Development and Evaluation of Injection-molded Bioplastic Container Prototypes

Sustainability and environmental impacts of container-crop production are important to producers and consumers.  While the performance, productivity, and low cost of petroleum-plastic containers have led horticultural industries to rely heavily on containers made of these unsustainable materials, emerging bioplastics technologies provide alternative container materials that may perform as well or better than petroleum plastics, yet are renewable and degradable.  We created prototype containers of 14 injection-moldable bioplastics and biocomposites and evaluated their effectiveness during greenhouse production of marigold, petunia, salvia, pepper, and tomato and during establishment of those plants outdoors with the container removed, crushed, and installed near plant roots.  Materials evaluated were Mirel® PHA formulations P1003, P1004, P1008, and P4010, and composites of P1003 and P1004 with dried distillers grains with solubles (DDGS); Ingeo® PLA and composites of PLA with DDGS, corn stover, and nano-clay; two high-percentage soy materials (SP and SP.A); and two soy-PLA formulations (SP-PLA and SP.A-PLA) blended 50:50 by weight.  All materials except high-percentage SP and SP.A processed well on standard plastics-processing equipment, and composites of PHA and PLA with DDGS or corn stover processed better than their base resins without composite materials.  After 5 weeks of greenhouse production, plants grown in containers made of blended SP.A-PLA and SP-PLA were healthier, larger, and of better quality than plants grown in control containers made of petroleum plastic, and with the exception of containers made of high-percentage SP and SP.A, plants grown in all other bioplastic containers were of similar health, size, and quality as those grown in control containers.  Grower rating of functionality, durability, and appearance was highest for containers made of PHA materials P1003, P1004, P1008, PHA composites with DDGS, and for controls.  Grower ratings were lowest for high-percentage SP and SP.A containers, which failed structurally in the greenhouse.  In the garden trial, plants grown for 8 weeks with bioplastic pieces installed near their roots were of similar health, size, and quality and showed similar fruit production as plants grown with petroleum-plastic containers removed and discarded, with the exception of those in the SP.A-PLA treatment, which were larger, of better quality, and produced more fruit than controls.  Our results demonstrate the potential to utilize injection-moldable bioplastics and biocomposites as replacements for petroleum plastics in specialty-crop containers that can improve sustainability and reduce environmental impact without sacrificing performance or productivity.