

Thermoplastic / Thermosets
Starch-based Plastic
Intermolecular Forces
Bioplastic / Green Chemistry

Produced by chemical synthesis (i.e. combination)
But what gives their wide range of properties?
Two Main Factors
1. The different molecular groups (monomers) that make up the plastic
polymer structure

The intermolecular forces
between the plastic polymers as a result of Factor #1
Where and how the molecular groups form the structure by binding to the Carbon chain
Chemical Fillers
Different effects on the IMFs between polymer strands
Intermolecular Forces Funnel
Hydrogen bonded to F, O, or N

Permanent Dipole Attraction
Strongest IMF
Two Polar Molecules

Partial positive attracted to partial negative charges

Weaker than H-bonding
London Dispersion
Two nonpolar molecules

Instantaneous dipole moments

Weakest IMF
Rigid or Malleable
Clear or Opaque
Chemically inert
Include substances that:
May increase IMFs (fire retardants or raise the melting points)
Change natural color (colorants)
Or act as
Often oily compounds that improve flexibility and the flow of the organic polymer structure
Two Main Classifications of Plastic
Once cooled and hardened, cannot return to original form
Used in products such as tires and are hard and durable
Uneasily recycled so are often re-purposed (tires as ground covering)
Less rigid than thermosets
Soften under heat returning to original form
More easily recycled
The Difference?
The Forces that hold the plastics together
This is a result of the Curing Process

or when has polymerization occurred and the plastic is allowed to set
Involve chemical reactions forming irreversible chemical bonds between species
IMFs are the attractive forces that act between the plastic polymer strands
Two-part Procedure
1. Casein Plastic
To test the plastic properties of a casein and a starch-based plastic

To compare the plasticity of each when under varying conditions
White Vinegar substitutes
Analyze the Green Chemistry applications
2. Starch Based Plastic
The Casein Protein
Found in Milk / Dairy Products
Test: Tensile Strength
Test: Malleability
Test: Brittleness
When soaked in distilled water, plastics observed to break readily
Starch-based plastics exhibited increased malleability to that of the casein
Sample 10 No Glycerin
Sample 9 Lemon Juice however was heated
Sample 11 Heated Sample
Casein Plastics exhibited greater brittleness than Starch Based
Sample 3 Lemon Juice
Sample 10 No Glycerin
Sample 11 Tore not Shattered NA
Sample 2 Room Temp
Sample 3 Cold Temp
Sample 5 Too brittle to Test NA
Sample 6 Cold Temp
Sample 8 Hot Temp
Casein exhibited greater tensile strength than the starch-based
Test: Ductility
Casein exhibited no observable ductility while starch-based showed minor
Sample 8 Hot Temp
Sample 9 Lemon Juice Reheated
Sample 11 Reheated
From Data Retrieved
Thermoplasticity Conclusions
Starch-Based Plastics exhibited more ductility than Casein samples, weaker forces holding plastic polymer together
Hot Temp and Reheated samples showed increased ductility, Heat increases ductility and decreases IMFs
Tensile Strength
Casein Plastics greater tensile strength than Starch-Based, Greater forces holding together, suggests more than just IMFs
In general, the cooler temps producing the greatest tensile strengths, Heat lowers tensile strength based off data retrieved
Casein more brittle than Starch-based, casein more rigid structure, Starch-based not held as strongly
Absence of glycerin in Starch based increased brittleness, suggesting glycerin plasticizer
The Starch-based plastics exhibited increased malleability than the casein and were less rigid supporting thermoplastic properties
The Starch-based plastics additionally experienced easier breaking (decreased number of bends until break) when soaked in water
Suggests water soluble
The casein plastics exhibited and were more rigid supporting thermosetting properties
The casein plastics saw no observable changes when soaked in water
Removing the glycerin decreases malleability suggests plasticizer
Heating of starch-based plastic
Increased ductility and malleability; reduced brittleness and tensile strength
Also Starch-based Plastic generally more flexible and weaker in tensile strength suggests weaker forces holding the plastic together than the casein, supporting the starch-based plastic to be a thermoplastic
Although thermoplastic traits (weakening IMFs however when heated, plastic would crumble before melting yielding inconclusive results
The failure to melt and the tensile strength of the Casein Plastic support that casein is thermosetting
What's Next?
Plastic Curing Conditions
Different methods of setting conditions
Different substitutes for White Vinegar (i.e. stronger acids)
Varied amounts of Acid(s) or Glycerin
Repeat for Lemon Juice Sample 9
Green Chemistry
The inconclusive thermoplasticity results fails to yield conclude on the ability for the plastics to reset
When the starch-based plastics were placed in water beaker and observed to dissolve, suggests water soluble
No set formula as it is made up of 193-203 different kinds of amino acids
When combined with acids the protein is denatured and the white casein monomers clump together to form polymers
During the drying process the plastic casein polymer is formed as the denatured amino acids form long chains
Starch Molecule
Can be extracted from plants with high starch content like potatoes
Starch contains two different polymers, one highly branched Amylopectin and the other a straight chain of glucose molecules called Amylose
Amylopectin is highly branched which hinders IMFs

For more plastic like properties White Vinegar is added as this breaks down the amylopectin
Long strands of Amylose left and result is H-bonding
Polymers begin line up and the structure becomes crystalline in some areas.. increased hardness and brittleness
To increase the flexibility a common plasticizer called glycerin is often added
This breaks up the H-bonding providing a lowering the hardness and strength
Plastics produced from renewable resources
Both Casein Plastic and Starch-Based Plastic
Starch Based Plastics swell as they absorb water, breaking the starch into smaller fragments
Part 1
Constant volume of milk and white vinegar used
Hot milk 80*C and added to vinegar
Coagulation then the curds formed were laid out to set

Sample 1: Hot milk
Sample 2: Room T Milk
Sample 3: Cold Milk
Sample 4: Lemon Juice
Sample 5: Reheated
Part 2
Constant volume of d-water, glycerin, white Vinegar and mass potato starch used
Cold 10*C d-water then combined with starch glycerin and white vinegar
Once boiled for 5 minutes, liquid poured onto aluminum foil to set

Sample 6: Cold Water
Sample 7: Room T Water
Sample 8: Hot Water
Sample 9: Lemon Juice
Sample 10: No Glycerin
Sample 11: Reheated
Hazardous Chemicals
Flammable and Fire Hazzard
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