Emergency application of knowledge about plastic modifications during epidemic

Emergency application of knowledge about plastic modifications during epidemic

During COVID-19 epidemic, demand for masks suddenly increased dramatically, coupled with uneven transportation and logistics, some of raw materials for making masks were out of stock. Around tenth day of new year, two friends called me.

Emergency application of knowledge about plastic modifications during epidemic

①Friend mainly produces mask breathing valves, which are made by "ABS + hard TPU" injection molding, because hard TPU cannot be bought during epidemic. It just so happens that my friend has a soft TPU factory installed, so I suggest mixing "soft TPU+ABS" directly to replace hard TPU. After checking with others, there are no problems.

For more information on ABS/TPU alloy, click here: TPU/ABS alloy introduction and application perspective

1. ABS and TPU compatibility

Thermoplastic polyurethane TPU and ABS (acrylonitrile-butadiene-styrene graft copolymer) can be mixed in any proportion, but they are still thermodynamically incompatible. The dispersed phase is distributed in ABS.

2. Improving blending performance of ABS and TPU

When TPU and ABS are mixed, synergistic effects occur and properties of respective components can be tailored to needs of different applications.

2.1 Adding ABS to TPU reduces density and elongation of material, increases tensile strength and modulus of elasticity, improves ozone resistance and processing performance, and reduces cost;

2.2 Adding TPU to ABS can improve wear resistance, shear resistance and low temperature performance of material, and at same time, coating performance, chemical resistance and oil resistance of material have been greatly improved.

Cheng found that when mixing TPU and ABS, TPU acts as a plasticizer, and when TPU is 10% to 20% in ABS/TPU blend, plasticizing effect is best. There are patent reports that with increasing addition of TPU (10%~50%) to ABS, tensile strength and tensile strength of ABS/TPU blends decrease, elongation at break increases, and melt flow rate (MFR) increases. The amplitude is growing.

In short, TPU/ABS material combines wear resistance, heat resistance, low temperature mechanical properties, toughness, TPU chemical stability and ABS rigidity, and has good comprehensive performance. TPU/ABS blends process well at high shear rates and are easy to injection mold. The addition of TPU to ABS is mainly to improve its tear resistance, and addition of ABS to TPU is mainly to improve its impact resistance at low temperatures. With an increase in TPU, wear resistance and impact resistance of material increase, formability improves, but stiffness, yield strength and thermal deformation temperature decrease; on contrary, with an increase in content of ABS, bending modulus and increase in material's Shore hardness are high.

3. Application prospects for ABS/TPU alloy

Because of its good rigidity, impact resistance, high hardness, small coefficient of linear expansion and good performance, ABS is widely used as a structural material. Since TPU abouthas same elasticity and toughness as rubber and excellent wear resistance, mixing TPU and ABS can improve toughness and wear resistance of ABS. Of course, price of polyolefin alloys is much lower than ABS/TPU, and it also solves coloring problem of polyolefin alloys. Some high-impact automotive parts are already dominated by TPO materials.

Therefore, ABS/TPU alloy will be applied in some special areas in future, such as parts made of impact-resistant material requiring ultra-high mechanical properties, durable materials that can be electroplated, and cases that can be bonded. and glued.

② Another friend makes nose bridge strips for masks, and there is no hardened PP. This is also very simple. I suggest mixing homopolypropylene + elastomer directly. TPE-S, etc. finally succeeded in emergency rescue.

After reading above examples, do you think that children's shoes have a bright future in rubber and plastics industry? learn, improve every day!

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