| Código SH | 689888 |
| Nome Químico | álcool polivinílico |
| Fórmula Química | (C2H4O) n |
| Número Cas | 9002-89-5 |
| Estado Físico | Grânulos sólidos ou pó |
| Aparência | Branco a creme |
| Solubilidade Em água | Solúvel em água (preferível água quente; a solubilidade depende do grau de hidrólise) |
| Grau De Hidrólise | Normalmente 87-89% ou 98-99% |
| Densidade | 1.19 - 1.31 g /cm³ |
| Ponto De Fusão | 180 - 230 ° C |
| Temperatura De Transição Vítrea | 60 - 85 ° C |
| Resistência à Tracção | 20 - 60 MPa dependendo do grau e da preparação do filme |
| Alongamento Na Ruptura | 100 - 300% dependendo do plastificante e do teor de umidade |
| Biodegradabilidade | Biodegradável em condições aeróbias /anaeróbias via ação microbiana |
| Tempo De Biodegradação No Solo | Várias semanas a meses, dependendo das condições do solo, espessura do filme e grau de PVA |
| Produtos De Degradação | Dióxido de carbono e água (em biodegradação completa) |
| Não Toxicidade | Não tóxico e seguro para microrganismos e plantas do solo |
| Faixa De Espessura Do Filme | 10 - 50 micrômetros típicos para filmes de cobertura morta |
| Resistência Aos Raios Uv | Moderado; muitas vezes requer aditivos para exposição prolongada aos raios UV ao ar livre |
Como fábrica acreditada de Álcool polivinil (PVA) para mulch agrícola biodegradável, aplicamos protocolos de qualidade rigorosos – cada lote é submetido a testes rigorosos para garantir padrões de eficácia e segurança consistentes.
| Embalagem | Fornecido em sacos kraft resistentes à umidade de 20 kg com revestimento de polietileno, claramente rotulados para uso em mulch agrícola biodegradável. |
| Carga de contêiner (20' FCL) | 20' FCL carregado com álcool polivinil para amortecedor biodegradável, paletizado, seguro e protegido para transporte seguro. |
| Envio | Enviar grânulos de PVA em sacos selados, resistentes à umidade ou recipientes a granel. Evite a exposição prolongada à umidade para evitar a congelação. Armazenar em uma área fresca e seca, longe de fontes de ignição. Nenhuma classificação perigosa para o transporte, mas cargas seguras para evitar derramamentos. Garantir a compatibilidade com as cadeias de fornecimento de mercadorias e agrícolas padrão. |
| Armazenamento | Guarde o álcool polivinil (PVA) em uma área fresca, seca e bem ventilada, longe da luz solar direta e da umidade. Mantenha os recipientes bem selados para evitar hidratação ou aglomeração. Mantenha a temperatura ambiente abaixo de 30°C. Evite contato com oxidantes fortes. Garantir rotulagem adequada e condições secas para preservar a integridade do polímero e o desempenho de decomposição do amortecedor. |
| Prazo de validade | Prazo de validade: normalmente 2 anos quando armazenado em um lugar fresco e seco longe da umidade e da luz solar direta. |
Alcool polivinil (PVA) para mulch agrícola biodegradável preços competitivos que se encaixam no seu orçamento - termos flexíveis e orçamentos personalizados para cada encomenda.
Para amostras, preços ou mais informações, entre em contato conosco em +8615380400285 Ou envie para sales2@liwei-chem.com.
Responderemos a você o mais rápido possível.
Telefone: +8615380400285
E-mail: sales2@liwei-chem.com
Pagamento flexível, preço competitivo, serviço premium - Consulte-nos agora!
Commercial PVA resins supplied for biodegradable agricultural mulch are predominantly partially hydrolyzed grades with residual acetyl content between 2 mol% and 12 mol%. The model designation typically encodes the viscosity and hydrolysis level: a grade marked PVA 1788 denotes a 4 wt% aqueous solution viscosity of 17±1 mPa·s at 20°C and a hydrolysis degree of 88±1 mol%. Fully hydrolyzed grades such as 1799 (>99 mol%) are unsuitable as the primary matrix in soil-contact films because their dissolution temperature exceeds 95°C, retarding biodegradation initiation beyond practical field timeframes. In contrast, 0588 (viscosity 5.5 mPa·s) provides low-molecular-weight chains that yield rapid cold-water solubility but compromise blown-film bubble stability unless coextruded or blended with higher-viscosity fractions. Gelation in aqueous environments occurs above a critical concentration that shifts with the degree of hydrolysis: for PVA 1788 at 20°C, the gel point lies near 12 wt%, whereas for PVA 1799 the same transition appears below 6 wt%. These solubility characteristics govern the initial fragmentation of mulch film in moist soil, making grade selection a precise lever for controlling the lag phase before microbial assimilation.
The fundamental difference is the primary degradation trigger: PVA films undergo hydrolytic chain scission coupled with dissolution, independent of enzymatic hydrolysis as the rate-limiting step, whereas thermoplastic starch (TPS) blends rely on amylase activity and polylactic acid (PLA) on ester hydrolysis that is kinetically frozen below its glass transition of ≈58°C. Consequently, PVA mulch can begin fragmenting within 6–10 weeks after incorporation into soil at 15°C and 60% water-holding capacity, while PLA mulch remains dimensionally stable for multiple growing seasons under identical conditions. Polybutylene adipate-co-terephthalate (PBAT), often marketed as the flexible component in biodegradable mulches, exhibits a comparable degradation onset to PVA but lacks the cold-water solubility pathway; its hydrolysis requires depolymerase activity and proceeds more slowly at temperatures below 20°C. A further distinction is the behaviour of PVA in anaerobic soil zones: the polyvinyl alcohol backbone can be metabolized by Pseudomonas and Sphingomonas species under both aerobic and nitrate-reducing conditions, a metabolic versatility not shared by PLA, which demands oxygenated compost environments to meet disintegration criteria under ISO 17088:2012. This positions PVA films as viable for no-till and minimum-till systems where soil contact is immediate and oxygen partial pressure at the soil–film interface fluctuates.
Mechanical property profiles also diverge sharply. PVA film conditioned at 50% RH exhibits a tensile strength of 30–45 MPa and elongation at break of 150–250% (ASTM D882), comparable to PBAT but substantially more ductile than pure PLA. Starch-blend films, even with plasticiser contents up to 25 wt%, rarely exceed 12 MPa tensile strength and suffer embrittlement at relative humidity below 30%. This means PVA mulch withstands mechanical laying on undulating terrain without pre-wetting, a common failure mode for starch-based sheets at planting speeds above 6 km/h on commercial tractor-drawn mulch layers (e.g., Forigo Roter Italia RM series). The critical difference for growers, however, is the absence of persistent microplastic residues: PVA’s water-soluble fraction ensures that film fragments smaller than 2 mm are dissolved or metabolised rather than accumulating as secondary microplastics, a documented concern with PBAT and PLA fragments in soils where composting conditions are not met.
Processing PVA into agricultural mulch film demands strict control of melt temperature and shear history due to the polymer’s thermal sensitivity. On a single-screw extruder with a 24:1 L/D ratio and three-zone screw, the feed throat must be water-cooled to below 45°C to prevent pellet bridging, while the barrel profile is typically set from 180°C (zone 1) to 220°C (die). A melt temperature exceeding 235°C initiates acetic acid evolution and crosslinking, visible as gel specks in cast film. Twin-screw compounding lines (L/D 40:1, co-rotating, D = 25 mm) allow incorporation of plasticisers—glycerol at 12–18 phr or sorbitol at 8–12 phr—without the pre-gelation risk encountered in single-screw mixing. Glycerol at loadings above 18 phr reduces film tensile modulus below 200 MPa, which can cause sagging in raised-bed mulch applications where the film must span 80 cm bed widths unsupported. The blend must also exclude amine-based processing aids because residual amine groups promote imine condensation with any acetic acid liberated during melt processing, accelerating discolouration and chain branching that raises the melt viscosity index. In practice, blown film lines (BUR 2.5–3.0) running PVA mulch compound at 200–215°C achieve a gauge variation of ±12% over 1.2 m lay-flat width when equipped with dual-lip air rings and internal bubble cooling; without IBC, gauge uniformity deteriorates to ±25%, rendering the film unsuitable for precision mechanical laying. Pre-drying of PVA granules is mandatory at 80°C for 4 hours to achieve a moisture content below 0.3 wt%, as residual moisture at 0.8 wt% generates steam bubbles that nucleate pinholes during die exit, particularly when the melt strength is already compromised by low-viscosity grades.
Thickness selection for PVA agricultural mulch is not a routine specification but a balancing parameter directly linked to the crop cycle and soil microbial activity. Films at 12 µm thickness suppress weeds adequately for 4–6 weeks in spring vegetable production, whereas a 25 µm film maintains integrity for 10–14 weeks, necessary for indeterminate tomato crops. However, below 10 µm, mechanical laying tension at values above 40 N/m width induces irreversible necking, reducing coverage width by 15–20%. Degradation synchronisation—the point at which the film breaches in multiple locations allowing crop roots unimpeded soil access—must occur before the reproductive stage of the crop. For processing tomato planted in April in Mediterranean-climate soils (sandy loam, pH 6.8, 70% WHC), a 15 µm PVA film incorporating 5 wt% micronised cellulose fibre initiates fragmentation at 55 days after laying, which coincides with canopy closure; a 30 µm film of the same formulation delayed fragmentation to 95 days, forcing manual removal to prevent interference with harvest machinery. The thickness-degradation relationship is not linear: below the percolation threshold of plasticiser migration at 14 µm, dissolution front propagation accelerates due to capillary wicking along the fibre–matrix interface, doubling the dissolution rate compared to films thicker than 20 µm. This non-linearity demands site-specific calibration through burial trials mimicking local irrigation patterns.
Field trials conducted under the European Biodegradable Mulch Standard EN 17033:2018 require evidence of at least 90% film surface fragmentation within a defined time window relative to the cultivar’s phenology. PVA-based films meeting this standard typically achieve the criterion within 24 months of soil incorporation, whereas starch/PBAT blends can require 30–36 months in northern European soils where soil temperatures remain below 12°C for five months annually. The EN 17033 ecotoxicity tests (OECD 208 and 222) also impose limits on heavy metals and perfluorinated compounds; PVA resin producers supply grades that conform to the 200 mg/kg combined heavy metal threshold with a margin of at least 30%, provided tin-based residual catalysts from the saponification step are fully removed through methanol washing. A notable limitation: PVA mulch films cannot be used in fields where the soil is periodically submerged or has a permanent water table within 30 cm of the surface, because prolonged saturation converts the film into a gel layer that restricts gas exchange at the soil surface, causing elevated ethylene concentrations and root hypoxia in sensitive crops like cucurbits.
| Property | PVA (1788 grade) | PLA/starch blend | PBAT/starch blend | PE (conventional) |
|---|---|---|---|---|
| Film thickness range (µm) | 12–30 | 15–40 | 12–25 | 15–50 |
| Tensile strength MD (MPa, ASTM D882) | 30–45 | 18–25 | 22–35 | 25–35 |
| Soil fragmentation onset (days, 20°C, 60% WHC) | 45–80 | 60–120 (PLA phase persists>2 years) | 55–90 | No fragmentation |
| Disintegration 90% (months, EN 17033 bury) | 18–24 | 28–42 (dependent on PLA content) | 24–30 | Not applicable |
| Aerobic biodegradation (ISO 14855-1, % after 180 days) | 65–75% | 40–55% (PLA component incomplete) | 50–65% | 0 |
| Water vapour transmission rate (g/m²·day, 23°C, 85%RH) | 350–600 | 200–400 | 150–350 | 10–20 |
The high water vapour transmission of PVA mulch, typically 350–600 g/m²·day at 85% RH gradient, distinguishes it from polyolefin films and offers an agronomic advantage in regions prone to soil overheating. The evaporation cooling effect reduces mid-day soil temperatures by 3–5°C compared to black LDPE mulch, a parameter quantified using soil thermocouples at 10 cm depth in melon fields in Almería, Spain. This cooling can be counterproductive for heat-loving crops such as watermelon if soil temperature dips below 18°C at night; in such cases, a black masterbatch addition (carbon black 2.5 wt%) selectively attenuates the IR transparency of PVA and lifts the daytime soil temperature by 2°C without eliminating the transpiration pathway.
PVA mulch’s solubility creates a specific incompatible interface with calcium nitrate and ammonium polyphosphate liquid fertilisers applied through drip systems. When these saline solutions, with electrical conductivity exceeding 3.5 dS/m, contact the film edge near emitter outlets, the high ionic strength salt out the polymer, precipitating a low-molecular-weight fraction that blocks the orifice. Emitter clogging has been documented in field trials with Netafim DripNet PC 1.6 L/h emitters after 6–8 irrigation events containing 200 ppm NO₃⁻ as calcium nitrate at pH 5.8. The mitigation strategy requires either maintaining a minimum distance of 15 cm between emitter line and mulch edge or switching to potassium-based nitrogen sources that exhibit a lower salting-out effect. Additionally, the solubility of PVA is acutely sensitive to borate ions present in certain soil amendments; sodium tetraborate at concentrations as low as 50 mg/kg soil can crosslink dissolved PVA chains, forming a viscous hydrogel that reduces infiltration rates. This interaction is underreported in manufacturer specifications and constitutes a site-specific exclusion criterion for fields previously treated with boron-based microelement fertilisers.
Published data for PVA mulch film’s long-term ecotoxicity under repeated annual incorporation cycles—more than five consecutive seasons—is limited. The accumulation potential of the non-degraded fraction in soils with low microbial carbon biomass (<100 µg C/g soil) has not been characterised against the full test battery of ISO 15799:2019 (soil quality — guidance on the ecotoxicological characterization of soils and soil materials). This knowledge gap necessitates a conservative approach: for soils with organic matter below 1.5%, PVA mulch should be applied only in alternate years until field-aged residue mineralisation rates are validated via 14C-labelled polymer tracing studies that can distinguish respiratory CO₂ from the mulch versus background soil respiration.
