Eco-Houses Based on Eco-Friendly Polymer Composite Construction Materials Conventional molding techniques applied for manufacturing of eco-composites Workshop , Ohrid 13-15 September 2007

Originally plastics were developed to replace natural materials, Nowadays, natural materials are developed to replace plastics

MOLDING TECHNIQUES WHICH WERE APPLIED IN ECO-PCCM PROJECT 1. Compression molding CM was the major method for processing plastics during the first half of the previous century. It is a process of applying heat and pressure to a plastic material in matched or open dies. The plastics melts due to the heat, then the pressure causes it to form into a desired shape. This is done in a compression molding press. This process is classified as high pressure process. Although this technology is the main processing method used with thermoset plastics, it can also be employed to process themoplastic materials The advantages of compression molding are short cycle time, high production rate and excellent surface finishes.

Materials used for CM SMC ( Sheet Molding Compounds) BMC (Bulk Molding Compounds) Pellets/granules

CM Techniques No mold technique - appropriate for SMC, prepregs Matched die technique – appropriate for BMC, pellets

1.a SMC Piston Guide No mold, single-opening press Stack of material Supporting plate Heated press platen

Blown-out press package Hot plate SMC layers Press piston Press plate Polster Release foil Thermocouple

2. No mold, multi-opening press MULTI-PANEL PACKAGE Release foil SMC Stainless steel press plate

SMC Piston Guide Stack of material Supporting plate Press platen MATCHED DIE TECHNIQUE Stack of material Supporting plate Press platen

Matched die molding SMC Appropriate for BMC , pellets and for SMC (simple shapes only) SMC Open mold Closed mold

Pellets MATCHED DIE TECHNIQUE

MOLDING TECHNIQUES WHICH WERE APPLIED IN ECO-PCCM PROJECT 2. Injection molding Injection molding is a manufacturing technique for making parts from both thermoplastic and thermosetting plastic materials . Molten plastic is injected at high pressure into a mold, which is the inverse of the product's shape. Injection molding is widely used for manufacturing a variety of parts, from the smallest component to entire body panels of cars. Injection molding is the most common method of production, with some commonly made items including bottle caps and outdoor furniture.

INJECTION MOLDING PROCESS SCHEME

PLA

Injection molding Appropriate for rather complicated and dimensional precise shapes Kenaf / PLA molding IM is the mostly used processing technique for PHB, PLA, PLLA plastics

Major differences between applied forms of materials SMC Pellets Appropriate for big size panels No molding tool is required Multiple panels can be produced in one molding cycle Cheaper manufacturing process Better mechanical properties since longer fibers can be applied Applicable only for flat and/or slightly curved shapes Inappropriate for big size panels Molding tool is required One panel only per cycle Expensive manufacturing process Only very short fibers can be used making panels with limited mechanical properties Better control of fiber/resin ratio Applicable for 3D shapes

CONCLUSION Biodegradable plastics can be processed as classic thermoplastics No exclusive technology for processing is required Typical processing techniques: IM, CM, extrusion No limitation for processing on classic machines Biodegradable plastics (PLA, PHB, PLLA) are polyesters obtained from renewable resources. The products are waterproof, heat resistant, have appealing surfaces, and are fully biodegradable. The pellets are processed on standard machines. The melt behaves like liquid crystalline polymers (LCP's). This property allows to mold thin walled or complex structures even on small machines.

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