biorenewable polymers

what is a biorenewable polymer

made wholly or partly from renewable biological resources, rather than from fossil-based feedstocks

which polymer does PLA stand for and what is it derived from

poly(lactic acid)

from starch and sugar fermentation

(corn starch or sugar cane)

where does polyurethane come from

plant oils

which types of polymers are PHE and PHB and what are they derived from

polyhydroxyalkanoates

microbial biosynthesis

which polymer does Bio-PE stand for and what is it derived from

bio-based polyethylene

from ethanol derived from sugarcane

monomer(s) and monomer type (A-A, B-B, A-B) of poly(lactic acid)

A-B monomer

show polymerisation to PLA

esterification reactions

3 bio properties of PLA

biodegradable, biocompatible, bioresorbable

what is PLA used in (3)

packing, textiles, medical devices

2 methods of producing PLA

which is used more in industy?

1. direct condensation method

2. ring-opening polymerisation method

2 used more in industry

show direct condensation method to make PLA

what type of polymerisation does it do?

molecular weight of polymer?

low molecular weight PLA

show ring-opening polymerisation method

what type of polymerisation does it do?

molecular weight of polymer?

high Mw PLA

why is ring-opening polymerisation more commonly used in industry to produce PLA

it is faster and more reliable

issues with PLA (3)

• use of genetically modified crops

• recycling of PLA not feasible

• PLA in landfill would not biodegrade (v slow) but over time create methane

monomer(s) and monomer type for Bio-PBS

A-A & B-B

show polymerisation to PBS

key properties of Bio-PBS (2+1 use)

• fully biodegradable and compostable

• strong, flexible and heat resistant

• used in food packaging, textiles & medical applications

how is bio-succinic produced

microbial fermentation

how can succinic acid be purified following this

crystallisation or electrolysis

how is bio-1,4-butanedoil produced

problem?

derived from biomass
produced from succinic acid through catalytic hydrogenation (Clemmensen reduction)

uses metal catalysis to convert which is not environmentally friendly

how is Bio-PBS synthesised

type of polymerisation? type of bond formed?

step-growth polymerisation

esterification between bio-BDO and bio-succinic acid

show reaction step and polymerisation step

temperatures for steps 1 and 2

1: 160-190

2: 220-240

catalyst required?

Lewis acids (Sc(NTf₂)₃, Sc(CF₃SO)₂, Ti(OBu)₄

solvent required?

none

monomer(s) of polyethylene

show polymerisation

non-renewable production of polyethylene?

thermal cracking of oil

where can ethylene be found in nature?

natural plant hormone, causes fruits to ripen

what are the 3 main stages of bio-ethylene production

1. sugar processing

2. ethanol production

3. ethylene production

show the conversion from ethanol to ethylene

catalyst and temperature?

what are the 2 types of polyethylene

high density (HDPE) and low density (LDPE)

low density polyethylene

• flexibility, toughness and cracking? compare to HDPE

• crystallisation?

• density?

• Mw?

• better flexibility, impact toughness and resistance to environmental stress cracking than HDPE

• crystallisation impeded by branching, so up to about 40%

• lower density due to higher amount of amorphous content

• Mw 80-40 g/mol

high density polyethylene

• crystallinity?

• Mw?

• stiffness and density?

• ratio?

• 70%+ crystalline

• Mw about 35 kg/mol

• increased crystallinity leads to increased stiffness, higher density

• large strength to density ratio

how are urethanes formed

reaction between an isocyanate and an alcohol

show 2-step urethane production from R₁-N=C=O and HO-R₂

how are polyurethanes produced?

(give type of polymerisation and between what)

step-growth polymerisation between an isocyanate and alcohol

show schematic monomers for polyurethane production

show polymerisation to polyurethane?

what can this be called

polyol

what are polyols derived from

natural sources such as corn

how are isocyanates derived

need to be derived from carboxylic acids, often using harsh conditions

stability of isocyanates? consequence for their production?

highly reactive, limiting their stability

usually prepared then used straight away

2 properties provided by polyurethanes

strength and elasticity

show which sections of polyurethane provided strength and elasticity

what are polyurethanes used in and give 3 desirable properties of these products

commonly used in textiles to make them durable, stretchy, waterproof