The modulus of a polymer is smaller compared to that of metals or ceramics due to its molecular structure. Polymers consist of long, coiled chains of molecules that can move and slide relative to each other under applied stress. This flexibility at the molecular level gives polymers their characteristic elasticity and plasticity, allowing them to deform more before breaking. In contrast, metals and ceramics have more rigid, tightly-packed atomic structures that resist deformation. Additionally, the presence of weak van der Waals forces between polymer chains (compared to the stronger metallic or ionic bonds in metals and ceramics) means less energy is required to deform a polymer, resulting in a lower modulus.

Yes, you can use emulsion paint over an oil-based primer, but it's crucial to ensure the primer is fully cured and sanded lightly to create a suitable surface for the emulsion paint to adhere to. Oil-based primers are excellent for sealing and providing a smooth base, especially on surfaces that may contain stains or are prone to moisture. The key to success lies in surface preparation. After the oil primer has dried completely (which can take longer than water-based primers), lightly sanding it will help the emulsion paint to bond better. Skipping this step might lead to peeling or an uneven finish. Also, applying a thin first coat of emulsion and letting it dry thoroughly before adding subsequent coats is advisable for the best results.

A carbohydrate polymer is created through a process called dehydration synthesis. When two monosaccharides (simple sugars) come together, a water molecule is removed, forming a covalent bond known as a glycosidic linkage. This reaction is energetically favorable and catalyzed by enzymes, facilitating the joining of additional monosaccharides to lengthen the chain. As more monosaccharides are added, the structure can become more complex, branching out or forming rings. Common examples of carbohydrate polymers include starch, glycogen, and cellulose, which serve various functions in energy storage and structural support in living organisms.