Recorded November 14th, 2012
Presented by RTP Company
Consumer demand for “Green” and “Eco-Friendly” products continues to gain momentum. This trend creates opportunities and challenges for product designers and manufacturers to use eco-friendly materials that also provide high performance. Bioplastics and recycled materials can be up-engineered to meet the requirements of semi-durable and durable products. Learn about these materials by joining Steve Maki, Vice President of Technology and Will Taber, Business Manager – Emerging Technologies at custom compounder RTP Company for a webinar on Eco Solutions.
Questions & Answers
Q: Does RTP Company have transparent green options that come in sheet form?
A: Yes, the PLA/PMMA alloy is a transparent compound that can be formulated to have the proper viscosity for sheet extrusion.
Q: Could you explain further on lower cycle time in cellulose PP vs glass fiber PP compound with regards to viscosity?
A: We have not come up with a scientific answer for this but feel that it has to do with frictional heating and thermal conductivity. Molders have reported to us that they are able to greatly reduce the barrel temperature settings on the mold machine when they run cellulose fiber filled PP.
Q: Any specific additive RTP Company uses to improve rheology?
A: We use the conventional methods of using process lubricants and lower viscosity resin feedstocks to improve the flow of the compound.
Q: How to keep natural fiber aspect ratio during compounding?
A: Cellulose fiber is actually much more resilient than the more brittle glass and carbon fiber so it retains it’s aspect ratio quite well in the conventional compounding processes
Q: Which are the recommendations to dry your PLA and PLA blends before injection molding? Which humidity content should be reached (in ppm)?
A: All should be dried to a moisture content of less than 0.02% in a desicant dryer capable of delivering -40F dew point air. Amorphous PLA compounds should be dried 2-6 hrs @ 120F, crystalline PLA compounds 2-6 hrs @ 130F, PLA/PC alloys 4 hrs @ 175F.
Q: Can you only use virgin material for production? No use of regrind?
A: The amount of regrind that can be used depends on the type of compound and desired end properties but a level of 20% has shown limited effects on properties for studies we have carried out on impact modified and glass reinforced PLA compounds.
Q: Does the PLA material has a ‘shelf life’? Think shenzhen during the summer, its extremely humid. Special storage required?
A: If stored at room temperature and humidity levels less than 50% shelf life should be indefinite (I have seen some PLA suppliers list 3 years max). If stored outdoors in high heat and humidity we would be unable to predict the shelf life unless we knew the exact conditions.
Q: For injection molding of PLA materials, is there a reduced % of regrind that can be used in molding?
A: For properly formulated robust biobased compounds, I expect regrind can be used and the % would need to be agreed on by the molder and user.
Q: How is the carbon fiber being recycle for your use?
A: Recycle carbon fiber can be recovered from the trimmings when woven fiber and cloth is being made. Processes are also being developed to recover it from a composite by burning off the host polymer using a controlled pyrolysis that will burn off polymer but retain carbon fiber.
Q: How does the cost of a 30% glass iber, impact modified PLA compare to a 30% glass fiber PP?
A: It depends on the exact glass fiber PP and your release quantities but in general you would likely see about a 20% increase. However, if it is a custom precolored glass reinforced PLA versus a custom precolored glass reinforced PP you would likely see little cost difference.
Q: Is the thin film industry keeping pace with your molded products? How available are biobased films?
A: The PLA film industry for packaging is quite advanced. We have done limited work with biobased films. However, we do have a sister division, Wiman Corporation, that has done some work and could evaluate programs for a capability fit.
Q: Do you make biobased compounds suitable for extrusion grades for thermoforming applications? If so what based resins are available PLA, PE, PP or others?
A: Yes, by choosing higher viscosity (higher MW) base resins we can develop biobased PLA, PE, and PP compounds for extrusion and thermoforming.
Q: Do you every use post or pre consumer recycled PLA as a raw material source?
A: We have used pre-consumer recyled PLA to make compounds and are aware of post-consumer recyled PLA that is available but have not yet worked with it.
Q: Do you employ any biobased additives that can increase the % biobased content of your various compounds, PLA or other polymers.
A: Yes, good examples of bio-based additives that we use include the cellulose and wood fibers.
Q: What about the plateability of PLA’s?
A: Our understanding is that standard PLA is not easy to plate using conventional plating. We expect, like other polyester based polymers, it can be made platable by compounding in mineral fillers that will promote plating adhesion.
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