Low-density polyethylene (LDPE) exhibits good chemical resistance across a broad range of substances, making it widely used in containers and packaging. It resists acids, alcohols, bases, esters, and most hydrocarbons, which means it's relatively unaffected by many common laboratory chemicals, household chemicals, and food substances. However, LDPE is not resistant to strong oxidizing acids, halogenated hydrocarbons, and some solvents such as acetone, which can cause swelling or degradation. Its chemical resistance, combined with its flexibility and toughness, makes LDPE an excellent choice for applications where chemical exposure is expected but where the chemical does not include the substance's LDPE is known to be weak against. Always consult compatibility charts specific to the chemical in question when designing or selecting materials for applications involving chemical exposure.

Once PVC cement is applied and set, removing it is challenging because it chemically bonds PVC materials together, creating a virtually inseparable joint. However, for excess cement or spills, you can try using acetone or a similar solvent to soften and remove it. Firstly, apply the solvent to a cloth and gently rub the affected area. This method is more effective on fresh spills. For hardened cement, mechanical means like sanding or scraping might be necessary, but this could damage the PVC surface. Always wear protective gear and work in a well-ventilated area when using solvents.

Polypropylene (PP) is a notoriously difficult material to bond due to its low surface energy. Traditional adhesives often fail to properly adhere to PP. However, there are specially formulated adhesives designed for plastics like polypropylene. Cyanoacrylate adhesives (super glue) can be effective for small repairs, but their bond can be brittle. For a stronger, more flexible bond, two-component epoxies specifically designed for polypropylene or plastic-specific adhesives containing MMA (methyl methacrylate) are recommended. Surface pretreatment with a plasma or corona treatment can significantly improve adhesion, but these methods are more complex and typically used in industrial applications. For DIY projects, using an adhesion promoter or primer designed for polypropylene before applying the adhesive can also enhance bond strength. Always follow the manufacturer’s instructions for the best results.