Ideally, a surface to be bonded should be dust free, wettable i.e. high surface energy, clean, smooth, dry and non-porous. There are numerous methods available for increasing the polarity and surface energy of plastics. These include treatments involving high temperature, wet chemicals, etc. which are not so friendly for the environment. Other methods consist of treating the plastic surface to a high voltage corona and plasma surface activation which is friendlier towards the environment than wet chemicals and high flames.