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Global Polymer Demand Trends
The global polymer industry consumes raw materials worth more
than US$500 billion per year and transforms them into plastics
products valued at more than US$1 trillion
The period since 1983 has seen world demand grow from just over
45 million tonnes to an expected market demand of over 250 million
tonnes for 2014
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Plastic Consumption World-Wide
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The Plastic Industry
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Materials Properties Comparison
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Product Design: it is the process of devising a product that
fulfills as completely as possible the total requirements of the
user, and at the same time satisfies needs in terms of
cost-effectiveness or ROI (return on investment).Design Technology:
It is the prediction of performance in its broadest sense,
including all the characteristics and properties of materials that
are essential and relate to the processing of the
plastic.Engineering Properties: correlative properties, together
with those that can be used in design equations
Industrial designer : Low processing cost, Appearance, Topical
decorationsHuman Engineering
Engineering designer tool builders processors
Engineering design Graphic design Innovative design
Some basic definitions
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Design Factors Influencing the Performance
ShapeMaterials selectionDesign constraints (Shrinkage,
Stresses)-Eliminate those!Precautionary measures-ribs
The solution is the development/adoption of a Check List!1.
Performance RequirementsColour, temperature, moisture, ultraviolet
exposure, exposure to fungus, flammability, chemical, electrical
resistance, arc resistance, light transmission, stability or
permanency, physical property, mechanical property, optical
property, heat and/or electrical insulation, resistance to
scratching (mar resistance), and special requirements such as
self-lubrication, lightness, hinging property, spring property,
time of exposure, etc. Also important will be meeting existing
government and/or industry regulation.
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2. Determine tolerance requirements that are expected in the
performance of the product. Shrinkage characteristics of the
selectedplastic should be as small as possible so that tolerances
can be anticipated with a reasonable degree of accuracy.
3. If required, determine the nature of the load to which the
product will be exposed, such as impact, creep, deflection,
stresses, bending, gliding, etc.
4. Color matching may be a factor.
5. Cost of plastic by volume and cost to fabricate.
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Materials selection e.g., based on strengthThe required data
are,1. Data sheets of the specific grade of material containing the
properties required,2. Stress-strain curves at the conditions of
product application. If applicable, this would usually indicate the
toughness of material bysizing up the area under the curve. It
would also show the proportional limit, yield point, corresponding
elongations, and other relevant data.3. Curves showing change of
tensile strength, flexural strength, and modulus with increasing
temperatures or other environments.4. Creep data for periods at 100
and 1000 hours (or more, if available) covering stress and
temperature conditions closely comparable to those of product
application5. The allowable working stress, based on successful
performance at conditions of product usage.6. Chemical and/or heat
resistance at conditions in service.7. Others (fatigue, etc.)
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Loads
type and duration of the load
the temperature conditions under which the load will be active
the stress created by the load
Load is continuous when it remains constant for a period of 2 to
6 hours, whereas an intermittent load could be considered of up to
two hours duration and is followed by an equal time for stress
recovery
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The relationships of machine capabilities, plastics processing
variables, and product performance
machine conditions include the operating temperature and
pressure, mold and die temperature, machine output rate, and so
on.
Processing variables are more specific, such as the melt
condition in the mold or die, the flow rate vs. temperature
It is the processing variables, properly defined and measured,
not necessarily the machine setting, that can be correlated with
product performance.
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Advantage and Disadvantage of Plastics
products fail not because of its disadvantage(s). They failed
becausesomeone did not perform in the proper manner
Plastics can be classified into various families
Cost of product= cost of plastic+ processing cost!
Low stiffness particularly at high temperature
Less density, strength through shape, good thermal insulation,
high degree of mechanical dampening, high resistance to corrosion
and
chemical attack, and exceptional electric resistance
Viscoelasticity: The behavior of most plastics is much more
dependent on the time of application of the load, the past history
of loading, the current and past temperature cycles, and the
environmental conditions