The crystal growth rate of polypropylene (PP) is significantly influenced by factors such as temperature, molecular weight, and the presence of any nucleating agents. Typically, PP crystallizes rapidly from the melt due to its semi-crystalline nature, with the growth rate accelerating as the temperature drops towards its glass transition temperature (T_g). However, the presence of high molecular weight chains or nucleating agents can enhance this rate by providing more nucleation sites or increasing molecular entanglement. The optimal temperature range for rapid crystallization is usually just above its T_g, where the mobility of polymer chains is sufficient for them to arrange into a crystalline structure efficiently. Adjusting cooling conditions, utilizing nucleating agents, or modifying the polymer’s molecular weight are strategies to control the crystal growth rate, crucial for tailoring the mechanical properties and processability of the final product.

Period 4 of the periodic table contains titanium.

According to the U.S. Geological Survey. titanium is present in approximately 0.66 percent of the Earth's crust. This may not seem like much. but overall. this means that there are approximately 12 percent of 100 million tons of titanium in the world. It's also important to note that not every single ounce of titanium can be extracted economically. Currently. there are about 602 million tons of titanium that are economically extracted.