Eco-Houses Based on Eco-Friendly Polymer Composite Construction MaterialsEco-Houses Based on Eco-Friendly Polymer Composite Construction Materials

Conventional molding techniques applied for Conventional molding techniques applied for manufacturing of eco-compositesmanufacturing 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

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 materialsThe advantages of compression molding are short cycle time, high production rate and excellent surface finishes.

MOLDING TECHNIQUES WHICH WERE APPLIED IN ECO-PCCM PROJECT

Materials used for CM

- SMC ( Sheet Molding Compounds)

- BMC (Bulk Molding Compounds)

- Pellets/granules

CM Techniques

1. No mold technique - appropriate for SMC, prepregs

2. Matched die technique – appropriate for BMC, pellets

Stack of material

Supporting plate Heated

press platen

Guide

Piston

1.a

No mold, single-opening press

SMC

Hot plate Hot plate

SMC layersSMC layers

Press piston Press piston

Press plate Press plate

Polster Polster

Release foil Release foil

Thermocouple Thermocouple

Blown-out press package

2. No mold, multi-opening press

Stainless steel press plate

SMC Release foil

MULTI-PANEL PACKAGE

Stack of material

Supporting plate Press platen

Guide

Piston

MATCHED DIE

TECHNIQUE

SMC

Matched die molding

Appropriate for BMC , pellets and for SMC (simple shapes only)

Open mold Closed mold

SMC

Pellets

MATCHED DIE

TECHNIQUE

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.

MOLDING TECHNIQUES WHICH WERE APPLIED IN ECO-PCCM PROJECT

INJECTION MOLDING PROCESS SCHEME

PLA

Appropriate for rather complicated and dimensional precise shapes

Injection molding

Kenaf / PLA molding

IM is the mostly used processing technique for PHB, PLA, PLLA plastics

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

Major differences between applied forms of materials

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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