Training day on program SML

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Training day on program SML. Exercises 5.12.2007. Exercise 1. Additive migration from a monolayer sheet Goal: searching data base, understanding temperature effect, introduction to partition coefficient. Packaging geometry and layer properties. Packaging

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### Training day on program SML

Exercises

5.12.2007

Exercise 1
• Additive migration from a monolayer sheet
• Goal: searching data base, understanding temperature effect, introduction to partition coefficient
Packaging geometry and layer properties

Packaging

LDPE, monolayerV = 1000 cm3S= 6 dm2thickness= 0.5 mm[conc.] =1000 ppmMW = 531 Da

CAS# 002082-79-3

Problems
• Approximate the diffusion coefficient at 20, 40 and 80 °C
• Calculate the time tc to reach the SML of 6 mg/kg
• What is the apparent effect of the partition coefficient K on tc (compare K = 1 and K = 10)

2

3

1

Solutions

High K (low solubility in food) increases time to reach SML

Exercise 2
• Soft drink contamination by a pigment degradation product
• Goal: apprehend untypical geometry with surface/volume ratio
C.I. Pigment Red 53

Extrusion at temperature > 150°C produces b-naphtol

Measured concentrations

article

concentration

1 mg/kg

closure HDPE

b-naphtol

190 mg/kg

masterbatch HDPE

• Define the simulation geometry for a 1 litre bottle
• Approximate D at 20°C (MW = 144 g/mol)
• Calculate the concentration of contaminant after 100 days
• Concentration in soft drinks was measured at 0.3 mg/kg; conclusion ?

2

Closure diameteris 3 cm

3

1

Surface of closure is onlyone part of package total surface !!

1

thickness of closure

2

b-naphtol is quite soluble in water

3

Approximate the diffusion coefficientfor a MW of 144 Da in HDPE

Select experimental T

Define MW

Selectpolymer

D is automatically calculated

Solution Q4

The measured concentration of 0.3 mg/kg cannot be reached with a concentration of 1 mg/kg in the closure. To get such a concentration in soft drink, the starting concentration of ß-naphtol should be > 200 mg/kg in the HDPE closure. This indicates that the closures that contaminate the soft drinks were more contaminated than the ones that were measured.

The HDPE closures and masterbatch were sent by the producer months after the soft drink analysis. Probably, ß-naphtol was lost during this storage time (volatility of the molecule).

Exercise3
• Degradation of a clarifying agent in polypropylene
• Goal: designing multilayer packaging, defining temperature profile

in polymer:

2000 ppm

in food (fresh ananas pieces in juice):

200 ppb

 cherry taste from 100 ppb

Simulation parameters
• Geometry: spherical segment (H=5, R=3, D=7, d=4 cm)
• Multilayer PP-EVOH-PP (thickness= 90, 10 and 200 µm)
• DPP: Ea =48.6 kJ/mol, D0 = 0.4 cm2/s
• DEVOH: approximate as PA (polyamide); (MW tolualdehyde = 121 Da)
• Assumption: tolualdehyde is 10X more soluble in EVOH than in PP
• Concentration in the food contact layer (200µm) is 20 mg/kg
Problems
• Estimate migration in food for a 3 days shelf life at 5°C
• Compare multilayer and monolayer packaging
• Estimate effect of hot filling (100°C, 10 min cooling to 5°C) on the migration

2

Define layers thickness, diffusant concentration in each layer and partition coefficient for each interface

4

1

Enter the Arrhenius parameters for the two PP layers

3

5

4

3 layers

3 days at 5°C  migration is 0.146 mg/kg

1 layer (PP, 200 µm)

3 days at 5°C  migration is 0.151 mg/kg

3 layers

Hot filling +

3 days at 5°C  migration is 0.150 mg/kg

1 layer (PP, 200 µm)

Hot filling +

3 days at 5°C  migration is 0.163 mg/kg