Module 3 Flashcards
are largely organic and usually based on synthetic resins or modified polymers of natural origin
Plastic materials
Plastics can be subclassified into two categories, according to their behavior after being cast into a permanent shape. They are:
Thermoplastics, Thermosets
are materials that soften when heated and harden when cooled. This process can be repeated indefinitely.
Thermoplastics
materials harden when heated or, in some cases, when they are treated with certain chemicals.
Thermosets
They are not recyclable except as inert fill in concrete or other materials.
Thermosets
The primary raw material used to produce synthetic polymers is
naphtha
naphtha is derived from
Petroleum
The second most common raw material to produce synthetic polymers is
natural gas
Synthetic polymers are generally produced by one of two types of polymerization reactions:
(1) addition reactions and (2) condensation reactions.
long molecule chains of the polymers from shorter molecule called
monomers
a conglomerate of very long molecule chains called
polymers
All plastics are composed of large molecules called _______, which are long chains of repeating units formed from shorter molecules
polymers
Among the natural polymers, the most representative are
polysaccharides, cellulose, proteins, and rubber
The first synthetic plastic, a form of cellulose nitrate called
parkesine
parkesine was invented in 1838 by
A. Parker
Parkesine was developed to replace some natural materials, particularly
ivory used for billiard balls
developed celluloid from a homogeneous colloidal dispersion of cellulose nitrate and camphor
J. Wesley Hyatt, during the late 1860s
developed another synthetic plastic material, phenol formaldehyde
L. Baekland, in 1907
Commonly known as Bakelite
phenol formaldehyde
A natural polymer of significance made from the sap of rubber trees
gulta-percha
proposed that all plastics, rubber, and materials such as cellulose were macromolecules or “polymers.”
H. Staundinger
Packaging is the largest market for
plastics
Packaging is the largest market for
plastics
The growth in the use of plastic packaging has accelerated rapidly since the 1970s, largely because of four characteristics of plastics:
• Low density
• Formability
• Strength and damage resistance
• Economics
makes the use of plastics attractive when compared to other materials because of the weight savings, which translates into lower energy requirements and lower cost for transportation of packaged goods.
Low density
There are several types of polyethylene. Three common forms that are frequently used for packaging are:
• Low-density polyethylene (LDPE)
• High-density polyethylene (HDPE)
• Linear low-density polyethylene (LLDPE)
is the most widely used packaging plastic. It is flexible, transparent, and low in cost.
Low-Density Polyethylene (LDPE)
is the most widely used type of plastic.
High-Density Polyethylene (HDPE)
is more dense than PE. It is available as a film or it can be molded into containers and closures. The material has excellent clarity and sparkle. In addition, it does not change color or get brittle with age.
Polypropylene (PP)
has good tensile strength. When formed into a bottle, it can resist the internal pressure from carbonation. This is why it is widely used as bottles for carbonated soft drinks.
Polyethylene Terephthalate-PET (Polyester)
PET containers are often made of different forms of PET; called copolymers. The most common are
PETE and PETG
is formed by adding ethylene glycol
PETE
is formed by adding glycol
PETG
known as polyester, can generally not be recycled into food packages, it can be made into carpets, fabrics, and many other products.
PET
is a tough film with excellent clarity.
Polyvinyl Chloride (PVC)
At one time, many packaging professionals felt that PVC would become the standard plastic packaging. However, this has not happened. One of the primary reasons is
the presence of chlorine in the PVC molecule
Polystyrene (PS) is available in _______ forms
foamed and unfoamed
The foamed (expanded) version of PS is called
expanded polystyrene or simply EPS
widely used for applications where products must be protected from damage by shocks.
expanded polystyrene or simply EPS.
This loose fill material is used to cushion products and fill the voids left in shipping containers after the product has been loaded into the box
packaging peanuts
developed a system used to identify the materials used in containers in the United States.
Society of the Plastic Industry (SPI)
Is a new, high-barrier plastic that several manufacturers are considering for use as plastic beer bottles.
PEN
material is referred to as ____ if it is thinner than 10 mils
plastic film
material is referred to as _____ if it is 10 mils or thicker
plastic sheet
is the basic process involved in plastic processing.
Extrusion
is similar to extrusion except that multiple extruders are involved.
Coextrusion
used to make multiple-layer plastic bottles, tubs, and other conatiners.
Coextrusion
the plastic is extruded out into a cold roller
Film Casting
starts with the extruder. The plastic is extruded through a rectangular die into a thin film, which is deposited on a smooth, polished, chilled rolls on a paper machine
Film Casting
is another method of manufacturing plastic film. Like casting, the process begins with an extruder or coextruder. The die is shaped like a ring, hollow in the center, and makes a continuous tube of plastic.
Film blowing
Cups, bowls, tubs, and similar containers, closures,
and many other objects are formed by
Injection Molding
is used to manufacture bottles, jugs, and jars of various sizes, shapes,
and materials
Extrusion Blow Molding (EBM)
Is the process of gluing sheets or webs of plastic film, paper, and/or aluminum foil together to form a new multilayer material.
Lamination
The advantage of lamination over coextrusion
paper and aluminum foil layers can be included in lamination.
A will-known laminated structure uses
paper, polyethylene, and aluminum foil in the following order from the outside to the inside of the package
If PVC is burned, the chemical processes involved in combustion may produce
dioxin
stories disclosed increased risk of cancer and other health problems among the workers in plants that produce
vinyl
is a plastic tube, similar to a test tube, with a complete bottle finish.
preform
The process, using sterile packaging and a sterile product, is an example of
aseptic packaging.
