PHOTODEGRADABLE MASTERBATCHES

PHOTODEGRADABLE MASTERBATCHES



GUIDELINES AND RECOMMENDATIONS

Photodegradable means that a product is degradable when exposed to sunlight. This term is most commonly used on plastic products such as trash bags and agricultural mulch film, and is often accompanied by the phrase "Will break down into small pieces if left uncovered in sunlight."


1. INTRODUCTION
PHOTODEG additives are photosensitive materials, which initiate a chemical and physical breakdown of the film’s polymeric backbone upon exposure to ultraviolet radiation. Farmers have used mulch films for years at the beginning of most growing seasons. This could help in increasing yield and reducing weed growth. The film of choice is naturally PE.
At the end of each season, the films that are used present a serious disposal problem. Disposal methods such as burning and landfills are either costly or prohibited. With PHOTODEG, degradation is triggered when a threshold value of UV energy has been absorbed. As it degrades, the film becomes brittle and breaks apart, and ultimately is reduced to fine powder.
BOD (biological oxygen demand) studies have shown that this powder shows some biological activity.
PHOTODEG concentrates for polyethylene films can be used in a variety of applications including trash bags and mulch film. The additives used are sensitive to light, heat, and humidity, both before conversion and during storage of the finished part.

2. FREQUENTLY ASKED QUESTIONS

Q - What happens to the product when it degrades?
A - The degradable plastic in the product will first change color, become brittle, and will start to break apart. It will break into smaller and smaller pieces until it virtually becomes undetectable to the naked eye. As the process continues, the plastic molecules get smaller and smaller until microorganisms that occur naturally in the environment can ingest the changed plastic molecule. By-products to this process are CO2, H2O and Biomass (small molecular organic fragments).

Q – Will it leave harmful residues?
A - The degradation process leaves no plastic fragments or harmful residues.

Q - How long does it take for the films to begin the disintegration process?
A - Degradation will start within months of exposure to the sun. It largely depends on the geographical location, the amount of additives in the film, the film thickness, the type of resins used and other uncontrollable natural factors like weather.

Q - Will the films start to degrade before I use them?
A - The degradation process will only start if the product is exposed to Ultraviolet Light. However, do bear in mind to use the masterbatch within the lifespan advised.

Q – Shelf Life
A – Product should be used within 4 months of the production date as labeled on the container. The viability of the material can be determined via the melt index. If the melt index is significantly higher than when the material was produced, degradation has started and the product may not perform as expected.

Q - What is ultraviolet light?
A - Ultraviolet light is sunlight. If a degradable product were to be exposed to sunlight for 30 to 40 days, it would start to degrade.

Q - Can the degradation process be stopped once it starts?
A - No. The process might be slowed, but it cannot be stopped. It will continue to degrade in the dark.

Q – Which resins are PHOTODEG compatible with?
A – LDPE, LLDPE, M-LLDPE, HDPE, and PP

Q – Stocking Position
A – To minimize the effect of storage and transit, these products are made to order.

Q – What is the advisable Let Down Ratio?
A – Ampacet photodegradable chemistry is based on an additive that does migrate, if application involves sealing of printing, the end product should undergo testing. Factors that affect their performance include high humidity, temperature during storage, geographical location,

3. AMPACET’S RANGE

Application
Product Name
Product Code
% Active Additives
Type of Additives
Mulch Film (color not critical)
PHOTODEG 91
30091-K
5
Proprietary
Trash Bags
PHOTODEG 96
30996-K
5
Proprietary


4. TECHNICAL INFORMATION

Degradation Factors
There are many factors that influence the degradation period of the films using PHOTODEG. From the data collected below, PHOTODEG 91 shows that a lower light intensity is needed for the films to start degrading in Autumn compared to Summer (please refer to graphs 1 and 2 below). This could be due to light inclination or weather conditions. Therefore, it is imperative that the geographical location, season, thickness of film, resins used, duration and exposure conditions be verified before deciding on the LDR of PHOTODEG.

Resins Type
From the study conducted, degradation rate increases from LDPE <> LLPDE > LDPE. Catalysts act as vectors to the rate of degradation. Therefore, degradation rates differ according to the type of resins used.


Film Gauge
From the graphs below, thicker films degrade faster compared to thinner films incorporated with the same amount of PHOTODEG 91. This could be due to the mass-effect taking place.

Light Intensity
It generally takes 8-10 kLys for the degradation process to start. And once it is triggered, the process cannot be reversed. The time taken for the films to be exposed to 8-10 kLys of light intensity varies according geographical locations and seasons. Therefore, although the light intensity needed for the films to degrade is similar for autumn and summer, the time they take to degrade differs significantly due to the variation in light intensity and inclination.

In Asia, this could vary from a week to a month (depending on film type and LDR).

We strongly encourage tests to be conducted at customer’s end to obtain the optimum LDR.
Do contact our Technical Service Department should you have further enquiries.

Graph 1: SUMMER EXPOSURE* (June 1991) FILMS using 30091-K


KILOLANGLEYS FOR 50% RETAINED ELONGATION AT BREAK



Graph 2: AUTUMN EXPOSURE* (Sept 1991) FILMS using 30091-K
KILOLANGLEYS FOR 50% RETAINED ELONGATION AT BREAK