Plastics Properties and Recycling

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

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.