PhiliFlyer
PhiliFlyer t1_j4qc8fj wrote
Reply to What makes a fiber or fabric absorbent, wicking, breathable, or cooling? by DisenchantedAuD
Fibers such as cotton absorb a substantial amount of water. Clothes made from cotton can therefore transport water from your skin to the outside of a garment where it can evaporate. This cools your skin because the heat of vaporization of water is quite large.
Cotton is mostly cellulose, a polysaccharide. It has hydroxyl (alcohol) groups in the repeat units, meaning that a single polymer chain has thousands of hydroxyl groups. Hydroxyl groups form hydrogen bonds with water, and are mostly responsible for the water absorbency of cotton.
Synthetic fibers such as polyesters are often co-woven with cotton to improve the mechanical properties of the cloth. Polyesters absorb much less water than cotton. Cloth made exclusively from polyester fiber is uncomfortable for this reason. There are synthetic polyester fibers such as poly(lactic acid) that absorb water and are more comfortable. They are more expensive, and therefore have not been widely adopted.
PhiliFlyer t1_j3aelpb wrote
Reply to comment by [deleted] in Is it true that rubber gaskets in a dishwasher will crack if unused? by iamaparttimemonster
This is not true. Plasticizers are generally not used in elastomeric seals (nor tires as in your previous reply). Elastomers (of which natural rubber is a member) embrittle due to oxidation and thermal degradation. In the case of polyurethane elastomers, water hydrolysis can cause degradation.
Leaving a dishwasher unused will actually prolong the life of the seals since there is less exposure to water, oils, and oxygen at high temperatures.
PhiliFlyer t1_jdyjp22 wrote
Reply to Why not increase a capacitor’s energy density by increasing the voltage? by FreakinGeese
I guess your calculations comparing a dielectric capacitor to gasoline are wrong. What are the dimensions of the capacitor? You'll need an enormous capacitor to store significant energy.
Electrolytic capacitors are used where substantial amounts of energy need to be stored. They can tolerate only low voltages (~2.5 V).