Meaning
Percentage light scattering represents the primary optical metric for evaluating wide-angle light diffusion through transparent plastic specimens. Within international testing protocols, astm d1003 haze quantifies the fraction of transmitted light that deviates by more than two point five degrees from the incident beam direction. This value isolates forward scattering caused by internal bulk clarity defects, such as crystallization nodules or microvoids, from surface roughness.
Measurement occurs on flat plaque samples using a spectrophotometer or hazemeter equipped with an integrating sphere.
Scattering Measurement
Instrumental configuration determines how scattered photons register at the detector during optical testing. Standard testing for astm d1003 haze relies on a sphere photometer that captures both total luminous transmittance and diffuse transmittance through an aperture port. Pigment agglomerates or immiscible polymer blends increase wide-angle forward scattering without necessarily causing complete opacity.
The resulting values assist processors in identifying contamination within virgin resin stocks.
Moulding Deviation
Thermal history during injection moulding alters the crystalline structure of semi-crystalline resins such as polypropylene or polyethylene terephthalate. Inadequate cooling rates in cold mould cavities permit excessive spherulite growth, which elevates astm d1003 haze far above the datasheet value of the base resin. Regrind additions introduce airborne dust or degraded polymer fragments that scatter light paths.
A moulder attempting to hold optical tolerances across a production run must control mould surface temperature and melt homogeneity.
Specification Boundary
Raw resin supplier datasheets record values measured under ideal plaque moulding conditions. Measured astm d1003 haze on a finished thin-walled part frequently exceeds supplier resin specifications due to flow orientation and part geometry. The test standard excludes narrow-angle scattering that affects image clarity, which requires distinct test protocols under standard optical methods.
