Which glue sticks two plastic bottles together?

A solvent that dissolves the plastic will be the best adhesive. Xylene is a good solvent, though others work. Plastic cement contains xylene among other solvents. As with working with such VOCs (Volatile Organic Compounds), ventilation is very important. read more

Other methods include drilling or poking small holes in the plastic, then using epoxy or a similar structural adhesive to glue the sides, allowing the adhesive to enter the holes, flow around the other side, and form what are essentially rivets that mechanically secure the two surfaces. read more

To glue plastic together, start by selecting the right glue. Find the recycling symbol on the plastic, which will have a number in the middle. If it’s a 6, use a poly cement or epoxy. For 2, 4, or 5, use plastic glue, such as Loctite Plastics Bonding System or Scotch Weld DP 1080. If the number is a 7 or 9, use an epoxy or cyanoacrylate. read more

Generally plastic bottles are made of PET or if you mean detergent bottles they are made of HDPE or PP. PET is a polar polymer and to bond two PET bottles you could use adhesives made of cyanoacrylates or for stronger bonds, phenolic resin based adhesives. read more