KNOWLEDGE REFERENCE
Glossary
Explore the published reference collection.
- Cap layer
- An outer layer modifying surface behaviour. Coverage, thickness and adhesion matter; a cap does not make cut ends or joints automatically waterproof. Names and abbreviations: capping; protective shell. Related terms: Co-extrusion; Hollow profile; Composite cladding. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Co-extrusion
- Simultaneous formation of multiple material streams into a layered product. A cap can differ chemically from the composite core. Names and abbreviations: multilayer extrusion. Related terms: Extrusion; Cap layer; Composite decking. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Compound
- A prepared blend of polymer, filler and additives. It may be supplied as pellets or processed directly into a product. Names and abbreviations: composite compound. Related terms: Wood–plastic composite (WPC); Reinforcement. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Coupling agent
- An additive promoting interaction between dissimilar constituents. A compatibiliser has a related role, but the terms are not exact synonyms in every chemistry. Names and abbreviations: interface modifier. Related terms: Polyvinyl chloride (PVC); UV stabiliser. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Creep
- Progressive deformation under sustained load. Temperature, stress and time affect it, so short bending tests cannot establish long-term deflection alone. Names and abbreviations: time-dependent deformation. Related terms: Joist spacing; Elastic modulus; Service life. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Extrusion
- Continuous shaping of a heated compound through a die. Cooling and calibration help establish the profile dimensions. Names and abbreviations: profile extrusion. Related terms: Co-extrusion; Extrusion die; Calibration. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Filler
- A dispersed ingredient modifying cost, processing or properties. A filler may improve stiffness without improving every strength or impact measure. Names and abbreviations: particulate filler. Related terms: Wood–plastic composite (WPC); Reinforcement. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- High-density polyethylene (HDPE)
- A polyethylene grade family used as a WPC matrix. Resin grade, melt flow and additives matter more than the acronym alone. Names and abbreviations: PE-HD. Related terms: Polyethylene (PE); Low-density polyethylene (LDPE); Recycled HDPE (rHDPE). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Matrix
- The continuous phase surrounding the filler or reinforcement. Its chemistry influences processing, temperature response and moisture behaviour. Names and abbreviations: polymer matrix; binder phase. Related terms: Wood–plastic composite (WPC); Reinforcement. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Water absorption
- Water taken up under specified exposure conditions. Duration, temperature and specimen geometry must accompany a reported percentage. Names and abbreviations: moisture uptake. Related terms: Thickness swelling; ISO 62; Drainage. Sources: https://research.fs.usda.gov/treesearch/68010, https://www.iso.org/standard/41672.html
- Natural fibre
- A fibre of natural origin; here mainly wood, flax, hemp or other plant material. Natural origin does not establish composite biodegradability. Names and abbreviations: plant fibre; natural fiber. Related terms: Wood flour; Polypropylene (PP). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Natural fibre composite (NFC)
- A composite containing natural fibres or particles in a matrix. NFC is broader than WPC: flax, hemp and agricultural fibres need not contain wood. Names and abbreviations: plant-fibre composite. Related terms: Wood–plastic composite (WPC); Natural fibre; Biodegradability. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Polypropylene (PP)
- A thermoplastic matrix used in natural-fibre composites. Processing conditions and compatibility with fibres must suit the selected grade. Names and abbreviations: polypropene. Related terms: Maleated polypropylene (MAPP); Coupling agent; High-density polyethylene (HDPE). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Product specification
- A document defining required characteristics and intended scope. It should identify the product, applicable tests, acceptance criteria and installation conditions. Names and abbreviations: technical specification. Related terms: Bio-based; ISO 16616. Sources: https://landingpage.bsigroup.com/LandingPage/Series?UPI=BS+EN+15534
- Polyvinyl chloride (PVC)
- A thermoplastic used in some composite profiles. WPC does not mean PVC-free; confirm the actual formulation rather than assuming resin identity. Names and abbreviations: vinyl polymer. Related terms: Wood–plastic composite (WPC); Thermoplastic; Polyethylene (PE). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Recyclability
- The ability to collect and process material into a useful output. Actual acceptance, sorting and local facilities must also exist. Names and abbreviations: recycling potential. Related terms: Recycled content; Bio-based; Biodegradability. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Recycled content
- The proportion of recycled material on a declared basis. Distinguish whole-product percentages from percentages referring only to the polymer fraction. Names and abbreviations: recycled material share. Related terms: Recycled HDPE (rHDPE); Recyclability; Bio-based. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Reinforcement
- A constituent used to improve selected mechanical properties. Fibre length, orientation and bonding determine how effectively loads are transferred. Names and abbreviations: reinforcing fibre. Related terms: Wood–plastic composite (WPC). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Service life
- The period a product meets stated requirements in its actual exposure and maintenance conditions. It is not identical to a warranty period. Names and abbreviations: useful life. Related terms: Warranty; Maintenance; Weathering. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Test method
- A defined way to measure a property. Naming a method does not provide a result or prove a product passed a requirement. Names and abbreviations: testing procedure. Related terms: Bio-based; ISO 16616. Sources: https://landingpage.bsigroup.com/LandingPage/Series?UPI=BS+EN+15534, https://www.iso.org/standard/57285.html
- Thermoplastic
- A polymer that softens on heating and hardens on cooling. Repeated processing can degrade it; remeltability does not guarantee practical recyclability. Names and abbreviations: melt-processable polymer. Related terms: Wood–plastic composite (WPC); Reinforcement. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Thermoset
- A polymer system forming a cured network that cannot simply be remelted. Phenolic and epoxy systems differ from ordinary thermoplastic decking. Names and abbreviations: crosslinked resin. Related terms: Wood–plastic composite (WPC); Reinforcement. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Traceability
- Connecting delivered products to manufacturing, raw-material and quality records. A supplier name alone is not complete batch evidence. Names and abbreviations: batch traceability. Related terms: Batch; Recycled content; Product specification. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Weathering
- Changes caused by sunlight, moisture and temperature exposure. Colour retention and retained mechanical performance are different outcomes. Names and abbreviations: outdoor ageing. Related terms: Tensile strength; Slip resistance. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Wood flour
- Finely ground wood particles. Particle-size distribution, species and moisture matter; wood flour is not identical to long reinforcing fibres. Names and abbreviations: wood powder. Related terms: Polypropylene (PP). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Wood–plastic composite (WPC)
- A material combining wood particles or fibres with a polymer. The formulation and finished profile determine performance; WPC is not a quality grade. Names and abbreviations: wood-polymer composite; woodfiber-plastic composite. Related terms: Natural fibre composite (NFC); Wood–thermoplastic composite (WTC); Matrix. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Antioxidant
- An additive limiting oxidative damage during processing or use. Its effectiveness depends on chemistry, concentration and exposure. Names and abbreviations: oxidation stabiliser. Related terms: Drying. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Aspect ratio
- The ratio of particle or fibre length to its transverse dimension. Higher values can assist reinforcement, but dispersion and processing damage also matter. Names and abbreviations: length-to-diameter ratio. Related terms: Wood flour; Polypropylene (PP). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- ASTM D7032
- A performance-rating specification covering composite and plastic-lumber deck boards, stair treads, guards and handrails. It is not a European approval. Names and abbreviations: composite decking performance ratings. Related terms: Composite decking; Joist spacing; Test method. Sources: https://store.astm.org/d7032-21.html
- Batch
- A traceable production quantity sharing defined manufacturing conditions. Batch identification helps connect deliveries, samples and quality records. Names and abbreviations: production lot. Related terms: Bio-based; ISO 16616. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://www.iso.org/standard/37456.html
- Bio-based
- Made wholly or partly from biological feedstock. Bio-based content does not mean biodegradable, compostable or automatically lower impact. Names and abbreviations: biomass-derived. Related terms: Recycled content; Biodegradability; Life cycle assessment (LCA). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://www.iso.org/standard/37456.html
- Biodegradability
- Breakdown through biological activity under specified conditions. Results depend on environment and time; wood content does not make ordinary WPC compostable. Names and abbreviations: biological degradation. Related terms: Bio-based; Recyclability; Life cycle assessment (LCA). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://www.iso.org/standard/37456.html
- Calibration
- Controlling an extruded profile's shape and dimensions while it cools. Poor control can produce distortion or inconsistent wall thickness. Names and abbreviations: profile sizing. Related terms: Extrusion die; Composite cladding. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Carbon footprint
- Greenhouse-gas emissions expressed as carbon-dioxide equivalents within a defined boundary. Transport distance alone does not establish the total product footprint. Names and abbreviations: greenhouse-gas footprint. Related terms: Life cycle assessment (LCA); Environmental product declaration (EPD); Recycled content. Sources: https://www.iso.org/standard/37456.html
- Cellulose
- A structural polysaccharide in plant cell walls. Its hydroxyl-rich surface contributes to water affinity and challenges bonding with nonpolar polymers. Names and abbreviations: cellulosic fibre component. Related terms: Wood flour; Polypropylene (PP). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Composite cladding
- Profiles used as an exterior covering. Fire, wind, fixing and ventilation requirements belong to the complete façade system. Names and abbreviations: WPC cladding; façade profiles. Related terms: EN 15534-5; Ventilation; EN 13501-1. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Composite decking
- Boards intended as an outdoor walking surface over supports. Verify span, slip behaviour, fastening and exposure for the exact product. Names and abbreviations: WPC decking; composite deck boards. Related terms: Joist; Hidden fastener; Joist spacing. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Composite material
- A material made from distinguishable constituents working together. “Composite” alone does not identify the resin, reinforcement or suitable application. Names and abbreviations: composite. Related terms: Wood–plastic composite (WPC); Reinforcement. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Composite fencing
- Composite elements used in fences or screens. Posts, foundations and connections must resist the site's wind loads. Names and abbreviations: WPC fencing; privacy screen boards. Related terms: EN 15534-6; Tongue and groove; Traceability. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Compounding
- Mixing constituents to distribute filler and additives through a polymer. Dispersion must be balanced against heat exposure and fibre damage. Names and abbreviations: melt blending. Related terms: Antioxidant; Drying. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Compression moulding
- Shaping material under pressure in a mould, often with heat. It differs from continuous extrusion and can suit panels or formed parts. Names and abbreviations: compression molding. Related terms: Antioxidant; Drying. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Density
- Mass divided by volume using a stated measurement basis. Profile geometry and internal voids complicate comparisons with material density. Names and abbreviations: mass per unit volume. Related terms: Recyclability. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Drainage
- Providing a route for water to leave an assembly. Board joints alone do not replace drainage design beneath a deck. Names and abbreviations: water management. Related terms: Ventilation; Water absorption; Maintenance. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Drying
- Reducing moisture before processing. The required target depends on feedstock, polymer and equipment; one universal drying schedule is inappropriate. Names and abbreviations: feedstock drying. Related terms: Antioxidant. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Differential scanning calorimetry (DSC)
- A method measuring heat-flow differences during heating or cooling. It can investigate polymer melting and crystallisation. Names and abbreviations: thermal analysis. Related terms: Density; Recyclability. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Elastic modulus
- The relationship between stress and strain in a specified range. Stiffness differs from strength; tensile and flexural moduli are not interchangeable. Names and abbreviations: stiffness modulus; MOE. Related terms: Tensile strength; Flexural strength; Creep. Sources: https://www.iso.org/standard/70513.html, https://www.iso.org/standard/527-1
- Embossing
- Creating a pattern on a surface, often to imitate grain. Visual texture alone does not prove wet slip resistance. Names and abbreviations: surface texturing. Related terms: Extrusion die; Composite cladding. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- EN 13501-1
- A classification standard using reaction-to-fire test data. Classification applies within its documented scope, not automatically to every assembly or profile. Names and abbreviations: reaction-to-fire classification. Related terms: Flame retardant; Composite cladding; Test method. Sources: https://knowledge.bsigroup.com/products/fire-classification-of-construction-products-and-building-elements-classification-using-data-from-reaction-to-fire-tests
- EN 15534-4
- The decking product part of EN 15534. Its scope is not automatically interchangeable with the cladding or fencing parts. Names and abbreviations: decking profiles and tiles. Related terms: EN 15534; Composite decking; ISO 16616. Sources: https://landingpage.bsigroup.com/LandingPage/Series?UPI=BS+EN+15534
- EN 15534-5
- The cladding product part of EN 15534. A decking result does not establish compliance for a façade application. Names and abbreviations: cladding profiles and tiles. Related terms: EN 15534; Composite cladding; EN 13501-1. Sources: https://landingpage.bsigroup.com/LandingPage/Series?UPI=BS+EN+15534
- EN 15534-6
- The fencing product part of EN 15534. Product requirements do not replace site-specific design of posts and foundations. Names and abbreviations: fencing profiles and elements. Related terms: EN 15534; Composite fencing; Product specification. Sources: https://landingpage.bsigroup.com/LandingPage/Series?UPI=BS+EN+15534
- EN 15534
- A multi-part series for cellulose-based materials combined with thermoplastics. Select the relevant test or product part; the number alone is insufficient. Names and abbreviations: European WPC/NFC standards series. Related terms: EN 15534-4; EN 15534-5; EN 15534-6. Sources: https://landingpage.bsigroup.com/LandingPage/Series?UPI=BS+EN+15534
- EN 15804
- Core rules for construction-product environmental declarations. Meaningful comparisons require compatible rules, declared units, modules and scenarios. Names and abbreviations: construction-product EPD rules. Related terms: Life cycle assessment (LCA); Environmental product declaration (EPD); Carbon footprint. Sources: https://www.environdec.com/pcr-library/pcr_6b99d07c-4b75-4763-4485-08dd775d2e49
- Environmental product declaration (EPD)
- A structured declaration of environmental data based on defined rules. An EPD is not by itself an environmental superiority label. Names and abbreviations: environmental declaration. Related terms: Life cycle assessment (LCA); Carbon footprint; EN 15804. Sources: https://www.environdec.com/pcr-library/pcr_6b99d07c-4b75-4763-4485-08dd775d2e49, https://www.environdec.com/news/comms-guidance-empco
- Expansion gap
- A designed clearance for dimensional movement. Required gaps depend on board length, temperature, material and the installation system. Names and abbreviations: movement allowance. Related terms: Thermal expansion; Tongue and groove; Joist spacing. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Extrusion die
- The tool opening that shapes an extrudate. Die geometry must account for flow, swelling, cooling and dimensional tolerances. Names and abbreviations: profile die. Related terms: Composite cladding. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Fascia board
- A finishing board covering deck edges or risers. Decorative fascia is not automatically suitable as a load-bearing tread or joist. Names and abbreviations: edge trim; finishing board. Related terms: Joist; Composite decking; Tongue and groove. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Fused filament fabrication (FFF)
- Layer-by-layer printing with heated filament. Wood-filled feedstocks require suitable moisture control, nozzle selection and extrusion settings. Names and abbreviations: fused deposition modelling; FDM. Related terms: Extrusion die; Composite cladding. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Flame retardant
- An ingredient intended to modify burning behaviour. Its presence does not establish a product fire classification without appropriate testing. Names and abbreviations: fire-retardant additive. Related terms: Antioxidant; Drying. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Flexural strength
- A strength measure obtained in bending under a stated method. Compare geometry and conditioning before comparing numerical values. Names and abbreviations: bending strength; MOR. Related terms: Tensile strength; Elastic modulus; ISO 178. Sources: https://www.iso.org/standard/70513.html
- Fourier-transform infrared spectroscopy (FTIR)
- A technique probing molecular vibrations through infrared absorption. It helps identify chemical groups; interpretation requires suitable controls. Names and abbreviations: infrared spectroscopy. Related terms: Density; Recyclability. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Hollow profile
- A profile with internal chambers. Wall thickness, rib arrangement, impact resistance and end detailing affect its suitability. Names and abbreviations: hollow-core board. Related terms: Solid profile; Composite decking; Fascia board. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Impact strength
- Resistance measured under a specified impact test. Notched and unnotched results, and different test methods, are not interchangeable. Names and abbreviations: impact resistance. Related terms: Tensile strength; Slip resistance. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Injection moulding
- Shaping a molten compound by injecting it into a mould. Flow, fibre orientation and cooling influence the finished component. Names and abbreviations: injection molding. Related terms: Antioxidant; Drying. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- ISO 1133-1
- A standard covering melt mass-flow and volume-flow measurement. Temperature and applied load are essential parts of a reported result. Names and abbreviations: thermoplastic melt-flow testing. Related terms: Melt flow rate (MFR); High-density polyethylene (HDPE); Compounding. Sources: https://www.iso.org/standard/83905.html
- ISO 16616
- A standard addressing test methods for exterior natural-fibre composite deck boards. A test report must identify the applicable edition and product. Names and abbreviations: NFC deck-board test methods. Related terms: EN 15534; Composite decking; Test method. Sources: https://www.iso.org/standard/57285.html
- ISO 178
- A method for investigating flexural properties of plastics. Use the stated edition, specimen and conditions; a draft revision is not a published replacement. Names and abbreviations: plastics flexural testing. Related terms: Flexural strength; Elastic modulus; Test method. Sources: https://www.iso.org/standard/70513.html
- ISO 527
- A series addressing tensile properties of plastics. Select the appropriate part and specimen conditions for the material being evaluated. Names and abbreviations: plastics tensile testing. Related terms: Tensile strength; Elastic modulus; Test method. Sources: https://www.iso.org/standard/527-1
- ISO 62
- A standard for determining water absorption under controlled conditions. It is not a blanket declaration that a finished assembly is waterproof. Names and abbreviations: plastics water absorption. Related terms: Water absorption; Thickness swelling; Test method. Sources: https://www.iso.org/standard/41672.html
- Joist
- A member supporting decking boards. Some WPC joists require continuous support and must not be assumed to be spanning structural beams. Names and abbreviations: deck support member. Related terms: Joist spacing; Composite decking; Creep. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Joist spacing
- The distance between support centre lines. Approved values depend on board geometry, loads, temperature and application, including stairs. Names and abbreviations: support centres; centre-to-centre spacing. Related terms: Joist; Flexural strength; Creep. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Life cycle assessment (LCA)
- Assessment of environmental impacts across a defined system. Comparisons require compatible functions, boundaries, assumptions and service-life scenarios. Names and abbreviations: life-cycle analysis. Related terms: Environmental product declaration (EPD); Carbon footprint; EN 15804. Sources: https://www.iso.org/standard/37456.html
- Low-density polyethylene (LDPE)
- A more highly branched polyethylene family. Its properties differ from HDPE; changing resin can alter composite stiffness and processing. Names and abbreviations: PE-LD. Related terms: Polyvinyl chloride (PVC); UV stabiliser. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Lignin
- A complex plant polymer associated with cell-wall rigidity. Its behaviour differs from cellulose and influences wood chemistry and weathering. Names and abbreviations: wood lignin. Related terms: Wood flour; Polypropylene (PP). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Lubricant
- An additive reducing friction during processing. Excess or unsuitable lubricant can affect bonding, surface quality and mechanical properties. Names and abbreviations: processing lubricant. Related terms: Polyvinyl chloride (PVC); UV stabiliser. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Maintenance
- Cleaning and inspection needed to retain function and appearance. Low maintenance does not mean no cleaning or no inspection. Names and abbreviations: deck care; routine cleaning. Related terms: Drainage; Weathering; Service life. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Maleated polyethylene (MAPE)
- A functionalised polyethylene used as a compatibiliser in suitable PE-based composites. It is not automatically interchangeable with MAPP. Names and abbreviations: maleic-anhydride-grafted polyethylene. Related terms: Maleated polypropylene (MAPP); Coupling agent; High-density polyethylene (HDPE). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Maleated polypropylene (MAPP)
- A functionalised polypropylene used to improve fibre–matrix compatibility in suitable systems. Dosage and effectiveness depend on the formulation. Names and abbreviations: maleic-anhydride-grafted polypropylene. Related terms: Maleated polyethylene (MAPE); Coupling agent; Polypropylene (PP). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Melt flow rate (MFR)
- Mass passing through a specified die over time at stated temperature and load. Values measured under different conditions are not directly comparable. Names and abbreviations: melt flow index; MFI. Related terms: ISO 1133-1; High-density polyethylene (HDPE); Compounding. Sources: https://www.iso.org/standard/83905.html
- Moisture content
- The amount of water in a material on a stated wet or dry mass basis. Excess moisture can cause processing defects. Names and abbreviations: feedstock moisture. Related terms: Wood flour; Polypropylene (PP). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Polyethylene (PE)
- A family of thermoplastics including HDPE and LDPE. Different grades have different density, flow and mechanical behaviour. Names and abbreviations: polythene. Related terms: Polyvinyl chloride (PVC); UV stabiliser. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Pigment
- A dispersed colouring material. Colour influences appearance and can affect solar heating; a dark surface is not necessarily cool underfoot. Names and abbreviations: colourant. Related terms: Antioxidant; Drying. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Polylactic acid (PLA)
- A polyester often made from renewable feedstocks. Bio-based origin does not establish outdoor durability or degradation under ordinary garden conditions. Names and abbreviations: polylactide. Related terms: Polyvinyl chloride (PVC); UV stabiliser. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Recycled HDPE (rHDPE)
- HDPE recovered for reuse. Contamination, previous ageing and batch consistency must be controlled when producing repeatable WPC formulations. Names and abbreviations: reprocessed high-density polyethylene. Related terms: Polyvinyl chloride (PVC); UV stabiliser. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Rice husk
- The protective covering of rice grains, usable as a composite filler after preparation. Its silica content distinguishes it from ordinary wood flour. Names and abbreviations: rice hull. Related terms: Wood flour; Polypropylene (PP). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Sanding
- Removing surface material to change finish or texture. Sanding a capped board can damage its protective layer; follow product instructions. Names and abbreviations: surface abrasion. Related terms: Extrusion die; Composite cladding. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Scanning electron microscopy (SEM)
- Imaging that reveals fine surface or fracture features. Images can support interface analysis but do not alone quantify bond strength. Names and abbreviations: electron microscopy. Related terms: Density; Recyclability. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Slip resistance
- Resistance to slipping under specified test conditions. Wetness, contamination, footwear and surface wear matter; grooves alone are not proof. Names and abbreviations: slip performance. Related terms: Composite decking; Maintenance; Test method. Sources: https://www.hse.gov.uk/pubns/geis2.htm
- Solid profile
- A profile without intentional longitudinal hollow chambers. Solid geometry alone does not establish structural capacity or a permitted support span. Names and abbreviations: solid composite board. Related terms: Hollow profile; Composite decking; Joist spacing. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Tensile strength
- Stress sustained during a defined pulling test. Specimen preparation, direction and conditioning affect results; it is not a deck span rating. Names and abbreviations: strength in tension. Related terms: Flexural strength; Elastic modulus; ISO 527. Sources: https://www.iso.org/standard/527-1
- Thermogravimetric analysis (TGA)
- A method measuring mass changes during a controlled temperature programme. It helps study decomposition but does not directly determine service life. Names and abbreviations: thermal mass-loss analysis. Related terms: Density; Recyclability. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Thermal expansion
- Dimensional change as temperature changes. The relevant coefficient, board length and temperature range inform movement allowances. Names and abbreviations: temperature-driven movement. Related terms: Expansion gap; Thickness swelling; Weathering. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Thickness swelling
- Increase in thickness following moisture exposure. It differs from mass-based water absorption and should be reported separately. Names and abbreviations: moisture-induced swelling. Related terms: Water absorption; Thermal expansion; Weathering. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Tongue and groove
- A joint with a projecting tongue fitting a groove. A closed-looking joint is not proof of a watertight assembly. Names and abbreviations: T&G; interlocking profile. Related terms: Hidden fastener; Expansion gap; Drainage. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- UV stabiliser
- An additive intended to reduce light-driven deterioration. It does not make every colour or exposed wood component permanently unchanged. Names and abbreviations: light stabiliser. Related terms: Polyvinyl chloride (PVC). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Ventilation
- Air exchange around an assembly to assist drying. Necessary clearances depend on the construction; an enclosed damp cavity can retain moisture. Names and abbreviations: under-deck airflow. Related terms: Drainage; Water absorption; Maintenance. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf
- Warranty
- A supplier's stated contractual remedy with conditions and exclusions. Its duration is not a measured physical lifespan. Names and abbreviations: commercial guarantee. Related terms: Service life; Product specification; Traceability. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/68010
- Wood fibre
- An elongated wood-derived component. Fibre damage during compounding can reduce its aspect ratio and alter reinforcement efficiency. Names and abbreviations: wood fiber. Related terms: Wood flour; Polypropylene (PP). Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721
- Wood–thermoplastic composite (WTC)
- A wood-filled composite with a thermoplastic matrix that softens when heated. The name excludes cured thermoset systems. Names and abbreviations: wood thermoplastic. Related terms: Wood–plastic composite (WPC); Thermoplastic; Thermoset. Sources: https://research.fs.usda.gov/download/treesearch/42497.pdf, https://research.fs.usda.gov/treesearch/36721