What are additives in plastics?
Chemicals added to plastics to improve processing or performance properties such as UV stability, lubrication, or flame resistance
Additives enhance the functionality of plastics.
Define annealing in the context of plastics.
Controlled heating and cooling of a plastic to relieve internal stresses and improve dimensional stability
This process is crucial for enhancing the performance of plastic materials.
What does ASTM stand for?
American Society for Testing and Materials
This organization sets testing standards for plastics.
What is the CLTE (Coefficient of Linear Thermal Expansion)?
Measure of how much a material expands per degree of temperature change
This property is important for understanding thermal behavior in materials.
What is creep in plastics?
The gradual deformation of a plastic under constant load or stress over time
Creep can affect the long-term performance of plastic components.
Differentiate between crystalline and amorphous plastics.
- Crystalline: Ordered molecular structure (e.g., Nylon)
- Amorphous: Random molecular structure (e.g., Polycarbonate)
This distinction affects the properties and applications of the materials.
What does elongation at break measure?
Percent increase in length a plastic can stretch before breaking under tension
This property indicates the ductility of the material.
What is the extrusion process?
Processing method that forces molten plastic through a die to create continuous shapes such as rods, tubes, or sheets
Extrusion is a common method for shaping plastics.
What is a filler in plastics?
Substance like glass fiber or mineral added to improve stiffness, reduce cost, or modify properties
Fillers can significantly alter the characteristics of plastic materials.
Define friction coefficient.
Measure of resistance between two surfaces sliding against each other; UHMW has a very low coefficient
This property is crucial for applications involving movement and wear.
What is the Glass Transition Temperature (Tg)?
Temperature where amorphous plastics soften without melting
Tg is important for understanding the thermal behavior of plastics.
What does HDT (Heat Deflection Temperature) indicate?
Temperature at which a plastic sample deforms under a specified load
HDT is a key parameter for assessing thermal performance.
What is impact strength?
Resistance of a material to sudden impact or shock loading
This property is vital for applications requiring durability.
Define machinability in plastics.
Ease of cutting or shaping a plastic without melting, chipping, or deforming
Machinability affects the manufacturing processes of plastic components.
What is modulus (Elastic Modulus)?
Measure of a material’s stiffness or resistance to deformation under stress
This property is essential for understanding the mechanical behavior of materials.
What does moisture absorption refer to?
Ability of a material (e.g., Nylon) to absorb water, affecting strength and dimensions
Moisture absorption can significantly influence the performance of plastic materials.
What is Nylon (Polyamide)?
Strong, wear-resistant engineering plastic that absorbs moisture and offers good toughness
Nylon is widely used in various applications due to its properties.
Define PEEK (Polyetheretherketone).
High-performance plastic with excellent mechanical strength, chemical resistance, and thermal stability
PEEK is suitable for demanding applications.
What is PET (Polyethylene Terephthalate)?
Strong, stiff engineering plastic with good dimensional stability and low moisture absorption
PET is commonly used in packaging and other applications.
What does PPS (Polyphenylene Sulfide) refer to?
High-temperature, chemically resistant plastic used in demanding environments
PPS is valued for its thermal and chemical stability.
What is PTFE (Polytetrafluoroethylene)?
Fluoropolymer with exceptional chemical resistance and the lowest coefficient of friction
PTFE is often used in applications requiring low friction.
Define PVDF (Polyvinylidene Fluoride).
Fluoropolymer with strong chemical resistance and good mechanical stability
PVDF is used in various industrial applications.
What is a reinforced plastic?
Plastic compounded with fibers or fillers to improve strength or stiffness
Reinforced plastics are used in applications requiring enhanced mechanical properties.
What does shrinkage refer to in plastics?
Reduction in dimensions of a molded or cooled plastic as it solidifies
Shrinkage can affect the final dimensions of plastic products.
