Using Clarified PP to Transform Refrigerator Design

For decades, manufacturers have balanced the competing demands of cost, durability, and aesthetics when developing refrigerators. Polystyrene (PS) plastic has long been the standard material for clear internal components, like crisper drawers and shelving. But using PS comes with inherent drawbacks. These components crack under heavy loads. They shatter when dropped. They aren't readily connected to the circularity discussions happening across the plastic industry.

Appliance designs evolve, and with those evolutions come discussions about material selection. By switching from naturally clear polymers like PS to clarified polypropylene (PP), manufacturers can deliver the glass-like transparency consumers expect while unlocking increased durability and positive impacts to the plastics value chain.

Read on to discover the difference a single material shift can make and how ultra-clear PP is revolutionizing refrigerator components.

The problem with traditional refrigerator plastics

To understand the appliance market, it's important to understand what modern users are looking for and how traditional materials are falling short.

Consumers expressed clear frustrations with conventional refrigerator storage. Survey participants reported that traditional drawers frequently crack under heavy loads, scratch easily from ice accumulation, and shatter entirely if accidentally dropped during cleaning. These pain points directly impact brand perception and customer satisfaction.

Furthermore, today's consumers want more from their appliances. They favor slim designs with massive capacities, ranging from 150 liters to over 400 liters. They want meticulous storage layouts, intelligent space planning, and food-safe environments. Delivering on these expectations requires a material that is lightweight, highly durable, and exceptionally clear.

Why clarified polypropylene?

Standard PP is a versatile and cost-effective polymer, but it naturally exhibits a cloudy, opaque appearance. In its conventional form, PP has a haze level of roughly 30-35%. This makes it unsuitable for applications where visibility is paramount, such as a crisper drawer where users need to see their fresh produce.

That is where our advanced chemistry comes into play. By adding Milliken’s Millad® ClearX 9000 clarifying agent to PP resins, we alter the material's crystalline structure during the cooling process. This additive allows polypropylene to take on a glass-like transparency, dropping its haze level to three to four percent.

Using our clarifying agent results in ultra-clear PP. It rivals the visual clarity of PS while retaining PP's inherent performance benefits.

Unpacking the benefits of ultra-clear PP

Switching to clarified PP for storage components offers a holistic upgrade for refrigerator manufacturers. From the production floor to the consumer's kitchen, this advanced material delivers value at every stage.

• Exceptional transparency and consumer appeal: Visibility is a non-negotiable feature for refrigerator interiors. Our survey revealed that 77% of consumers prefer natural-colored transparent drawers, citing a cleaner look and easier identification of the items inside. Ultra-clear PP delivers this pristine, unclouded aesthetic. It allows users to quickly locate their groceries, reducing the time the refrigerator door stays open.
• Enhanced durability and impact resistance: Consumers want appliances that withstand the rigors of daily life. Clarified PP offers an outstanding stiffness-to-impact balance that PS does not. It features high ductility, meaning the material will flex and bend under stress rather than snapping or shattering. This effectively addresses a common consumer pain point: PS drawers failing under heavy loads or cracking when dropped.
• Lighter-weight components for value-chain impacts: Polypropylene has a lower density than polystyrene—roughly.9 g/cm3 for PP as compared to 1.050 g/cm³ . This means manufacturers can produce the same volume of product using less raw material by weight, resulting in a difference that consumers notice. During on-site testing, 97% of survey participants reported that the PP material drawers were noticeably lighter than the PS material drawers. Beyond user preferences, these lightweighting opportunities translate into value chain opportunities.
• Cost efficiency in manufacturing : Advanced performance does not have to come at a premium. Ultra-clear PP is a highly cost-competitive material option. Historical data show that prices for PP clarified materials have consistently trended lower than those for general-purpose polystyrene (GPPS). Additionally, PP offers superior design flexibility and processing efficiency. Manufacturers can mold more complex shapes, optimize internal layouts, and streamline their production cycles. It delivers better chemical resistance and superior physical stability, ensuring the final product withstands the test of time.

Discover the future of appliance design

Consumers are ready for a new chapter in refrigerator appliances, and 65% of users surveyed stated they would not mind if a refrigerator featured mixed materials—like a PS door and an ultra-clear PP drawer—so long as overall performance improved.

At Milliken, we combine material science expertise with deep consumer insights to develop solutions that solve complex manufacturing challenges. Our plastic additive portfolio, including our clarifying agents, is uniquely situated to enhance and elevate plastic performance with production and consumer goals in mind.

Let's transform your next generation of refrigerator components. Reach out to our team to learn more.