all about the properties of packaging materials

1. PROPERTIES OF
PACKAGING MATERIAL

2. Contents
• Tensile strength
• Bursting strength
• Tearing resistance
• Puncture resistance
• Impact strength
• Tear strength
• Permissibility (GTR, WTR)
• shelf life of products, selection and designing

3. Tensile strength
• Tensile strength is the ability of a material to resist
a direct pull. When referring to ultimate tensile
strength, it is the maximum stress that can be
withstood before breaking. Commonly the tensile
strength is expressed in pounds per square inch.
• Typically noted in either pounds per square inch
(psi) or megapascals (MPa)

4. MACHINE USED:
• Universal testing machine

5. calculation
• Tensile strength (nominal), max. load
kg/cm2 = original min. cross sectional area of specimen
• Tensile strength (at break), max. load at break
kg/cm2 = original min. cross sectional area of specimen
• Breaking factor (nominal), max. load
kg/cm2 = original thickness of specimen
For paper: tensile strength is reported as Kgf/cm

6. BURSTING STRENGTH
• It is the hydrostatic pressure in pounds/inch2 (kg/cm2
• A property of paper or paperboard used in packaging that
measures its resistance to rupturing, defined as the hydrostatic
pressure needed to burst a paperboard sample when it is
applied uniformly across its side
• MACHINE USED:
• Bursting strength tester

7. Calculation:
• Busting Strength(Kg/cm2)= Bust
Factor(B.F)*GSM(Gm/m2)/1000
• Burst factor= bursting strength((Gm/m2)
• grammage (gm/m2)

8. Tearing resistance
• is a measure of how well a material can withstand the
effects of tearing.
• Noted in kilonewtons per meter (kN/m) or pound force per
inch (lbf/in)
• MACHINE USED
ELMENDORF TEAR
TESTER

9. CALCULATION
R= S*C
n
R= tear resistance in grams
S- corrected scale reading
C= machine capacity in grams
N= Number of sheets in each test

10. PUNCTURE RESISTANCE
1.Puncture resistance is a measure of the maximum force
or energy required to penetrate a material. This type of
biaxial stress is seen by packaging films when packing
hard protuberances such as pelleted dry foods and frozen
vegetables.
• MACHINE USED: puncture resistance tester

11. CALCULATION

12. IMPACT SRENGTH
• is the capability of the material to withstand a suddenly
applied load and is expressed in terms of energy.
• Volume, modulus of elasticity, distribution of forces, and
yield strength affect the impact strength of a material.
• MACHINE USED
• Izod impact testing machine

13. calculation
The impact strength is calculated as the ratio of impact absorption to test
specimen cross-section
Impact absorption: test specimen cross section

14. Permissibility
• GAS TRANSMISSION RATE:
OTR,” is the steady state rate at which oxygen gas can
permeate through a film.
OTR is expressed as a volume of oxygen that penetrates a
given area in a one-day period; cc/m2/24hr…or…cc/100
in2/24hr, measured at a standard temperature of 73°F (23°C),
and 0% relative humidity (RH).
General comparisons of barrier capabilities are as follows:
Relative Oxygen
Barrier Capability
cc/m2/24hrs cc/100 in2/24hr
High Barrier ~ 1-10 ~ 0.06-0.65
Moderate Transmitter (of O2) ~ 1000 ~ 64.50
High Transmitter (of O2) ~ 10,000 ~ 645.20

15. Water transmission rate
• WVTR), often referred to as “moisture vapour transfer rate” (MVTR), is the
standard indicator of how easily moisture can permeate a packaging film.
• Its values expressed as g/m2 and g/100in2 at 38°C and 98% relative humidity.
• Increasing WVTR values indicate greater permeability, and lower ability to
keep dry products dry, and moist products moist.

16. • Factors affecting WVTR values include…
• Thickness
• Resin Composition
• Molecular weight distribution
• Crystallinity/density
• Chain-length and chain-length distribution
• Chain orientation
• Polymer blends
• Additives
• Coatings – PVdC, metalizing
• Processing Parameters – BUR, frost-line height, die gap

17. SHELF LIFE OF PACKAGED FOODS
• Shelf life is the length of time that a commodity
may be stored without becoming unfit for use or
consumption. The test that determine the shelf
life of products are:
1. Moisture content of the products.
2. The moisture content of the product at the which the
product becomes unacceptable to the consumer
3. The RH and the temp of the surrounding atmosphere at
which the equilibrium moisture content is maintained in
the product.