1 PP/PE toughening system

LDPE toughening: Other mechanical parameters, such flexural modulus, rapidly decline as a result of the toughening effect. It is therefore limited to situations where impact strength is the primary requirement and other mechanical qualities are not highly valued.

HDPE toughening: When less than 10% is applied, it has a stiff and toughening effect on PP, meaning that other mechanical qualities do not degrade even while the impact performance is improved.

LLDPE toughening: The added quantity should ideally range between 5% and 20%, and the toughening effect will fall between LDPE and HDPE.

In addition to having a toughening effect, UHMWPE also has the ability to achieve an in-situ fiber-forming reinforcing effect. The notched impact strength, tensile strength, and elongation of PP1330 are enhanced by 3.5 times, 1.5 times, and 2.5 times, respectively, when 10% of UHMWPE is added for toughening.

2 Toughening system with  PP/EVA

EVA may increase PP's tous while also enhancing surface gloss, elongation at break, and melt flow index.ghnes

The amount of VA in the chosen EVA ranges from 14% to 18%. When PP is toughened with 20% EVA-15, its impact strength may be increased by up to 12 times, its stiffness is reduced somewhat, it costs less than when PP is toughened with elastomer or rubber, and its overall performance is superior to that of a PP/EPDM system.

3 PP/PA6 Toughening system 

The PP/PA6 mix method may fix the two materials' intrinsic flaws, resulting in a material with good all-around performance characteristics. The impact strength may be enhanced by 50% and the tensile strength can be decreased by 13.8% if 15% PA6 is added to PP. The impact strength could be raised by 113% and the tensile strength could be lowered by 2.7% when 5% PP-g-MAH was employed as a compatibilizer.

4 mPE/PP Toughening system

The toughening modification of PP is a perfect fit for mPE since it has a high elongation at break and a very low glass transition temperature.

PP is effectively toughened by mPE. The notched impact strength at -30°C is more than 20 times greater when 40% mPE is added to PP and increases by around 9 times compared to pure PP when the same mass fraction of EPDM is used. It was also discovered that by employing mPE to toughen PP, the composite material has reduced tensile, compression, and creep permanent deformation, outstanding low temperature performance, and processing performance, and has emerged as a serious rival to EPDM.

Ethylene-octene copolymer, a recently created toughening substance, may boost the impact strength of PP by up to nine times.

5 POE toughened PP system

An elastomer-toughened PP system called PP/POE was developed recently. The best toughening effect, weather resistance, fluidity, thermal stability, and processability are all strengths of this material. Additionally, it is the most widely employed elastomer hardened PP system.

In comparison to EPDM and EPR, POE and PP have greater compatibility and a more pronounced toughening effect when temperatures are low. The sequence of the toughening effects is POE > EPDM > EPR, and the flexural modulus and tensile strength marginally decrease.

When POE is added to PP in amounts more than 15%, the toughening effect grows quickly. For instance, the notched impact strength of PP improves from 76.4J/m of pure PP to 626J/m when 30% POE is applied.

POE offers better weather resistance, a lower cohesive energy than EPDM, and no double bonds. It is a reliable replacement for EPDM.

6 SBS toughened PP system

Although EPDM has a better toughening effect on PP, SBS may still be employed in a variety of applications.

According to studies, when the SBS content is between 0 and 10 parts, the impact strength improves with the addition of more SBS; however, when the SBS content is greater than 15 parts, the impact strength drops. Impact-resistant PP constructed of SBS and PP may boost its room temperature and low temperature impact characteristics by five and ten times, respectively. When the precise formula is PP:SBS:CaCO3=48:40:12, the associated properties' Izod impact strength is 70KJ/m2.

7 EPDM, EPR toughened PP system

The most popular elastomeric toughening compounds for PP, particularly EPDM, are EPR (ethylene-propylene binary copolymer) and EPDM (ethylene-propylene-diene terpolymer), both of which have great elasticity and strong resistance. Low temperature capabilities can enhance PP's impact and low temperature resistance capabilities. Both structures have strong thermal stability and good compatibility with PP because they include propyl groups.

With a rise in its addition, the system's impact strength improves swiftly and roughly linearly within the content range of 5%–30%, but at the same time, the system's bending strength, tensile strength, thermal distortion temperature, etc. all dramatically decline.

In comparison to EPR, EPDM has superior interfacial contact with PP, comparable solubility characteristics (both are 8.1), higher compatibility with PP, and a more pronounced toughening impact on PP.

Using EPR as an example, 20% added to PP increases notched impact strength at room temperature by up to 10 times while lowering embrittlement temperature by up to 4 times.

The impact of toughening PP using EPDM-g-MAH, which is created by grafting EPDM with MAH, is superior than that of pure EPDM.

8 BR toughened PP system

High elasticity, outstanding low-temperature performance (glass transition temperature: -110°C), wear resistance, and flex resistance are all benefits of butadiene rubber (BR). The solubility parameter of BR is comparable to that of PP, and the two materials get along well together. effective at toughening.

When PP/BR is 100/15, the embrittlement temperature falls to 8°C (down 23°C), and the impact strength practically doubles.

9 Plastic/Elastomer Synergistically Toughened PP System

Excellent impact strength is achieved by combining elastomers and PP, but stiffness, strength, and thermal distortion temperature are dramatically diminished, and the cost is greatly raised. Plastics are added to the elastomer/PP toughening system to create an elastomer/plastic/PP ternary mix system, which improves mechanical qualities while lowering costs.

In the ternary mix system, HDPE and LLDPE are the most often used plastics; examples include PP/SBS/HDPE, PP/EPR/HDPE, PP/EPDM/LLDPE, PP/HDPE/BR(100/15/15), PP/PS/mPE, PP/PS/SBS, etc.

When the ratio is 100/15/15, the PP/HDPE/BR ternary toughening system not only has good toughness but also strong tensile strength and flexural strength.

The PP/SBS/BR ternary mix system has an amazing synergistic impact that is far superior to either the PP/SBS or PP/BR toughening effects alone.

The following considerations should be made in the formulation design of the aforementioned toughening system.

① Hardening impact. POE is superior than mPE, TPE, and EPDM, however EPDM is favored economically.

② Choosing a compatibilizer. PP-g-MAH is frequently utilized as a compatibilizer in formula design for toughened materials that are incompatible with PP. The improvement range of the impact strength is obviously expanded by the use of the compatibilizer. All materials, including PA, PS, PVC, etc., require compatibilizer.

③ calculating how much is added. The toughening effect of PP has an appropriate range for all types of toughening materials. SBS, for instance, performs better at lower than 15%, whereas POE performs better at more than 15%.

④Material selection for toughening. The performance needs of PP in various applications are also variable, thus toughening materials should be chosen based on particular qualities. variable toughening materials have distinct toughening effects and varying impacts on other properties. For instance, EPR hardened PP has poor aging resistance, and EPDM, which has greater weather resistance, is typically chosen for outdoor automobile bumpers instead of EPR.

⑤Toughening the composite. While PP toughened by a single material improves in terms of impact strength, other attributes are greatly affected. Compound toughening is frequently employed to achieve cost-effective performance balance across all performance aspects.

⑥ The elastomer's particle size. It is possible to get a better toughening effect when the particle size is smaller than 1.5 microns.

10 Inorganic rigid particle toughened PP system

The inorganic stiff toughening minerals mica, talc, wollastonite, calcium carbonate, and barium sulfate are frequently employed.

It is possible to create a core-shell dispersion structure with inorganic rigid particles acting as the core and rubber acting as the shell using rubber as a pre-toughening system, and the toughening impact of inorganic rigid particles is quite considerable. Examples of specific applications include PP/EPDM/CaCO3, PP/EPDM/talc, and PP/EPDM/wollastonite, among others.

The pre-toughening technique without rubber offers improved treatment resistance for inorganic stiff particles. To ensure a successful composite treatment, it is recommended to add a coupling auxiliary agent simultaneously with the coupling agent. A shell-shell dispersion structure with the inorganic rigid particle as the core and the interface modifier as the shell may also be created for the inorganic rigid particles optimized by the interface modifier. For instance, in a PP/optimized kaolin toughening system, the impact strength may reach 480J/m when 30% kaolin is applied. In another example, when 50% of CaCO3 treated with an alkyl carboxylate and a co-coupling agent is added to PP, the impact strength can rise by roughly one times.

11 Organic/inorganic nanomaterial toughening

The most promising new materials of the twenty-first century are nanomaterials, which are relatively recent inventions that were first discovered in the 1980s. at order to achieve the goal of strengthening and toughening, the effect can enhance the mechanical behavior of polypropylene at the interface area as well as the crystallization behavior and structure of PP.