G1-5 SCL Flashcards
A manufacturer needs polyethylene (PE) for a flexible packaging application. Which type is most suitable and why?
LDPE, due to its branched structure that provides flexibility and lower density.
A car manufacturer needs a plastic that resists chemical attacks and abrasion for fuel tanks. Which type of polyethylene should be used?
HMW-HDPE or UHMWPE for their toughness and chemical resistance.
Why is LDPE not suitable for structural applications compared to HDPE?
LDPE’s branched structure leads to lower crystallinity, reducing its strength and rigidity compared to HDPE’s linear chains.
How does the polymerization process affect the properties of different types of Polyethylene?
High-pressure polymerization creates branched structures (e.g., LDPE), making it less dense, whereas low-pressure processes with catalysts yield linear chains (HDPE), increasing strength and density.
What makes Polypropylene (PP) suitable for medical applications?
High chemical resistance, sterilizability, and rigidity.
A company needs a material for outdoor chairs that resists moisture but is cost-effective. Which polymer would you recommend?
Polypropylene PP due to its excellent moisture resistance and affordability.
A lab wants to sterilize its plastic equipment repeatedly without deformation. Which polymer is suitable?
Polypropylene PP, as it can withstand high sterilization temperatures.
Compare Polypropylene PP and Polyethylene PE in terms of chemical resistance and flexibility
Polypropylene PP has better chemical resistance but is less flexible than LDPE or VLDPE due to its higher rigidity and crystallinity.
Why is UV stabilization important for Polypropylene PP in outdoor applications?
Polypropylene PP degrades under UV light, leading to brittleness and loss of strength over time.
What makes PVC flexible or rigid?
Addition of plasticizers makes it flexible; without them, it remains rigid
What happens when PVC decomposes?
It releases hydrogen chloride (HCl) gas.
A construction company requires a material for plumbing pipes that resists weathering. Which polymer should they use?
Rigid PVC, due to its durability and weather resistance.
An electric wire manufacturer needs a covering material with good dielectric properties and flexibility. Which polymer is suitable?
Flexible PVC, as it combines flexibility with electrical insulation.
Why does PVC have limited thermal capability despite being widely used?
PVC begins to decompose at relatively low temperatures, evolving HCl, which limits its use in high-temperature applications.
Analyze the environmental impact of PVC compared to PET.
PVC releases toxic gases (HCl) upon decomposition and is harder to recycle, while PET is easier to recycle but less durable in some applications.
What polymerization method is used for Polystyrene?
Free radical addition polymerization.
What property makes Polystyrene unsuitable for high-temperature applications?
Poor thermal stability.
Cannot withstand prolonged heat above 65C
Why is Polystyrene widely used for packaging?
Its low cost, good moldability, and light weight.
A food company needs clear plastic for disposable containers. Which polymer should they use?
Polystyrene due to its optical clarity and low cost.
A toy manufacturer needs a lightweight, low-cost plastic. Which polymer should they use?
Polystyrene PS, as it is low cost, lightweight and moldable.
Why is Polystyrene considered unsuitable for eco-friendly applications?
Polystyrene is non-biodegradable and has poor recyclability, contributing to environmental waste.
How would you address the flammability issue in Polystyrene applications?
By using flame-retardant additives or switching to alternative polymers for fire-prone applications.
What is the primary advantage of PMMA over glass?
It is lightweight, good resistance to weather and shatter-resistant.
What makes PMMA suitable for optical applications?
Outstanding optical clarity and UV resistance.
Which polymer would you recommend for aircraft windshields?
PMMA, due to its lightweight, impact resistance, excellent weather and UV resitance and transparency.
An advertiser needs durable, weather-resistant signs. Which polymer should they use?
PMMA for its UV resistance and optical clarity.
Why is PMMA not suitable for high-temperature applications?
PMMA has a limited continuous service temperature of 93°C, making it unsuitable for prolonged exposure to high heat.
Analyze the trade-off between PMMA’s rigidity and flexibility in various applications.
While PMMA’s rigidity provides structural stability, its lack of flexibility can limit use in applications requiring high impact absorption
What is a unique feature of Polycarbonate compared to other thermoplastics?
It has high impact strength and transparency.
List two common applications of Polycarbonate.
Safety helmets and optical lenses.
Which polymer would you recommend for safety helmets that require both high impact resistance and lightweight properties?
Polycarbonate (PC), because of its high impact strength and low density.
An electronics manufacturer needs a material for transparent housing that must resist heat and electrical currents. Which polymer should they choose?
Polycarbonate, due to its good electrical insulation and high-temperature resistance.
Why does Polycarbonate require UV stabilization for outdoor use?
Polycarbonate is prone to degradation and yellowing when exposed to UV light, requiring stabilizers to maintain durability and transparency.
Compare Polycarbonate and Acrylic (PMMA) in terms of impact resistance and optical clarity.
Polycarbonate has superior impact resistance, making it suitable for safety applications, but PMMA provides better optical clarity at a lower cost.
