Impact Modified Styrenic Polymers Stress Crack Resistance
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Solution Overview
Problem
Polystyrene compounders face challenges in handling polybutene due to its high viscosity and sticky consistency, making it difficult to incorporate into high impact modified polystyrene (HIPS) materials for enhanced environmental stress crack resistance, as existing methods require specialized equipment.
Innovation Solution
A method involving combining 95-99.5 wt.% impact modified styrenic polymer with a polymer solution containing 25-75 wt.% polyisobutylene and 25-75 wt.% polyolefin, forming a master batch that converts polybutene into easier-to-process coarse solid particles, allowing for improved stress crack resistance without the need for specialized equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyisobutylene is added to HIPS to improve stress crack resistance, then environmental stress crack resistance is improved, but the material becomes difficult to handle and process due to high viscosity and sticky consistency
Solution Approach 1:
The patent uses a master batch as an intermediary carrier to deliver polyisobutylene to the HIPS compound. The master batch contains polyisobutylene dispersed in a carrier resin, making the viscous additive easier to handle and distribute uniformly throughout the HIPS material without requiring specialized equipment.
Solution Approach 2:
The patent changes the physical state and distribution parameters of polyisobutylene by incorporating it into a master batch system. This transforms the handling characteristics from thick liquid requiring specialized equipment to a dispersible concentrate that can be easily incorporated into HIPS using standard compounding equipment.
2Reliability
If polyisobutylene is incorporated into HIPS to enhance stress crack resistance, then ESCR performance is improved, but specialized equipment is required for handling the viscous material
Solution Approach 1:
The master batch serves as an intermediary that eliminates the need for specialized handling equipment. By pre-dispersing polyisobutylene in a carrier resin within the master batch, the system allows standard HIPS compounding equipment to effectively deliver the stress crack resistance benefits without requiring additional specialized devices.
3Reliability
If high concentrations of polyisobutylene are used to maximize stress crack resistance, then ESCR performance increases, but the material becomes increasingly difficult to process and blend
Solution Approach 1:
The master batch acts as an intermediary vehicle that enables effective blending of high polyisobutylene concentrations into HIPS. The carrier resin in the master batch provides a manageable medium that facilitates uniform distribution of polyisobutylene throughout the HIPS compound using standard mixing equipment.
Solution Approach 2:
The polyisobutylene is preliminarily dispersed and prepared in the master batch before being incorporated into HIPS. This preliminary action of pre-dispersion in a carrier resin makes subsequent blending with HIPS much easier and more effective, allowing high concentrations to be achieved without excessive blending difficulty.
Data Source
AI summary
A method of improving the stress crack resistance of an impact modified styrenic polymer comprising (a) combining about 95 to about 99.5 wt.% of an impact modified styrenic polymer with about 0.5 to about 5 wt.% of a polymer solution comprising about 25 to about 75 wt.% polyisobutylene and about 25 to about 75 wt.% of a polyolefin comprising one or more C2 to C12 alpha olefins.