Bio-Plastic PLA Injection Moulding: Sustainable Manufacturing

Polylactic acid (PLA) is a bio-sourced, compostable thermoplastic derived from corn starch or sugarcane. At Moulding Injection, we process PLA and other bio-plastics on our standard injection moulding presses, offering our clients a pathway to reduced carbon footprint without sacrificing part quality.

What is PLA?

PLA is a polyester produced by fermenting plant sugars. It offers properties comparable to PS and PET: good stiffness (flexural modulus 3.5 GPa), excellent surface finish, and natural transparency. Its carbon footprint is 60-70% lower than petroleum-based plastics, and it is industrially compostable (EN 13432).

Processing PLA by Injection Moulding

PLA processes at lower temperatures (170-200°C melt, 25-55°C mould) than most engineering plastics, reducing energy consumption per cycle. However, PLA is sensitive to moisture (must be dried to <0.025% before processing) and has limited heat resistance (HDT 55°C without modification).

For improved heat resistance, we use PLA blends with nucleating agents (HDT up to 120°C) or PLA/PBAT blends for increased flexibility. These modified grades extend PLA applicability to dishwasher-safe tableware and automotive interior components.

Applications

Single-use food packaging (certified compostable), cosmetic packaging (premium eco-positioning), promotional items (trade show giveaways with sustainability messaging), medical disposables (PLA is biocompatible), and agricultural films and clips.

Limitations and Honest Assessment

PLA is not a universal replacement for petroleum plastics. It degrades slowly in home compost (6-12 months vs weeks in industrial composting). It is not suitable for outdoor or high-temperature applications without modification. And "bio-sourced" does not automatically mean "better for the environment" — lifecycle analysis must consider land use, water consumption, and end-of-life infrastructure.

Our Bio-Plastics Portfolio

Beyond PLA, we process: PHA (marine-degradable, limited availability), PBS (soil-degradable), bio-PA (Rilsan from castor oil), bio-PE (from sugarcane ethanol, recyclable in PE stream), and starch blends. We help clients select the bio-plastic that genuinely matches their sustainability goals and technical requirements.

Frequently Asked Questions

Is PLA more expensive than standard plastics?

PLA costs approximately 2-3x more than commodity PP or PE. However, for premium products where sustainability is a selling point, the material cost is a small fraction of the retail price. We provide cost comparisons for every project.

Can PLA parts be recycled?

PLA is industrially compostable (EN 13432) but not recyclable in conventional plastic recycling streams. It must be collected separately and processed in industrial composting facilities (>58°C for >12 weeks).

Technical Specifications

Bio-Plastic PLA Injection