Raising the Heat Deflection Temperature of PLA LAPOL HDT TECHNICAL BULLETIN OCTOBER 2014 1
Polylactic Acid (PLA) The Front Runner in Bioplastics 100% degradable thermoplastic resin Made from renewable resources Flexible or rigid Processed on standard converting equipment Multiple consumer and industrial applications
Limitations of PLA Low Heat Deflection Temperature (HDT) 50 60 C Sticking and Deformation During Transport, Storage and Use Brittleness Poor Impact Resistance Long Mold Times Too Costly to Process
Lapol HDT Chemistry Lapol HDT increases crystallinity and reduces crystallization time of PLA creating high heat deflection temperatures. Lapol Offers Solutions Different grades of Lapol HDT Additives that reduce brittleness with limited effects on heat tolerance properties Additives that reduce crystallization time that act synergistically with Lapol HDT As a result, there is a trade off between brittleness and improved heat tolerance.
Lapol HDT Ratios with PLA Lapol HDT A copolyester of d lactide based on the stereochemistry of PLA. Lapol HDT / PLA 50/50 Free volume is reduced, the crystallization increased, and the melting temperature is around 240 o C, but it is too brittle to be processed usefully. PLA/Lapol HDT 80/20 A resin that processes well in many applications while increasing use temperatures.
Thermal Mechanical Analysis of Lapol HDT After annealing PLA requires annealing for increased HDT, but will distort rendering the parts unusable; whereas, Lapol HDT does not require annealing and will not distort under elevated temperatures
Thermal Mechanical Analysis of NatureWorks PLA with Lapol HDT PLA grades respond differently to Lapol HDT at lower concentrations, but all show an improvement in their heat tolerance at greater than 20%. Concentrations of 20% show the best combination between acceptable mechanical properties and heat tolerance improvement.
Physical Properties of Lapol HDT PROPERTIES LAPOL HDT Melting Point 170-180 C Density Color State 1.25 g/cc Off White Solid Can modify the heat deflection temperature of PLA Excellent miscibility with commercial PLA FDA Compliant Compostable Renewable
Addition of Vinnex with Lapol HDT to Reduce Brittleness with NatureWorks PLA Lapol HDT is effective with NatureWorks Ingeo 4032D, but will increase the heat tolerance of any PLA grade with more than 95% d lactic acid content. Lapol HDT with Vinnex 2504 or 2505 improves the impact resistance with limited effects on heat tolerance of the blends. Addition of more than 10% Vinnex 2504 or 2505 is not recommended. Thermoforming cycle times have been shown to be reduced by 40%.
Thermal and Mechanical Properties of PLA/Lapol HDT with Vinnex Formulation 1 2 3 4 5 6 7 8 Ingeo 2003D 100 80 72 64 Ingeo 4032D 80 76 72 68 Low IV Lapol HDT 20 18 16 Low IV Lapol HDT 20 19 18 17 Vinnex 2504 10 20 Vinnex 2504 5 10 15 Mechanical Properties Tensile Draw speed: 50 mm/min Sample Size mm 3.79 3.85 3.82 3.88 mm 4.28 4.34 4.27 4.24 Tensile Strength Max [MPa] 72 62 42 25 [MPa] 49 57 47 37 Tensile Strength Avg. [MPa] 64 61 38 24 [MPa] 49 54 45 36 Elongation @Break [%] 3 2 13 19 [%] 1 2 4 3 Modulus [MPa] [MPa] Draw Speed: 1 mm/min 3803 3622 2699 1986 3872 3267 2832 2467 Thermal Properties Heat Distortion Temperature Vicat A 1019 g [ C] 60 142 122 74 [ C] 158 157 154 150 Vicat B 5097 g [ C] 55 62 59 53 [ C] 105 97 85 79 Impact Properties Charpy Impact Avg [kj/m²] 18.8 9.98 49.0 57.2 [kj/m²] 8.79 11.1 25.2 30.8
Effect of Lapol HDT with Vinnex 2504 on NatureWorks PLA 4032D and 2003D Lapol HDT Low IV in NatureWorks 4032D with Vinnex 2504 Lapol HDT Low IV in NatureWorks 2003D with Vinnex 2504 Charpy [kj/m2] Tensile Strength [MPa] 160 140 120 100 80 60 40 20 0 Elongation@ Break [%] Charpy [kj/m2] Tensile Strength [MPa] 160 140 120 100 80 60 40 20 0 Elongation@ Break [%] Ingeo 2003D HDT (Vicat A) [ C] Ingeo 4032D 80/20 blend 5% Vinnex 2504 10% Vinnex 2504 HDT (Vicat A) [ C] 80/20 blend (low IV Lapol HDT) 10% Vinnex 2504 20% Vinnex 2504 20% Vinnex 2504
Lapol HDT with PBS
Thermo Mechanical Analysis (TMA) Different Lapol HDT Ratios with PBS and PLA The Synergistic Effects of Lapol HDT and Polybutylenesuccinate (PBS) Adding 5% PBS with 6% Lapol HDT Extends the Temperature Deformation to 150 C with Little Dimensional Change 13
55/45 Lapol HDT/PBS Reduces Cost and Improves Performance Adding 11% Lapol/PBS 55/45 Lowers the Overall Lapol HDT percentage requirement from 20% to 6% PBS is about 1/3 the cost of Lapol HDT Maintains the Heat Deflection Temperature performance Reduces Brittleness Both Lapol HDT and PBS can be supplied as a compound or neat to be directly fed in the extruder 14
SUMMARY Lapol HDT Attributes Increases heat deflection temperatures in PLA to greater than 150 C (Vicat A) Lapol HDT does not require annealing and will not distort under elevated temperatures Lapol HDT Biopolymer Resins are: Renewable Compostable FDA Compliant Thermoforming cycle time has been shown to be reduced by 40% Can be added directly at the thermoformer extruder or injection molder Adding PBS can increase elongation and reduce cost while maintaining HDT www.lapol.net 3757 State Street Suite 2A Santa Barbara, CA 93105 805 456 7950 15