The cost of polypropylene per pound can fluctuate significantly due to factors such as crude oil prices, demand in various industries (like automotive and packaging), and global economic conditions. As of my last knowledge update in 2023, prices generally ranged from $0.50 to $0.80 per pound for bulk quantities in the United States. It's important to note that prices can vary based on the grade of polypropylene and the volume of the purchase. For smaller quantities or specialized grades, prices can be higher. For the most accurate and current pricing, contacting suppliers directly or checking market reports is recommended, as these figures can quickly become outdated due to market volatility.

Polypropylene (PP) inherently has some resistance to ultraviolet (UV) radiation, but it is not fully UV stable. Under prolonged exposure to sunlight, PP can degrade, leading to changes in color, loss of strength, and brittleness. This degradation is due to the polymer chain breaking down when exposed to UV light. However, the UV stability of polypropylene can be significantly improved through the addition of UV stabilizers during the manufacturing process. These stabilizers absorb or screen out UV radiation, protecting the polymer from damage. For applications that require prolonged outdoor exposure, it is essential to use UV-stabilized PP to ensure durability and longevity. In summary, while polypropylene has some natural resistance to UV light, for outdoor applications, it is crucial to use PP that has been specifically treated with UV stabilizers.

Composite materials made from polyvinyl chloride resins and various added additives and reinforcing materials are different types of an engineered material called PVC composites. This combination would improve mechanical properties, stability, and flexibility of standard PVC, which is designed for a wide range of applications. Usually, reinforcement might include wood flour, fiber glass, and other natural fibers to improve strength and reduce thermal expansion. PVC composites have several advantages over traditional materials like wood or metals; they are lightweight, moisture-, rot-, and insect-resistant, and require minimum maintenance. Other advantages range from outdoor furniture, window frames, fencing to decking. These can be further custom designed by coloring and texturing processes to imitate the beauty of wood and other materials. That said, despite these qualities, there remain those who argue that PVC, used as production and disposal processes, has a bad environmental impact; therefore, producers are trying to identify more sustainable alternatives.