eco-houses based on eco-friendly polymer composite construction materials conventional molding...
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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.
THANK YOU FOR YOUR ATTENTIONTHANK YOU FOR YOUR ATTENTION