Urban spheres of influence and rural urban fringe

Urban spheres of influence and rural urban fringe Urban spheres of influence Urban spheres of influence reflect centre-to-hinterland relationship, compared with the non-central region, the centre assumes more complex economic functions, and provides more economic activities. Famous theoretical contributions to this research field are the Central Place Theory (Christaller, 1933), the extension to the Central … Read more

Properties of polyvinyl chloride

Properties of polyvinyl chloride What is Polyvinyl Chloride (PVC), and What is it Used For? Polyvinyl Chloride (PVC) is one of the most commonly used thermoplastic polymers in the world (next to only a few more widely used plastics like PET and PP). It is a naturally white and very brittle (prior to the additions of plasticizers) plastic. PVC has been around longer … Read more