As I walk through my neighborhood, I see more and more homeowners installing vinyl fencing around their property. It seems to contrast well with their home’s architecture and their landscaping. However, vinyl fencing looks like a plastic material, what is it actually made of and will it hold up over time?
Vinyl Fencing is made out of polyvinyl chloride—PVC. It is commonly manufactured with two dually enhanced layers that are co-extruded with the addition of UV inhibitors, impact resistant polymers and strengthening acrylic modifiers to make an incredibly durable material highly resistant to UV radiation and harsh outdoor exposure.
The end result from the complex manufacturing process of vinyl fencing yields a product that is extremely durable, 5 times stronger than wood, highly resistant to UV rays, color retentive, and impervious to rot and decay. It is a material that will last for decades. In fact, most vinyl fence manufacturers guarantee their product with a limited lifetime warranty.
Knowing more about its composition and construction can help you understand why more and more people are choosing vinyl as the solution for their privacy, decorative, and property perimeter fencing needs.
What is the Difference Between Vinyl Fencing and Regular PVC?
The PVC material used for PVC plumbing is quite different from the PVC used for vinyl fencing. PVC plumbing is usually installed in a protected and enclosed environment. Left alone, secured and unexposed, PVC plumbing can function reliably for a very very long time.
However, if PVC plumbing is left to UV exposure and drastic change in temperatures, the material can quickly degrade, yellow, and become brittle.
On the other hand, a vinyl fence is consistently under intense UV exposure and drastic changes in temperature. It is thwarted by wind and rain and buffeted by other outdoor related percussions.
Subsequently, the PVC resin for vinyl fencing must be significantly enhanced to meet the specific conditions of outdoor exposure. It needs to be able to resist UV rays from the sun to prevent it from discoloring and deteriorating. It needs to be able to expand and contract with temperature change.
Vinyl fencing needs to be flexible to absorb the variable assailment of high winds. It also needs to be resistant to a barrage of outdoor related impacts such as, getting pegged by soccer balls, small rocks from mowing, etc. And finally, it needs to be sturdy enough to carry the specific load of the fence.
With all of this in mind, additional additives are included into the fabrication process of the vinyl fencing materials to make them more durable and resilient. The reinforced PVC resin is either mono extruded (injected into a single solid layer of combined materials), or co-extruded—creating an inner layer (substrate) and an outer layer (capstock) to concentrate the fortifying ingredients where they are needed most.
What is Vinyl Fence Co-Extrusion?
Most vinyl fence materials are co-extruded. The process involves melding together, under extreme high temperatures, the substrate and capstock resins. The heated material is either injected or extruded into, or through, specific molds that contour the material into posts, pickets and rails.
The substrate is typically composed of PVC filler and other compounds that add strength to the material. The capstock is concentrated with UV inhibitors, pigments, acrylic modifiers and impact resistant polymers.
The Secret Ingredients of Vinyl Fencing
PVC
PVC, or polyvinyl chloride, is one of the most common building products used in construction. Some of its applications include indoor plumbing, flooring, exterior siding, windows, outdoor irrigation, and fencing.
The chlorination of ethylene (a natural occurring hydrocarbon) and pyrolysis (the heating of organic materials) produces a vinyl chloride monomer (VCM). PVC is produced through the polymerization (molecular bonding) of VCM and other chemicals, particles and ingredients to create a high-strength thermoplastic. Source: https://omnexus.specialchem.com/selection-guide/polyvinyl-chloride-pvc-plastic#Manufacture
Vinyl Fence PVC Would be Worthless Without UV Inhibitors, Impact Polymers and Acrylic Modifiers
UV Inhibitors
When unfortified, PVC is exposed to UV radiation where photons in the PVC material can become “excited” and create free radicals that may cause splitting, cracking and the breakdown of the PVC material.
In order to resist UV radiation and the degradation of vinyl fencing materials, UV inhibitor polymers are added to the PVC resin. Source: What does UV radiation actually do to degrade plastics?
There are various types of UV inhibitors that may be incorporated into the manufacturing of vinyl fencing:
- Absorbers: absorb UV light and disperse it as heat or harmless ultraviolet radiation
- Hindered Amine Light Stabilizers (HALS): hinder photodegradation by trapping free radicals caused by photo-oxidation
- Quenchers: prevent the creation of free radicals by returning UV induced excited particles to their ground level state. Source: Top 3 Plastic Additives for UV Stabalization
A Superior UV Inhibitor Used in Vinyl Fencing: TiO2
TiO2 (Titanium Dioxide): fine white titanium-based pigment powder used in the outer capstock of vinyl fence posts, rails, pickets and panels. It filters and scatters UV rays from the sun and reflects non UV light. Its UV repulsion qualities help the vinyl fence to maintain its bright color and to prevent yellowing and fading.
Impact Modifiers
Because a vinyl fence is subject to the thwarting of occasional pummeling winds and other outdoor related assailments, impact modifiers—rubberized particles and polymers—are added to the PVC resin to reduce PVC’s natural brittle tendency to chip and crack.
Impact polymer modifiers provide flex to the vinyl fencing material and the ability to absorb impact.
Impact modifiers have a similar function as rebar installed into concrete to prevent cement driveways and sidewalks from cracking. Examples include: Methacrylate butadiene styrene (MBS) terpolymer, Chlorinated polyethylene (CPE), Ethylene vinyl acetate copolymer (EVA), and Acrylonitrile butadiene styrene terpolymer (ABS) Source: Practical Guide to Polyvinyl Chloride.
Acrylic Modifiers
Another additive used to enhance vinyl fencing material is the acrylic modifier. Acrylic modifiers reduce outdoor weathering, increase strength, and improve resistance to damage from the heat in hot climate regions and the cold in cold weather regions. Examples: Acrylonitrile butadiene styrene terpolymer (ABS), Acrylate polymethacrylate copolymer (acrylic).
Acrylic modifiers are commonly used in paint to reduce brittleness and cracking—even with thin coat applications. Source: Paraloid Performance Additives for CASE.
Vinyl Fencing is a Lifetime Product
The quality of vinyl fencing materials has been progressing steadily because of continual technology enhancements and progressive standard industry practices. The culmination of the latest vinyl fence manufacturing techniques and composition yields a superior product that can durably withstand decades of harsh outdoor exposure while maintaining remarkable aesthetic qualities. Because vinyl fencing has such exceptional characteristics, manufacturers nearly always back their product with a limited lifetime warranty.