Avient Polystrand ThermoPro™ IE7015 Unitape is a continuous unidirectional E-glass fibre reinforced polypropylene composite tape supplied in slit roll form for consolidation into structural and semi-structural thermoplastic laminates. The product is based on collimated continuous glass rovings melt-impregnated with a polypropylene matrix at a nominal fibre mass fraction of 70% when tested according to ISO 1172. Because the matrix is a thermoplastic, the tape does not require refrigerated storage or controlled out-time management typical of thermoset prepregs; however, ambient handling should maintain relative humidity below 60%. If surface condensation or storage moisture is suspected, drying at 80°C for 4 h is applied before hot consolidation. The material is intended for use in panel stiffening, load-floor elements, underbody shields, door intrusion beams, battery-tray stiffeners, and other components where high longitudinal stiffness and tensile strength per unit thickness are required.

Property references and test programme for consolidated IE7015 laminates

Published data for the 70 wt% continuous E-glass/polypropylene unitape class indicate that the consolidated laminate is highly anisotropic. Longitudinal properties are fibre-dominated, while transverse and through-thickness properties are resin-dominated and strongly influenced by tape thickness uniformity and void content. The following ranges are representative of unidirectional 0° laminates consolidated under matched-tool pressure; they are not release limits and should not replace a lot-specific certificate of analysis.

Transverse tensile properties are limited by the polypropylene matrix and are not representative of the fibre-direction values. For cross-ply and quasi-isotropic laminates, the lay-up schedule controls stiffness and strength, and the unidirectional ply should not be used as a direct substitute for woven glass-reinforced polypropylene sheet in load cases that generate significant transverse stress.

In production-scale double-belt lamination, incoming tape thickness variation greater than ±0.03 mm promotes resin-rich interply boundaries because the rigid unidirectional glass bed prevents thickness redistribution during compression. Laminators equipped with segmented heating zones, closed-loop roll-gap control, and infrared line scanners maintain panel surface temperature within ±2°C across the working width. The polypropylene melting range is approximately 160–170°C, and thermal oxidative degradation can accelerate when material temperature exceeds 220°C for standard stabiliser packages. Belt pressure in the range of 0.2–0.8 MPa is adequate for consolidation of thin stacks up to approximately 6 mm; thicker laminates require staged pressure or increased dwell time to prevent ultrasonic C-scan indications of unbonded zones and internal voids.

How does continuous fibre content change failure mode compared with short-glass compounds?

The principal difference between IE7015 unitape and injection-moulded short-glass reinforced polypropylene is fibre continuity and orientation. In a 0° consolidated laminate, tensile failure is dominated by fibre fracture rather than fibre pull-out. Injection-moulded 40 wt% short-glass polypropylene typically retains fibre lengths of 0.2–0.8 mm after plastication, which is below the critical transfer length required for full load transfer in a polypropylene matrix. As a result, tensile modulus of a 40 wt% short-glass polypropylene compound is typically 7–9 GPa when tested according to ISO 527-2, whereas the continuous unidirectional tape achieves 35–40 GPa in the fibre direction according to ISO 527-5.

This mechanical divergence influences downstream selection. The unitape is used for stiffness-critical planar or gently formed reinforcements, while short-glass polypropylene remains suitable for high-flow geometries with ribs, bosses, and snap-fits. The unitape is not a drop-in moulding feedstock; it requires ply cutting, lay-up, consolidation, and secondary trimming or overmoulding. The fibre alignment creates high longitudinal bearing strength but low transverse resistance to splitting around holes. Mechanical fastening with self-tapping screws in unidirectional plies requires pilot holes of at least 0.8 times the nominal screw diameter to reduce fibre-direction splitting under hoop stress. Pull-through and boss retention should be evaluated according to ASTM D7332 or an end-use specification rather than inferred from short-glass polypropylene data.

When a matched-tool process exceeds the upper pressure boundary

Matched-tool compression consolidation of IE7015 tape generally uses cavity-surface temperatures of 195–210°C and final-part pressures of 1.5–3.0 MPa for 0°/90° stacks. If pressure exceeds 4.0 MPa at the final thickness, transverse resin squeeze-out can occur at tape edges, reducing the surface resin layer and increasing glass exposure. Continuous glass fibres show negligible transverse melt flow, so the tool cannot compensate for poor blank tolerances by displacing reinforcement. Packing pressure is held until the core temperature falls below 120°C to reduce ply spring-in and warpage. Asymmetric lay-up schedules, unbalanced fibre orientations, or single-sided cooling create panel distortion on demoulding; balanced lay-ups and matched cooling rates are therefore required for large-area parts.

For thermoforming or overmoulding, blank preheat at 190–210°C is applied for approximately 10–20 s per mm of laminate thickness. Draw ratios above 1.5:1 are difficult in unidirectional plies because the glass bed does not stretch; ply slip and interply shear dominate formability. When matched-tool forming is performed below 185°C, the polypropylene matrix viscosity remains high and interply slip is insufficient, producing fibre buckling and surface wrinkles. Above 215°C, surface oxidation of the polypropylene matrix may occur unless the process uses an inert gas purge or the residence time is limited. Published data for this specific IE7015 configuration in deep-draw thermoforming is limited; therefore tool trials with embedded thermocouples and full-field strain measurement are recommended before part release.

The polypropylene matrix provides resistance to moisture, mineral acids, and many aqueous salt solutions at ambient temperature, but chemical compatibility with strong oxidising acids, chlorinated hydrocarbons, and aromatic solvents should be verified for continuous exposure above 40°C. The product is a hydrocarbon matrix system and does not possess an inherent vertical burn rating; applications requiring flame performance should use a flame-retardant facing layer or coating and must be evaluated under FMVSS 302 or ISO 3795. Regulatory status under REACH and RoHS should be confirmed from the supplier certificate for the specific production lot because sizing chemistry and stabiliser additives may vary within the product family.