Bioplastics – the North American agenda

The PLA is compounded to improve properties so that it can be used as a drop in replacement for petroleum based plastics such as PE, PP and PS. There is a new 3-layer film with high clarity and 30-50% renewable content for applications including the back film of diapers, frozen McCain food bags and form-fill-seal.

Additives corporations have studied the appropriate agents for PLA. Clariant International has found that the light stabilizers and anti-blocking agents used for polyesters such as benzotriazoles and fatty acid esters respectively, can be used for PLA as well. There are also special masterbatches like the CESA-extend chain extender for melt stabilization. In terms of mineral fillers, talc and calcium carbonate can be used as nucleating agents and to increase stiffness. Clariant also has a premium range of naturally sourced pigments and additives which are “OK Compost” certified including a beeswax, a pale yellow color from fruit and an antioxidant based on vitamin E.

Charlie Martin of Leistritz in New Jersey is well-known for his expertise in twin screw extrusion and he has applied his extensive knowledge to the compounding of and the machine should be of stainless steel to avoid the corrosive effects of PLA. There should be provision for devolatilization of undried PLA. The material is heat-sensitive, so cooling systems are important.

The torque should be increased, for example by changing the shaft design to include more splines and asymmetric geometry, as well as by upgrading the gearbox. Gala Industries as worked on pelletizing systems for bioplastics.
Natureworks LLC is probably the best known supplier of PLA worldwide. It produces three lactide monomers from corn, L-lactide, meso-lactide and D-lactide, and these are polymerized using a catalyzed ring-opening process.

The monomer ratio can be used to develop different properties. There are film, fiber, thermoforming, injection molding and injection stretch blow molding grades. The Ingeo 3801X injection molding materials is compounded with a core-shell impact modifier from Arkema, a dioctyl adipate crystallization accelerant from HallStar, mineral reinforcement from Specialty Minerals and a nucleating agent from Takemoto Oil & Fat Co. The company is currently developing improved injection molding and higher performance materials.

Another company that is working on new PLA compounds is Techmer PM. The company has molding and film grades, some of which are compostable and have FDA food contact approval. It has worked with talc as a natural mineral filler and with a yeast filler, which adds bio-based content. Its PLA masterbatches have applications in nonwoven fabrics.

Brand owner Kimberly-Clark is “weaving environmental sustainability into its products” and has been named as a leader in the Dow Jones Sustainability Indexes. Current projects include testing high percentage bio-based materials to replace 100% petrochemical plastics.

This includes polyethylene-starch blends to manufacture films., which requires plasticizers and compatibilisers for processing, and gives films that have a suitable modulus for flexible packaging.


sent: 2012-02-12 10:24:02 Pretty sure Wellington now has a group. One pseron’s trash is another pseron’s treasure.


sent: 2012-03-12 22:08:18

Crunchy,As long as cigarette feltirs will not count as hazards to wild and domestic animals, I doubt ocean plastic dumping will raise much fuss.My thinking is that tobacco companies got caught lying about the dangers of smoke, of second hand smoke, of third hand smoke residue (residue deposited by cigarette smoke in vehicles, rooms, and on clothes that later causes bad effects). So now the 'conversation' is over. Those discarded cardboard and foil packages, the filter parts (containing residues of the cigarette as well as their chemical composition -- I don't see 'biodegradable' used to describe feltirs any time recently -- or non-toxic after use, either).I am completely sold on the notion that recycling is dangerous to America and the world - it burns tax dollars and oil. Even the recycling that is shipped to Mexico 'cause they don't have our EPA banning the processing.Recycling, by it's presence, gives permission to those making plastic stuff and those choosing plastics.And yet, there is the plastic cereal box liner -- when was the last time you got a box of corn flakes with bugs going wild? Zip-loc bags - each, when new, is sanitary.If not for plastic buckets - would that mean lots of metal buckets, with the cost in energy to mine, refine, manufacture, and transport the metal and metal products? I am thinking of the massive use of plastic 55 gallon barrels for oil products, for lead detector solution, etc. Paint buckets for the big jobs, in five gallon buckets.Aluminum was once called 'solid electricity', from the practice of building a hydroelectric generator/dam near a bauxite (aluminum ore) mine, to smelt the aluminum on-site.I remember years ago the angst over how much more energy a can with a pop-top took to make than a simple can that you used a can opener to puncture. It seems that conversation diet. But now, look at the number of two-liter soda and half-liter water bottles are churned out. Or disposable juice six-packs and eight-packs. With a market place seemingly addicted to plastic bottles - what is the alternative? The old 48 ounce juice cans can still be found, sometimes. How many people today have ever bought one? When single-serving frozen meals (TV dinners for us old-timers) moved from the oven to the microwave, they moved from aluminum foil to plastic - with plastic film tops.Is waxed paper still made with petroleum/plastic coating or paraffin, or still real wax? I doubt the wax part. And, again, how many homemakers have ever wrapped a lunch sandwich in waxed paper -- that was still 'sealed' when opened?I am not disputing that reducing plastic use is essential. What I don't see is a path forward.Using glass in the microwave works well. Also ceramic. But that pretty much eliminates the reduction of spoilage from single serving packaging. And also contradicts the single-serving lifestyle so many families seem addicted to (and the only heritage their children will realize).It seems that in order to diminish relying on plastics, you have to first dismantle the current lifestyle of endless ambition, and the corporate-like rush to efficiency.And stop recycling. It is 'false efficiency'.@ Beth Terry,I find the 'pure cornstarch' baby powder works pretty good.