SINOPEC EVA 14F1

Ethylene-vinyl acetate copolymer grade SINOPEC EVA 14F1 is a high-pressure random copolymer supplied for blown-film and cast-film conversion. The grade identifier encodes two primary property separators: nominal vinyl acetate incorporation of 14 wt% and a film-extrusion melt mass-flow rate of 1.0 g/10 min when determined at 190°C under a 2.16 kg load by ISO 1133-1:2022. Density at 23°C is approximately 0.934 g/cm³ under ISO 1183-1, and the melting temperature is approximately 92°C by ISO 3146. The comonomer is incorporated as a random acetate side group along the polyethylene backbone; this reduces crystalline order relative to LDPE and imparts lower seal initiation temperature, improved low-temperature toughness, and higher surface polarity. The 1.0 g/10 min melt index positions the grade for heavy-gauge film rather than high-speed thin-gauge coating, because higher viscosity improves bubble stability but limits melt extensibility. The product is supplied as translucent pellets and is typically converted in heavy-duty sacks, frozen-food packaging, agricultural cover films, and coextruded sealant layers.

Before extrusion, incoming lots are commonly screened by Fourier-transform infrared spectroscopy for vinyl acetate content, melt flow rate by ISO 1133-1:2022, density by ISO 1183-1, and differential scanning calorimetry by ISO 11357-3 to confirm the melting endotherm. Batch-to-batch variation in vinyl acetate content of even ±1 wt% can shift seal initiation temperature and blocking behaviour; certificates of analysis should be retained for lot traceability. The acetate group is thermally labile, and storage above 40°C or prolonged exposure to UV can prematurely discolour pellets and generate acetic acid odour. Warehousing in a dry, shaded environment below 40°C is recommended. Moisture pick-up is generally low, but bags opened under high relative humidity can develop surface moisture; if bubble pinholes or surging occur, pre-drying at 60°C for 2–4 h in a desiccant or hot-air dryer is sufficient. Resin that has been allowed to reach >60% RH for extended periods should be dried before use to avoid hydrolysis at processing temperatures.

What temperature and rheological boundaries govern 14F1 conversion?

Melt processing of 14F1 is bounded primarily by the thermal stability of the acetate substituent, not by the crystalline melting point. Above approximately 230°C, deacetylation accelerates, releasing acetic acid, producing gel particles, brown specks, and acidic plate-out on die lips. The degradation products are corrosive to unplated carbon steel and can etch chrome-plated surfaces over sustained campaigns. On production-scale blown-film lines with single-screw extruders of L/D 30–36 and screw diameters from 45 mm to 90 mm, start-up profiles typically use feed-zone temperatures of 120–140°C, compression-zone temperatures increasing from 160°C to 200°C, and adapter/die zones at 200–215°C. Melt temperature measured at the adapter should remain below 220°C; excursions above 230°C for more than several minutes are associated with die-lip build-up and loss of melt strength. The low melt index of 1.0 g/10 min generates higher melt pressure than LDPE film grades of 1.8–2.5 g/10 min; extruders with shallow-grooved feed sections or undersized motors may exhibit screw-speed limits, feed starvation, or high melt-pressure alarms before the desired throughput is reached. Chrome-plated screws, bimetallic barrels, and stainless-steel die lips are standard corrosion-control measures.

Blown-film conditions are normally set with blow-up ratios between 2.0:1 and 3.0:1 and die gaps from 0.8 mm to 1.5 mm. Increasing the die gap raises melt residence time and output but can increase gel formation if melt temperatures are not adjusted. Frost-line height is maintained at a level that balances bubble stability and impact toughness; an excessively high frost line increases crystallinity and reduces dart drop impact. In cast-film and extrusion-lamination lines, melt temperatures can be held at 200–210°C, but draw resonance appears more readily than in LDPE because the lower melt strength of the acetate-containing chain reduces extensional viscosity. Die-lip deposits are controlled by periodic purging with a low-MFI LDPE or a commercial polyolefin purging compound. Shutdowns should avoid extended hold times above 180°C; stagnant melt degrades quickly in dead zones and discolours during restart.

Producer technical literature for SINOPEC EVA 14F1 reports the typical property envelope shown in Table 1. These values are indicative for incoming quality assessment and should not replace the supplier certificate of analysis for lot-specific release limits.

The property combination differentiates 14F1 from LDPE film grades of similar melt index: the vinyl acetate units depress Vicat softening and melting point, reduce tensile modulus, and increase elongation at break. The material retains more stiffness and crystallinity than conventional 18–28 wt% VA copolymers, making it easier to handle in thin films and less prone to blocking in warehouse rolls. The 1.0 g/10 min MFR is suited to heavy-gauge bubble stability; converters requiring higher output on narrow-gap film lines may blend with LDPE or LLDPE to raise melt flow and reduce backpressure.

Seal initiation, dart impact, and low-temperature behaviour compared with LDPE

Replacing a portion of LDPE with 14F1 in a blown-film sealant layer reduces the heat-seal initiation temperature by disrupting crystallinity at the sealing interface. Seal initiation is commonly evaluated by ASTM F88/F88M or by internal peel methods referenced to ISO 527-3; the absolute reduction depends on dwell time, seal bar temperature, and film gauge. In blown-film trials, addition of 20–30 wt% 14F1 to an LDPE-rich formulation lowers seal initiation by approximately 10–20°C relative to the LDPE control, although published data for this specific blend ratio is limited. The same structural change raises low-temperature puncture and dart impact resistance; films are tested under ISO 7765-1 or ASTM D1709 Method A/B. The resin’s vinyl acetate units also increase surface polarity, improving ink wetting and lamination bond without corona treatment, but water-vapour transmission rate increases relative to a nonpolar LDPE of comparable crystallinity.

Compared with a typical LDPE film grade, 14F1 has a lower Vicat softening temperature, lower tensile modulus, and higher elongation at break. These differences are attributable to reduced lamellar thickness and lower crystallinity. Processors should not use 14F1 as a direct drop-in for LDPE in high-stiffness applications; the stiffness loss must be compensated by blending with HDPE or by increasing film gauge. The melt index of 1.0 g/10 min is lower than many commodity LDPE film grades, which increases backpressure and may reduce throughput on older extruders, but improves bubble stability in thick-gauge sacks and heavy-duty shipping bags. In coextruded structures, 14F1 is frequently placed in the sealant or core layer, while LDPE or HDPE skins provide stiffness and blocking resistance.

Three-layer greenhouse and tunnel films using 14F1 as the core layer exploit the higher infrared absorption of vinyl acetate sequences to reduce nocturnal heat loss. The effect is concentration-dependent, gauge-dependent, and influenced by anti-drip and anti-dust surface treatments. Quantified infrared retention data for SINOPEC 14F1 in specific greenhouse structures is limited in publicly available technical literature, so validation should use thermal transmittance measurements under EN 673 or field comparison with an LDPE control of identical thickness and additive package. Light transmission in the photosynthetically active radiation range is evaluated with ASTM D1003 or ISO 13468-2; film haze is controlled by die temperature, frost-line height, and dispersion of inorganic anti-block. In agricultural film, incorporation of 14F1 improves low-temperature flexibility and impact resistance, reducing film failure at folds and attachment points during winter installation.

The same polarity that improves infrared retention also attracts dust and reduces light transmission over time in arid regions unless anti-dust or anti-fog additives are included. Additive packages containing strongly basic amines should be tested for compatibility because base-catalysed ester hydrolysis can increase deacetylation and shorten film life. Long-term aging is assessed by ISO 4892-2 accelerated weathering or multi-season field exposure; 14F1 requires UV stabilisation at loadings appropriate for the intended exposure period.

When higher-VA EVA grades are replaced with 14F1

Substitution of 14F1 for an 18–28 wt% VA copolymer in foam, hot-melt, or high-adhesion extrusion coating is not a direct replacement. The lower acetate fraction raises melt viscosity, raises Vicat softening, reduces adhesion to polar substrates, and limits foam expansion at low density. In extrusion coating on aluminium foil or paper, peel adhesion should be measured by ASTM F904 or a substrate-specific peel standard; 14F1 typically develops less fibre tear than an 18 wt% VA grade at equivalent coating weight. Where a seal initiation temperature below 85°C is required, 14F1 may be unsuitable without blending with a higher-VA copolymer or plastomer. Conversely, for blown-film packaging and agricultural applications, 14F1 offers better blocking resistance and faster line start-up than higher-VA grades because the lower acetate content reduces tack, lowers melt adhesion to metal surfaces, and widens the available processing window before deacetylation becomes significant. The material is also less dependent on slip and anti-block additives, although such additives remain necessary in thin-gauge films.

Regulatory compliance for food contact must be verified for the specific formulation and converting conditions. Ethylene-vinyl acetate copolymers may be evaluated under FDA 21 CFR 177.1350 or Regulation (EU) No 10/2011, with migration testing according to EN 1186 and the specific migration methods referenced in the applicable regulation. Industrial use is typically addressed through REACH registration and RoHS restricted-substance screening. No conclusion regarding global food-contact approval is implied by the property data alone.