Can an HDPE Plastic Protective Case hold acids and alkalis?

Answer: At room temperature, pH 1 to 14 works. Sulfuric acid at 20 percent moves 0.1 percent in 60 days and sodium hydroxide at 40 percent 0.15 percent. Concentrated nitric and 98 percent sulfuric acid are not suitable.

What does 1000 hours of ESCR mean?

Answer: Under ASTM D1693 condition B it is the time for half the specimens to crack in pure nonylphenol ethoxylate at 50 °C. With surfactants it predicts life better than impact strength.

Does the case really survive −40 °C?

Answer: The shell does: 12 kJ/m² notched, six cases through a 1.5 m corner drop. The EPDM gasket is what fails, so specify silicone for cold service.

Rotomoulded or welded construction?

Answer: Under a thousand units with a complex shape, rotomould. Bodies beyond three metres can only be welded, at 85 percent of parent strength.

Is recycled HDPE acceptable?

Answer: Up to 20 to 30 percent in non-structural parts. The chains are already cut, so ESCR falls to about 300 hours, which rules it out for an HDPE Plastic Protective Case holding surfactants.

HDPE Plastic Protective Case: Density, ESCR and Cold Weather

Quick answer: Choose an HDPE Plastic Protective Case by density first, ESCR second, wall thickness last. A copolymer at 0.948 to 0.955 g/cm³ holds ESCR beyond 1000 hours and keeps 12 kJ/m² notched impact at −40 °C.

Where an HDPE Plastic Protective Case Starts: Density
ESCR Hours Beat Impact Strength as a Life Estimate
Impact and Drop Testing at Minus Forty Degrees
Chemical Resistance: Acid, Alkali and Solvent
Rotomoulding and Hot-Plate Welding
FAQ

1. Where an HDPE Plastic Protective Case Starts: Density

Density comes before wall thickness. Every 0.001 g/cm³ lifts flexural modulus about 3 percent and drops ESCR by a visible step, so the two pull against each other on an HDPE Plastic Protective Case.

Melt index splits the family: rotomoulding powder runs 3.5 to 5 g/10 min and sheet grades 0.3 to 0.6 for molecular weight and ESCR. Wall and density are fixed together; 8 mm at 0.950 absorbs a 1.2 m drop, while 0.960 is stiffer and cracks sooner.

Density (g/cm³)	Melt index	Modulus (MPa)	ESCR (h)	Typical use
0.948	4.0	800	over 1000	Large rotomoulded shells
0.950	0.4	950	over 1000	Sheet, liners, pallets
0.955	3.8	1100	600 to 900	Mid-size bodies and lids
0.960	5.0	1250	200 to 400	Fast-cycle tote boxes

2. ESCR Hours Beat Impact Strength as a Life Estimate

ESCR measures how long the resin survives medium and residual stress together. Under ASTM D1693 condition B, an HDPE Plastic Protective Case specimen sits in pure nonylphenol ethoxylate at 50 °C, and the time for half the samples to crack is F50: copolymers pass 1000 hours, homopolymers often fail inside 100.

That number predicts service better than impact does, because surfactants migrate into micro-cracks and residual stress then opens them. Annealing at 70 °C for two hours halves moulded-in stress, and R5 corners remove the points where cracks begin.

3. Impact and Drop Testing at Minus Forty Degrees

Cold is where HDPE earns its place. The glass transition sits near −120 °C, so chain segments still move at −40 °C and an HDPE Plastic Protective Case fractures ductilely rather than shattering.

After four hours at −40 °C, notched Izod reads 12 kJ/m² against 28 at room temperature, about 43 percent retention, and six cases dropped 1.5 m on a corner show no crack and no latch release. The gasket is the weak link: silicone seals at −40 °C, EPDM does not.

4. Chemical Resistance: Acid, Alkali and Solvent

pH 1 to 14 at room temperature is routine for an HDPE Plastic Protective Case. Twenty percent sulfuric acid moves 0.1 percent in 60 days, 40 percent sodium hydroxide 0.15 percent, and 12 percent hypochlorite 0.3 percent in 30 days if kept dark.

Organics behave differently. Gasoline takes up 5 percent in a week and turns tacky, toluene 12 percent in a day with visible swelling, and chlorinated solvents soften the wall outright. Judge medium and stress together, never the medium alone.

Medium (room temperature)	Duration	Mass change	Verdict
20% sulfuric acid	60 days	+0.1%	suitable
40% sodium hydroxide	60 days	+0.15%	suitable
12% sodium hypochlorite	30 days	+0.3%	suitable, keep dark
Gasoline	7 days	+5%, tacky	not for long storage
Toluene	24 hours	+12%, swells	not suitable

5. Rotomoulding and Hot-Plate Welding

Rotomoulding sets the wall: 40 mesh powder near 420 µm, a 3 mm steel mould, 290 °C for 25 minutes, an 8 mm wall at ±0.8 mm. Coarse powder leaves pinholes, while powder that is too fine sticks to the cavity and tears.

Hot-plate welding runs 200 to 210 °C at 0.02 MPa, about 10 seconds per millimetre of wall. Extrusion welding with a 4 mm rod reaches 85 percent of parent strength and hot air about 70 percent. Dry the bevel first; trapped gas becomes a crack.

Conclusion

Four groups of numbers decide the purchase: the density and melt index pair, the ESCR F50 hours, the −40 °C impact and drop result, and weld strength against parent material. Put all four on the drawing with the medium and the stack height. An HDPE Plastic Protective Case built to that sheet holds acid without weeping and keeps its seams closed.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.