Yes, you can glue ABS (Acrylonitrile Butadiene Styrene) to PVC (Polyvinyl Chloride), but it requires the appropriate adhesive and proper preparation. Traditionally, ABS and PVC are not compatible with standard glues due to their different chemical compositions. For a reliable bond, use an adhesive specifically designed for both materials, often marketed as a "universal" or "multi-material" glue. Thoroughly clean and dry the surfaces to be bonded. A specialized solvent cement intended for ABS-to-PVC joints can also be used, designed to slightly melt and fuse the surfaces. Note that building codes in some areas may restrict the use of mixed-material joints for plumbing, so it's crucial to check local regulations if applicable.

Polypropylene (PP) and polystyrene (PS) are both widely used plastics, each with distinct properties. In terms of strength, PP generally exhibits superior resistance to fatigue, making it more durable for items that undergo repetitive stress. It has a higher tensile strength, meaning it can withstand greater pulling forces before deforming or breaking. On the other hand, PS, particularly in its solid form, offers greater rigidity and can maintain its shape under a load but is more prone to cracking under impact. However, its brittleness limits its use in applications where durability against impact or bending is crucial. Therefore, if the definition of strength includes resistance to impact and flexibility, PP would be considered stronger. However, for applications requiring rigidity and form stability under weight, PS could be more appropriate.

Polypropylene is a thermoplastic polymer used in a wide array of applications, including packaging, textiles, and automotive parts. Generally considered safe, polypropylene is recognized for its low reactivity and is used in containers for food and drinks, indicating its minimal health risk when used properly. Unlike some other plastics, it does not release harmful chemicals under normal conditions, making it a safer choice for consumer goods. However, like any plastic, when burned, polypropylene can release toxic fumes, including carbon monoxide and volatile organic compounds, posing inhalation risks. There's minimal risk associated with direct contact or ingestion under normal use circumstances. Continuous research and regulatory standards monitor its safety to ensure it remains a low-risk material for everyday use. Individuals concerned with plastic's environmental impact might seek alternatives, but in terms of direct health effects, polypropylene is among the safer plastics available.