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Questions and Answers
Which testing method is used to determine the modulus of rigidity for structural beams made of wood?
What does ASTM D638 specifically test in relation to plastics?
What type of specimen is used in ASTM D70 for testing flexural strength of plastics?
What aspect of wood testing does the reference to slenderness ratio pertain to?
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Which testing standard determines the tensile properties of polymer matrix composite materials reinforced by high modulus fibers?
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Which property of plastics is essential for their use as thermal insulators?
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What is the primary advantage of using wood in construction?
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What differentiates lumber from timber?
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What is a common method used to test the quality of wood materials?
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Which statement correctly describes the optical properties of plastics?
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Which of the following is a significant disadvantage of wood as a construction material?
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What characteristic of plastics makes them suitable for recycling?
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What is a primary thermal property of composite materials?
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At what approximate temperature do some plastics begin to melt?
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Which optical property describes plastics that allow light but change its direction?
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What is a common use for recycled plastics?
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What property of plastics makes them effective thermal insulators?
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What method is used to determine the mechanical properties of wood?
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What happens to most plastics when exposed to ultra violet rays from sunlight?
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Which of the following best describes the weight of plastics in relation to their specific gravity?
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Which material is commonly produced from the saturation of phenolic resins?
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Study Notes
Humidity
- Cellulosic plastics are affected by moisture
- PVC pipes are highly resistant to moisture
Maintenance
- Plastics are easy to maintain
- Plastics do not require surface finishing coats or paints
Melting Point
- Plastics have low melting points
- Some plastics melt at 50°C
- Plastics cannot be used in high temperature environments
Optical Property
- Some plastics are transparent, allowing light to pass through in its original direction
- Some plastics are translucent, allowing light to pass through but changing its direction
Recycling of Plastics
- Plastic waste can be used to create drainage pipes, fencing, handrails, carpets, benches, etc.
Sound Absorption
- Acoustic boards are made by saturating phenolic resins
- Acoustic boards absorb sound and provide sound insulation
Strength
- Plastics are strong materials
- There is no ideal plastic design for structural components
- Plastics are not preferred over metal despite similar strength-to-weight ratios
Thermal Property
- Plastics have low thermal conductivity, similar to wood
- Foamed and expanded plastics are used as thermal insulators
Weather Resistance
- Most plastics resist weathering, except for a few types
- Sunlight exposure can damage plastics, causing them to become brittle due to ultraviolet rays
Weight of Plastics
- Plastics have low specific gravity, generally ranging from 1.3 to 1.4
- This makes them lightweight and easily transportable in large quantities
ASTM D198
- Determines the flexural, compression, tension, torsion, and shear modulus of wood for structural members
ASTM D143
- Determines the flexural properties of wood for small specimens
Flexure
- Test method for determining the flexural properties of structural beams
- Material can be solid wood, laminated wood, or a composite construction of wood or wood combined with plastics or metals
Compression (parallel to grain)
- Test for determining the compressive properties of structural members made of solid or laminated
- Applies to elements with a slenderness ratio (length to least radius of gyration) of less than 17 and greater than a nominal 2 by 2-in. (38 by 38-mm) cross-section
Tension (parallel to grain)
- Test for determining the tensile properties of structural elements made primarily of lumber
- Applies to elements equal to and greater than a nominal 1 in. (19 mm) thick
Torison
- Test for determining the torsional properties
Shear Modulus
- Test for determining the modulus of rigidity (G) or shear modulus of structural beams made of solid or laminated wood
ASTM D638 (Tensile Strength)
- One of the most common plastic strength specifications
- Covers the tensile properties of unreinforced and reinforced plastics
- Uses a "dogbone" shaped specimen, 14mm in thickness
ASTM D70 (Flexural Strength)
- Uses a universal testing machine and a three-point bend fixture to bend plastic test bars
Compression
- ASTM D695M (Rigid plastics)
Puncture
- ASTM F1306
ASTM D3039 (Tensile Strength)
- Determines the in-plane tensile properties of polymer matrix composite materials reinforced by high modulus fibers
Woods, Plastics, and Composites
- Identify different types of wood materials used in construction
- Identify different construction materials using paper products
- Determine the plastic properties of materials used in construction
- Identify different methods of testing woods, plastics, and composite materials
Different Types of Wood Materials Used in Construction
- Wood has been used as a building material for thousands of years
- Commonly used to build houses, shelters, boats, furniture, and home décor
- Wood is a renewable, durable, readily available, and has a high strength-to-weight ratio
- It is also a good insulator and can be easily shaped, repaired, and altered
- Disadvantages of wood include flammability, susceptibility to decay due to moisture and insects, volumetric instability, variation in strength within the cross-section of a tree log, non-homogeneous and non-uniform properties
Timber as a Structural Material
- Beams and girders
- Columns
- Railway foundation
- Trusses
Lumber or Timber?
- Lumber: pieces of wood smaller than 5 inches wide by 5 inches thick (regardless of length), machine-planed and sawn to fit certain dimensions, primarily used in residential construction
- Timber: pieces of wood over 5 inches wide by 5 inches thick (regardless of length), larger in dimension
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Description
Explore the various properties of plastics, including their interaction with moisture, maintenance requirements, melting points, and optical characteristics. Additionally, discover the recycling possibilities of plastic waste and the advantages of acoustic boards made from phenolic resins. Test your understanding of these important aspects of plastics in this quiz.
