1. What is FRP?
FRP, fiberglass reinforced plastic, is a composite made from fiberglass reinforcement in a
plastic
(polymer) matrix. By reinforcing the plastic matrix, a wide variety of physical strengths
and
properties can be designed into the FRP composite. Additionally, the type and configuration
of the
reinforcement can be selected, along with the type of plastic and additives within the
matrix. These
variations allow an incredible range of strength and physical properties to be obtained. FRP
composites can be developed specifically for the performance required versus traditional
materials:
wood, metal, ceramics, etc.
Engineers can design the FRP composite to provide the needed characteristics, and avoid cost
penalties of an over-engineered product.
2. What is Fiberglass?
Fiberglass fibers are made from molten glass extruded at a specified diameter. The fibers
are
gathered into bundles and the bundles combined create a roving. Rovings are a continuous
rope,
similar to twine, and are wound on a mandrel to form a ball called a doff. Reinforcements
for FRP
are made from rovings that are either chopped into short strands or woven into a
cloth.
There are many factors that affect the reinforcement characteristics of
fiberglass:
Fiber and bundle diameter and type of glass
Direction of the fiberglass reinforcement
The amount of fiberglass reinforcement
The physical contact (wetout) of the fiber with the polymer
All of these factors must be taken into account when designing a FRP composite so that the
required
physical property strengths are met.
3. What are Plastic/Polymers?
There are two basic types of plastics/polymers: thermoplastic and thermoset. In general, FRP
composites utilize a thermoset plastic.A plastic in which the polymer molecules are not
crosslinked
(not chemically bonded to other polymer molecules) is a thermoplastic. Since the molecules
are not
connected by crosslink's, it allows the molecules to spread farther apart when the
plastic is heated.
This is the basic characteristic of a thermoplastic; the plastic will soften, melt, or flow
when heat is
applied. Melting the plastic and allowing it to cool within a mould will form the finished
product.
Typical thermoplastics are: polyethylene (PE)– used in making garbage bags; polyvinyl
chloride
(PVC)– used for house siding; and polypropylene (PP)– used as carpet fibers, packaging, and
diapers.
A plastic in which the polymer molecules are crosslinked (chemically bonded) with another
set of
molecules to form a "net like" or "ladder-like" structure is a
thermoset. Once crosslinking has
occurred, a thermoset plastic does not soften, melt, or flow when heated. However, if the
crosslinking occurs within a mould, the shape of the mould will be formed. Typical thermoset
plastics are: unsaturated polyester (UP)– used for bowling balls and boats; epoxy– used for
adhesives and
coatings; and polyurethanes (PURs)– used in foams and coatings.
In addition to these basic characteristics, polymers provide the FRP composite designer with
a
myriad of characteristics that can be selected, depending on the application. Combined with
reinforcement of the polymer matrix, a vast range of characteristics are available for FRP
composites.
4. What are Physical Properties?
The properties of FRP composites are measured the same way that traditional materials are
measured so that comparisons can be made for evaluation. Typical measurements
include:
Compressive Strength
Describes how much of a load a material can take before it is crushed or fractured
Flexural Modulus
A number associated with the flexibility or stiffness of a material. It indicates how far a
material will
bend when a certain load is applied to it. The lower the modulus, the more flexible the
material.
Flexural Strength
Measures how much of a load a material can take before it fractures or breaks when it is in
the
process of being bent.
Impact Strength
There are two primary impact tests; one is called IZOD impact and the other is called
Gardner
impact. IZOD impact measures the energy required to fracture or break a material when it is
struck
on its edge. Gardner impact measures the energy required to damage or puncture a material
when
it is struck on its front surface.
Rockwell or Barcol Hardness
Measures the surface hardness of a material. The higher the hardness value, the more
resistant a
material is to scratching, abrasion, and denting.
Tensile Modulus
A number associated with pulling or stretching a material (tension) and how much it
elongates when
a certain load is applied to it. The lower the modulus, the more the material will elongate
or stretch.
Tensile Strength
Measures how much of a load a material can take before it fractures or breaks when it is in
the
process of being stretched.
5. How Durable is FRP?
FRP products are extremely durable versus many traditional products. The thermosetting resin properties provide chemical, moisture, and temperature resistance, while the fiberglass reinforcement increases strength and provides good performance over a wide temperature range (the properties of thermoplastics are greatly affected by temperature).
6. How Cleanable is FRP?
FRP finishes can be either smooth or embossed. Testing has shown that either finish performs (cleans) as well as a#3 finish on stainless steel. Tests for bacteria and mould growth indicate that FRP does not support the growth of either. An embossed finish has the added benefit of providing a more scuff resistant surface than smooth.
7. Does FRP burn?
FRP can be modified with additives to meet the code requirements of the particular application, either building construction or use in OEM equipment. Like other organic building materials (e.g., wood), products made of FRP resins will burn. When ignited, FRP may produce dense smoke very rapidly. All smoke is toxic. Fire safety requires proper design of facilities and fire suppression systems, as well as precautions during construction and occupancy. Local codes, insurance companies and any special needs of the product user will determine the correct fire-rated interior finish and fire suppression system necessary for a specific installation.
8. What are Composites?
A composite is a solid material, made out of two or more constituent, different and distinct
substances
that retain their physical characteristics, while contributing desirable properties to the
whole.
Composites and composite fabricating is not new. Actually, it is one of man’s oldest
engineering
methods. Composites, like straw reinforced mud, were used for construction in prehistoric
times.
Today, composites are everywhere around us. For example, most buildings are composites, made
out
of newer materials like steel reinforced concrete or various kinds of panels. Likewise,
glass fiber
reinforced polyester is used extensively for the construction of many products like boats
and yachts,
tanks or piping.
Composite materials are the constituent materials that are used to fabricate composite
products.
Three types of materials are mostly used, or overwhelm the industry today: The matrix is a
form of
glue that surrounds, supports and keeps together in position the reinforcement.
The reinforcement is usually some type fiber material in the form of fabric that exhibits
some special
physical characteristics (like mechanical or electrical).
The core is usually some type of solid lightweight material used in-between the layers of
fiber
reinforced matrix forming a type of sandwich structure.
When matrix and reinforcement are combined in a laminate to form a new material, the
imparting
special characteristics of each are combined and enhanced by synergism (=working together.)
Moreover, core can be utilized to improve the stiffness and strength of the product even
further,
resembling the effect of steel ‘I’ beam at a very low weight.
Growing demand for better performance on products and materials has led to continuous
developments on the field of composites. Advanced, special fibers (like carbon or aramid) or
resins
(like epoxy) and cores (like PVC foam or honeycomb), and new fabricating methods were
developed
and utilized to construct other materials or products that have outstanding mechanical
properties
thought to be “exotic” a few decades ago. Those advanced composites are used in many
industries
like aerospace, automotive, energy, important sports/recreation and just about everywhere
low weight
and other special properties are needed.
Year by year, more and more designers and engineers recognize the values of composites over
other
traditional materials like metal alloys, plastics etc. This is because composite material
systems result
in performance unattainable by their individual constituents. Fiber reinforced (FRP)
products are more
reliable, more durable, easy and safe to use, more economic to produce, and individually
solve many
problems and offer many benefits. As a result, manufacturers are abandoning old materials
and
fabricating methods and turn to composites. Composites are no longer just the privilege of
aerospace,
defence and high priced products. They are rapidly becoming a way of achieving high
structural
performance at a low cost. They are found in most of the cars we drive, in all busses and
trains, boats,
and recreation and sports equipment such as skis or canoes we use on the weekends.
9. What are the Benefits of using Composites?
Composites offer many advantages: