Application of FC 60140 Polylactic Acid/PBAT Bioplastic Straw Profile Extrusion Blend
When Melt Pressure Exceeds 14 MPa on QSR Cold Beverage Straw Lines
On production lines configured for cold beverage straw extrusion supplying quick-service restaurant chains, the processing behavior of FC
60140 is governed by the relationship between screw geometry, barrel temperature profiling, and the hydrolytic sensitivity of the PLA/PBAT polyester matrix. Pre-drying in a desiccant dryer at
70–80 °C for
4–6 h to achieve residual moisture below
250 ppm (
0.025 wt%) is non-negotiable; moisture ingress above
500 ppm triggers ester bond cleavage in both the polylactic acid and poly(butylene adipate-co-terephthalate) phases, producing a measurable drop in melt viscosity exceeding
15% within
20 min of residence time at processing temperature and resulting in bubble-laden extrudate, surface pitting, and longitudinal die lines on the finished straw wall. Extrusion on a single-screw extruder with L/D ratios between
28:1 and
33:1 is recommended; screws with compression ratios between
2.5:1 and
3.5:1 and chromized or nitrided barrel surfaces minimize material hang-up and thermal degradation in dead spots. Barrel temperature zones are programmed from
155–165 °C at the feed throat to
170–185 °C in the metering zone, with die temperature held at
178–190 °C; sustained melt temperatures above
200 °C accelerate thermal lactide reformation and PBAT chain scission, while temperatures below
165 °C elevate melt viscosity to a range where screw torque rises and output stability deteriorates. Melt pressure upstream of the breaker plate typically stabilizes between
8 MPa and
14 MPa for die diameters of
5.8–6.2 mm; pressure fluctuation exceeding
±0.5 MPa at steady state indicates surging, often traced to inadequate feed-throat cooling or bridging in the hopper. The profile die incorporates an annular gap of
0.45–0.60 mm with land lengths of
12–18 mm, producing a draw-down ratio of
2.0:1–2.8:1 against the final wall thickness of
0.18–0.25 mm. Vacuum calibration follows within
50 mm of the die face; calibration sleeve vacuum levels of
−30 kPa to
−45 kPa with sleeve temperatures maintained by recirculating water at
20–35 °C establish the outer diameter before the straw enters an atmospheric cooling bath of
4–8 m length. Belt puller or caterpillar haul-off speeds between
25 m/min and
35 m/min for
6 mm OD straws correspond to line outputs of
45–70 kg/h on a
50 mm extruder. In-line cutting by rotary fly-knife units synchronized to the haul-off encoder produces cut lengths of
140 mm,
180 mm, and
210 mm with length tolerances of
±2 mm per
ISO 18188:2016, Clause
5. Industry compliance for QSR straw applications rests on three pillars: food contact suitability under
FDA 21 CFR 176.170 (aqueous and fatty food simulants) and
EU Regulation 10/2011 (overall migration limit
10 mg/dm²); compostability per
EN 13432:2000 Annex B (biodegradation
≥90% in
180 days via
ISO 14855-1:2012); and dimensional specification per
ISO 18188:2016. Formulation addition ratios for QSR lines typically retain FC
60140 at
100% of the polymer fraction, with color masterbatch let-down at
1–3 wt% and no additional plasticizer or processing aid required; regrind from edge trim and changeover purges is incorporated at
≤20 wt% when dried to the same moisture specification as virgin pellets. Failure modes observed at production scale include ovality exceeding
0.3 mm diametral difference when vacuum distribution in the calibration sleeve is asymmetric, brittleness proportional to excessive draw-down ratio or melt temperatures below
170 °C, and surface roughness characterizable as sharkskin when shear rate at the die land exceeds critical stress thresholds for the PBAT-rich matrix phase. Terminal product types from this configuration include unwrapped or machine-dispensed cold beverage straws in inner diameters of
4.5–6.5 mm, wall thicknesses of
0.15–0.30 mm, and cut lengths from
120 mm to
260 mm, supplied in bulk-corrugated or poly-bagged formats to QSR distribution centers.
Retail Multipack Straw Production and the Automated Wrapping InterfaceRetail multipack straw production for consumer home use places the greatest downstream constraint not on the extrusion line itself but on the interface between the extruded profile and automated wrapping equipment. When individually wrapped straws are produced at retail grade, the outer diameter consistency entering the wrapper infeed must be maintained within
±0.05 mm of nominal across the entire reel length; wrapper jaw timing and film heat-seal dwell are calibrated against straw OD, and any drift exceeding this tolerance produces seal failures, film wrinkling, or wrapper jams that force line stoppage. Extrusion parameters for retail-grade production are derated from QSR output rates by approximately
20–30% to achieve the dimensional stability required; typical haul-off speeds are
18–25 m/min on
65 mm extruders, with melt temperature maintained at the low end of the processing window (
172–180 °C) to enhance melt strength and reduce post-extrusion diametral relaxation. Compliance obligations for retail multipack products include certification to
EN 13432:2000 and
ASTM D6400-23 for compostability claims placed on consumer packaging,
EU Regulation 10/2011 for food contact when the product is marketed as a drinking straw, and
REACH Regulation (EC) No 1907/2006 for substance registration and SVHC screening of all additives present above
0.1 wt%. Formulation addition ratios in retail configurations commonly include slip and antiblock additives at
0.5–1.5 wt% total loading to reduce straw-to-straw coefficient of friction and prevent nested straws from jamming in automatic wrapping mechanisms; titanium dioxide or organic pigment masterbatches are added at
1–3 wt% for opaque white, black, or brand-specific color matching, with no impact on compostability when certified masterbatches meeting
EN 13432 Annex A.1 heavy-metal limits are selected. Production lines for wrapped retail straws integrate the extruder and vacuum sizing tank with a downstream orientation conveyor feeding individual straws into the wrapping station; the wrapping station operates at wrapped-unit rates of
400–800 straws/min, and the extruded profile must be cut to length with an accuracy of
±1.5 mm before transfer to the wrapper infeed to prevent protruding straw ends beyond the film seal. Published data for the specific interaction between FC
60140 surface energy and low-temperature hot-melt or pressure-sensitive wrapper seal adhesion is limited; however, industry practice indicates that surface corona treatment is generally not required for PLA/PBAT blends with PBAT content above
20 wt% when using standard wrapper films. Terminal product configurations include individually wrapped straws in
100-count,
200-count, and
500-count consumer boxes, individually wrapped straws with printed paper or compostable film outer wraps, and unwrapped multipacks sealed in compostable polybags. Batch-to-batch variance in pellet moisture content from the supplier is a recognized failure source on retail lines; incoming resin moisture above
400 ppm is sufficient to produce visible surface defects in wrap-sealed product, and therefore in-house pre-drying with dew-point monitoring below
−40 °C is maintained even when supplier certificates indicate compliance.
Aseptic Carton Straw Attachment and Hot Melt Adhesive Compatibility
Straws intended for aseptic beverage cartons are extruded under a dimensional control regime that diverges from QSR and retail profiles due to the downstream attachment machine's mechanical registration requirements. Aseptic carton filling lines from suppliers such as Tetra Pak, SIG Combibloc, and Elopak position and bond individual straws to carton panels at throughputs of
6,000–12,000 cartons/h; the straw placement mechanism uses vacuum pickup heads that require a consistent straw outer diameter of
5.5–6.0 mm with tolerance class not exceeding
±0.05 mm over any
1 m length of extruded profile. Compliance for this application is anchored to
EU Regulation 1935/2004 (framework regulation for food contact materials),
EU Regulation 10/2011 with overall migration testing per
EN 1186-1 series at
40 °C for
10 days using
3% acetic acid and
10% ethanol simulants,
FDA 21 CFR 176.170 for aqueous and fatty foods, and compostability certification to
EN 13432 where the end-product is marketed within the EU as industrially compostable packaging. The hot-melt adhesive interface presents a material-specific consideration: PLA/PBAT blend surfaces exhibit polar surface energy values typically in the range of
38–42 mN/m, which is sufficient for bonding with EVA- and APAO-based hot-melt adhesives applied at
160–180 °C without corona or plasma pre-treatment, but inadequate substrate adhesion has been documented when low-surface-energy metallocene hot melts designed for polypropylene straws are substituted without reformulation. Extrusion process configuration for carton-attached straws uses reduced haul-off speeds of
15–25 m/min and melt temperatures of
175–183 °C to minimize post-extrusion ovality and diametral eccentricity; the vacuum calibration sleeve is positioned within
30–50 mm of the die face, and the sleeve length is extended to
300–500 mm compared with
200–300 mm for conventional line configurations to extend the effective sizing window. Wall thickness for carton straws is specified at
0.18 ± 0.02 mm, thinner than QSR profiles, to reduce polymer consumption per unit and to maintain flexural compliance when the straw is pulled from the carton surface by the consumer. Die gap is correspondingly set at
0.40–0.50 mm, producing a draw-down ratio of
2.2:1–2.8:1. Terminal finished product types comprise cellophane- or polypropylene-wrapped straws integrally adhered to
125 mL,
200 mL,
250 mL, and
330 mL aseptic cartons containing UHT milk, juice, plant-based beverages, and liquid meal replacements. The addition ratio of FC
60140 in this application remains
100% of the polymer fraction, with no filler or stiffening additive added; however,
0.2–0.5 wt% of an erucamide-based slip agent may be incorporated to facilitate carton machine conveyance and to prevent straw-to-straw blocking in bulk storage hoppers feeding the attachment station. Operational boundaries include the requirement that ambient relative humidity in the extrusion hall not exceed
60% RH when pellet storage silos are open to atmosphere, and that regrind material from carton-attached straw production be limited to
10 wt% due to the tighter dimensional requirements imposed by downstream automated adhesive application.When the die inner diameter increases beyond
9 mm and wall thickness specifications move into the
0.30–0.40 mm range to meet bubble tea and thick-beverage drinking requirements, the extrusion dynamics shift from standard straw profiling to a differentiated tooling regime that must be treated as a separate process class. Bubble tea straws with nominal inner diameters of
10 mm,
12 mm, and
16 mm and a characteristic point-cut or bevel-cut tip of
30–45° for piercing sealed cup lids cannot be extruded through conventional
6 mm QSR die tooling without unacceptable wall thinning and ovality; dedicated dies with annular gaps of
0.65–0.85 mm and land lengths extended to
20–30 mm are required to stabilize the melt flow at the higher volumetric throughput. The increased cross-sectional area imposes a substantially longer atmospheric cooling requirement: for a
12 mm OD straw with
0.35 mm wall thickness, the total cooling path from die face to haul-off entry must be extended to
8–12 m compared with
4–6 m for standard profiles, with staged water temperatures of
30 °C in the first tank and
15–20 °C in the second to prevent differential shrinkage shell formation that manifests as longitudinal warping in thick profiles. Haul-off speeds are derated to
8–15 m/min for bubble tea diameters; the reduced linear throughput is compensated by the higher mass per meter, maintaining extruder utilization within the same
40–60 kg/h band. Vacuum levels in the sizing sleeve are reduced to
−20 kPa to
−30 kPa because the larger diameter profile requires less external pressure differential to hold the wall against the sleeve; excessive vacuum on large-diameter thin-wall profiles produces visible suction marks and periodic radial collapse. Formulation-wise, FC
60140 is used at
100% polymer fraction with no modification to the base blend; however, the practical addition ratio of
0.3–0.8 wt% internal lubricant or process aid is observed on some production lines to reduce die lip buildup, which becomes more problematic at the lower shear rates encountered in large-diameter dies. Compliance for bubble tea straws references the identical food contact framework as QSR product (
FDA 21 CFR 176.170,
EU 10/2011,
EN 13432), but the point-cut tip introduces an additional safety requirement per
ISO 18188:2016 Clause
6 regarding the absence of sharp edges and the integrity of the bevel cut after tip-forming; tip-forming is performed by a secondary rotary cutter with heated blade elements at
60–80 °C to eliminate micro-fracture cracking at the cut interface that would propagate through the PLA phase. Published data for the specific bevel-cut fracture mechanics of PLA/PBAT blends at blade temperatures below
50 °C indicates an elevated probability of delamination at the PLA-PBAT phase boundary; this effect is mitigated by maintaining the cutting blade temperature above the glass transition of PBAT but below the Vicat softening point of the blend. Terminal product types include individually poly-wrapped bubble tea straws in
12 mm and
16 mm diameters with lengths of
210–270 mm, point-cut boba straws in mixed-color multipacks, and unwrapped bulk straws supplied to tea-shop chains in display boxes.
What Limits Regrind Inclusion Rates in HoReCa Bulk Straw Extrusion?
Bulk dispensed straws for hotel, restaurant, and catering (HoReCa) applications represent a lower unit-cost product class where regrind economics directly determine manufacturing profitability. The limiting factor on regrind inclusion is not the mechanical property loss—tensile property retention above
85% of virgin values at
30 wt% regrind inclusion is documented for PLA/PBAT blends shredded and re-dried under controlled conditions—but the cumulative effect of repeated thermal history on melt viscosity stability and color drift. Each pass through the extruder reduces intrinsic viscosity by
0.05–0.10 dL/g for the PLA phase; after more than two regrind cycles, the melt flow rate measured per
ISO 1133-1:2022 at
190 °C,
2.16 kg increases beyond the usable processing window, and the extrudate transitions from stable profile to die-drip-prone melt. Production practice therefore limits in-house regrind inclusion to
15–25 wt% for HoReCa bulk product, with the upper bound applied only when the regrind has been sieved through a
4 mm mesh, dried to
<250 ppm moisture, and blended in a gravimetric dosing system. Compliance for this product class is identical to QSR:
EU 10/2011,
FDA 21 CFR 176.170, and
EN 13432:2000 for compostability claims in European hospitality sectors. Extrusion configuration for bulk product does not require a wrapping station downstream; haul-off speeds of
25–40 m/min on
50–65 mm extruders are used, with the vacuum calibration tank and cooling bath dimensions corresponding to standard
6 mm profile tooling. No additional additives beyond color masterbatch at
1–3 wt% are required. Terminal product types include loose straws packed in
500 and
1,000-count bulk bags, straws supplied for tabletop dispensers, and unwrapped straws in dispenser cartons for event and institutional catering.
Vending Machine Dispensing Requires Dimensional Stability Below ±0.10 mm
Straws dispensed from automated vending machines and integrated beverage dispensing kiosks require a level of diametral and length consistency exceeding even carton-attached product. The dispensing mechanism in typical vending configurations uses roller traction or gravity-feed channels with clearance tolerances set for a specific straw diameter; deviation from nominal OD of more than
±0.10 mm produces misfeeds, double-dispensing, or complete jamming in the mechanism. Extrusion lines producing vending-grade straws operate with derated throughput averaging
60–70% of QSR capacity, and the calibration sleeve is maintained at a negative pressure of
−40 kPa to
−50 kPa with temperature uniformity across the sleeve circumference verified by onboard pyrometry.
ISO 18188:2016 Clause
5 specifies dimensional tolerances for drinking straws, but vending applications adopt tighter internal specifications aligned to OEM equipment requirements. Compliance does not differ from QSR product:
FDA 21 CFR 176.170,
EU 10/2011, and compostability certification per
ASTM D6400-23 or
EN 13432. A notable additive consideration for vending-grade product is the potential incorporation of
0.5–1.0 wt% anti-static masterbatch to reduce static cling in dry dispensing chutes; PLA/PBAT blends are inherently hydrophobic at the surface but can build triboelectric charge during high-speed cutting and conveying. Terminal product types include straight-cut
6 mm straws dispensed from coin-operated vending machines, straws co-packaged with vended cold beverage cups, and unwrapped straws for self-serve kiosk dispensing in convenience retail.In clinical and institutional settings, the operational requirements for biodegradable straws diverge not by tooling or throughput but by the constraints imposed on material purity, packaging, and traceability. Hospital wards, long-term care facilities, and correctional institutions that procure PLA/PBAT straws typically specify no added colorants, no regrind content, and no use of processing aids containing substances listed on the facility's restricted material inventory. Formulation addition ratios are therefore constrained to FC
60140 at
100% of the polymer fraction with zero regrind and zero color masterbatch; the natural off-white or translucent straw color is the only acceptable presentation unless a facility-specific white pigmentation is agreed with the purchasing department. Compliance obligations extend beyond food contact to include documentation of heavy-metal content below the limits established by
EN 13432:2000 Annex A.1 and
EU Directive 94/62/EC packaging and packaging waste concentration limits (
100 ppm sum of lead, cadmium, mercury, and hexavalent chromium); ISO
13485 quality management documentation is increasingly requested for medical-environment suppliers even when the product is not classified as a medical device. Extrusion processes for institutional product are run with the same screw and die configurations as standard profiles, but the production environment must support documented separation of the material flow from regrind-generating operations; purges and start-up scrap are fully segregated and not fed back into the product stream. The cooling water and contact surfaces in the vacuum tank are specified for food-grade cleanliness, with no recirculated water exposed to atmospheric contamination. Terminal product types include individually paper-wrapped drinking straws in
4.5–6.0 mm diameters and lengths of
150–210 mm, unwrapped bulk straws for patient meal trays, and bendable straws with a formed corrugated flex section produced by downstream mechanical corrugation after initial profile extrusion. Published data for the mechanical integrity of the corrugated flex section in PLA/PBAT blends under repeated bending at
2–6 °C (refrigerated beverage service) indicates that the flexural fatigue performance is governed primarily by PBAT content and phase morphology; blends with PBAT content below
20 wt% exhibit crack initiation at the corrugation roots after fewer than
20 bending cycles, whereas PBAT contents above
30 wt% maintain flexural integrity beyond
100 cycles under the same conditions.
| Parameter | QSR Standard Straw | Bubble Tea Straw | Carton-Attached Straw |
|---|
| Nominal inner diameter | 5.8 mm | 10.8 mm | 5.5 mm |
| Target wall thickness | 0.20 ± 0.03 mm | 0.35 ± 0.05 mm | 0.18 ± 0.02 mm |
| Die annular gap | 0.50 mm | 0.70 mm | 0.45 mm |
| Draw-down ratio | 2.5:1 | 2.0:1 | 2.5:1 |
| Sizing vacuum level | −35 kPa | −25 kPa | −40 kPa |
| Melt temperature | 180–185 °C | 175–180 °C | 178–183 °C |
| Haul-off speed | 25–35 m/min | 8–15 m/min | 20–30 m/min |
| Cooling path length | 4–6 m | 8–12 m | 4–6 m |
| Regrind ceiling | ≤20 wt% | ≤10 wt% | ≤10 wt% |
| Standard reference | Method / clause | Parameter | Threshold |
|---|
| EN 13432:2000 | Annex A.1 | Heavy metals / hazardous substances | Below specified volumetric limits |
| EN 13432:2000 | Annex B / ISO 14855-1:2012 | Aerobic biodegradation | ≥90% in 180 days |
| EN 13432:2000 | Annex C | Disintegration | ≥90% particles <2 mm in 12 weeks |
| EN 13432:2000 | Annex D / OECD 208 | Ecotoxicity (plant germination) | Germination rate ≥90% of control |
| ASTM D6400-23 | Sections 6.2–6.5 | Compostability (US) | Criteria equivalent to EN 13432 |
| EU 10/2011 | Annex II | Overall migration | ≤10 mg/dm² |
| EU 10/2011 | Annex I | Specific migration of lactic acid, adipic acid, butanediol, terephthalic acid | As specified per FCM substance listing |
| FDA 21 CFR 176.170 | Table 1 and Table 2 | Extractives in aqueous and fatty food simulants | Per regulation |
| ISO 18188:2016 | Clause 5 | Dimensional tolerances (diameter, length) | As specified |
| ISO 18188:2016 | Clause 6 | Safety requirements (sharp edges, integrity) | As specified |
| REACH (EC) No 1907/2006 | Article 33 | SVHC declaration | 0.1 wt% per article |
FC 60140 Polylactic Acid/PBAT Bioplastic Straw Profile Extrusion Blend is a pelletized thermoplastic compound supplied for monolayer drinking straw profile extrusion. The formulation uses a PLA-majority matrix modified with PBAT to increase ductility and reduce the brittle fracture observed in neat PLA straws. The grade is typically run on single-screw extruders equipped with a specialized straw die, vacuum calibration sleeve, and rotary cutter. Typical straw dimensions include outer diameters of 3 mm to 8 mm and wall thicknesses of 150 µm to 250 µm. The compound is positioned for cold-service drinking straws, stirrers, and short profile tubes where industrial compostability and dimensional stability are required. Published lot-specific certification should confirm the exact melt flow index and tensile values; the property ranges supplied below are representative of PLA/PBAT straw extrusion compounds with a PLA-majority composition.
Does the 60140 designation correspond to a fixed PLA/PBAT ratio or a property envelope?
The numerical designation is commonly read as a 60:40 PLA-to-PBAT mass ratio, but compounding practice allows the PBAT fraction to shift within 30 wt% to 45 wt% to meet melt tension and die-swell requirements. The blend is not a simple physical mixture; melt-phase morphology depends on screw shear history, residence time, and compatibilizer selection. Typical density falls between 1.22 g/cm³ and 1.28 g/cm³ under ISO 1183-1:2019. Melt mass-flow rate at 190°C and 2.16 kg is generally bracketed between 3 g/10 min and 8 g/10 min under ISO 1133-1:2022. A narrower MFI band of 4 g/10 min to 6 g/10 min is preferred for high-speed profile lines because lower melt flow can overpressurize the die while higher melt flow can cause draw resonance and wall-thickness variation. The property envelope is controlled more by PBAT domain size than by ratio alone; therefore, extrusion temperature and screw speed are treated as part of the specification boundary.
Thermal analysis by differential scanning calorimetry under ISO 11357-2:2020 reveals two glass transitions: the PLA-rich phase near 55°C to 60°C and the PBAT-rich phase near -35°C. The PBAT phase remains elastomeric at chilled-beverage temperatures, which accounts for low-temperature ductility. The PLA phase contributes stiffness but begins softening near the upper service range. This phase-separated morphology explains why the compound cannot be modeled accurately by simple rule-of-mixtures equations; dispersed PBAT domain size and interfacial adhesion, not only composition, control tensile elongation.
Moisture control is the principal process gate. PLA and PBAT polyesters undergo hydrolytic chain scission when melt moisture exceeds approximately 250 ppm. Pellets are pre-dried in a desiccant hopper dryer at 70°C to 80°C for 3 h to 4 h, with a supply-air dew point no higher than -40°C. Residual pellet moisture is kept below 0.25 wt% when measured by ISO 15512:2019. Field observations on single-screw straw lines show that a dew-point fault of -20°C or wetter produces melt flow index drift of 0.5 g/10 min to 1.2 g/10 min within 30 min, followed by die droplet formation, gas specking, and brittle welds at the die entrance. A vented barrel with L/D of 30:1 and vacuum below -0.08 MPa is recommended if in-line regrind is being fed at addition rates above 10 wt%. Drying is not optional; damp feed is the most common root cause of cutting-station cracking and variable straw ovality.
Process limits in the profile die and calibration zone
Barrel settings should follow a rising flat profile from 160°C in the feed section to 180°C to 190°C at the metering section and die. Melt temperature must remain below 200°C; at 210°C and above, PLA chain scission and PBAT thermal degradation accelerate sharply. A barrier screw with an L/D ratio of 28:1 to 32:1 and compression ratio of 2.5:1 to 3:1 reduces shear heating. Die pressure should be held below 120 bar; increasing pressure at constant throughput often signals gel build-up on the 40/60/80 mesh screen pack or stagnated melt in the adapter. Calibration sleeve water temperature is controlled at 20°C to 30°C. Vacuum calibration is set between -0.2 bar and -0.6 bar; excessive vacuum collapses the still-soft profile, while insufficient vacuum produces ovality and poor diameter control. Haul-off speed is set to match volumetric output with allowance for 10% to 20% die swell. During startup, the first 5 m to 10 m of profile is discarded until melt pressure and cooling stabilize.
The die land length and internal spigot configuration determine wall-thickness uniformity more than barrel temperature alone. A typical straw die uses a central mandrel and an external die body with an annulus gap of 0.3 mm to 0.5 mm to produce a finished wall thickness of 150 µm to 250 µm after draw-down. The melt must exit the die without melt fracture; PBAT-modified melts can exhibit stick-slip flow if die roughness exceeds 0.2 µm Ra in the final 5 mm of the land. Low-shear regions near the mandrel tip are common sites of gel accumulation, and scheduled purging every 8 h to 12 h is recommended. Die temperature is held at the upper edge of the barrel profile, 185°C to 190°C, while the mandrel temperature is often 5°C to 10°C lower to hold the internal weld line open.
Capillary rheometry at 190°C shows shear-thinning behavior typical of immiscible PLA/PBAT blends. At apparent shear rates of 100 1/s to 1000 1/s, viscosity decreases by approximately one order of magnitude. This shear sensitivity assists filling of the thin annular die. However, at very low shear rates near the mandrel inner surface, a yield-like plateau can produce no-flow layers. Die design with tapered flow channels of 15° to 20° is therefore preferred to avoid stagnation.
Batch-to-batch variation in MFI is typically held within ±0.5 g/10 min for optimized lines. A shift of 1 g/10 min can change draw-down ratio by up to 5% and require haul-off speed adjustment. Production records often tie that variability to PBAT supplier lot changes rather than PLA, because PBAT viscosity varies more widely.
The values in the table are not certified lot limits; they represent the working envelope for PLA-majority PBAT-modified straw extrusion compounds and should be read against the supplier certificate of analysis.
| Property | Typical range | Test method |
|---|
| Melt mass-flow rate | 3–8 g/10 min | ISO 1133-1:2022 |
| Density | 1.22–1.28 g/cm³ | ISO 1183-1:2019 |
| Tensile strength at yield | 20–35 MPa | ISO 527-2:2012 |
| Tensile elongation at break | 150–320% | ISO 527-2:2012 |
| Flexural modulus | 600–1400 MPa | ISO 178:2019 |
| Heat deflection temperature | 45–60°C at 0.45 MPa | ISO 75-2:2013 method B |
| Residual moisture | ≤0.25% | ISO 15512:2019 |
Axial tensile tests on cut straw profiles are more relevant than injection-molded plaques. When wall thickness is below 1 mm, ISO 527-3:2018 is applied; the blend shows a yield stress and a long cold-drawing plateau rather than the abrupt break of neat PLA. Flexural modulus by ISO 178:2019 provides ring-stiffness information but does not directly predict lip-contact collapse. The PBAT phase reduces notch sensitivity during shoulder forming and improves resistance to longitudinal splitting at the cutter edge. U.S.-based validation may also use ASTM D638-14 Type IV specimens. In accelerated shelf testing, dried samples stored at 23°C and 50% relative humidity retain tensile elongation within 20% of initial values, although published data specific to FC 60140 storage stability is limited.
High-speed rotary cutting of PLA/PBAT straws requires blade edge temperature below 50°C. Friction heat can generate adhesive fines that redeposit on the bushing and create surface defects. Cutter speed is matched to line speed; if line speed exceeds 150 m/min, the material’s characteristic cold-drawing plateau reduces shattering at the cut face. Dust extraction at the cutter and vacuum sizing units is recommended because the fines are electrostatically active.
When food-contact and compostability documentation is required for retail acceptance
Compostability claims require evidence on the finished article, not only the base resin. The relevant industrial composting standards are EN 13432:2000, ASTM D6400-23, and ISO 17088:2021. Disintegration is tested under industrial composting conditions, commonly 58°C with forced aeration; these conditions are not present in home compost bins, soil burial, or marine water. Food-contact compliance must be documented under EC 10/2011 for EU applications and under a valid U.S. Food Contact Notification or the applicable 21 CFR clearance for the specific polymer and additives. The base resin itself does not confer food-contact approval; migration testing on the finished straw is necessary. Pigment concentrates can violate heavy-metal limits under EN 13432 and ASTM D6400 even when the base compound passes. Supplier documentation should include REACH and RoHS declarations, but these declarations do not replace food-contact or compostability certifications. For biobased carbon content, ASTM D6866-22 distinguishes renewable carbon from petroleum-derived PBAT; the PLA fraction is renewable, while PBAT may be petroleum-derived or partially bio-based.
Parting from neat PLA, neat PBAT, and starch-based compounds
Neat PLA extrusion grades frequently exhibit tensile elongation at break below 10% and split during cutting. The PBAT-modified FC 60140 grade lifts elongation at break into the 150% to 320% range. Neat PBAT typically has flexural modulus below 100 MPa and may suffer pellet blocking in warm storage; the PLA-majority blend raises flexural modulus to 600 MPa to 1400 MPa, providing sufficient stiffness for thin-wall profile roundness. Starch-based PLA compounds may show lower melt consistency and higher moisture uptake, resulting in more die plate-out and surface roughness. The PBAT phase also reduces equilibrium water uptake relative to starch-filled systems, although moisture drying limits remain mandatory. Compared with polypropylene homopolymer, FC 60140 has higher density, lower heat-deflection temperature, and lower tensile strength; the selection basis is industrial compostability and renewable carbon rather than mechanical performance. Polyolefin recycling operations should not receive this material because it behaves as a contaminant in the PP stream.
| Material class | Tensile elongation at break | Flexural modulus | HDT at 0.45 MPa | Industrial compostability |
|---|
| Neat PLA | 3–10% | 2500–3500 MPa | 50–60°C | Possible if certified to EN 13432 |
| FC 60140 | 150–320% | 600–1400 MPa | 45–60°C | Possible if certified to EN 13432 |
| Neat PBAT | 400–700% | 60–100 MPa | <40°C | Possible if certified to EN 13432 |
| Starch/PLA compound | 5–30% | 800–2000 MPa | 35–50°C | Possible if certified to EN 13432 |
| PP homopolymer | 100–600% | 1200–1800 MPa | 90–110°C | Not compostable |
The product is not intended for hot beverages. Continuous contact with liquids above 45°C can soften the profile and cause ovalization under lip or clamp load. It is not certified for marine, freshwater, or soil biodegradability unless separately tested and explicitly stated. Storage should be sealed below 60% relative humidity; above this threshold, moisture uptake shortens remaining drying capacity and can cause feed-throat hydrolysis. If the compound has been stored beyond the supplier shelf life, melt mass-flow rate should be rechecked under ISO 1133-1:2022 and residual moisture under ISO 15512:2019 before startup. Addition of incompatible fillers, pigments, or plasticizers should be avoided without verification, because dispersed phase size and migration behavior can shift elongation and food-contact performance.
