Stress cracking
- Filed in:
- Bottles,
- Optimization,
- Beverage
Waterboy
I need some help. The rule of thumb is that HDPE bottles are higher risk of stress cracking in summer months due to higher heat/humidity. Can anyone tell me what actually happens to the plastic to make it more susceptible in the summer? What does the heat and humidity affect to weaken the plastic?
This is a key question going forward as we look for more environmental optimizations for this bottle. I would like to take material out and/or add recycled content, but do not want to get into a leaker situation in the field. I feel if I could at least understand why HDPE becomes more vulnerable, then I can make better and safer informed decisions to proceed.
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HDPE
Tim Traub...There are any number of reasons for stress cracking in HDPE including detergents and fatty acids. Another issue can be caused by too much heat and dwell time during the forming of the bottle. Both cause the plastic to crystalize which increases the risk for environmental stress cracking.
Work with your forming company to identify and use a copolymer HDPE which will help reduce crystallinity and deliver better resistance to cracking.
ESC in summer
Arno Melchior...Have a look at this link:
http://www.thefreelibrary.com/Get+a+handle+on+stress-cracking+in+HDPE+bo...
It will explain what you want to know.
HDPE Stress Cracking
Waterboy
Thanks Arno. I had seen that article before and it is a good one. After more digging, we finally found that the problem was more related to mechanical damage to the bottle corner than a summer phenomenon. A number of years back we saw the same thing happen with product produced in October and the actual complaint was registered in late Dec. The summer affect seems related more to extra volume and less vigilence at molder and possibly at our plant to. I am not saying that there is no such thing as summer stress cracking, but in our case it looks to be old fashioned physical damage. Once we got through all the BS from molder and resin company, we finally lucked into finding the root cause.
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