paints & plastics

These flashcards cover key concepts and facts from the Materials Lecture 9 focusing on paint systems and plastics.

What are the primary reasons we need to paint objects?

Decoration and protection from water, UV, corrosion, and chemical attacks.

What are the main constituents of paint?

Vehicle, pigments, additives, binder, and solvent/thinner.

What is the role of the binder in paint?

The binder holds together the coloring and other chemicals; it converts from liquid to a hard elastic skin and provides resistance to water, chemicals, and abrasion.

Why have oil-based binders fallen out of favor?

They are less environmentally friendly and can present more health hazards than water-based binders.

What is the function of additives in paint?

Additives enhance the performance of paints, aiding in flow, coalescing, evaporation, and preventing brittleness.

How is protection against UV degradation achieved in paint systems?

By ensuring that the paint has opacity; clear varnishes, for example, do not provide adequate protection.

What is the significance of surface preparation for effective paint application?

The surface must be firm, clean, and chemically stable for protection to be effective.

What are the definitions of primer, undercoat, and top coat?

Primer prepares the substrate, undercoat masks discoloration, and top coat provides color and protection.

What are thermoplastics?

Plastics that can be softened by heating and hardened by cooling without changing their properties.

What are thermosetting plastics?

Plastics that harden permanently upon heating and cannot be remelted or reshaped.

What is PVC and what are its applications?

Polyvinyl chloride, used for pipes, window frames, and as insulation due to its durability and cost-effectiveness.

What is fiber-reinforced plastic (FRP)?

A composite material made of a polymer matrix reinforced with fibers, commonly used in construction and aerospace industries.

What properties make plastics advantageous compared to materials like metals?

They can be molded inexpensively, resist chemicals, have a high strength-to-weight ratio, and are non-conductive.

What are some common defects in paint applications?

Blistering, alligatoring, cracking, and chalking.

What is the implication of humidity on paint drying?

Excessive humidity can prevent evaporation of water from water-based paints, affecting adhesion.