Economic Manufacturing Method to Produce Controlled-density Panels  

Project Title: Economic Manufacturing Method to Produce Controlled-density Panels

Applicant: Hong Kong University of Science & Technology

Total Approved Grant: $150,000 (Actual expenditure: $149,205.45)

Duration: 1.9.2001 to 30.8.2002

Project Status/Remarks: Completed

To investigate an economical method for manufacturing controlled-density panels using plastic waste. It is essential to find an economical method not only to reuse the recovered plastics locally, but also to encourage further recovery of plastic waste that are produced from non-renewable natural resources. If successful, such panels would replace the wood composite panels in construction works.

Summary of the Findings/Outcomes:

There are about 550,000 tonnes of waste plastics generated in Hong Kong annually. On the other hand, there were 85,100 newly completed residential flats in Hong Kong in 1999. A conservative estimate indicates that the construction work requires over 35 million m2 of concrete forms that require over 1.5 million m2 of panels. Currently, most of these panels are made of wood or wood composite materials. If all of the plastic waste generated in Hong Kong were used in the manufacturing of controlled-density (CD) panels, then more than 500,000 trees would be saved. The idea of using plastic waste to manufacture CD panels for concrete forms has been investigated and found to be successful. This requires, however, a significant capital investment.

Extrusion is a relatively more economical process. The pilot plant study carried out in our laboratory demonstrated the possibility of obtaining CD-panels from the mixture of PE, PP and ABS. The extruded plastic was not in very good shape because of the inadequate coaling and pressing system in the lab. The density decrease was successfully obtained. As expected, Young's modulus and the bending modulus were found to decrease significantly with the decrease of density. There are some decreases in hardness also. The water adsorption test shows that the CD-panels have a very good water resistivity.