Base Properties of Plasticized Vinyls
Standard PVC materials are rigid and inflexible, yet PVC is commonly used in a wide array of applications that require a flexible substrate. This flexibility is achieved via the addition of plasticizers, however this flexibility comes at the expense of other physical properties including flame and smoke generation.
TempRite® Engineered Polymers CPVC can replace PVC – either in part or in whole – for plasticized applications and deliver a significant improvement in a wide array of properties.
Plasticizer Reduction
While plasticizer absorption in CPVC occurs at a higher temperature than PVC, the viscosity of plasticized CPVC is lower than that of plasticized PVC. This means that the same degree of ductility can be achieved in plasticized CPVC using less plasticizer.
In a formulation using 60phr Dioctyl phthalate (DOP) plasticizer, PVC achieved a Shore A Hardness of 71. Replacing just 10% of the PVC with CPVC reduced the hardness to 68 and a 40% replacement led to a Shore A Hardness of just 62.
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Depending on the requirements of the application, the combination of additional CPVC loading and reduced plasticizer usage can achieve the same level of plasticization at a lower cost, while maintaining or improving other material properties.
Flame and Smoke Performance
The introduction of plasticizers significantly reduces the limiting oxygen index of a vinyl material. While base PVC has an LOI of about 45, plasticizers can reduce that level as much as half, often requiring the use of additional flame and smoke additives to achieve minimum required flame and smoke resistance.
Base CPVC on the other hand, has a starting LOI of 60 which is 33% higher than base PVC. While the addition of plasticizer will reduce that LOI, the combined impact of a higher starting point and the ability to achieve comparable performance with less plasticizer leads to far superior flame and smoke properties.
This impact will vary depending on whether pure CPVC is used or a CPVC/PVC blend is employed and with the type and amount of plasticizer, but smoke density can easily be reduced by 30% or more with the use of TempRite CPVC in plasticized applications.
Printability
One popular application of plasticized PVC is for flexible calendared sheets used as printing substrates for wall coverings, hanging signs and numerous other printed applications. The use of TempRite CPVC in these applications can significantly improve printability.
In printing test of substrates ranging from 100% PVC to 100% TempRite CPVC, using inks with variable surface tensions shows that printability increases consistently as the CPVC content increases.
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Other Property Improvement
In addition to improving flame and smoke properties and printability of plasticized PVC, TempRite CPVC can also improve both gas permeability and weldability.
In testing on a 1.5mm thick sheet formulated with 50phr DOP, the use of a 50/50 CPVC/PVC blend reduced gas permeability by 21-60%:
- Oxygen: 30% reduction
- Carbon dioxide: 21% reduction
- Nitrogen: 60% reduction
- Water vapor: 36% reduction
With respect to weldability, flexible PVC that has been welded for less than 0.5 seconds will fail via weld delamination when subjected to a dynamometric tension test. Introducing just 50% TempRite CPVC will reduce the welding time to 0.3 seconds.
The use of CPVC in plasticized vinyl applications is relatively new and there is plenty of opportunity to explore how TempRite CPVC can improve your products and processes. Contact us today to learn more about how we can help.