Recorded March 16th, 2011
Presented by RTP Company
Due to their inherent physical properties, most bio-polymers were previously relegated to low performance commodity applications. Today, bioplastics are quickly becoming more than just another industry buzzword. Join in as Steve Maki, vice president technology for custom compounder RTP Company, reveals how these materials can now be engineered for applications requiring higher performance. During this informative webinar, Steve will review:
- The latest advancements in compounding bio-polymers.
- Properties of commercial bioplastic compounds – PLA, polyamides, & polyesters.
- Uses these advanced bio-based compounds have in semi-durable goods.
Don’t miss this opportunity learn what bioplastics have made out of the lab and that you will likely soon be using to meet consumer demand for environmentally-conscious products derived from renewable resource
Questions and Answers
Q: How are these types of compounds or similar types being used in the flexible packaging industry?
A: Unfilled PLA from NatureWorks has become popular in many clam-shell packaging applications already. The compounds I presented can be considered if additional performance, heat and/or impact, is required.
Q: Hi. Is it possible to have monofilaments and multifilaments made of PLA?
A: Yes, NatureWorks has filament extrusion grades of PLA available from which companies are making clothing, etc.
Q: We make plastic cultery. There is always an issue with the spoon getting soft in the hot coffee. Is there any improvement or combination of PLA and HIPS that withstand this heat?
A: The nucleated & mineral filled PLA I described should be able to withstand this heat for a one time or limited time usage. As we discussed, PLA in high moisture/high temperature environments will eventually hydrolyze and become brittle.
Q: co-polymer impact modifiers, compatabilizerrs, mineral/glass additives, etc
A: The minerals and glass fibers are used in all plastics. The minerals are around you in the environment like talc and calcium carbonate. The glass is also non-toxic. Impact modifers vary considerably in content but are used in all current plastics as well and are not considered toxic. Most plasticizers companies looking to work in PLA are trying to introduce biobased plasticizers to match the PLA sources.
Q: What do we know about the toxicity of the additives you discussed? When talking about being green are these toxicities in the whole life cycle of the product being considered?
A: Although not all additives that we discussed are FDA or ISO 10993 biocompatible compliant, non should present any high level of toxicity to the human body.
Q: What are the recyclability of these new engineered biopolymers?
A: The products discussed are stabilized and designed to be robust and should be capable of regrinding and recycling as would a normal plastic. Since PLA is a polyester, the regrind must remain dry when reprocessed.
Q: How does bioresin typically compare price-wise with conventional resin of similar characteristics.
A: They are typically more expensive and thus the customer must value the green aspect.
Q: Are there any equipment modifications required to run bio? (screw/barrel mods?)
A: No major modifications required. For the PLA and bio-based polyester, make sure that you have a good desiccant drier as you should with any polyester polymer like PBT or PET.
Q: You show that the properties of PLA with 60% long fiber are good. Do you have other materials for comparison such as Nylon, PP with similar loading of long fiber?
A: Yes, please go to the RTP website where we list properties for all our long fiber reinforced compounds.
Q: Do you have any products available for the container industry? PP Substitutes?
A: I would need a little more information on you application to answer this. Please feel free to contact me.
Q: If no, do you have any biocompatibility data?
A: We have yet asked to test any biocompatibility data on these compounds but the base resin suppliers may have some that can be shared.
Q: Have any of these materials been used in a medical field? For either instruments or implants?
A: None of RTP compounds, bio or fossil based, can be used in implants that will be in the body over 30 days. The reason for this is that no resin supplier will grant permission for a compounder to do this. Many bio-based polymers are being used in or being evaluated for use in other medical applications.
Q: Have you used these biopolymers with natural fibres? How do they compare to the glass fibre properties indicated here?
A: Most natural fibers are very poor when it comes to reinforcing any polymer (bio or fossil based). One exception that we have found is a modified cellulose fiber that is giving performance similar to glass fiber. Because it is cellulose based, it does need to go into lower temperature polymers such as PP, PE, and PLA.
Q: Have there been any fire testing done on these Biopolymer compounds? Do they need more or less FR than their counterparts to meet requirements?
A: Biobased polyester can be flame retarded similar to PBT and biobased polyamides can be flame retarded similar to other nylons. PLA has been a difficult resin flame retard, especially using eco-friendly non-halogen FRs. We have had some limited success with making a non-halogen FR PC/PLA alloy and plan to do more work on this in the near future.
Q: Are there any odour issues? Off gassing?
A: PLA gives off a pleasant corn syrup like odor when melt processed. We have done some ionic purity and outgassing studies on the PLA and it shows nothing detrimental.
Q: Have you worked with any biobased thermosets?
A: No thermosets to-date.
Q: How it works PLA in a normal process, What will be the differences about tool design, hot runner systems, shrinkage, banana gates and steel treatments?
A: Suggest tools for PLA be designed similar to any polyester resin (PBT, PET, etc). If you want the PLA to nucleate and be in the crystalline state, you need to be able to maintain a mold surface temperature above 200F. If you want the PLA to remain amorphous, suggest you be able to cool mold surface to around 70F.
Q: have the recent cost increases affected the supply of post consumer content?
A: Yes, now that recycled content has value to customers the supply has become tight and price has gone up.
Q: what materials do you see as cost alternatives to HIPS and ABS?
A: Unmodified PLA from NatureWorks will be close. The modified compounds I described in the presentation will be slightly more costly but hopefully will have more performance and value.
Q: Are any of the biopolymers food contact approved?
A: Yes, grades of PLA, bio-based polyester, and bio-based polyamide with FDA compliance are available.
Q: Are any of these bio-polymers RF weldable? If so, which ones?
A: We have not participated in any RF welding applications but they work
Q: What is base resin of the impact modifier used in the PLA?
A: We have a variety of different impact modifiers available. The composition is proprietary but none are biobased themselves.
Q: Can these biopolymers be extruded into film (presumably via RTP’s film division, Wiman)?
A: Yes, RTP’s Wiman division is making PLA based films.
Q: How does the price of your bio-based polyester compare to PBT?
A: It is typically higher than typical PBT. It does not vary as much with the price of oil though
Q: Are there any transparent bio-based plastics available with HDT above 170°F? What is then the bio-based content?
A: RTP’s PLA/PMMA blend RTP 2099 X 115375 C is transparent and comes close with an HDT@66 psi = 150F
Q: What is about high performance plastics based on renewable resources?
A: The biobased polyesters and polyamides have quite good temperature performance and it has been announced by such suppliers as Solvay that they will be introducing a bio-based PPA high temperature polyamide.
Q: Can the Bioplastics be compounded with antimicrobial properties?
A: Yes, especially the silver based antimicrobials.
Q: Aesthetic quality is important for us, being a product design office. What’s the surface quality of bio-plastics?
A: This will depend on biopolymer and filler but work that we are doing in the cell phone industry has shown excellent surface finish with the PLA/PC blends. The bio-based polyester will have surface finish similar to PBT and bio-based polyamides, similar to nylon 6 or 66.
Q: What’s the carbon footprint of the bio plastics, compared to the normal engineering plastics?
A: NatureWorks has published that CO2 emissions to produce PLA is 2.4X less than PP, 4X less than PET or Polystyrene, 9.5X less than PC, 9.9X less than nylon 6, and 11.4X less than nylon 66. These might even be more dramatic now as NatureWorks has been improving their process.
Q: regarding the PC/PLA blend, do you manage to get a transparent material?
A: No the difference in index of refraction of these 2 polymers results in a white opaque blend.
Q: 3) How is molding vs PP, PA & PBT? Is necessary a special mold or can be used the same mold that PP, PA or PBT?
A: Suggest tools for PLA be designed similar to any polyester resin (PBT, PET, etc). If you want the PLA to nucleate and be in the crystalline state, you need to be able to maintain a mold surface temperature above 200F. If you want the PLA to remain amorphous, suggest you be able to cool mold surface to around 70F. As with any polyester, PLA must be dried to moisture content <0.02% before molding.
Q: 1) How is durability comparison vs PP, PA & PBT?
A: Bio-based polyester and bio-based polyamide have proven to be just as durable as PBT and nylon. We have designed PLA to be durable but you must avoid high moisture coupled with high temperatures >130F.
Q: 2) How is cost comparison vs PP, PA & PBT?
A: They are typically more expensive and thus the customer must value the green aspect
Q: 4) How is appearance vs PP & PA? Can be molded in color? What are the range glosses bio-plastics have?
A: This will depend on biopolymer and filler but work that we are doing in the cell phone industry has shown excellent surface finish with the PLA/PC blends. The bio-based polyester will have surface finish similar to PBT and bio-based polyamides, similar to nylon 6 or 66. Biopolymers can be colored similar to PP and PA
Q: what Ford & Chrysler specification do the biopolymers meet?
A: Automotive companies have developed specifications/approvals for biobased nylons such as nylon 11, 6-12, 6-10. They may even have some specs for bio-based polyesters such as PTT. I am not aware of any yet for PLA but they all have interest in this polymer.
Q: Are any of these compounds approved in the Automotive world?
A: Automotive companies have developed specifications/approvals for biobased nylons such as nylon 11, 6-12, 6-10. They may even have some specs for bio-based polyesters such as PTT. I am not aware of any yet for PLA but they all have interest in this polymer.
Q: what’s the best way to determine what type of biomaterial to use for your product?
A: Very similar to any plastic; by knowing your environmental & physical requirements, and cost constraints. Also it is very important to understand why and how much your customer values the green component.
Q: If you want to have green compounds, did you try to use flax fibres in your compounds ?
A: We have but it did not provide much reinforcing value. Modified cellulose fiber has been promising.
Q: Do you think we have enough corn for food and for PLA ? Using PLA in mass, does this will increase the price of food ?
A: The portion of the corn that is used to make PLA has less value to that used to produce food. As with most bio-based polymers, PLA can be produced from other plant sources if this should ever become a global concern.
Q: price, biopolymer compared with wo. bio-based polymer. thank you.
A: Depending on the polymers you are comparing it can typically be slightly higher as is usually the case with PLA and bio-based polyester to quite a bit higher as with bio-based polyamides.
Q: How much higher? 20%?
A: I would need to know exactly which polymers you are comparing.
Q: Could you please send out this presentation? It is very good reference and eduication material. Thank you so much.
A: It will be posted on the IDES website
Q: How truly green is PLA? does it take more energy to make it than it would to make an equivalent amount of PC/ABS?
A: The overall footprint of the PLA is lower than most polymers like PC. There are a number of studies available online from Natureworks showing carbon footprint and energy consumption to make. The energy used in compounding is similar to PC/ABS. NatureWorks has published that CO2 emissions to produce PLA is 2.4X less than PP, 4X less than PET or Polystyrene, 9.5X less than PC, 9.9X less than nylon 6, and 11.4X less than nylon 66. These might even be more dramatic now as NatureWorks has been improving their process.
Q: How moisture sensitive is PLA? Does it distort/warp with humidity?
A: It is a polyester and must be dried before processing just like PET. It does not absorb large amounts of water like nylons so it does not warp or distort.
Q: PLA has been used for RESORBABLE implants for decades.
A: Thanks, these would not be products that a company like RTP could supply as I would expect that they would most likely be 100% pure PLA and contain no compounded additives
Q: What is the potential in terms of flame retardant? Thank you.
A: Biobased polyester can be flame retarded similar to PBT and biobased polyamides can be flame retarded similar to other nylons. PLA has been a difficult resin flame retard, especially using eco-friendly non-halogen FRs. We have had some limited success with making a non-halogen FR PC/PLA alloy and plan to do more work on this in the near future.
Q: Can any of the PLA or PBT products be manufactured in a clear/transparent product
A: Unmodified PLA is transparent and RTP’s PLA/PMMA blend RTP 2099 X 115375 C is transparent.
Q: You stated that PBT resin can simply be replaced by a current, non sustainable resin. If purchased through RTP, the factory currently used by the manufacturer just simply replaces its old resin with the new RTP PBT resin?
A: If you are currently using a PBT based compound, let’s say a 30% glass fiber reinforced PBT, and you want a similar performing product but with bio-content, RTP could simply create a new product for you by substituting the bio-based polyester resin for the PBT.
Q: Do the PLA+CaCO3 and PLA+talc grades you have shown us have the nucleation package you mentioned or the properties are obtained just by the mineral?
A: These compounds contain the PLA, stated mineral, an impact modifier, and nucleation package.
Q: How do you control / reduce warp with the PLA sheet?
A: Warp is always associated with differential shrink rates. PLA will shrink when it goes from its amorphous state to its crystalline state and this happens when the polymer is exposed to a temperature around its Tg (130F for PLA). If the PLA is in its amorphous state when the sheet is made, you will need to ensure that it does not see a temperature of 130F in its future life. If it will see temperatures above 130F you will need to ensure that the PLA nucleates into its crystalline state when the sheet is produced (by using a PLA that contains a nucleating agent & a hot roll temp. Since PLA crystallizes so slow, this might be a challenge)
Q: Can you explain a little further how to move the PLA from an amorphous to crystalline state, and the challenges here.
A: PLA is very similar to PET in this regard. In order to get it to crystallize in an injection molding application you need to add a nucleation site (an fine mineral or salt) from which the crystals can start to grow from. You also need to ensure that the PLA molecules are mobile enough to move to the growing crystal so the it can continue to grow. You do this by adding a chain mobilizer which could be a plasticizing agent or a slip agent. You also use a mold temperature hot enough to promote mobility (>200F).
Q: Is your PLA sourced through Natureworks?
A: Yes, they are a partner in supplying us with PLA.
Q: With respect to sustainability at RTP, are you also looking at post-consumer recycled materials or keeping your focus on bioplastics?
A: We are looking a bioplastics, natural fiber/fillers, and recycled content (post and pre consumer).
Q: is the HI-PLA still transparent compare to PLA ?
A: The one being discussed is not transparent. Some transparent impact modified grades are available but have much lower impact strength.
Q: Have there been tests with nanofillers?
A: RTP has put nanoclays into polyamides (including bio-based polyamides) to reduce vapor permeability. We have also put carbon nanotubes in bio-based polyesters and polyamides for electrical conductivity
Q: Has compounding PLA with conventional polymers reduced its sensitivity to degradation in conventional material drying systems?
A: Compounding PLA with PC has allowed it to be dried at higher temperatures without getting tacky/sticky (175F vs 120F), but the PLA will still be susceptible to hydrolysis degradation and the same temperature as would the non-modified PLA.
Q: What is any difference is there from the PLA to conventional polymers in regards to how they degrade in a conventional landfill environment?
A: The conventional landfills in the world are not compositing sites and thus they do not have the heat, moisture, and oxygen needed to hydrolyze the PLA and start the bio-degradation, thus I do not expect much difference comparing PLA to conventional polymers relating to degradation in a landfill. This is one reason why RTP is not yet promoting biodegradability of these polymers, because our landfills are not equipment to do it.
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